Ok,

I read through everything in the two major posts below along with the associated web sites and everything makes sense except for one thing....

If you have an F-Body equipped with Front and Rear discs (Standard 10.X" Front and 1LE Rear Discs ... as on any '90-'92 L98) then what should be changed in terms of the proportioning valve and/or master cylinder?

Some entries indicate nothing. Other entries indicate to use a master cylinder from a disc/drum setup. Other entries indicate to use a different proportioning valve (10136840).

What's the deal? Swap both the master cylinder and the prop valve? Swap just the master cylinder? Swap just the prop valve? Swap nothing? What gives?

Tim

------------------
TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

From what I understand. If you have disk brakes all around already you dont need to change the master cylinder or add a proportioning valve. If you have drums in the back then you need proportioning valve. Or elce the rear will lockup quicker then the front. Some correct me if I'm wrong.

 

Disc/drum setups use the same proportioning valve as the 89-92 disc/disc setups. I dont know if the proportioning valve is different for 1LE front brakes.

------------------
West Coast GM Shootout 2001!
1991 Camaro Z28
5.7L 5-Speed (originally 305)
13.25 @ 107.18 MPH
Southern California
Member: SoCal 3rd Gen F-Bodies
Webmaster: SoCal F-Bodies
-=ICON Motorsports=-

 

I thought it was the master cylinder that was the same. I'll have to re-check my parts manual at home to verify. I'm positive the prop. valve is the different between the disc/disc and disc/drum cars...

------------------
Greg Westphal
'87 IROC 305TPI/A4

 

I could be wrong, but my dad switched his 92 RS from 92 3.08 drums to 89 3.27 9-bolt discs and he didnt have to change a thing. It bolted right in and everything hooked up and works fine.

 

The prop valve is different on 1LE equipped cars. The 1LE calipers have more piston area,ETC.

------------------
82Z 305 w/comp 270 magnum cam,Edelbrock Performer RPM,Holly 1850-4,serpentine belt drive.TH700R4 w/B&M holeshot 2000 converter,& megashifter.1LE front brakes, 9bolt 3.27 w/1LE rear brakes.Aluminum driveshaft,boxed rear susp.poly everything,IROC swaybar+wonderbar. 70mph@2200rpm ASE Master Tech plus L2
also recently obtained a
'69 chevelle SS396 w/Turbo 400,3.31 posi,11.0 to 1, headers,etc. Latest project car,'86 IROC stock 305TPI hit on left side,but not too bad

 

Andy,

So you are saying that for a 1990 IROC with the stock 10.x" front brakes and the stock 1LE rears .... that if I convert to the 1LE brakes that I will need a new proportioning valve? How do you know? What is the PN from GM?

BTW - this has to be the most conflicting subject. Even after posting this post I have heard YES I need a new proportioning valve and NO I don't need a new proportioning valve.

Tim

------------------
TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

The proportioning valve is different from the drum brake rear. However, you can put it together without changing it and see how it feels. If the rearend locks up easier than you'd like, change it. I would be tempted to just buy an adjustable one so that I can dial it in the way I want. The proportioning valve on our car is actually a combination valve. This valve sets the front/rear bias, but also applies pressure to the rear brakes first to even out pad wear. After a certain pressure is applied the valve adds the front brakes.

Another great upgrade is to use a master cylinder from a fourth-gen. It has a constant bore cylinder vs. the stepped-bore cylinder in our cars. The stepped bore was used for fuel economy reasons when they put calipers that retracted when the brake was released on cars. (early models). The newer master cylinder will give you better pedal feel and eliminate the small delay in caliper application after applying the brake. One note though, you will have to change the fittings that go into the master cylinder to a metric thread and use a single flare vs. a compound flare. If you do it, cut the lines on the newer car and compare them and you'll know what I mean. You may want to cut your stock lines and use compression fitting to attach to the newer style fared lines and fittings.

Here are the part numbers for the combination valve/proportioning valves for various options. It looks like you need 10164112, which looks the same as a regular J65 rear disc car.

Year Option Design Part #

1989 J50 1st 14089495
1989 J50 2nd 10136839
1990 J41, J42 2nd 10136839
1989 J65, 1LE, Y82 1st 14089496
1989 J65, 1LE, Y82 2nd 10164112
1990 1LE, J65 2nd 10164112
1989 J65,EXC 1LE,Y82 N/A 10164112
1990 J65, EXC 1LE N/A 10164112

Option Codes Description

J65 Power Front and Rear Disc
Y82 Trans Am Base
J50 Power Brakes
1LE Heavy Duty Brakes (12" Dual-piston)
J41 Rear Iron Drum
J42 Rear Aluminum Drum

Design Description

1st M1 Tube Nut Threads
2nd M1.5 Tube Nut Threads


------------------
1992 Camaro Z28; Engine:383 w/Ported Edelbrock RPM heads. Lunati Solid Roller Cam 224/232 .502/.502, Fluidampr, Comp Cams 1.5 Roller rockers and lifters, Comp Cams Triple Valvesprings, SVO 30 lb injectors. Holley/Walbro 255 lph in-tank pump, Haltech E6GM DFI, SLP 1 3/4" headers, 4" Mufflex, T56, SLP Clutch, Pro-5.0 Shifter, 4.10 Gear, Auburn Offroad Pro Posi. Super Ram. 17" X 9.5" Ronal FireHawk Rims w/ 275 40ZR17 Bridgestone RE 730's up front and Nitto Drag NT 555R's out back.

Double-Pump This! EFI Rules!

 

Ok,

Now we are back to you DON'T have to change the PV. Andy says YES you do have to change it. 3rdgenfreak says NO you don't have to change it (for a 1990 with both front and rear disks). So far, 3rdgenfreak is the only one that has supplied any information supporting one or the other ....

1990 1LE, J65 2nd 10164112
1990 J65, EXC 1LE N/A 10164112

Same PV for either one.

Tim

------------------
TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

[This message has been edited by TRAXION (edited April 06, 2001).]

 

I believe that you will need GM# 10136840 (which I see is discontinued. '89 & later 1LE proportioning valve. And by the way see the big 1LE post. I took my new 1LE brakes for a road test today.WOW!!

 

oh geesh...here we go again. do yourself a favor and call your local dealer and ask. thats the best thing to do.

 

Who is this Camaro_hunter flamer? You don't even know who you're talking to do you? I can't believe you'd say "oh geesh" to Tim, he's forgotten more about thirdgen's than you'll ever know.

Tim, I went to the dealer to order pn 10136840 which was the "90-92 1LE prop valve". It was superceded with 10164112. It cost me $70 @ the dealer, and Its going in in about 3 weeks once I get the 97 rear end in. I think you can get 10164112 from GMpartsdirect.com for like $55 or 60. The dealer had to order mine from lansing so it took a week. I have an ACDelco Durastop drum brake MC, which i believe you need with the 10164112 prop valve to operate the 1LE brakes.

------------------
-Jason M. 1991 Camaro Z28

 

So here is what I am going to do.I am going to install a disc/drum master cylinder and propotioning valve on my 1LE equipped '82 Z28 and take it for a ride. A pretty serious ride!! And see what happens! Ya can't beat that for a deal. This way we can put theory on the pavement.

[This message has been edited by ANDYZ28 (edited April 08, 2001).]

 

Jason,

Hmmmm. This is starting to get really interesting

OK - 3rdgenfreak indicated that 1990 disk/disk setups came with the 10164112 prop valve STOCK. This valve is apparently the same valve that you just ordered. This valve is also the valve that is currently on my car. However, I do have the Disk/Disk Master Cylinder whereas you indicate that the Disk/Drum master cylinder is the one that you think I might need.

This is the entire reason that I brought this subject up. There are sooooooo many different opinions on what is needed for the '90-'92 cars. Some say to change the PV. However, all the information that I have seen indicates that the PV does not need to be changed if your car came with Disk/Disk brakes. This makes sense given what both 3rdgenfreak and Jason just said. The 10164112 PV is BOTH the 1LE PV and the stock PV for the '90-'92 Disk/Disk setups.

So - lets look at the info that we have so far....

3rdgenfreak: Change Nothing
Andy: Change the PV
Jason: Change the Master Cylinder (I already have the 10164112 PV).

Egad.

Just for reference, I also posted a message to the thirdgen mailing list. The information from that list agrees with 3rdgenfreak; namely, the PV and the master cylinder do not need to be changed for the '90-'92 disk/disk setups if you convert to 1LE brakes.

I guess I'll talk to a couple of my GM contacts this week. I always try to find the answers via the internet first before bothering them (I don't want to bug them too much).

Tim

------------------
TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

Frank not freak. Thanks.

------------------
1992 Camaro Z28; Engine:383 w/Ported Edelbrock RPM heads. Lunati Solid Roller Cam 224/232 .502/.502, Fluidampr, Comp Cams 1.5 Roller rockers and lifters, Comp Cams Triple Valvesprings, SVO 30 lb injectors. Holley/Walbro 255 lph in-tank pump, Haltech E6GM DFI, SLP 1 3/4" headers, 4" Mufflex, T56, SLP Clutch, Pro-5.0 Shifter, 4.10 Gear, Auburn Offroad Pro Posi. Super Ram. 17" X 9.5" Ronal FireHawk Rims w/ 275 40ZR17 Bridgestone RE 730's up front and Nitto Drag NT 555R's out back.

Double-Pump This! EFI Rules!

 

DOH! Sorry Frank. You think I would have learned to call people by the right name - especially since I get 1-2 e-mails a week with people calling me TRAXXION, TRAXXON, TRIXON, TRIXION. Get it right - TRAXION (pronounced as 'traction' - or just call me Tim). Again, sorry about that.

Tim

------------------
TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org

 

You don't need to change the master cylinder, after 1989 all F-bodies used the same 24mm M/C regardless of whether they had drums, discs, or 1LE discs.

The M/C swap is necessary for older cars with disc brakes (like mine) which have a 1" cylinder. Older cars with drum brakes use a 24mm cylinder and don't need to change.

Let's try to make this clear as mud, this is what it looks like to me:

<table border=1><tr><td>Year</td><td>Brakes</td><td>Master Cylinder</td><td>Proportioning Valve</td></tr><tr><td>Pre 1989</td><td>Drum</td><td>No Change</td><td>14089496</td></tr><tr><td>Pre 1989</td><td>Disc</td><td>Change</td><td>14089496</td></tr><tr><td>Early 1989</td><td>Drum</td><td>No Change</td><td>14089496</td></tr><tr><td>Late 1989 & Later</td><td>Drum</td><td>No Change</td><td>10164112</td></tr><tr><td>All 1989 & Later</td><td>Disc</td><td>No Change</td><td>No Change</td></tr></table>


[This message has been edited by Apeiron (edited April 09, 2001).]

 

Money.

Tim

------------------
TRAXION's 1990 IROC-Z
Best Time = 12.244 @ 112.51mph (1.778 60' / 7.819@88.32mph in the 1/8)
All Natural. No Force. No Drugs. Stock Bottom End. Stock Body Panels.
Gunning for NA 11's with bigger cam, bigger stall, and bigger exhaust.
-=ICON Motorsports=-
Moderator: PROM board at thirdgen.org