Jump to content
Sign in to follow this  
RogerH

Girling Brake Caliper seal query

Recommended Posts

Over many many months there have been a number of complaints/questions about bleeding the brakes after either fitting new calipers or simply replacing the seals.

I did this two days ago and although the brakes were bled properly, with no air in the outflow of DOT4,  there was still a long travel and spongy pedal.

I put the old piston bore seals back in and the pedal travel was sorted.

The general conclusion is that the new seal is gripping the piston and after the pedal is released the seal pulls the piston all the way back again (or there abouts).

So where to get original Girling seals (the present crop are made by TRW). I had a trawl of the web yesterday and found RaceParts in Wallingford (just across the road from Protek)

I have purchased  4 seals at £5.08 each plus VAT - wow!!!  The  counter lad suggested they were Girling seals but could not back that up. thery have a colour code  yellow/yellow/white/grey

Early next week I shall fit these seals to see if they do the proper job.

 

Roger

Share this post


Link to post
Share on other sites

Hi Roger,

my overhauled system is not rock-hard either, I thought I had to do more bleeding or maybe bed in the shoes and pads, but your experience makes me think. I have rebuilt my calipers with TRW seals too. Think they were stamped from rubber plate so not exactly square in cross section. Could this be a clue?

Best regards,

Waldi

Share this post


Link to post
Share on other sites

Looking forward to hearing the outcome. My TR6 stops well enough but the front brakes tend to squeal at low speed. All investigations by yours truly and my friendly MoT tester have failed to show any problem. But the squeal is still there at parking speed, thought brake pedal travel is good.

I'm now suspecting the pads are held too close to the discs by recalcitrant caliper seals!

Nigel

Share this post


Link to post
Share on other sites

Hi Nigel,

the squealing is caused by the pad vibrating immediately after it makes contact but before the piston pressure holds it in place.

The flatter the pad upon contact the worse it can be.

One cure is to have a sprung plate under the pad to push it forward on the cock. So you get an edge to make contact first and the rest follows.

Another is to use the PTFE adhesive sheet between pad and piston - usually works on EBC pads.

Also if the pins that hold the pads in place are tight in the pad holes that can cause a racket. Make sure the pin holes are a loose fit.

Never thought about the bore seals causing it.

 

Roger

 

Share this post


Link to post
Share on other sites

Hi Roger,

I am sure that you probably do this but if not try this!

I fill a small clear plastic syringe with Castrol Red Rubber grease and lift the piston seal and inject under the seal to the piston in three places.I then worked the rubber grease round to ensure that the grease is all round the piston. Clean any excess with a dry cloth and fit and forget. Never had any of the issues described after doing this.

The grease coats the piston on the "dry" side and does not drag  on seal.

If you have podgy fingers fit a small tube to the syringe outlet and carefully ease it under the seal.

Rod.

Edited by Rodbr

Share this post


Link to post
Share on other sites

Hi Rod,

that sounds interesting.

Oddly, the seals come in a sealed pack with no grease - unlike the rear slave seal kit - as if it is not needed.

 

I shall be fitting the new seals this morning .

 I now have a dilemma !!! - do I fit them with only the DOT4 or also with red grease. What would I owe the success to if it worked.

 

 Roger

Share this post


Link to post
Share on other sites

Roger. 

Looks like you have to do the “dry” fit first. 

If that doesn’t work ?

Then the over night pressure on with the stick. 

Or

the red grease “wet” method. 

Share this post


Link to post
Share on other sites

Hi Roger,

I would be tempted to suggest that you fit the piston as usual with brake fluid of your choice and bleed as normal. I  would coat the seal with grease and work in in all round the seal finally injecting greaseso the piston always moves in a sticky gease envelope.

Rod

Share this post


Link to post
Share on other sites

Hi Rod,

I have made a grand decision.

As it takes only about 1/2 hour to remove, swap seals and refit the caliper I shall fit the new seals with DOT4 and see how they go.

If no improvement then I shall repeat using your trick.

If that fails then I will fish the old seals out of the dustbin again !!! 

 

Roger

Share this post


Link to post
Share on other sites

 Roger,

FWIW It must depend on the shape and attitude of the seal to the piston how much lubrication you get from the DOT 4. It has to act a scraper of the bore surface causing a degree of friction?

The grease does stick like sh1t to a blanket but if going down your route I would bleed, block the pedal overnight and then run for a week or so to give things a time to bed in.

It is easy peasy if you remove the caliper and get the syringe nozzle under the seal and then run it round whilst injecting the grease. Be advised it takes some time to draw the grease into the syringe but worth the effort.

The other thing is that the surface of the piston is much better protected with the grease from corrosion unless you have stainless or ceramic pistons.

IMHO cant see a down side to my way but each to his own, as it is belt braces solution to infrequently used brakes compared to daily driver.

Rod

 

Share this post


Link to post
Share on other sites

Thanks Roger for keeping me posted.

I have used a vaseline-like product from ATE to install rubber seals (rings, cups) in brake systems for 30 years, assuming this was how it should be done. 

So..... should this special grease be used or not?

Waldi

Share this post


Link to post
Share on other sites

Hi Waldi/Rob,

I have now installed the new (jolly expensive) seals. The pistons seemed to go in easier than when using the TRW seals. however this could be because I now have my eye in.

The system bled OK and the pedal feels, after the initial tack up of slack very solid.  

Not sure at present if this take up of slack is the new seals pulling the pistons back or not.

I shall do a test drive shortly and see how they feel.

 

If this attempt is not so good then I will do ot again using Rob's grease method.

 

Another issue I have found is that the outer dust seals appear to be slightly bigger than what was previously in there. The edge of the dust seal is rubbing against the brake disc hub

These are EBC  vented discs so the central hub may be bigger diameter. The previous dust seals also touch but to a lesser extent.

 

Roger

 

 

 

 

 

Share this post


Link to post
Share on other sites

I always assemble with red grease first as last, been doing this for years especially useful if its going to be a while before using the system as in a complete nut and bolt rebuild. Never had a problem with calipers.

Stuart.

Share this post


Link to post
Share on other sites

Thanks Stuart,

                 interesting that the seal kit does not included a sachet of grease as they do for the rear slaves.

The brakes are working well. If anything arises I'll go down the grease route..

Roger

Share this post


Link to post
Share on other sites

Hi Roger,

Strange that, I remember there was always a small sachet of red rubber grease in the Girling packet.

Economising or knicked?

Kind Regards,

Dave from a sunny Spain after the "Gota Fria"

Share this post


Link to post
Share on other sites

Hi Dave,

simply being cheap I think - where will it end.

 

I think I understand why the outer dust cover rubs on the EBC brake disc.

The EBC brake disc is a square section coincident with the dust seal. The original brake disc was conical so had a smaller diameter where the  dust seals sit.  

Why is nothing straight forward.

 

Roger

Share this post


Link to post
Share on other sites

Hi Roger,

knowing you a bit by now, did you spot any differences between the TRW and “racing” seals?

Thanks,

Waldi

Share this post


Link to post
Share on other sites

Hi Waldi,

visually they looked pretty similar.

The TRW had a polish to the surfaces where as the racing seal was a matt surface.

The Racing seal had a colour coding (haven't a clue of its meaning. The TRW was blank.

The pistons popped in easier with the racing seal than the TRW. The TRW needed a fair bit of push top ghet the piston past the seal.

From a feel point of view - I held the pedal down on the TRW seals for mpre than 12 hours (over night) - the pedal felt better but not perfect.

I held the pedal down on the racing seals for more than 24 hours and the pedal felt very good.

I did not grease either seal.

Not very scientific.  However I feel happier with the raconmg seals.

 

Roger 

 

 

 

Share this post


Link to post
Share on other sites

Thank you Roger.

I have not driven my car yet (besides a couple of short distances at low speed to test things, so hope my pedal will improve once the pads/shoes are bedded in. If not, I will become a racing (seal) boy too.

Best regards,

Waldi

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
Sign in to follow this  

×
×
  • Create New...

Important Information

Please familiarise yourself with our Terms and Conditions. By using this site, you agree to the following: Terms of Use.