Best gears for 88 Trans Am
06-16-2011, 06:02 AM
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Car: 1988 Trans Am
Engine: 305 TBI
Transmission: 5 Speed Manual Transmission
Axle/Gears: Stock
Best gears for 88 Trans Am
What are the best gears for drag racing a 1988 5 speed trans am with a stock 305
06-16-2011, 07:01 AM
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Car: '90 Formula 350
Engine: 383 SBC
Transmission: ProBuilt S/S 700-R4 & ACT 9" Stall
Axle/Gears: 10 bolt 3.23
Re: Best gears for 88 Trans Am
Depends on what rearend you have too. 10 bolt gears will not fit 9 bolt and vice versa. Carriers will need certain gears too depending on the series. I don't know about 305 TBIs, but I would probably say 3.45 or 3.73s.
Last edited by fireturd350; 06-16-2011 at 07:15 AM.
06-16-2011, 03:17 PM
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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: Best gears for 88 Trans Am
According to the Tech Data page for Firebird/Trans Am "if" its still stock you have 3.08 ring and pinion.
Here's a link to that page if your interested.= https://www.thirdgen.org/1988-pontiac-firebird
Here's a link to that page if your interested.= https://www.thirdgen.org/1988-pontiac-firebird
Last edited by Ron U.S.M.C.; 06-16-2011 at 10:55 PM. Reason: add info.
06-16-2011, 03:21 PM
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Car: 1984 Z28 Hardtop
Engine: 383 Carb
Transmission: 4L60
Axle/Gears: 3.54 Dana 44
Re: Best gears for 88 Trans Am
Whatever ratio has you at redline in 4th at your trap speed.
06-16-2011, 04:27 PM
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Car: 1988 Trans Am
Engine: 305 TBI
Transmission: 5 Speed Manual Transmission
Axle/Gears: Stock
Re: Best gears for 88 Trans Am
Yeah on the tech data it says I have 3.08 so what would it be safe switch?
06-16-2011, 04:51 PM
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Car: '90 Formula 350
Engine: 383 SBC
Transmission: ProBuilt S/S 700-R4 & ACT 9" Stall
Axle/Gears: 10 bolt 3.23
Re: Best gears for 88 Trans Am
You shouldn't just plan gear swaps off Tech sheets. You really need to know what you have in it first. You could try to count the turns and etc to find out the ratio, but the safest way is to manually check IMO. Gears should have a metal stamping on the ring gear. That way you can see what the conditions look like in there. If you crack it open and there is metal debris around well then you know you need to get a bearing kit too.
I just got done swapping out a 9 bolt for a 10 bolt few weeks back. If the next owner just went off tech sheets that they would be getting the totally wrong parts since they wouldn't know the carrier series or etc.
Have you considered normal gear labor installs can cost $250-$750 depending on the shop that does them? Throw in another $200-$250 for parts and seals, etc.
I just got done swapping out a 9 bolt for a 10 bolt few weeks back. If the next owner just went off tech sheets that they would be getting the totally wrong parts since they wouldn't know the carrier series or etc.
Have you considered normal gear labor installs can cost $250-$750 depending on the shop that does them? Throw in another $200-$250 for parts and seals, etc.
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06-16-2011, 07:04 PM
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Car: 1989 GTA
Engine: SuperRam 350
Transmission: Pro Built S/S TH700R4
Axle/Gears: 3.27
Re: Best gears for 88 Trans Am
Put your car in 4th gear (1:1) and drive at 70 mph. The RPM's will tell you your axle ratio.
3.08 = 3000 RPM
3.45 = 3450 RPM
This is assuming stock tire size.
3.08 = 3000 RPM
3.45 = 3450 RPM
This is assuming stock tire size.
06-16-2011, 11:37 PM
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Car: 1988 Trans Am
Engine: 305 TBI
Transmission: 5 Speed Manual Transmission
Axle/Gears: Stock
Re: Best gears for 88 Trans Am
70 mph? Gulp! Sounds past speed limit!! 
Yeah I checked and I do indeed have 3.08 and yeah man I know how much it ranges for.
Yeah I checked and I do indeed have 3.08 and yeah man I know how much it ranges for.
06-17-2011, 09:57 PM
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Car: SOLD IT. Mopar guy only now.
Engine: gone
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Re: Best gears for 88 Trans Am
I have heard of some TPI guys going 3.73 or more and losing e.t. and going back to 3.23 i dont know about it in your case...you should think about the future what do you plan on doing. are you trying to get more acceleration out of it? If not then just keep your 3.08's and fuel mileage...
06-19-2011, 05:57 AM
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Car: 1988 Trans Am
Engine: 305 TBI
Transmission: 5 Speed Manual Transmission
Axle/Gears: Stock
Re: Best gears for 88 Trans Am
I'm trying to get better take offs
06-19-2011, 08:52 PM
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Re: Best gears for 88 Trans Am
I thought it was tpi not tbi...i'd run 3.73's if it was purely for drag racing. I drive my car all over the place so I run 3.42's
09-13-2011, 06:10 PM
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Car: 1988 Trans Am
Engine: 305 TBI
Transmission: 5 Speed Manual Transmission
Axle/Gears: Stock
Re: Best gears for 88 Trans Am
is the 305 tbi 9 bolt or 10 bolt?
09-13-2011, 10:55 PM
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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: Best gears for 88 Trans Am
If your running 3.08 ratio than you also have a 26 spline ,2 series carrier.That means a complete up grade would be in your future if you want to use at least a 3.42 ratio.Thats including 28 spline axles,28 spline 3 series carrier (I went with a Eaton Posi.) with a support cover. Either that or if you have bigger plans for a engine I would say 12 bolt or 9". I went with a complete up grade to my 10 bolt but my cars a DD with street tires.Its not intended for the track.
Last edited by Ron U.S.M.C.; 09-14-2011 at 12:01 AM. Reason: add info.
09-13-2011, 11:19 PM
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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: Best gears for 88 Trans Am
3.08 ratio = "10 Bolt"
as far as I can tell no TBI in "88" came with a 9 bolt.
as far as I can tell no TBI in "88" came with a 9 bolt.
Last edited by Ron U.S.M.C.; 09-13-2011 at 11:58 PM. Reason: change info.
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