Marc's 1990 4.2L V8 Twin Turbo Coupe Quattro

WAUG0806 · Post by **WAUG0806** » Thu Aug 09, 2007 5:38 am

Is there a way to vacuum test the booster in the car?

Post by **Marc** » Thu Aug 09, 2007 6:08 am

WAUG0806 wrote:Is there a way to vacuum test the booster in the car?

yes, I attempted to mightyvac it at the port and it doesn't hold vacuum so thats certainly part of the problem, I just didn't think that would cause the symptom I'm getting. I would have expected just little or no vacuum assist. I think its because there is supposed to be a membrane that pushes with an air gap between the metal pushrod attached to the booster and the rod on the master cylinder but with a torn diaphragm I'm essentially collapsing that airspace before I get any braking. Thats my guess, anyway.

Post by **HT Motorsport** » Thu Aug 09, 2007 6:41 am

:wink: :wink: :wink:

you know you want to.....

Post by **Marc** » Thu Aug 09, 2007 6:56 am

timmmy wrote::wink: :wink: :wink:

you know you want to.....

eeeeeeeeeeeviiiiiiiiiiiiiiil

mr_aj_johnson · Post by **mr_aj_johnson** » Thu Aug 09, 2007 7:39 am

tried to bleed the brakes on the 240z, couldnt get any air out of the front calipers, then we realized that the supra calipers we put on were on the wrong sides, and that the bleed valve was at the bottom of the caliper so all the air was floating up and away from the valve :slap:

Post by **Marc** » Thu Aug 09, 2007 7:54 am

lol, yeah, bleed valves are definitely right side up

Post by **Marc** » Thu Aug 09, 2007 10:28 am

Huw Powell to the rescue again, he's got a complete setup off a 90 that we'll throw on the bench side by side to see whats wrong/different.

WAUG0806 · Post by **WAUG0806** » Thu Aug 09, 2007 12:31 pm

a4kquattro wrote:
WAUG0806 wrote:Is there a way to vacuum test the booster in the car?

yes, I attempted to mightyvac it at the port ............I'm essentially collapsing that airspace before I get any braking. Thats my guess, anyway.

I recall that vac boosters have a check valve near the vac inlet that gives you a hard pedal when there is no vacuum...

my impression (in my short drive) :wink: was that pedal was OK/firm... just really low and this would suggest torn diaphram or other internal vacuum leak in the booster...

Post by **Marc** » Thu Aug 09, 2007 6:51 pm

Yep. That'll do it.

"old"/not working

"new"/working

I've never stared down a vacuum booster before so wasn't sure what to expect when putting it together. I guess the answer is, one of those pointy rod thingies should really be in there... :bashtard:

Derracuda · Post by **Derracuda** » Thu Aug 09, 2007 6:52 pm

haha, yeah! good find

3bAudios · Post by **3bAudios** » Thu Aug 09, 2007 7:42 pm

:woowoo:

Post by **HT Motorsport** » Fri Aug 10, 2007 8:21 am

Yup - that woudl definately do it!!!!

WAUG0806 · Post by **WAUG0806** » Fri Aug 10, 2007 10:05 am

a disposessed protruberence!

Ronald G Wainwright+ · Fri Aug 10, 2007 11:34 am

You sure you got that from Huw....it's not Yellow

zarati · Post by **zarati** » Fri Aug 10, 2007 1:54 pm

Nice Car,
Yu already have a Turbo 20v right. If so then go for the V8. Why have two of the same thing.

Toxcheap · Post by **Toxcheap** » Fri Aug 10, 2007 2:18 pm

zarati wrote:Nice Car,
Yu already have a Turbo 20v right. If so then go for the V8. Why have two of the same thing.

He has a twin turbo V8!!

couperman · Post by **couperman** » Fri Aug 10, 2007 8:13 pm

:slap: Marc's V8 Twin Turbo CQ is the most discussed coupe on motorgeek!

I had people calling me who saw this car on websites after WaterFest and said "Dude, you think your car is sick, there was this coupe with a V8 TwinTurbo packed into it!!" They're not even MG members......!

zarati · Post by **zarati** » Sun Aug 12, 2007 12:39 am

Yea,
My bad. Must have been WAY to late. Although I've been dormant on the Audi front for about 3-years now and am just now getting back into it. Last car of his I was familiar with was the 4ktq. Somehow I read the Beginning of this thread. 37 pages ago and posted to that.
OOPS!
I guess I need to catch up.

Post by **Marc** » Sun Aug 12, 2007 1:06 pm

aaaaaaand we have brakes

Didn't get a chance to actually put the booster on the car until today. Went for a drive, nice to not sweat every time I push the brake pedal

GillaumeDeBellvue · Post by **GillaumeDeBellvue** » Sun Aug 12, 2007 3:21 pm

:woowoo:

Toxcheap · Post by **Toxcheap** » Sun Aug 12, 2007 3:23 pm

a4kquattro wrote:aaaaaaand we have brakes Didn't get a chance to actually put the booster on the car until today. Went for a drive, nice to not sweat every time I push the brake pedal

Have you decided yet when you're going down to the dyno?

Post by **Marc** » Sun Aug 12, 2007 4:18 pm

I need to talk to Tony. I'll be down in CT on business the week of the 20th so I might try to sneak on the dyno at that point.

GTIVR62801 · Post by **GTIVR62801** » Sun Aug 12, 2007 5:36 pm

Are you bringing the CQ to Tremblant Marc?

Post by **Marc** » Sun Aug 12, 2007 6:19 pm

GTIVR62801 wrote:Are you bringing the CQ to Tremblant Marc?

yes :-D

V8QinNJ · Post by **V8QinNJ** » Tue Aug 14, 2007 11:50 am

so I might try to sneak on the dyno

Humm... maybe you're going to use the dyno and sneak out for some work! 8)

That under hood shot is simply awesome!