Need Advise: Master Cyl Brake intercepts Shifter

[Schmieder]

1996 Grand Prix SE 3100 SFI
Getrag-282 swap

After the manual swap, the master cylinder interferes with the shifter selector (left/right spring loaded). Mounted normally it makes shifting into 5th and R far too stiff and difficult to be safe on the trans.

When I loosen the Master Cylinder to the Brake Booster and lift it up about 1/4" it clears the shifter and I can row through the gears normally.

Right now the Master Cylinder is shimmed where it meets the Brake Booster. The pedal still travels properly. But I can not leave it that way.

I need to find a master cylinder that has more clearance on the bottom of the assembly. Does not need to be ABS. In fact, Jeff mentioned a non-ABS master cylinder should fix the issue.

A few things to note:

- Engine and trans mounts are in proper and the subframe has not be raised.
- Using the proper mounts for the W-Body Manual.
- Original brake booster w/ no modifications
- Transmission shifting levers are on properly

I'm open for options, suggestions, etc.

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[jman093]

I think you actually need a new booster. 99% sure 5 speed w-bodies had a smaller brake booster than autos for clearance purposes. I'm parting a 5 speed car and can get you a booster and cylinder if you want them.

[robertisaar]

correct, 5 speed brake boosters on W's are smaller.

[Schmieder]

Okay, sounds good and cheap....

[pocket-rocket]

You know, the more I think about this, the more I wonder about my 91... I never touched the booster, yet I didn't have clearance issues when I did my 5 speed swap. Maybe from the factory GM put the small booster in the 91-93 cars just like the manuals got the 9396 ECM despite not needing the extra ram?

[robertisaar]

possibility.

but since you mention it, the manual trans cars DO need the 9396's extra RAM to run $DF code, since nearly the entire added RAM chip is used for stack purposes. it's not specifically for 4T60E control as it's been mentioned in the past.

[jman093]

You know, the more I think about this, the more I wonder about my 91... I never touched the booster, yet I didn't have clearance issues when I did my 5 speed swap. Maybe from the factory GM put the small booster in the 91-93 cars just like the manuals got the 9396 ECM despite not needing the extra ram?

Looking at part numbers on compnine. 88-91 used the same booster, 92 had another one, 93 yet another one, and then finally another one for 94-99. The one thing I noticed is no year shows more than one booster meaning they probably weren't different between autos and 5 speeds. Since 5 speeds were available 88-93 I would think that any of those would work except the 94-99 booster.

[pocket-rocket]

Looking at part numbers on compnine. 88-91 used the same booster, 92 had another one, 93 yet another one, and then finally another one for 94-99. The one thing I noticed is no year shows more than one booster meaning they probably weren't different between autos and 5 speeds. Since 5 speeds were available 88-93 I would think that any of those would work except the 94-99 booster.

Kinda what I figured, but I didn't look it up. It is sorta strange that they used 3 different ones through the years, though. But hey, it's GM.

Given that information, I bet the 93 would be the best bet since it would be the newest of the 5 speed friendly revisions.

[Schmieder]

I agree about the 93 booster. Thank you guys, I always get a good answer here.

It just occured to me I need to make/obtain a vacuum chamber for the accessory vac line. The old one is done for, old and cracked. I always wondered why the blower would switch up under WOT. That should stop w/ the vac chamber. And hooking the brake booster to an additional vac chamber couldn't hurt any, but I don't see myself using the brakes AND boost at the same time, lol.

[pocket-rocket]

I don't see myself using the brakes AND boost at the same time, lol.

You mean the GP isn't made by Toyota?