Jump to content

Brake problems


Recommended Posts

3400 lb street stock (metric) using a stock master cylinder no power assistance.

left front only caliper and rear drum brakes.

 

Everything bleed with no issues. Pedal is hard and has about a good 1 1/2" of throw before getting hard.

This weekend I raced when I hit the pedal the only thing you feel is the left front grabbing and jerking the car towards the infield. This was ok as I was fast enough to qualify 2nd row and stay out front w the leader. So my brakes were only for setting up the car entering the turns. If needed to I would not be able to shut down the car with no rear brakes. Again they are drum. We set the adjustment up so the drums barely would go over the shoes. Wheel cylinders both look good and do move when the pedal is hit.

Open for suggestions before I start digging into it.

Link to comment
Share on other sites

lol...rears dont stop...guess you learn something everyday...

 

Are you saying they didnt work from the start? or stopped working?

 

On the wheel pulling...all my 3 wheel brake cars do that...so thats normal...but to me sounds like the rears are just not doing anything...something i like to do with stock master cylinders...is to plumb the front and rear ports of the master cylinder together...(normally more for all disk cars though) on your deal my first inclination would be bad master cylinder...(after trying to bleed them again...cause air is tricky)

 

less likely would be bad shoes..(or installed wrong?) I have had some that looked great..but just didnt do anything but make the pedal hard... I kinda check drums by having someone pump the brakes with the wheel off..you can see the drum move when the pressure is applied...and kinda see how hard the wheel cylinders are working....

 

one more thing would be a kink in the lines...the way I understand it...disk brakes work off pressure...drum brakes off volume... (could be remembering it backwards) so..something to check....

 

good luck...(I hate bleeding brakes)

Link to comment
Share on other sites

by selector valve are you refferring to the prop valve (stock has the brake warning light connector)?

 

If so this can even be replaced with an adjustable to kinda bias more back to the rears. Won't help with fading issues - asking the backs to stop ya will heat em REAL fast especially drums - but may help when they are not hot.

Link to comment
Share on other sites

3400 lb street stock (metric) using a stock master cylinder no power assistance.

left front only caliper and rear drum brakes.

 

Everything bleed with no issues. Pedal is hard and has about a good 1 1/2" of throw before getting hard.

This weekend I raced when I hit the pedal the only thing you feel is the left front grabbing and jerking the car towards the infield. This was ok as I was fast enough to qualify 2nd row and stay out front w the leader. So my brakes were only for setting up the car entering the turns. If needed to I would not be able to shut down the car with no rear brakes. Again they are drum. We set the adjustment up so the drums barely would go over the shoes. Wheel cylinders both look good and do move when the pedal is hit.

Open for suggestions before I start digging into it.

for almost 2 years our car vertually had no back brakes but bled out jus like you're sayin. for some reason i changed the rear rubber hose that leads to the differential and believe it or not the back breaks started grabbin.when i took it off i could not see any blockage but it worked! IDK...

Link to comment
Share on other sites

for almost 2 years our car vertually had no back brakes but bled out jus like you're sayin. for some reason i changed the rear rubber hose that leads to the differential and believe it or not the back breaks started grabbin.when i took it off i could not see any blockage but it worked! IDK...

SAw the same thing with a front hose once - we replaced it and played with the old one until we "discovered" what was happening. The hose is a multi ply hose - worked a little but as soon as we cranked the pressure the fluid would get between the plys and shut the hose down. Definately a good place to start looking!

Link to comment
Share on other sites

Sorry I didnt see the post soon enough, but on rear drum brakes to counter act the return spring tension the brakes should be adjusted with the drums installed and then adjust them where the drum has enough drag on it at rest where it is a little stiff to turn by hand. This will do two things, one it will cause the shoe to be seated on the metal stops of the adjuster wheel and two it will reduce the travel that the shoe had to make when the wheel cylinder actuates , as the rear wheel cylinders dont have very much travel to do their job. but you have basically done the same thing with the residual device, which comes in two different pressure settings.

Link to comment
Share on other sites

As I am not a dirt racer I see no benefit in 3 wheel brakes - other than to pitch the car quicker. On dirt you can't whoa up enough to avoid a whole lot anyway so brakes are pretty much optional in that regard so giving up 40% of your stopping power for an entry aid seems logical.

 

Question remains - considering that even on dirt LR to RF weight transfer is occuring, is it worth giving up all of your RF anti-dive just to get the back end around faster? Seems the ability to overbrake in (and still have some control via brake pedal over rate of weight transfer) would be diminished and take passing opportunities away for the sake of higher potential speed - which does no good when stuck behind a slower car taking two grooves!

 

In that context isn't it better to just proportion the fronts L/R leaving at least SOME RF brake?

Link to comment
Share on other sites

I tried the 3 wheel set up, it takes a lot of finess, if you hit the brakes too hard you're coming around. If the weight isn't too big a issue you're better with 4 wheel brakes and get more reaar bias to bring the car around.The class I was in only required 2 wheel brakes, but having 4 wheel brakes helped me weave thru and miss a big first lap wreck the first night out with the car.

Link to comment
Share on other sites

As I am not a dirt racer I see no benefit in 3 wheel brakes - other than to pitch the car quicker. On dirt you can't whoa up enough to avoid a whole lot anyway so brakes are pretty much optional in that regard so giving up 40% of your stopping power for an entry aid seems logical.

 

Question remains - considering that even on dirt LR to RF weight transfer is occuring, is it worth giving up all of your RF anti-dive just to get the back end around faster? Seems the ability to overbrake in (and still have some control via brake pedal over rate of weight transfer) would be diminished and take passing opportunities away for the sake of higher potential speed - which does no good when stuck behind a slower car taking two grooves!

 

In that context isn't it better to just proportion the fronts L/R leaving at least SOME RF brake?

I am a dirt racer and I agree with you, I want all four brakes, it helps to get deeper into the turn and with the correct biasing 4 brakes work so much better than 3. You would also be surprised at how much traction you get on a properly setup dirt car.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...