FAQ About 10-Bolts
02-21-2009, 10:27 AM
#1
FAQ About 10-Bolts
How Do I know If I Have a 10-bolt?
Count the bolts on the differential cover.
What Ring Gear Do I Have?
The ten-bolt 7.5 (7 1/2) and 7.625 (7 5/8), the latter introduced in 85, are virtually the same. With the exception of size, all else is the same. For example, all ring gears fit all years of carrier whether they're 7.5 or 7.625.
What Gear Ratio Do I Have?
Jerk the diff cover. The numbers are stamped on the ring and pinion. The RPO’s are usually found in the center console:
41 : 15 = 2.73 (RPO GU2)
41 : 14 = 2.93 (RPO GU3)
40 : 13 = 3.08 (RPO GU4)
42 : 13 = 3.23 (RPO GU5) / Approx. RPM’s at 70 mph--2133
41 : 12 = 3.42 (RPO GU6) / Approx. RPM’s at 70 mph--2255
41 : 11 = 3.73 (RPO GT4) / Approx. RPM’s at 70 mph--2463 (Note that 3.73's were only available 1983-86)
Or from Randy’s Ring and Pinion:
Jack up one tire if you have an open diff, or both tires if you have a working posi or locking differential. Rotate the tire one full revolution for posi’s and lockers and 2 full revolutions for open diffs. Carefully count the number of full revolutions the driveshaft makes. This is your gear ratio. In other words, if the drive shaft turns 3 ¾ turns, you probably have a 3.73 gear ratio. Turning the tire for twice the number of full revolutions and dividing the drive shaft revolutions by two will give you a more accurate reading.
Axle tube codes can be found in the following link (though rust usually makes them indecipherable, and they, like the RPO codes, indicate how the car was equipped new, and not necessarily what’s currently in place): http://sethirdgen.org/reardata.htm
Do I Have a Limited Slip (aka Posi) (RPO G80*)?
Jerk the diff cover.** Open/Standard can be seen in the following link (post #1): https://www.thirdgen.org/forums/tran...1073-posi.html
Gov-loc (post #5): https://www.thirdgen.org/forums/tran...rear-diff.html
Auburn (post #3): https://www.thirdgen.org/forums/tran...ing-axles.html
*Apparently, G80 was an extra-cost option which could be special ordered on any rear regardless of ratio.
**The most reliable way to determine if your car is equipped with a limited slip is to look. That said, this from big gear head: With the tires off the ground and the transmission in neutral, you should be able to turn one wheel and the other will follow in the same direction. This is limited slip or "posi". If the wheels turn in opposite directions, it’s a standard/open differential—OR a worn out limited slip.
Can I Swap in a Limited Slip (aka Posi)?
Yes. Purchase the carrier of your choice and use the appropriate axles for that carrier. For example, the 93-97 Auburn carriers and the 98-02 Zexel-Torsen carriers will swap in as long as the axles used are 28-spline. (A carrier that accepts the stronger 28-spline axles would be more desirable than one that accepts 26-spline).
What Carrier Do I Have?
There are two: Series II is 3.08 down, series III, 3.23 up. Steeper gears, say 3.73’s, can be swapped into a series II with gears designed for such a swap, or by purchasing a series III carrier. (This would be an appropriate time to upgrade to limited slip and 28-spline axles.)
How Difficult Is Changing Gears?
You decide: https://www.thirdgen.org/forums/tran...axle-gear.html
What Is the Width of My 10-Bolt?
Approx. 57" from backing plate to backing plate and 62" from axle flange to axle flange.
How Many Splines Do My Axles Have?
82 to 89 cars have 26-spline axles, though a few 28's may have found their way into late 89 cars; 90 up have 28 splines. After market axles, such as Moser and Superior, can be had from Summit and Jegs. According to big gear head, beware of Alloy USA axles. Apparently the C-clip button isn't cut correctly, which causes problems with C-clip and cross-shaft installation.
How Long Are My Axles?
All thirdgen axles are 30 5/16" long. (Always replace the axle bearings and seals when installing new axles.)
Are Drum/Disc Axles Interchangeable?
Yes, but the drum axle flange will have to be turned down to fit the rotor.* The flange diameter on the drum shaft is 6.0"; the disc shaft is 5.850" and the ID of the brake rotor is 5.900". (Oddly, there is no distinction made between drum and disc when ordering after market axles.)
*The exception to the above seems to be the drum to PBR swap. Apparently LT1 rotors (93-97) have a 6.25" ID which will fit over the drum flange. Raybestos part number 56407.
Is It Normal for My Axles to Have a Bit of In/Out Play?
Yes, because of the "C" clips (p/n 344171). Typical end play is about 1/32 of an inch. Note post #1 for a pic: https://www.thirdgen.org/forums/tran...roc-z-g80.html
What Size Are My Wheel Studs?
12mm x 1.5 (press-in, right-hand thread).
What Is the Wheel Stud Pattern?
5 x 4.75 inches.
What Is the Wheel Nut Torque?
The 85 shop manual says 80 ft. lbs, the 91 says 81 ft. lbs.
How Do I Remove/Install Axles, Axle Bearings, and Axle Seals?
https://www.thirdgen.org/forums/tran...ing-axles.html
How Do I Remove/Install the Pinion Bearing Seal?
https://www.thirdgen.org/forums/tran...ring-seal.html
What Gear Oil Should I Use?
Standard 80-90 weight and a friction modifer (GM P/N 1052358) if the limited slip is an Auburn.* A Gov-Lock or open/standard differential doesn’t require the additive. The rear holds approximately two quarts of gear oil or a bit more with an after market cover.
*Though some TGO members use a full synthetic, such as Mobil 1 75-90, along with the above friction modifier, both Auburn and Eaton do not recommend synthetics for usage with their limited slips.
How Do I Change the Gear Oil?
Pull the cover and drain as much fluid as possible (Before yanking the cover, make sure that the fill plug will come out). Clean the housing/cover surfaces of old gasket or RTV. Reinstall with a gasket or RTV.
What Size Are the Cover to Differential Housing Bolts?
BOLT, HWH Serr Face 5/16"-18 x 7/8". GM 22507583. Torque to 30 ft. lbs. using a crosswise pattern.
Where Is the Fill Plug?
On the pass side of the center casting, close to the axle tube. Fill until fluid dribbles from the hole. Torque to 20 ft. lbs.
What Size Is the Fill Plug?
1/2-14x39/64. GM 25522466.
What is the White Plastic Piece on the Center Casting?
Axle vent (press fit) GM 1236317. 82-88 driver's side, 89+ pass side. It should have a cap that allows venting but obstructs foreign material from entering.
Is There a Round Magnet on the Inside of my Diff Cover?
Some models were so equipped, some weren't.
How Is the Rear Fabricated?
With mild steel tubes and a cast-iron center.
What 10-Bolt Will Swap into My Car?
Any third- or fourthgen*. While a fourthgen rear is a direct bolt-in, it'll be 2" wider or a bit less per side (note the link below for more info about width). Also, take note that if the gear ratio is changed in a swap, for example 3.08's to 3.42's, the speedo won't read correctly unless the transmission's drive and/or driven gears are changed. If you have a T-5, note the following link for gears and a how-to: https://www.thirdgen.org/forums/tran...ve-driven.html
The following link provides more info about the fourthgen rear/swap: https://www.thirdgen.org/forums/faq-...-gen-rear.html
*Take note that no other 10-bolt will fit our cars without major modification.
Is a Fourthgen 10-Bolt Stronger?
No stronger than a thirdgen rear with 28-spline axles.
How Can I Strengthen My 10-Bolt?
http://www.ws6transam.org/10bolt.html
http://www.z28boy.cz28.com/mods-rearend.htm
http://www.nastyz28.com/forum/showth...ing+axle+tubes
What Rear Disc Brakes Do I Have?
82-86* cars are equipped with iron, single-piston Delco-Moraine calipers and 10.5" rotors. In those years, the pass side caliper with its flex line is mounted in front of the axle, the drivers’ side with its hardline to the rear (I've heard that some early model cars, perhaps 82-83, have hardlines to both sides).** The parking brake on these years adjusts the brakes, so use it frequently. If yours doesn't function correctly, take note of the "recall": http://members.shaw.ca/crussel/recalls/86c28/86c28.html
See the link to follow for the fix kit: http://www.flynbye.com/catalog/i208.html
90-92* cars are equipped with alum, single-piston PBR calipers and 11.6" rotors (the so-called 1LE or performance package; however, all rear disc brake cars, 89-92*, have them). Both calipers are mounted to the rear and both have flex lines.** All four-wheel disc cars, regardless of year, are RPO J65.
*87, 88, and 89 cars with rear discs are equipped with 9-bolts (87 and 88 with the Delco-Moraine calipers and 89 with PBR's).
**A note on brake lines: 82-88 cars require 4 lines. One at the rear pass side, one at the pumpkin (and two at the front calipers). 89-92 cars require 5 lines. One at each rear caliper, one at the pumpkin (and two at the front calipers).
Why Does My Rear Have Spacers?
The spacer was apparently used on 16" wheels when GM switched from aluminum to iron drums, which created a .187 size difference. The spacer, however, seems to be hit or miss and essentially unnecessary. Even some disc brake cars received them.
Could My Car Have Been Equipped With Aluminum Drums?
Yes (RPO J42), but most were cast iron (RPO J41).
If I Swap From a Drum to a Disc Rear End Do I Have to Change the Master Cylinder?
No. https://www.thirdgen.org/forums/susp...fferences.html
If I Swap From a Drum to Disc Rear End Do I Have to Change the Parking Brake Cables?
Yes, the lengths are different.
If I Swap From a Drum to a Disc Rear End Do I Have to Change the Combination Valve?*
If I Swap From Standard Discs to PBR's Do I Have to Change the Combination Valve?
Yes, for the best brake performance. Use a standard disc brake valve for 82-88 swaps**. Use the appropriate 1LE valve for 89+ swaps into an earlier model year.
1st design: M1.0 tube nut threads (for 1982 to early 1989 applications)
2nd design: M1.5 tube nut threads (late 1989 through 92).
Either of the 1LE valves can be purchased from Ed Miller at http://www.flynbye.com/catalog/c1_p1.html
*The combination valve is often called the proportioning valve; however, the proportioning valve is only one section of a block which also contains a metering valve and a brake light warning switch.
**Apparently the 82-83 (I've seen reports of some as late as 85) cars have SAE fittings unlike the metric fittings on later cars. Moreover, the alum valves look nothing like the earlier cast iron ones and the line connections are different as well. Note post #1 and #2 of the following link for a comparison of the early and late valves: https://www.thirdgen.org/forums/brak...rop-valve.html
Note: There has been verification that in later years some of the old-style combination valves are metric.
If I Swap to a Disc Rear End Will My Parking Brake Work?
Yes. For 82-88 cars simply buy the correct application. For example, if the rear is from an 88, order disc brake cables for an 88. For 89-97 rears into earlier models, check the following link:
https://www.thirdgen.org/forums/brak...r-e-brake.html
EDIT: ED Miller has added the following cables to his site: http://www.flynbye.com/catalog/i199.html
Modification of some sort is required for the 98+ to work. The following links provide ideas: https://www.thirdgen.org/forums/brak...ny-tricks.html
https://www.thirdgen.org/forums/brak...-ls1-swap.html
EDIT: Ed Miller now has direct-fit cables for the LS1 swap:
http://www.flynbye.com/catalog/i153.html
How Do I Adjust My Parking Brake?
82-89 cars have a tunnel-mounted adjuster above the drive shaft. 90-92 cars are self adjusting.
Can I Swap Discs to My Drum Rear End?
Yes. Though the housing ends can be modified (https://www.thirdgen.org/ls1reardisc),
the easiest method is to purchase a kit from Ed Miller: http://www.flynbye.com/catalog/i30.html
Can I Swap in Larger Discs and Calipers?
Yes. The following link details the PBR swap:
https://www.thirdgen.org/forums/faq-...iscs-89-a.html
However, check with Ed Miller’s site for many other possibilities, such as LS1's:
http://www.flynbye.com/index.html
Are All Spares and Disc Brakes Created Equal?
No, there are three spare sizes, a 14" (P195/75-14) and two 15's (a T125/70-D15 and a P195/75-D15). Only the latter, which is black-painted alum, will fit 1LE/LT1 rear calipers. More info/pics in the following link: https://www.thirdgen.org/forums/brak...e-4th-gen.html
Many thanks to big gear head and Pat Hall for their suggestions and comments.
I don’t pretend to be an expert in the above matters, so if I’ve made a misstep, feel free to correct me—or add pertinent information.
JamesC
Count the bolts on the differential cover.
What Ring Gear Do I Have?
The ten-bolt 7.5 (7 1/2) and 7.625 (7 5/8), the latter introduced in 85, are virtually the same. With the exception of size, all else is the same. For example, all ring gears fit all years of carrier whether they're 7.5 or 7.625.
What Gear Ratio Do I Have?
Jerk the diff cover. The numbers are stamped on the ring and pinion. The RPO’s are usually found in the center console:
41 : 15 = 2.73 (RPO GU2)
41 : 14 = 2.93 (RPO GU3)
40 : 13 = 3.08 (RPO GU4)
42 : 13 = 3.23 (RPO GU5) / Approx. RPM’s at 70 mph--2133
41 : 12 = 3.42 (RPO GU6) / Approx. RPM’s at 70 mph--2255
41 : 11 = 3.73 (RPO GT4) / Approx. RPM’s at 70 mph--2463 (Note that 3.73's were only available 1983-86)
Or from Randy’s Ring and Pinion:
Jack up one tire if you have an open diff, or both tires if you have a working posi or locking differential. Rotate the tire one full revolution for posi’s and lockers and 2 full revolutions for open diffs. Carefully count the number of full revolutions the driveshaft makes. This is your gear ratio. In other words, if the drive shaft turns 3 ¾ turns, you probably have a 3.73 gear ratio. Turning the tire for twice the number of full revolutions and dividing the drive shaft revolutions by two will give you a more accurate reading.
Axle tube codes can be found in the following link (though rust usually makes them indecipherable, and they, like the RPO codes, indicate how the car was equipped new, and not necessarily what’s currently in place): http://sethirdgen.org/reardata.htm
Do I Have a Limited Slip (aka Posi) (RPO G80*)?
Jerk the diff cover.** Open/Standard can be seen in the following link (post #1): https://www.thirdgen.org/forums/tran...1073-posi.html
Gov-loc (post #5): https://www.thirdgen.org/forums/tran...rear-diff.html
Auburn (post #3): https://www.thirdgen.org/forums/tran...ing-axles.html
*Apparently, G80 was an extra-cost option which could be special ordered on any rear regardless of ratio.
**The most reliable way to determine if your car is equipped with a limited slip is to look. That said, this from big gear head: With the tires off the ground and the transmission in neutral, you should be able to turn one wheel and the other will follow in the same direction. This is limited slip or "posi". If the wheels turn in opposite directions, it’s a standard/open differential—OR a worn out limited slip.
Can I Swap in a Limited Slip (aka Posi)?
Yes. Purchase the carrier of your choice and use the appropriate axles for that carrier. For example, the 93-97 Auburn carriers and the 98-02 Zexel-Torsen carriers will swap in as long as the axles used are 28-spline. (A carrier that accepts the stronger 28-spline axles would be more desirable than one that accepts 26-spline).
What Carrier Do I Have?
There are two: Series II is 3.08 down, series III, 3.23 up. Steeper gears, say 3.73’s, can be swapped into a series II with gears designed for such a swap, or by purchasing a series III carrier. (This would be an appropriate time to upgrade to limited slip and 28-spline axles.)
How Difficult Is Changing Gears?
You decide: https://www.thirdgen.org/forums/tran...axle-gear.html
What Is the Width of My 10-Bolt?
Approx. 57" from backing plate to backing plate and 62" from axle flange to axle flange.
How Many Splines Do My Axles Have?
82 to 89 cars have 26-spline axles, though a few 28's may have found their way into late 89 cars; 90 up have 28 splines. After market axles, such as Moser and Superior, can be had from Summit and Jegs. According to big gear head, beware of Alloy USA axles. Apparently the C-clip button isn't cut correctly, which causes problems with C-clip and cross-shaft installation.
How Long Are My Axles?
All thirdgen axles are 30 5/16" long. (Always replace the axle bearings and seals when installing new axles.)
Are Drum/Disc Axles Interchangeable?
Yes, but the drum axle flange will have to be turned down to fit the rotor.* The flange diameter on the drum shaft is 6.0"; the disc shaft is 5.850" and the ID of the brake rotor is 5.900". (Oddly, there is no distinction made between drum and disc when ordering after market axles.)
*The exception to the above seems to be the drum to PBR swap. Apparently LT1 rotors (93-97) have a 6.25" ID which will fit over the drum flange. Raybestos part number 56407.
Is It Normal for My Axles to Have a Bit of In/Out Play?
Yes, because of the "C" clips (p/n 344171). Typical end play is about 1/32 of an inch. Note post #1 for a pic: https://www.thirdgen.org/forums/tran...roc-z-g80.html
What Size Are My Wheel Studs?
12mm x 1.5 (press-in, right-hand thread).
What Is the Wheel Stud Pattern?
5 x 4.75 inches.
What Is the Wheel Nut Torque?
The 85 shop manual says 80 ft. lbs, the 91 says 81 ft. lbs.
How Do I Remove/Install Axles, Axle Bearings, and Axle Seals?
https://www.thirdgen.org/forums/tran...ing-axles.html
How Do I Remove/Install the Pinion Bearing Seal?
https://www.thirdgen.org/forums/tran...ring-seal.html
What Gear Oil Should I Use?
Standard 80-90 weight and a friction modifer (GM P/N 1052358) if the limited slip is an Auburn.* A Gov-Lock or open/standard differential doesn’t require the additive. The rear holds approximately two quarts of gear oil or a bit more with an after market cover.
*Though some TGO members use a full synthetic, such as Mobil 1 75-90, along with the above friction modifier, both Auburn and Eaton do not recommend synthetics for usage with their limited slips.
How Do I Change the Gear Oil?
Pull the cover and drain as much fluid as possible (Before yanking the cover, make sure that the fill plug will come out). Clean the housing/cover surfaces of old gasket or RTV. Reinstall with a gasket or RTV.
What Size Are the Cover to Differential Housing Bolts?
BOLT, HWH Serr Face 5/16"-18 x 7/8". GM 22507583. Torque to 30 ft. lbs. using a crosswise pattern.
Where Is the Fill Plug?
On the pass side of the center casting, close to the axle tube. Fill until fluid dribbles from the hole. Torque to 20 ft. lbs.
What Size Is the Fill Plug?
1/2-14x39/64. GM 25522466.
What is the White Plastic Piece on the Center Casting?
Axle vent (press fit) GM 1236317. 82-88 driver's side, 89+ pass side. It should have a cap that allows venting but obstructs foreign material from entering.
Is There a Round Magnet on the Inside of my Diff Cover?
Some models were so equipped, some weren't.
How Is the Rear Fabricated?
With mild steel tubes and a cast-iron center.
What 10-Bolt Will Swap into My Car?
Any third- or fourthgen*. While a fourthgen rear is a direct bolt-in, it'll be 2" wider or a bit less per side (note the link below for more info about width). Also, take note that if the gear ratio is changed in a swap, for example 3.08's to 3.42's, the speedo won't read correctly unless the transmission's drive and/or driven gears are changed. If you have a T-5, note the following link for gears and a how-to: https://www.thirdgen.org/forums/tran...ve-driven.html
The following link provides more info about the fourthgen rear/swap: https://www.thirdgen.org/forums/faq-...-gen-rear.html
*Take note that no other 10-bolt will fit our cars without major modification.
Is a Fourthgen 10-Bolt Stronger?
No stronger than a thirdgen rear with 28-spline axles.
How Can I Strengthen My 10-Bolt?
http://www.ws6transam.org/10bolt.html
http://www.z28boy.cz28.com/mods-rearend.htm
http://www.nastyz28.com/forum/showth...ing+axle+tubes
What Rear Disc Brakes Do I Have?
82-86* cars are equipped with iron, single-piston Delco-Moraine calipers and 10.5" rotors. In those years, the pass side caliper with its flex line is mounted in front of the axle, the drivers’ side with its hardline to the rear (I've heard that some early model cars, perhaps 82-83, have hardlines to both sides).** The parking brake on these years adjusts the brakes, so use it frequently. If yours doesn't function correctly, take note of the "recall": http://members.shaw.ca/crussel/recalls/86c28/86c28.html
See the link to follow for the fix kit: http://www.flynbye.com/catalog/i208.html
90-92* cars are equipped with alum, single-piston PBR calipers and 11.6" rotors (the so-called 1LE or performance package; however, all rear disc brake cars, 89-92*, have them). Both calipers are mounted to the rear and both have flex lines.** All four-wheel disc cars, regardless of year, are RPO J65.
*87, 88, and 89 cars with rear discs are equipped with 9-bolts (87 and 88 with the Delco-Moraine calipers and 89 with PBR's).
**A note on brake lines: 82-88 cars require 4 lines. One at the rear pass side, one at the pumpkin (and two at the front calipers). 89-92 cars require 5 lines. One at each rear caliper, one at the pumpkin (and two at the front calipers).
Why Does My Rear Have Spacers?
The spacer was apparently used on 16" wheels when GM switched from aluminum to iron drums, which created a .187 size difference. The spacer, however, seems to be hit or miss and essentially unnecessary. Even some disc brake cars received them.
Could My Car Have Been Equipped With Aluminum Drums?
Yes (RPO J42), but most were cast iron (RPO J41).
If I Swap From a Drum to a Disc Rear End Do I Have to Change the Master Cylinder?
No. https://www.thirdgen.org/forums/susp...fferences.html
If I Swap From a Drum to Disc Rear End Do I Have to Change the Parking Brake Cables?
Yes, the lengths are different.
If I Swap From a Drum to a Disc Rear End Do I Have to Change the Combination Valve?*
If I Swap From Standard Discs to PBR's Do I Have to Change the Combination Valve?
Yes, for the best brake performance. Use a standard disc brake valve for 82-88 swaps**. Use the appropriate 1LE valve for 89+ swaps into an earlier model year.
1st design: M1.0 tube nut threads (for 1982 to early 1989 applications)
2nd design: M1.5 tube nut threads (late 1989 through 92).
Either of the 1LE valves can be purchased from Ed Miller at http://www.flynbye.com/catalog/c1_p1.html
*The combination valve is often called the proportioning valve; however, the proportioning valve is only one section of a block which also contains a metering valve and a brake light warning switch.
**Apparently the 82-83 (I've seen reports of some as late as 85) cars have SAE fittings unlike the metric fittings on later cars. Moreover, the alum valves look nothing like the earlier cast iron ones and the line connections are different as well. Note post #1 and #2 of the following link for a comparison of the early and late valves: https://www.thirdgen.org/forums/brak...rop-valve.html
Note: There has been verification that in later years some of the old-style combination valves are metric.
If I Swap to a Disc Rear End Will My Parking Brake Work?
Yes. For 82-88 cars simply buy the correct application. For example, if the rear is from an 88, order disc brake cables for an 88. For 89-97 rears into earlier models, check the following link:
https://www.thirdgen.org/forums/brak...r-e-brake.html
EDIT: ED Miller has added the following cables to his site: http://www.flynbye.com/catalog/i199.html
Modification of some sort is required for the 98+ to work. The following links provide ideas: https://www.thirdgen.org/forums/brak...ny-tricks.html
https://www.thirdgen.org/forums/brak...-ls1-swap.html
EDIT: Ed Miller now has direct-fit cables for the LS1 swap:
http://www.flynbye.com/catalog/i153.html
How Do I Adjust My Parking Brake?
82-89 cars have a tunnel-mounted adjuster above the drive shaft. 90-92 cars are self adjusting.
Can I Swap Discs to My Drum Rear End?
Yes. Though the housing ends can be modified (https://www.thirdgen.org/ls1reardisc),
the easiest method is to purchase a kit from Ed Miller: http://www.flynbye.com/catalog/i30.html
Can I Swap in Larger Discs and Calipers?
Yes. The following link details the PBR swap:
https://www.thirdgen.org/forums/faq-...iscs-89-a.html
However, check with Ed Miller’s site for many other possibilities, such as LS1's:
http://www.flynbye.com/index.html
Are All Spares and Disc Brakes Created Equal?
No, there are three spare sizes, a 14" (P195/75-14) and two 15's (a T125/70-D15 and a P195/75-D15). Only the latter, which is black-painted alum, will fit 1LE/LT1 rear calipers. More info/pics in the following link: https://www.thirdgen.org/forums/brak...e-4th-gen.html
Many thanks to big gear head and Pat Hall for their suggestions and comments.
I don’t pretend to be an expert in the above matters, so if I’ve made a misstep, feel free to correct me—or add pertinent information.
JamesC
Last edited by JamesC; 09-21-2017 at 01:04 PM.
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nschrader9 (01-18-2021)
02-21-2009, 03:58 PM
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re: FAQ About 10-Bolts
I can't make that a sticky or else I would. That answers the same questions that seem to be asked at least once a week about the 10 bolt.
02-21-2009, 08:55 PM
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re: FAQ About 10-Bolts
This will help with a swap from a standard differential to a posi. http://www.nastyz28.com/forum/showth...t=install+posi This is for the 8.5 rear end, but the 7.5 is the same.
I have found that the Auburn usually requires 2 bottles of the oil additive to make it stop popping. The Ford additive sometimes works better.
I have found that the Auburn usually requires 2 bottles of the oil additive to make it stop popping. The Ford additive sometimes works better.
02-21-2009, 09:01 PM
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re: FAQ About 10-Bolts
really really great info here! Sticky for sure!
02-22-2009, 12:32 AM
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re: FAQ About 10-Bolts
Great write-up 
Should almost be mandatory to read stuff like this before you register 
However unless your talking about the lead singer for Guns N' Roses, it's spelled "axle"
Should almost be mandatory to read stuff like this before you register However unless your talking about the lead singer for Guns N' Roses, it's spelled "axle"
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03-03-2009, 08:39 PM
#10
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re: FAQ About 10-Bolts
In the 3rd gen Camaro and Firebird welding the axle tubes doesn't help much. Amlost all of the torque is transfered into the torque arm, so there is very little twisting in the tubes.
03-03-2009, 08:52 PM
#11
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Car: 89 Camaro
Engine: 383 w/ 450HP
Transmission: TKO-600
Axle/Gears: 3.42
re: FAQ About 10-Bolts
Ok so i guess my next question then is what can be done to beef up the 10 bolt?
03-04-2009, 09:08 AM
#13
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re: FAQ About 10-Bolts
Replace it with a Moser 12 bolt.
There isn't a lot that can be done for the 10 bolt. It's just a small rear end and you can't get past that. There are a few things that can help a little. A few upgrades like an Eaton posi, 28 spline axles and a T/A Performance aluminum cover will help some, but not much. As always, correct set up of the ring and pinion gears is VERY improtant.
There isn't a lot that can be done for the 10 bolt. It's just a small rear end and you can't get past that. There are a few things that can help a little. A few upgrades like an Eaton posi, 28 spline axles and a T/A Performance aluminum cover will help some, but not much. As always, correct set up of the ring and pinion gears is VERY improtant.
03-05-2009, 08:37 AM
#14
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Car: 1991 Formula Firebird
Engine: Pontiac 355 stroker (305 TBI 4Sale)
Transmission: Pending Manual , 700r4 for sale...
Axle/Gears: Stock... for now
re: FAQ About 10-Bolts
I didn't want to post something like this up, But, I'm looking at getting a 10 bolt rear with 4.11 gears, and a 8" Pinion gear from a 60's Chevelle... Is there any light of hope that these will work on my 91 Bird? Thanks in advance.
ps, Gear Head, How much $ are the Mosers running? I'm guessing a few grand?
ps, Gear Head, How much $ are the Mosers running? I'm guessing a few grand?
03-05-2009, 09:04 AM
#15
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re: FAQ About 10-Bolts
The ring gear will be 8.2 inches. The pinion gear will be much smaller than that. The Chevelle rear end will not fit your car without a lot of fabrication work. There is no mount for the torque arm on the Chevelle rear end.
The Moser is over $2000. I don't have my price sheet with me right now, but I can look it up later. There are several options for the Moser rear ends that affect the price.
The Moser is over $2000. I don't have my price sheet with me right now, but I can look it up later. There are several options for the Moser rear ends that affect the price.
03-05-2009, 12:12 PM
#16
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Car: 1991 Formula Firebird
Engine: Pontiac 355 stroker (305 TBI 4Sale)
Transmission: Pending Manual , 700r4 for sale...
Axle/Gears: Stock... for now
re: FAQ About 10-Bolts
Gotchya, Thanks for clearin a few things up for me. And you're right, it was an 8" Ring gear, not pinion 
03-20-2009, 01:05 PM
#17
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Car: 87 iroc
Engine: 350 with weiand 144
Transmission: tremec TKO 600,mcleod street twin
Axle/Gears: strange s60
Re: FAQ About 10-Bolts
The ring gear will be 8.2 inches. The pinion gear will be much smaller than that. The Chevelle rear end will not fit your car without a lot of fabrication work. There is no mount for the torque arm on the Chevelle rear end.
The Moser is over $2000. I don't have my price sheet with me right now, but I can look it up later. There are several options for the Moser rear ends that affect the price.
The Moser is over $2000. I don't have my price sheet with me right now, but I can look it up later. There are several options for the Moser rear ends that affect the price.
Can I use a pinion yoke from a 10 bolt on my borg warner 9 bolt?
03-21-2009, 08:22 PM
#18
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Car: 1983 z-28/SFC/bilsteins/adj.arms
Engine: 355sbc/Demon650dp/hedmanheaders/
Transmission: t-5, alum DS
Axle/Gears: 3.42 torsen posi, baer discs
Re: FAQ About 10-Bolts
Anybody have info on the 10 bolt 8.5" rears?
03-22-2009, 07:18 AM
#20
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Car: 1983 z-28/SFC/bilsteins/adj.arms
Engine: 355sbc/Demon650dp/hedmanheaders/
Transmission: t-5, alum DS
Axle/Gears: 3.42 torsen posi, baer discs
Re: FAQ About 10-Bolts
the 2nd gen 10 bolts...are they the same width as the third gen rears? Besides the need for different brackets to be welded on, is the swap easy? What did you do for the torque arm mount?
04-08-2009, 04:44 PM
#21
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Car: 87 Irocz, 95 Z28, 71 Z28 /RS
Engine: 355 Tpi, LT1, 355
Transmission: Auto, Auto, 4sp
Re: FAQ About 10-Bolts
Major questions here, I didnt see anything about the 3.27 (RPO code GW6) thats what I have in my 87 Iroc. Just called the dealership & they said it was the 7.75" but I cant find anything for that rear end. I am planning on moving up to 3.73 gears since My car is slatted to go in to pinks all out this summer.
HELP.
HELP.
04-08-2009, 05:43 PM
#22
Re: FAQ About 10-Bolts
Major questions here, I didnt see anything about the 3.27 (RPO code GW6) thats what I have in my 87 Iroc. Just called the dealership & they said it was the 7.75" but I cant find anything for that rear end. I am planning on moving up to 3.73 gears since My car is slatted to go in to pinks all out this summer.
JamesC
05-17-2009, 06:58 PM
#24
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Car: 1990
Engine: 305
Transmission: 700r4
Axle/Gears: stock
Re: FAQ About 10-Bolts
i dont know what anyone else did but i copied your great analysis and put it in my camaro - rear end - file for future reference.
really a fine job.
really a fine job.
05-17-2009, 08:33 PM
#25
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Car: 89 Camaro
Engine: 383 w/ 450HP
Transmission: TKO-600
Axle/Gears: 3.42
Re: FAQ About 10-Bolts
Does anybody know whats the lowest gear you can get for our ten bolt? Anything past a 4.56?
08-19-2009, 05:22 PM
#28
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Car: 86 Camaro iroc-z28
Engine: 305 TPI
Transmission: 700R4
Axle/Gears: 3.42 Posi
Re: FAQ About 10-Bolts
the recall on cars with rear discs equipped with delco moraine calipers. does the dealership only have to fix the recall if the car is equipped with a manual transmission?
08-31-2009, 11:30 AM
#30
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Car: 1989 Iroc Z
Engine: 496 BBC
Transmission: th400
Axle/Gears: 4.11
Re: FAQ About 10-Bolts
I have a 10 bolt with 2.73 gears and i'm wanting to switch to 3.73s or 3.90s. do i have to order a gear with a 2 series carrier? There are many different kinds of 10 bolts and i have no idea which one is equipped on mine. after i blew a 3.42 kirsch auto put this one in with limited slip and stock 2.73s. what can i do to figure out the right gear to buy?
08-31-2009, 03:09 PM
#31
Re: FAQ About 10-Bolts
JamesC
09-01-2009, 08:20 AM
#32
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Car: 1989 Iroc Z
Engine: 496 BBC
Transmission: th400
Axle/Gears: 4.11
Re: FAQ About 10-Bolts
There are two: Series II is 3.08 down, series III, 3.23 up. You have a series II. Steeper gears, say 3.73’s, can be swapped into a series II with gears designed for such a swap, or by purchasing a series III carrier. (This would be an appropriate time to upgrade to limited slip and 28-spline axles.)
JamesC
JamesC
09-01-2009, 08:29 AM
#33
Re: FAQ About 10-Bolts
A thirdgen was never equipped with an 8.5.
JamesC
09-01-2009, 08:40 AM
#34
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Car: 1989 Iroc Z
Engine: 496 BBC
Transmission: th400
Axle/Gears: 4.11
Re: FAQ About 10-Bolts
You might reread the FAQ: The ten-bolt 7.5 (7 1/2) and 7.625 (7 5/8), introduced around 86, are virtually the same. With the exception of size, all else is the same. For example, all ring gears fit all years of carrier whether they're 7.5 or 7.625.
A thirdgen was never equipped with an 8.5.
JamesC
A thirdgen was never equipped with an 8.5.
JamesC
09-01-2009, 10:04 AM
#35
Re: FAQ About 10-Bolts
JamesC
Last edited by JamesC; 09-01-2009 at 10:24 AM.
09-26-2009, 11:05 PM
#38
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Car: 1989 Iroc-Z Camaro
Engine: TBI,5.0
Transmission: Automatic 700R4
Axle/Gears: Eaton Posi,3.42,LPW Ultimate Cover
Re: FAQ About 10-Bolts
Here's a link to the 10 bolt build =
https://www.thirdgen.org/forums/tran...de-photos.html
Here's a link to L.P.W Racing that I found very helpful when deciding on a "Support Cover".= http://www.lpwracing.com/Diff_Cover_...omparison.html
here's were I bought it.= http://www.jegs.com/i/L.P.W./619/301-7.5G/10002/-1
https://www.thirdgen.org/forums/tran...de-photos.html
Here's a link to L.P.W Racing that I found very helpful when deciding on a "Support Cover".= http://www.lpwracing.com/Diff_Cover_...omparison.html
here's were I bought it.= http://www.jegs.com/i/L.P.W./619/301-7.5G/10002/-1
Last edited by Ron U.S.M.C.; 02-25-2013 at 07:49 PM. Reason: add image
10-06-2009, 03:05 PM
#39
Re: FAQ About 10-Bolts
i have a question. can i put a 28 spline Detroit locker http://www.jegs.com/i/Detroit-Locker...2A317/10002/-1 in my rear i can get the 28 spline axles the moser one's http://www.jegs.com/i/Moser/718/A102804/10002/-1
im not going to race my car.. i just go out cruising. im looking for 300 to 350 to the wheels. i want to rebuild my drive train b4 i put in my 350 just wondering if i could save some money on my rear getting these two items
thanks guys
im not going to race my car.. i just go out cruising. im looking for 300 to 350 to the wheels. i want to rebuild my drive train b4 i put in my 350 just wondering if i could save some money on my rear getting these two items
thanks guys
10-06-2009, 03:34 PM
#40
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Re: FAQ About 10-Bolts
You can use a 28 spline Detroit locker and 28 spline axles in your rear end. Why did you choose the locker over the Eaton Posi if this is just going to be a cruiser?
10-06-2009, 05:35 PM
#42
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Re: FAQ About 10-Bolts
I didn't check the link before. That's not a Detroit Locker, it's a Detroit Truetrac. Big difference. Be sure that you get bearings and shims for it so that you can set the backlash and bearing preload.
10-19-2009, 12:58 PM
#43
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Car: 92 RS
Engine: 2000 454 Carb
Transmission: T-56
Re: FAQ About 10-Bolts
What would I have to do to my 92 rs Equiped with a 454 and t-56. Like you said before it should be a 10 bolt. But it's a non posi. I want to make it posi, what is the cheapest proffesional way of doing this?
10-20-2009, 09:10 PM
#47
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Car: 92 RS
Engine: 2000 454 Carb
Transmission: T-56
Re: FAQ About 10-Bolts
Thanks for all help. I'll switch to a 9" or Dana 60 around tax time. This is a great thread. Really appreciate all help.
11-08-2009, 12:17 AM
#48
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Car: 86 TA, 91 B4C
Engine: 5.3, 4.8
Transmission: 4L80 4000, T56
Axle/Gears: 4.30 M12, 23.42 10 bolt
Re: FAQ About 10-Bolts
There is the hard to find replacement that i had at one time. They are priced right, but in the late 80s early 90s, GM did offer and sell several dana 44 rearends that were the 8.5 ring and pinion. They will take what most dish out for a street car. I sold mine since i got a 12 bolt Moser, but the parts are there for them, but they are just not easy to find.
This is what the cover looks like if you ever see one in the junk yard.
Score of a life time.
This is what the cover looks like if you ever see one in the junk yard.
Score of a life time.
11-11-2009, 04:44 PM
#49
Re: FAQ About 10-Bolts
If I Swap From a Drum to a Disc Read End Do I Have to Change the Proportioning Valve?
Yes, for the best brake performance. Use a standard disc brake valve for 82-88 swaps*. Use the appropriate 1LE valve for 89+ swaps into an earlier model year. Either of the 1LE valves can be purchased from Ed Miller at http://www.flynbye.com/catalog/c1_p1.html
*Apparently the 82-83 (and maybe 84) cars have SAE fittings unlike the metric fittings on later cars. Moreover, the 84-92 valves look nothing like the earlier ones and the line connections are different as well. How this would affect a swap I’m unsure.
JamesC
I've swapped a PBR rear from a '91 Z into my '87 Sport Coupe. I tried to swap the proportioning valve today, but as you have mentioned above, the proportioning valve fittings are different. Looks like in '87 they used extra fine threads, and in '91 they used standard threads. I went to Napa today to try and get an adapter, the best he could come up with is this:
NAPA adapter
Do you think this will work, or am I going to have to trade the '91 proportioning valve for a valve from a 88 or older car with rear disks?
11-11-2009, 05:48 PM
#50
Re: FAQ About 10-Bolts
James,
I've swapped a PBR rear from a '91 Z into my '87 Sport Coupe. I tried to swap the proportioning valve today, but as you have mentioned above, the proportioning valve fittings are different. Looks like in '87 they used extra fine threads, and in '91 they used standard threads.
I've swapped a PBR rear from a '91 Z into my '87 Sport Coupe. I tried to swap the proportioning valve today, but as you have mentioned above, the proportioning valve fittings are different. Looks like in '87 they used extra fine threads, and in '91 they used standard threads.
http://www.flynbye.com/catalog/i40.html
JamesC
