Brakes wont hold ANY boost.

[jcj53115]

Hopefully I can get a few Ideas here, All this year I havent been able to build any boost at all while foot braking the car. If I hit so much as 1lb of boost it just hazes the tires. I'm still running the power master, and about a month ago did a complete rear brake job, 2 large shoes on both sides, completely flushed the PM and brakes and re-bleed everything. And everything is adjusted correctly. Doing this made NO difference at all. Brakes work AWESOME for normal driving but suck at the line!!!!!

Last year I had NO problem holding 9lbs off the foot brake on reg. radial tires. This year I have the MT DR on it and it just blows em away at 1lb on the brakes. I made several changes to the car last winter ie.. turbo, converter ect but wouldnt think this would effect my ability to foot brake the car?

Anyone have any ideas short of switching over to vac, or hydro boost brakes?

 

[TurboDave]

Tighter converter would add to your holding problems.
ANY heat in the rear shoes will also kill their ability to hold well.

 

[johnnyttype]

so r u saying no more john force burnouts?
have u tried the e-brake to see if it will hold any more boost? im addicted to using mine now...hope i dont break it!

 

[jcj53115]

Tighter converter would add to your holding problems.
ANY heat in the rear shoes will also kill their ability to hold well.

i was using the stock re-stalled D5 last year and was able to hold 9lbs, this year I installed a BB67 and Pats 10" 3200 , I wold think that this would help build boost if anything, but maybe im wrong

so r u saying no more john force burnouts?
have u tried the e-brake to see if it will hold any more boost? im addicted to using mine now...hope i dont break it!

Same out come even with the e-brake!!!! 1lb and there up in smoke

 

[johnnyttype]

time for a trans brake?!

my converter is understalled in my combo plus i have a cracked header right now and i can still get 4lbs.

what r ur RPM's when u do this?

 

[jcj53115]

time for a trans brake?!

my converter is understalled in my combo plus i have a cracked header right now and i can still get 4lbs.

what r ur RPM's when u do this?

A trans brake would certianly fix the problem, but there gotta be something Im missing here. i cant see that as being my only option:frown: altho I will be getting a new trans this winter and it will include a brake, but something else has gotta be up thats causing this. As for the Rpms im at about 3K rpms when I hit 1lb and i blows the tires away

 

[Dreamcar86]

Hopefully I can get a few Ideas here, All this year I havent been able to build any boost at all while foot braking the car. If I hit so much as 1lb of boost it just hazes the tires. I'm still running the power master, and about a month ago did a complete rear brake job, 2 large shoes on both sides, completely flushed the PM and brakes and re-bleed everything. And everything is adjusted correctly. Doing this made NO difference at all. Brakes work AWESOME for normal driving but suck at the line!!!!!

Last year I had NO problem holding 9lbs off the foot brake on reg. radial tires. This year I have the MT DR on it and it just blows em away at 1lb on the brakes. I made several changes to the car last winter ie.. turbo, converter ect but wouldnt think this would effect my ability to foot brake the car?

Anyone have any ideas short of switching over to vac, or hydro boost brakes?

If memory serves the car came out of the factory with a combination valve that puts 70% of the pressure to the front brake pads and only 30% to the rear. You can actually install a valve that would allow you to transfer more pressure to the rears when you are at the track and switch it back when you are on the street. I cannot remember who sells the valves. I may be wrong on the 70 -30 it may be 80 - 20.

 

[POWERBRAKEBOB]

Hydroboost Conversion

Have You Considered The Hydroboost System? It Runs Off Of The Power Steering Pump Pressure. No Vacuum Involved. As You Bring Up The Rpm's, The Pump Spins Faster, Holding The Hydroboost On Even Harder. It Will Deliver Up To 2000psi To The Calipers. Guys Are Reporting 22lbs Of Boost On The Line, With Their Foot On The Brake. The Powermaster Can't Do It. Also The Stopping Power At Any Speed Is Dramatically Improved, With Lowered Rotor Heat From Shorter Stopping Distances.

 

[Brer Rabbit]

Looks like my Gremlin jumped to ur car at Byron.

Ur describing the same problem I had. I even did the wheel cylinder upgrades with new shoes, the whole 9 yards. Even put a line lock in to prevent heating the shoes during a burnout. Nothing seemed to help. I think I found my problem when I had my covertor cut open and found 6 or 7 fins broken off and running around in the convertor. The guys at the shop where I took it made it clear that there was no way in their opinion that the convertor they cut open ever stalled 36-3800 as advertised. They said it was more like a true 2800 stall. If I were you I would go back to the D5 and see what happens since U know that worked well. I had my convertor rebuilt and they also increased the stall to flash at 3500. Im shootin for 1.49 60 fts. off the foot brake. (I hope)

 

[POWERBRAKEBOB]

Hydroboost Conversion

The Hydroboost Will Hold The Car, And Allow The Engine To Rev Above The Rated "flash" Stall Speed. It Holds Harder As The Pump Speed Goes Up. It Is Best With A Drag Car That The Crank Pulley Is A Reduced Diameter To Slow Down The Accessories. At 6000 Rpm, The Pump Is Spinning At 10,000 Rpm. (or More) At That Pump Speed, It Can Cavitate And Lose Pressure.

 

[FreeBoost]

How good does the hydro boost work when the engine stalls (not too good I think)? Before getting a Turbo Tweak chip my car would stall during normal driving when the throttle was quickly released after boosting. The combination of losing power steering, power brakes and going around a curve could be catastrophic. The tendancy of these cars to stall is probably why they came with hydro-electric brakes, not hydro-pnuematic brakes.

 

[UNGN]

If the converter is the only thing you changed, its the converter or the sealing of the crossover pipe (if you took it off in the swap).

If I have a dime for every time a "3200 stall" converter stalled at 2000.

 

[turbocamino1]

..powerbrakebakebob..where can one find the "hydroboost"system ?sounds like the ticket! and what do they cost? thanks

 

[TurboDave]

How good does the hydro boost work when the engine stalls (not too good I think)? Before getting a Turbo Tweak chip my car would stall during normal driving when the throttle was quickly released after boosting. The combination of losing power steering, power brakes and going around a curve could be catastrophic. The tendancy of these cars to stall is probably why they came with hydro-electric brakes, not hydro-pnuematic brakes.

I think you're over stating a minor issue. These cars are NOT known to have stalling problems. No more so than any other car on the road. The only ones I know of or hear of are those that are badly out of tune, and are trying to be "band aided" over the symptoms instead of trying to fix the problem.

I've owned my 87 now for over 18 years, and it's never stalled a single time. My 86 will on occasion when slipping it into gear, but that's my doing (converter), and in the 21 years that I've owned it, it's never stalled a single time while the car was moving.

If people choose to keep driving a badly tuned car, then they'll suffer with the consequences.

 

[8AV8]

..powerbrakebakebob..where can one find the "hydroboost"system ?sounds like the ticket! and what do they cost? thanks

Amazingly enough....POWERBRAKEBOB sells them...

 

[wagon]

A trans brake will certainly eliminate your not holding boost with the brakes, since you won't be using them to hold boost. BUT, if you can't even hold 1#, then you have something else wrong there. Also, if you can't hold even with the e-brake, then I doubt that a hydroboost will help. It seems to me that you have a problem with the mechanicals of the rear brakes.
Check to make sure that both pistons on both rear brakes are free. Put in th elarger wheel cylinders, and tighten your brakes up to the drums so there is a bit of drag. Bleed the wheel cylinders, and once you are sure you did a good job, do it some more. Then after driving a little, pull the drums and tighten them again. You should be able to hold alot more than 1#. Tell us what you find.

 

[wagon]

Oh, you may have a problem with the proportioning vavle too, but I doubt that.

 

[kingots2004]

i dont want to hijack your thread but i just changed my wheel cylinders today with hydroboost and same thing i cant hold not 1 lb either .as soon as my gage gets in the little 0 block tires start to haze

 

[FreeBoost]

I think you're over stating a minor issue. These cars are NOT known to have stalling problems. No more so than any other car on the road. The only ones I know of or hear of are those that are badly out of tune, and are trying to be "band aided" over the symptoms instead of trying to fix the problem.

I've owned my 87 now for over 18 years, and it's never stalled a single time. My 86 will on occasion when slipping it into gear, but that's my doing (converter), and in the 21 years that I've owned it, it's never stalled a single time while the car was moving.

If people choose to keep driving a badly tuned car, then they'll suffer with the consequences.

WOW! I guess I hit a nerve. Apparently I wasn’t very clear. The stalling problem wasn’t tune, it was programming in the chip. I’m glad your cars don’t stall, but I do know of a few that do and I’ve been driving these cars for a long time too. Before you get your undies in a bunch again, all I was doing was pointing out a potential down side of the system, not saying it’s no good. Personally I like the power master system but I haven’t had any problems other than accumulator failures but I know some people can’t stand it – I can’t accept that.
I do agree that bandaiding the loss of rear braking power with the hydro boost system isn’t a good idea. Installing for it’s own merits is a different story.

 

[wagon]

i dont want to hijack your thread but i just changed my wheel cylinders today with hydroboost and same thing i cant hold not 1 lb either .as soon as my gage gets in the little 0 block tires start to haze

I would bleed the brakes and bleed them again. Tighten the rear brakes until there is a bunch of drag. Drive the car around until the brakes clearance themselves, then tighten them again. The more you do this, the more material from the brake shoes you will have in contact with the drums when you apply the brakes. A new set or freshly turned set of drums is important too. Did you install the bigger wheel cylinders, or the stock size?