AE82 brake shudder issue!

[XS1V]

Hey guys

Been working on this issue for the last few months with no resolution yet found. So scenario is AE82 FXGT with 20v Blacktop, C56 torsen gearbox, AE101 S/S calipers with machined discs to fit, new EBC yellowstuff pads, Equal length driveshafts.

When applying the brakes more at slower speeds there is a large vibration from the front axle, it does it on the road, on the jack stands, wheels on or off.

Now things that have been changed or tried:
Cleaned up (again) the axle flange and back of discs to ensure sitting flat
Brand new TGP discs - No change
New set of driveshafts, hanger bearing - No change
Changed to my spare box, C52 with TRD LSD - No change
Different caliper brackets and slide pins - No change
Bypassed brake booster - No change
Another set of decent engine mounts - No change
Checked clutch, seems ok - Is a TRD unit

Have got another set of calipers to try next and failing that I will be getting brand new wheel bearings fitted to another set of hubs and try that. I am running out of ideas and am uber frustrated and its the last thing to sort for cert so I can get out on track and on the gravel in it. Any ideas, thoughts, previous experiences please shout out.

Brad

[molex]

Any detectable play in the wheel? What are the pads looking like? Pads would be an easier test than callipers. I've got some spare Oem stuff you're welcome to.

Wedge shaped pads can cause the behaviour you're describing

[GOLDAE86]

When did it start happening . Eg hitting something racing and .... etc etc

[sergei]

Are the rotors hub-centric?
Is the hub flange surface clean?
Is the hub flange straight?
Is the drive shaft straight?
Does it happen on both sides or one?

[XS1V]

molex - No play in wheels to point at wheel bearings but I am suspecting bearing not put in straight?? Pads are brand new, I havent driven bugger all on them, only testing drives around home as the vibration was there from the get go of putting the car together

GOLDAE86 - As above, hasnt been raced yet, cant get a cert like this

sergei - Rotors are hub centric, have wire brushed multiple time the hub flange etc. Hub flanges being straight is a good point and as above is my next look into as hubs are only thing really left now unchaged. Driveshafts have been changed three times through my spares and all measure straight with same results. Have done some testing with Ken (kinloud) clamping brakelines on either side and it appears it is there when either side is braked

Brad

[sergei]

Are you using AE111 drive shafts? The track is narrower on AE82 which could cause the drive shafts to bind...

[GOLDAE86]

What about putting the standard brakes back on with standard pads and try that?

[85AW20v]

Inner CV shafts too long and touching each other in the centre of the LSD when the brakes are applied?

[Bazda]

AE82 hub drive flages use a 54mm ID disc.
The SS discs are 55mm ID.

That could be your problem right there, not very noticeable when installing as it only has 0.5mm play side to side.

[1I1]

You can get 54mm ID super strut rotors off early AE101

[Bazda]

You can get 54mm ID super strut rotors off early AE101

All ae101 are 55mm. Ss ae101 only came in the late model versions.

The hubs are usually stepped. So the outer part is 54mm where you would run a hub centric spacer when running after market mags.
The inner part is 55mm where the disc sits. its only 7mm wide (thickness of the disc face)

When I get free time I go to pick apart and grab drive flanges for spares lol.

[Grrrrrrr!]

You can get 54mm ID super strut rotors off early AE101

All ae101 are 55mm. Ss ae101 only came in the late model versions.

Incorrect, my 91 was superstrut. Dunno about the rotor ID tho, never had any issues with the dba rotors I put on it.

[sergei]

My non-ss AE101 was 55mm.

[Bazda]

SS or no SS, All 55mm brake disc centre.

[allencr]

Any runout AT ALL on the hub, and on the disk?
What does 'shudder' mean? Noise, vibration, pulsing in the brake pedal, the steering wheel, in the body/chassis, engine, by themselves or in combination or in all 4?
Good luck.

[XS1V]

Ok so since changing discs again, the shudder is now gone with suspension sitting at normal angle (so car is on jacks and both a arms are jacked up) which is good, but if you have the suspension at full travel the shudder is still very prominent.

When I say shudder, the whole car shudders in time when braking force is applied and higher application equaling more shudder. There is no feedback through the pedal from pulsing and run out measures within limits. Steering wheel vibrates the same as the car does.

FYI AE101 S/S discs are 54mm not 55mm and they came out from production start in 1991 - I dont know where you got that from but I have the discs right in front of me and that is the measurement. Non S/S AE101 IS 55mm and so are AE111 S/S discs.

So..... Any ideas on why a change in geometry would bring on this shudder under braking??

Brad

[1I1]

Are you using AE111 drive shafts? The track is narrower on AE82 which could cause the drive shafts to bind...

This perhaps

[Bazda]

Ok now I remember that the early SS discs are 54mm as I have a drive flange off one!

[XS1V]

I am using AE92 shafts now, have had AE111 in previously with same issue.

Barry, know of any suppliers of discs for these other than Toyota?? Have not found any yet as all that have them listed that we have tried are wrong

Brad

[Grrrrrrr!]

So..... Any ideas on why a change in geometry would bring on this shudder under braking??

Brad

Cant see why it's only under braking, but CV joints bent beyond their design limit would be the most obvious one. Which would make me ask how serious is this in the real world,.. how often are you trying to brake when wheels are at full extension? Or is this a cert/wof issue?