Problem: Alcon/Prodrive vs. Godspeed discs
 

Hello everyone,

I have an impreza classic my99 witch have the alcon/prodrive brake kit.

I needed to replace the discs so I asked for Ian from Godspeed to send me new discs and brake pads.

Installed them and took it for a test drive (keeping low speed of course).

I started to feel some vibration on the steering wheel while braking. Especially on speeds higher than 60 miles per hour.



I've been asking for some help from Ian, but so far he hasn't replied my emails.


Yesterday I took off the discs to see if I could find anything strange.

And I think I have.


The screws on witch the disc attaches to the car have 2 different areas. One area with screw, and another just simple diameter. As I place the disc on it's place I believe that the disc is not going all the way to be locked on the normal diameter of the screw.


I saw on another post the similar assembly of my discs and they seem to attache a bit deeper than mine.


I had no major problems on fixing the clipper where it belongs and also placing the brake pads.


My question is: the diameter of the hole in the discs is supposed to have some gap in order to fit to the screws?

Please give me some advice as I’m getting none from Godspeed.


Thank you!

i have a 98 sti. and it has no screw to fit over. They should be kept flush with the HUB and held on by the wheel, again flush.

The whole you may be refering to. is it threaded?

Previous disks have had a retaining screw, however i think the threaded hole is so you can screw something in to push the disk off if it becomes stuck on.

Can you post a picture please.

The feeling I have is that the disc is not in full contact with the hub. As soon as I place the disc in its place it seems that it gets “stuck” in the screws and not in contact with the hub.

Also when I removed the original alcon discs they came off fairly easy. These ones and only after driving 50 miles were really hard to take off the hub.

I hope the user V7 SYN wont mind me using his pictures as I don’t have mine…

Painted red and the part of the screw I mentioned previously.

http://i152.photobucket.com/albums/s..._sagan/2-2.jpg

After I assemble my discs I only can see the tread part of the screw and no normal diameter like we see on this picture.

http://i152.photobucket.com/albums/s...ro_sagan/1.jpg


And again I have the feeling the disc is not fully in contact with the hub and just “stuck” on this normal diameter part of the screw.

Anyone using godspeed discs!?!?

I really hope to get some feedback from Ian about this.

The discs I'm talking about are these:

http://i152.photobucket.com/albums/s...gan/Img001.jpg

Sorry for my English! I’m trying my best to explain the situation…

I've got a feeling, by the sound of it the off set on the bell could be wrong. (Maybe) without looking at I can't really say. On my there is no hole for a screw, the disc is held on by the claiper and the wheel. If you can get some pics of yours that would help. If you have any more question just ask.

ian is on holiday till the end of the week so his voicemail says

ok thank you.

i was finding a bit strange to not get a reply.

i guess he's way better than we are! :)

Just so I can make some points clear, the discs I got have 5 holes. My bad English sorry!

If the part of the screw that I marked as red is for instance 8mm diameter and the disc is also 8mm diameter this may cause the bad contact. The holes in the disc should have like 8,05mm diameter holes.

I really have the feeling that the disc doesn’t fully contact with the hub due to this.

From the pictures, the concern is that the bells are getting stuck on the studs in the vicinity of the hub and that this is preventing proper alignment of the bell/disk assembly onto the hub/flange.

Exactly!!!

So should the studs have a smaller diameter than the holes in the bell of the disk!?

If so, there should be a sinificant gap!? Or just very thight?

I'm willing to drill a bit on the bell so it fits all the way to the end of the stud.
But I'm also afraid that by doing this i'll create bad fitment...

Drill it, i'll be alright. :)

Yesterday I took the car to an expert on brakes.

He double checked everything and it seems everything is well assembled and as it’s supposed to be.

The disc is in full contact with the hub after all.

We took the car for a test drive and the steering wheel still shakes while braking at higher speeds.

He told me that this is coming from warped discs…

He asked me if I wanted to remachine the discs so it would be ok, but I prefer to talk to Ian first.

Mean while I got an email from Ian and in fact he’s on vacation.

Next week we’ll see how we can solve this.

Here’s a picture of the hub.

http://i152.photobucket.com/albums/s...gan/Img002.jpg

Perhaps read this first..

StopTech : Balanced Brake Upgrades

anyone else with ideias to solve this!?

Hi
Have you checked all what I emailed you today ?
Cheers Ian

yes Ian.

and i've replyed.

but still not problem solved... :(

basic things but have you checked the set-up for run-out with a dial gauge???
also i have had a warped drive flange in the past that caused a myriad of problems on a customers rally car when switching from std 4pots to AP's that had previously had no issues.........

alyn

Curious to know mate...did you get this sorted?

I've got a P1 with the Alcon calipers and Godspeed discs which had been fitted by the previous owner.

I remember when buying the car about 4 months ago, the previous owner mentioned the garage fitting the discs had to fit some shims to allow the calipers to clear either the hubs or discs, I can't remember.

This is worrying as I know my front discs will need replacing soon and would want to go for the the Godspeed discs over the Prodrive one's due to cost but don't want any hassle fitting them.

Hope you sorted it out.

Hi

I didnt have more time to solve the issue. been quite busy at work.

but right now my mechanic assures me that the problems are in the discs. either the rotor or the hub.

ian from godspeed just didnt care about my satisfation with his product. i'm complaning about this and so far havnt had any solution.

by this point i'm regreting having picked godspeed brakes.
the alcon original discs for sure are more expensive but i think i would have any of these issues...

Why lie ? I have emailed you things to look for and check and get back to me , which you havent done , I would like to know the problem , and help you sort it as much as you do.

I had someone else with a P1 who fitted these discs a couple of months ago and phoned me shortly after fitting them they were warped , they had not been fitted correctly and this is why they warped , the Alcon brakes have shims supplied new with the kit to centralise the calipers over the discs , if you do not set this up correctly then the pads will be a very tight fit going in and will drag on the discs and overheat them , this is a very bad thing to do to a new disc.

Your discs were absolutly perfect and running true when they left us , we check and double check this before shipping them out to customers , so I do not believe that it is a disc issue , it might be now after you have run them , if they are not fitted and set up right.

I have asked you to check the runnout and let me know what it is , if you dont have anyone local to you that really knows brakes , and I dont mean who knows how to fit them , anyone can ' fit ' brakes , someone who can check the runnout on both discs and bells to find whats gone wrong , send them back to me , I will check them , put whatevers right , and ship them back to you in Portugal for free.

Cheers Ian

hello ian,

i'm sorry if i'm saying something that may seem unfair.
but the simple fact is that i bought the discs and they are giving me problem.

if there are some specific instructions to assemble (different from any kind of disc) there should be instruction proceadures like on any normal new material.

i even had to look for the right rotation of the discs to assemble them.

i know you have a good reputation and also of seeling great material, that's why i decided to buy from you.

but each case is one case and mine is that i'm not happy with the discs.

i'm only posting here because someone might have had the same problem as i'm having.

i'm sorry but can you explain what ddo you mean with the runout test? do you mean to cheack if both discs have right now the same thikness?

If there was run-out on the disc, would you not feel the problem through the brake pedal (pulsing?)
Before dismissing the discs, get the wheels accurately balanced in both planes i.e. static and dynamic.
I've had steering wheel vibration, ONLY APPARENT WHEN BRAKING, cured by wheel balancing.

JohnD

Mmmmm. This is all very interesting.
I have had a similar experience to the OP. Fitted new Godspeed discs with my Prodrive/Alcon calipers and experienced a lot of brake judder through the pedal. The discs were bedded in as per Ian's instructions "normal road use" - none of the heavy stops mentioned in the Stoptech article referenced above.
I was left wondering if the calipers are in desperate need of refurb after 140K miles, so I have just stripped off the whole system and replaced the standard 4-pot calipers (one of which is now leaking fluid! Ho hum...)

Question for Ian then: how should I check the condition of my discs now they are off the car? Can I tell if I "warped" or damaged them by incorrect caliper spacing when they were fitted?
Surface flatness test maybe?

BTW - How do you measure disc run-out on a Subaru? With one corner jacked up the diff stops the wheel from turning!

Hi Mike
I fit the discs into my lathe , put it in neutral so I can spin it and check it for runnout with a dti gauge , if your discs are off the car you can send them back for me to check them ,
Cheers Ian