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Discussion Starter · #1 ·
Just fitted S3 rear brakes to my 2000T Mk 4 1.8T, using new vented discs, S3 callipers, mounts, new Pagid pads and Foxys adapter plates

Dispensed with backing plates and fitted a new NSR hub/bearing unit after original inner race was seized on stub axle and had to be ground off!

Only problem is still long and squodgy pedal, even after pressure bleeding with Sealey pump-up unit, although it stops great when hitting the pedal hard ? just doesnt feel good

Letting the car stand and settle for the weekend, then taking it back to workshop early next week for further pressure bleeding with the callipers off, this time will be using Goodridge ss hoses and Ate Racing Blue fluid from ECP

Anyone else experienced similar problems?
 

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New calipers usually dont take much to bleed.

New pads can cause a spongy pedal at first, need bedding in, how many miles have you done.

Just a question, why did you get rid of the backing plates?
 

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Discussion Starter · #3 ·
Quote: posted by budge on 17/12/2004 19:47:17

New calipers usually dont take much to bleed.

New pads can cause a spongy pedal at first, need bedding in, how many miles have you done.

Just a question, why did you get rid of the backing plates?

No definitely not just 'green' pads ? have given plenty of time for the adjustment to take up and the pads to set to te discs and pedal is still too long and feels squodgy

The new vented discs are larger diameter and foul the original back plates. Could have trimmed back the lip, but decided to take them off
 

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Hi Neil, did you use a puller to take the old rear hubs off?, and what did you use to put the new hub on to the stub axle?

Zak

P.S.recieved my bentley manual today, THANKS
 

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Discussion Starter · #5 ·
Quote: posted by hz2921 on 18/12/2004 17:58:58

Hi Neil, did you use a puller to take the old rear hubs off?, and what did you use to put the new hub on to the stub axle?

Yes, used a conventional gear puller, except that the inner race was stuck on the stub axle and didnt come off!

Drifted the new hub on using a socket which fitted perfectly over the inner race
 

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Neil, did you get the backing plates from a golf anni?, i have which is why i have to change the hubs as well, as the hubs have to be taken off , before removing the backing plate.
 

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Discussion Starter · #7 ·
Quote: posted by hz2921 on 21/12/2004 01:34:41

Neil, did you get the backing plates from a golf anni?, i have which is why i have to change the hubs as well, as the hubs have to be taken off , before removing the backing plate.

No, I should have done as I now know they only cost about 10 quid each. But in the heat of the moment, I decided to dispense with the backing plates altogether, the alternative being to trim off the flange of the original backing plate which interferes with the larger disc. But, to remove them, as you say, you have to pull off the hubs...
 

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Discussion Starter · #9 ·
Quote: posted by PJ52GLY on 21/12/2004 17:33:11

i just trimmed back where did you get them s/s hose from as i could not get hold of any

No, you are right. When I first mentioned them, I had ordered a set through ECP, who then got in touch to say they didnt stock them. Spoke to Goodridge who say they have withdrawn Mk 4 kits from sale, and also Automec who expressed surprise at first and then confirmed the Goodridge story. Not quite sure what the problem is, but I have posted a separate thread about ss hoses for Mk 4. It is quite a complicated set-up on the Mk 4, so I guess there are production problems for aftermarket manufacturers...?

BTW We have now bled the system again (vacuum and pressure methods) using Ate Racing Blue fluid, this time taking the rear callipers off and turning them over to release any air lock. System now works fine, although still needs bedding in.
 

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I've just done the 312 conversion on my TDI (originally 280mm up front) combined with the std solid rear discs and pagid FR pads all round.

I have the same 'dead travel' on the pedal before the brakes bite. It seems likely the problem we describe is caused by vehicles originally fitted with the 312front / vented rear brake set up having a much larger master cylinder. Vehicles equipped with 280/288 front discs have a smaller master cyl.

The larger calipers require a greater volume of fluid to function, and thus more force to shift the pistons. Sourcing an upgraded larger master cylinder will bring the brake pedal back to its forocious self so i'm led to believe.
 

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Ive never heard this before about needing a bigger master cylinder.

Ive fitted the 312mm discs to front, no problems, there brilliant, just got to do the rear.

What about people that fit alot bigger calipers to the front, like porsche or brembo ones, do they have any problem with the master cylinder?
 

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I have fitted 312mm front discs to 2 Golfs one that originally had 280mm and one that had 288mm neither presented any problems with pedal feel and as for the bigger caliper needing a bigger master cylinder to operate it this is not true as all the calipers have the same size piston and the 288 & 312mm calipers being identical using leverage to increase braking effect rather than extra pressure that a larger piston would provide

p.s. You can use Vag-Com when bleeding the brakes completly using this method makes sure the ABS block is properly bled
 

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Very relevant topic for me at the moment! Last week I had my 280mm front discs and hubs changed for the 312mm ones from a V6 4motion. I picked up new discs and pads from the dealer, cleaned up the carriers and callipers before spraying them red.

Everything went on well, with no problems at all. I was told to give the brakes some bedding in so on the trip home some 40miles they got warmed up nicely and then some more by my father the day after with some vigorous stopping!

After all that the pedal still felt spongey and needed pressing down quite a way before the brakes would pull the car up. I have been in a car with the 312's on and mine were in no way working 100%. I suspected there may be some air in the brake pipes, so the car was pressure tested the day after and everything was fine, no probs!

They suggested that during the bleeding and then getting the pressure back into the brake pipes that the master cylinder might have been damaged! Apparently the piston inside might have travelled too far in the cylinder and damaged the seal...!

How likely is this to happen? I was thinking about having the master cylinder changed hoping this was the problem?

Anyone have any thoughts on this?
 

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The master cylinder piston seals can `go` but this is usually when you press the pedal all the way down to bleed the system manually, if you use a pressure/vacuum system then the piston seals should not break, which is why pressure /vacuum systems are the best , but manually pressing the pedal to bleed pushes the master cylinder piston further down the bore where it hasnt had to travel in normal use, maybe theres a little lip there?, and if the seal hits the lip, it bends in a bit not creating a perfect seal, this may be whats damaged the master cylinder?, Just my 2p worth of advice, need input from a proper mechanic?
 

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Quote: posted by Neil-S on 27/12/2004 13:24:39

i have fitted 312mm front and 288mm rear with no problems and i agree with TIW30.

Sorry to be pedantic but you surely mean 256mm rear i.e. Anni/S3 vented spec[:I].
 

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Quote: posted by TIW30 on 27/12/2004 13:16:20

as for the bigger caliper needing a bigger master cylinder to operate it this is not true as all the calipers have the same size piston

Ah, OK then i'm wrong! Was suggested a bigger MC was necessary by a not so clued up specialist...

I too have dead travel on my pedal before it bites. Might get that looked into.
 

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ok 256 it was boxing day and i was still hung over. just a thought the rears sit lower when used with the adapter plate than on the anni, s3 etc and it would be posible to have air trapped in the pipe if it was higher than the caliper when it was bled, it may not be this just a thought!. when i fit i always ensure this does not happen
 

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Quote: posted by NBirkitt on 23/12/2004 14:00:46

Quote: posted by PJ52GLY on 21/12/2004 17:33:11

i just trimmed back where did you get them s/s hose from as i could not get hold of any

No, you are right. When I first mentioned them, I had ordered a set through ECP, who then got in touch to say they didnt stock them. Spoke to Goodridge who say they have withdrawn Mk 4 kits from sale, and also Automec who expressed surprise at first and then confirmed the Goodridge story. Not quite sure what the problem is, but I have posted a separate thread about ss hoses for Mk 4. It is quite a complicated set-up on the Mk 4, so I guess there are production problems for aftermarket manufacturers...?

BTW We have now bled the system again (vacuum and pressure methods) using Ate Racing Blue fluid, this time taking the rear callipers off and turning them over to release any air lock. System now works fine, although still needs bedding in.

Good news Neil......

Did you get my email?
 
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