BRAKE SHUDDER ISSUE

[FORDTECH]

Fordtech

Thanks for that.

Neither of our cars has the dreaded shudder issue yet, so I think I'll check the torque, make sure it's spot-on and cross my fingers that it never happens. If I understood you correctly, if the torque is right, the rotors won't distort and the revised shims won't be necessary??

I know that the dealers/tyre places are supposed to get it right, but my experience is that it never hurts to check.

Regards

zeke

Zeke,

Even if the wheel nuts are torqued to the right spec you still nee the revised shims to enable the pads to move more freely in the calipers.Also your rotors may have DTV already but it's just not noticable yet.I'm afraid you'd only be prolonging the inevitable.But I could be wrong.

[Guest Mo2003turbo]

.....so if FORDTECH is correct are they "spinning me a line" ....when they say say my T has been delayed off the line because they are fitting new calipers ?

Mo

[Guest 56Mainline]

FORDTECH, DBASTEVE or others in the know:

If you replace the standard Ford rotors with, say 4000 series DBA rotors, but still use the standard Ford calipers (with new/better pads), then will this DTV (Disc Thickness Variation) continue to be a problem that results in brake shudder?

How critical will each of the following be given that the non-Ford rotors are used:

• revised shims
  
• correct hub to rotor torque
  
• correct wheel nut torque
  

Thanks in advance....

[GOLDIE]

We fitted dba gold disc's with the standard ford pads after 10000km the shudder started again, changed front pads to QFM pads and there has not been any shudder since I have also noticed that all the funny marks on the disc have gone.It will be interesting if shudder comes back.

I have been using QFM on taxi's and limo's for eight years now and they have done a lot of work to improve there pads.

Ian

[FORDTECH]

.....so if FORDTECH is correct are they "spinning me a line" ....when they say say my T has been delayed off the line because they are fitting new calipers ?

Mo

Mo2003,

There is some truth to the line they're spinning you.There is a revised caliper being fitted to the latest built Falcons but I'm not sure about the production delay.

56Mainline,

From what I know most of the problem is to do with the disc and hub being 2 seperate components(As opposed to the early hub assy's where the rotor and hud is 1 peice). Being seperate components they are reasonably thin in construction and therefore suceptable to distortion when over tightened.So I dont see why any other rotor that you fit would be any different.

[aniken]

So the cause is over-tightening of the wheel nuts, which is something that is done during pre-delivery at the dealers. Do Ford have any stats on the number of warranty claims for DTV (brake shudder) by each dealer site? Would be interesting to see if some dealers are getting more claims than others...

[GOLDIE]

The basic design of the disc and hub assy is the same as was on the au and with the hardest of driving we could give it I only machined the disc once in 130000 km or four years.

So as to say it is the torque of the wheel which clamps the disc to the hub being the problem I do not think it is the major cause of the problem.Expensive Daewoo have had this fault for a number of years and I do not beleive they have find it to be the torque of the wheels,they use the same hub and disc design set up as the falcon.

I beleive it is the compostion of the pads and disc that are the major problem now.

There is no longer any aspesdose allow in the pads now and this help to hold the pads together and reduce heat.

I have just got back home from a very spirited run though hilly and long straighted roads with hard braking and with the pads that I fitted[QFM brand] I could not even get them hotter enough to get them to smell and also the marks left on the disc from the ford pads have also gone and there is no signs of heat spots on the disc.

I will let you know how they go after some more driving so far so good.

Ian

[FORDTECH]

Ok guy’s I’ll try and explain it the best I can. Please remember though that this is the official Ford explanation and remedy (So don’t shoot the messenger). This problem has been extensively investigated and after trying a sh*tload of different methods of repair and different torque settings on the associated components and this is the end result.

The basic problem to start with is what is called DTV (Disc Thickness Variation), which is caused by excessive runout of the front rotors. The excessive runout is caused by inconsistent wheel nut torque. What actually happens when the wheel nuts are tightened the disc and hub distort (or warp), causing the excessive runout. While the vehicle is being driven the disc brake pads can no longer maintain the air gap from the rotor because the rotor is no longer spinning true (it now wobbles like a buckled rim, but not as exaggerated). Now ordinarily the disc pad would be forced back into the pad retainers of the calliper. But there in lies the problem (hence the revised shims). The shim that is already fitted to the callipers doesn’t allow the pad to move far enough away from the rotor, so it slowly machines the high spots off the rotor until eventually the thickness variation in the diameter of the rotor is that inconsistent that when you apply the brakes you now apply pressure to a rotor that is thinner in certain spots, and voila, Brake shudder.

Now the fix that every Ford dealer in Oz should know is as follows:

First you have to remove the calliper and rotor, remove the ABS sensors, clean both mating surfaces of the disc and hub, refit the disc to the vehicle making sure the phase marks on both are aligned correctly (Yellow paint on 1 wheel stud and a date stamp on the rotor near the relevant stud hole), attach the on car lathe adapter to the hub and torque the retaining nuts to 50nm, attach the lathe to the adapter and start machine, allow machine to calibrate itself before starting to cut the rotor, once calibrated start machining the rotor, once the machining is completed and before removing the lathe hub adapter attach the digital dial indicator and measure the TIR(Total Indicated Runout), it should measure 40microns or less (the procut lathes that are used have been calibrated to 20microns (25.4microns = 1 thousandth of an inch), remove the lathe hub and remove all the metal swarf from around the rotor and hub area, refit the ABS sensors, refit the brake callipers, remove the bottom main calliper body retaining bolt and pivot body out of the way, remove both pads and retaining shims, fit new level shims and refit both pads, replace main calliper body and refit wheels, tighten wheel nuts in a star patter using a 135nm tork stick, or using a tension wrench and socket torque the wheel nuts to 135nm.

The unfortunate thing about this is that if you get a flat tyre or if you have had other wheels fitted and the nuts are not re torqued to specification then you reintroduce the problem. So while this may be a permanent fix at the dealerships it can become a problem as soon as certain circumstances arise.

Hope this helps

FORDTECH

P.S This procedure should not effect your pedal travel in anyway. If it doesnt feel right take it back.

If this method of repair is correcting the problem,then it's pretty safe to say it was problem.

[Guest Mac_Dude]

231 kms and no shudder yet

BUT, the XR6T STINKS!!!!!!!!!!!

There is a 'burning' smell coming from somewhere. It's worse than the 'new car smell' I'm used to.

All I can say is that it is NOT from the engine bay - it doesn't get worse when I stick my nose in the bonnet.. Rear brakes?????

Oh, and there is a small puddle of 'red something' under the right front wheel. Tomorrow in the light I'll look at the fluid levels.

[Guest Mo2003turbo]

Mac_Dude,Nov 3 2003, 08:55 PM]231 kms and no shudder yet

.....did they tell you anything about ??? "the new brake components" on your new vehicle.....they have delayed my "baby's" delivery for another week but I did give them "heaps" when I was ordering it, about the apparent brake problem.....it might be pay back time !

Sorry about the smell.....a bit rough when your new toy stinks so foul..... please let me know what it is, if you can locate it

Mo