Toyspeed.org.nz Message Board

by **RS13** » Thu Oct 22, 2009 6:21 pm

R32 (not mine!) failed warrant on pulling to left under braking. Pads have been replaced, brakes have been bled, what else could it be? Faulty proportioning valve? How exactly do these work?

by **matt dunn** » Thu Oct 22, 2009 6:25 pm

more likely to be in a caliper i'd think.

Single or twin pot calipers,
i.e. one piston on each side of the disc,
or all the pistons on the same side of the disc?

by **RS13** » Thu Oct 22, 2009 6:33 pm

Just called the owner, he took it to Autocity, they diagnosed and replaced front caliper seals. Took it back to wof, they said no change. Its' only a GTS, so single pots.

Could you explain how a proportioning valve works?

by **matt dunn** » Thu Oct 22, 2009 7:00 pm

RS13 wrote:Just called the owner, he took it to Autocity, they diagnosed and replaced front caliper seals. Took it back to wof, they said no change. Its' only a GTS, so single pots.

Could you explain how a proportioning valve works?

No,

As I dont know, lol. But could guess.
and i still doubt it will be in that anyway.

If it's single pot it may be in the caliper slides?

Take it back to Autocity and tell them it's no better?

Website · by **Bling** » Thu Oct 22, 2009 7:12 pm

matt dunn wrote:If it's single pot it may be in the caliper slides?

Had the same WOF problem with my car and this ^^ was the problem. I took the calipers to brake and clutch by the hamburger shaped place in sockburn hornby side of overbridge.

by **jondee86** » Thu Oct 22, 2009 7:14 pm

RS13 wrote:Could you explain how a proportioning valve works?

Google can

Proportioning valve or Equalizer Valve
These valves are mounted between the master cylinder and the rear
wheels. They are designed to adjust the pressure between the front and
rear brakes depending on how hard you are stopping. The shorter you
stop, the more of the vehicle's weight is transferred to the front wheels,
in some cases, causing the rear to lift and the front to dive. These valves
are designed to direct more pressure to the front and less pressure to
the rear the harder you stop. This minimizes the chance of premature
lockup at the rear wheels.

DO NOT FCUK WITH THE PROPORTIONING VALVE. You could die...

And it will not be the cause of the car pulling left or right.

Cheers... jondee86

by **mjrstar** » Thu Oct 22, 2009 8:13 pm

jondee86 wrote:
And it will not be the cause of the car pulling left or right.

Cheers... jondee86

not totally true, I had bad left/right bias in a corolla, it has a twin system which was seperated by the bias valve.
IF the bias valve was to fail you normally end up with too muchy pressure to the other side of the car not a weak caliper. (anyone with a brake testing rolling road will be able to diagnose that pretty quickly)

Could have a warped disc or loose wheelbearing which cause excessive knock-off. although there are other sympons that these causes would be. like a softer than usual pedal, and getting pinged for said loose wheel bearing.

I'd suggest swapping pads from left to right. (free and pretty easy).
Or as mentioned above with single pots it may have a shitty slide.
Or check for poor brake balance on the rear, this will still make the car 'pull'.
the fault might not be where you 'think' it is..

by **slammed_integral** » Thu Oct 22, 2009 8:38 pm

what is the brake balance on your wof sheet? are the numbers even for front and rear? which one is low? theres your problem

if this doesnt fix it, try rebuilding your proportioning valve, professionally.

by **matt dunn** » Thu Oct 22, 2009 10:06 pm

mjrstar wrote:
not totally true, I had bad left/right bias in a corolla, it has a twin system which was seperated by the bias valve.

FWD corolla right.

FWD and RWD braking systems are plumbed quite different.

In a RWD the two fronts always get the same pressure,
and the two rears always get the same pressure,

so a faulty valve can cause a front/rear issue, but not a left right.

FWD are
LHF and RHR on one circuit,
and
RHF and LHR on the other so can cause it,
It's done that way as there is no engine braking on the rear wheels.

Pretty sure R32 Skyline's are RWD or 4WD which are front rear.

by **frost** » Thu Oct 22, 2009 10:52 pm

when changed pads, did he have the rotors machined?
if not then there is your problem, one side has more full face contact then the other,

by **RS13** » Fri Oct 23, 2009 6:57 am

frost wrote:when changed pads, did he have the rotors machined?
if not then there is your problem, one side has more full face contact then the other,

Nope, from the sounds of it, they just did the caliper kit, he replaced the pads and bled the brakes, so rotors won't be the issue. I haven't seen the wof sheet, not my car, I'm having a look at it tomorrow after hes' been back to Autocity.

Sounds like sliders might be worth looking at, thanks for the advice guys!

by **B_giB** » Fri Oct 23, 2009 7:47 am

Sounds silly, but check your tyre pressures, if one side is lower than the other it can cause a pull.

by **themaleman** » Fri Oct 23, 2009 10:20 pm

i had to replace my proportioning vaulve on my levin for a warrnt once

by **frost** » Fri Oct 23, 2009 10:58 pm

RS13 wrote:
frost wrote:when changed pads, did he have the rotors machined?
if not then there is your problem, one side has more full face contact then the other,

Nope, from the sounds of it, they just did the caliper kit, he replaced the pads and bled the brakes, so rotors won't be the issue. I haven't seen the wof sheet, not my car, I'm having a look at it tomorrow after hes' been back to Autocity.

Sounds like sliders might be worth looking at, thanks for the advice guys!

ok well i think the rotors are the issue, whenever doing pad change u must always machine the rotors flat so the new pads bead in.

and if pads need changing on a daily driven car, then the rotors will have massive groves in them.
have a feel of the rotor face and if it is like a old vinyl record, time for replacement,

by **Loudtoy** » Sat Oct 24, 2009 7:46 am

frost wrote:
ok well i think the rotors are the issue, whenever doing pad change u must always machine the rotors flat so the new pads bead in.

Really? I've done a few pad changes and never had the rotor's machined, then i guess if you run the pads right out you'd have issues. Never had a problem with the rotors warping or anything either, no lips, obviously oyu check the disk before you put the new pads on but haven't come across any lips or grooves as you describe, little scratches but nothing resembling a groove yet, Run some pretty hard pads on the front of me liftback as well.

by **Mr Revhead** » Sat Oct 24, 2009 8:51 am

yeah, rotors are only machined if worn.... and on the toyotas that most of us have, the pads wear a LOT faster than the rotors.
now, if you had a euro or a lexus you may find the rotors wear a lot faster

by **Flannelman** » Wed Oct 28, 2009 1:04 pm

There are load operated proportioning valves on utes to let more braking force to the rear when load is on the back tray - in reverse to a car.

As for the pulling, it can be any side, front or rear that will be the problem. The WOF sheet will pinpoint which corner to give atention.
Drum brake rears are good for blowing the wheel cylinder and coating the lingings in slipery brake fluid. It is easy to see as the fluid sprays around the inside of the wheel too. A failed diff seal (solid axil) will have the same issue, but smell of diff oil.
Check to see all the steel brake lines aren't damaged by being crushed or bent.
Then check caliper/brake pads/rotor condition
Make sure when ever bleeding brakes that the master cylinder NEVER runs dry.
Also, has it got ABS?

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