3200 GT Brake Juddering

[sdlangford]

My 3200 gt has been away having some work done over the past few months and today i took her out for the first time for a good run, well first time in a few months.

Had a bit or grinding on the brakes to start with, but nothing i have not experienced on my other cars.

When i was braking from 60/70mph down, i got a terrible judder through the brake pedal and the car generally.

Not had this before.

I did post on this forum in early autumn i had a "soft break" feel, and the odd exerience of the pedal going to the floor. After a brake fluid change i do not have this experience but still to me the pedal feels softer than i would expect for a car of this nature. I have not driven another 3200 gt so have nothing to compare it with. My 911 has a very firm and crisp feel to the brake pedal.

The car is going into the local garage for a service and cam belt next month so i am thinking of getting the brakes overhauled.

I just wanted to see if anyone else had any advice to give incase i get fobbed off with the old "warpped discs" diagnosic.

Many thanks.

Simon

 

[conaero]

The warped discs would be the obvious one but you would not get this through the pedal, it would be the steering wheel where the vibration would occur. Through the pedal would suggest ABS or calipers issues.

It sounds like a pad/sticking calipers to me.
Especially as this has occurred after a period of no use.

Take the pads out and make sure they drop into the calipers and not require tapping in.

Clean the pad guides and file the pads if required.

Next I would make up some pads dummies out of plywood, place them in the calipers and observe as the pedal is depressed. A bit of lube/silicone spray under the piston seals always helps.

Work the pistons in and out until the move freely.

Also look at loose suspension such as the track rod ends.

 

[allandwf]

Although I wouldn't think it would lead to your symptoms, check the handbrake shoes. They can stick and delaminate if left, causing noise.

 

[davy83]

i would say warped disks or sticking pistons in the calipers. overheating the disks is quite easy, and the pistons in the calipers corrode and sieize up. i have jsut had my calipers stripped and re-manufactured as the sticking pistons were getting bad, and i think 3 of them were seized.

 

[voicey]

Discs don't really warp although they do vary in thickness, which gives the juddering. The thickness variation is commonly from pad material transferring onto the surface of the disc although I suspect in the OPs case they have rusted up.

I would recommend a few good hard braking events from >100mph to about 40mph followed by at least 10 miles of constant motorway driving to sort the discs out.

 

[sdlangford]

Thank you for your suggestions, i will take the car out again this week and see if i can try your suggestions.

I did notice today a lot of the drill holes in the discs were full of brake build up aswell.

Simon

 

[davy83]

I think a lot of cars have either the wrong disks on them and also do not have the air vents in tact, so if you push it at all the disks get too hot and this can cause distortion.

Discs don't really warp although they do vary in thickness, which gives the juddering. The thickness variation is commonly from pad material transferring onto the surface of the disc although I suspect in the OPs case they have rusted up.

I would recommend a few good hard braking events from >100mph to about 40mph followed by at least 10 miles of constant motorway driving to sort the discs out.

 

[Assetto 52]

Sounds like as stated before sticky piston on callipers its a Brembo thing.

 

[alfatwo]

Its an old car thing, they all do it..

 

[CatmanV2]

I think a lot of cars have either the wrong disks on them and also do not have the air vents in tact, so if you push it at all the disks get too hot and this can cause distortion.

It doesn't really, you know. This argument went on and on in the bike world. It *feels* like they are warped but I've never heard of anyone that actually measured one and found it to be the case.
YMMV of course

C

 

[alfatwo]

Just chuck a new pair of discs and pads on the front and your back to normal!

Dave