Car pulls to right under heavy breaking

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Creech

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heymagic
Wow, that kinda looks like something in an old navy training film......

Gonorrhea and YOU......

Not me...maybe JV

Ok... I got the car all put back together. I thought the new right front ball joints and torsion arm bushings would solve the problem. It did not.

Mark drove the car around the street and I followed him in my car. Under heavy braking it looked like the right rear tire was locking up.

The right rear suspension is fine, since we disassembled it to check things over. So, I'm stumped. I guess I can try and look at the right rear caliper and see if it is sticking?

Look to the left side and see if it is not working.

Are your brakes plumbed corner-to-corner, side-to-side, or front-to-back? I ask because, on a car that is plumbed corner-to-corner, we once had the front-left caliper seize, which would cause the rear-right to lock up. If you are plumbed side-to-side, then that funky front-right caliper could cause your rear-right to lock up.



Edited 1 time(s). Last edit at 06/17/2013 01:00AM by Iowa999.

plumbed front to back. I also have a hydraulic handbrake.

last night in the garage I pulled the handbrake little by little and checked to make sure it was applying pressure to each rear wheel. It seemed to be working equally.

(I also bled the brakes)

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johnhuebbe
plumbed front to back. I also have a hydraulic handbrake.

last night in the garage I pulled the handbrake little by little and checked to make sure it was applying pressure to each rear wheel. It seemed to be working equally.

(I also bled the brakes)

AND???? what did you see? ANY bubbles? any screwy color?

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

No bubbles, fluid looked good actually. I was running Super Blue fluid. Switched to Motul 600 (was having some brake fade at STPR)

The only things I can think of:

- Rotor, one side warped/glazed? They didn't look like it, but I didn't test runout.
- Pads. I have a spare set that I can swap out and check if that helps.
- Brake lines. I don't have any spares. Last changed out in January 2012.

I'm stumped. I guess if I can't fix it, maybe I'll adjust the balance bar more forward.

do you regularly de-glaze your discs? 220 paper and brake clean, ya noez?

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

No I do not. Is this something I should be doing after each rally?

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johnhuebbe
No I do not. Is this something I should be doing after each rally?

No. A couple of hard stops with cold race pads will do the same.

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johnhuebbe
No bubbles, fluid looked good actually. I was running Super Blue fluid. Switched to Motul 600 (was having some brake fade at STPR)

The only things I can think of:

- Rotor, one side warped/glazed? They didn't look like it, but I didn't test runout.
- Pads. I have a spare set that I can swap out and check if that helps.
- Brake lines. I don't have any spares. Last changed out in January 2012.

I'm stumped. I guess if I can't fix it, maybe I'll adjust the balance bar more forward.

What calipers do you have in the rear? 4 pots? Are they the same size pistons by any chance? (I've seen it unfortunately) And the caliper pistons are they free or jammed? How about the damper is it good or sticking? You can try and see if the lines to the left side aren't kincked. Putting the balance bar all the way to the front to check to see if its a brake issue will work. If it still shows the same syndrome then its in the suspension.

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Cosworth
What calipers do you have in the rear? 4 pots? Are they the same size pistons by any chance? (I've seen it unfortunately) And the caliper pistons are they free or jammed? How about the damper is it good or sticking? You can try and see if the lines to the left side aren't kincked. Putting the balance bar all the way to the front to check to see if its a brake issue will work. If it still shows the same syndrome then its in the suspension.

4" Hawk brand, Black Compound

Calipers are CNC brand, SERIES 625, Four Piston
Piston diameter is 1.75”, I believe the rotor is 11" Diameter
http://www.cncbrakes.com/bac.asp?grp=bac&subgrp=4&series=624-625&subseries=

I didn't pull the rear calipers off of the car, just the fronts. I can check it tonight.

Brake lines looked good, no kinks when I checked them all. Shocks were good, moved freely. I had the rear shocks off when I adjusted the torsion bar to raise the car a bit and the fronts off when I replaced the ball joints & torsion arm bushings.

I'll also try putting the balance bar all the way forward and see what happens.

Also, I must say up to this point, that Mark and I have been happy with the CNC brakes. Only issue has been brake fade on long stages with lots of downhill parts. STPR had a few stages with some steep downhills. (why we decided to switch brake fluid)

And... We should probably install some openings in the front of the car and duct some air to the brakes.



Edited 1 time(s). Last edit at 06/17/2013 01:37PM by johnhuebbe.

John, this is very general. But you know I try and start from what i call "praxis" or previous (established/proven) practice, right? Seems a good starting place...

So when it comes to brake stuff, we look at sumpin very successful in hard competition of about same size and weight and see what they used.
MkII Escort is a good starting point cause there so much published...

Front calipers for the nasty ones, the Gp4 ones were originally from F3 or F3000 cars cause those water-bug looking things --which were ex F1 chassis in those days, had 13" wheels so here was a caliper that was STRONGER than hell that would go under 13"...they use 4 x 1.5"/38mm pistons front

http://www.apracing.com/product_details/race_car/brake_calipers/historic_range/cp2361-closed_backed_caliper-38.1mm_bores-%C3%B8267x21mm_disc.aspx


TECHNICAL SPECIFICATIONS
Piston Sizes - mm Ø38.1 x 4<------------
Piston Area cm³ 45.6
Disc Diameter - mm - Max = Ø267.0
- Min = Ø248.0
Disc Thickness - mm 20.7
Weight (no pads) - Kg 2.0
Hydraulic Threads 3/8"x24UNF
Mounting Type Blank Lug
Mounting Centres - mm 76.2 / 94.0
Mounting Offset - mm 28.7 / 31.2
‘PL’ Dimension - mm 55.1 / 81.2


OK then came bigger cars like the Sierras i like or 240 Volvo or Golf or Opels
they used progressive 2 x 1.5" and 2 x 1.625 on a car from say 2300-2600 lbs..
on Gravel, remembering average speeds were around 95/100 km/hr

In Finland, Ford used 4 x 1.625"/41.3mmm, higher average speeds, and Volvo in WTCC or road race used them also on some tracks..

Whas all this about?
4 x 1.75" is a typical circle track size....ie a car weighing min3500lbs and going 120-180mph..
Some tracks they might use 2 x 1.75 and 2 x 1.81" or even 4 x 1.81"

You have huge pistons for a car your size/weight/speed...
I posit that if you get the pedal to feel good, like a pedal not a squishy thing, then you brakes are going to be REALLY TOUCHY...

The other thing is pads: isn't Hawk Black so really vicious pad? I know from locally that they EAT---or have eaten---discs..

Maybe you just have way too much touchy brakes?

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

While you may be correct with what you wrote, when Mark and I originally put on the new brakes & MC, Paul helped us out with picking sizes and where the balance bar should be. Up to this point everything has been fine and there were no lock-ups and the car stayed straight while under heavy braking. So, it seems like something is broken/has changed and this is causing it.

I can measure the disc thickness tonight to compare with what they were originally, but when I was disassembling the front, there was no noticeable lip from where the pad contacted the rotor.