I have just replaced the Brembo rear brake pads that were supplied by SNG Barratt. When I received them each pad was fitted with a snug fitting, purpose made metal shim on the back. I have installed them as instructed by the workshop manual:

“Apply a uniform layer of grease to backplate shoulders, making sure the whole shoulder is covered”

I now find the brakes have a very noisy squeal. Any brake pads I have installed in the past I have also smeared grease between the back of the pad and the piston, which I did in this case.

I have looked through previous posts for information on Brembo pads but could find nothing regarding this metal shim. So my question is, should there be grease smeared between the pad and the shim, and between the shim and the pistons, or should the shim just be discarded.

Thanks for any help in advance

 

Oh well I’m sure I will be able to work it out anyway

 

Sorry, just saw your question. I had to go to aftermarket pads plus skim the rotors to eliminate the dreaded “Brembo” squeal. Sometimes a couple hard stops from 60 mph plus can break the glaze. By the way, I assume you used disc brake anti squeal specific grease and not regular petroleum or chassis/wheel bearing grease? If not, I would remove it immediately.
good luck!

 

Hi Moseleykmc, thanks for getting back to me. I have tried bedding the pads in, with as you say giving them a few hard stops. I have used ordinary grease, I have done this for many years and it has always fixed the problem or prevented it. But I realise it may not be correct for all situations. I will take your advice onboard, and maybe you could suggest the best product for this.

I am still looking at removing the metal shim that came with the pads. The front pads and the old rear pads look the same as the new pads but did not need the metal shim.

Thanks for your help.

 

Did you have the rotors turned before installing the new pads ???

Any brake or wheel shop can turn them (machine them perfectly flat) while you wait for very little $$$.

Not doing that will cause a lot of issues, the squealing you have, poor braking performance, etc etc.

you cannot just look at a rotor and tell if it is perfectly flat. Throwing on a set of pricey pads without spending a little time and $$$ to have the rotors turns is wasting the money spent on the pads.

Z

 

Yes, I used the old school term skimmed, as it only took one pass to remove the glaze as the surface was still true.

 

The anti squeal product can be obtained at any auto supply under several brand names. I would definitely retain the shims.

 

Many thanks for the feedback guys, it gives me something to work on.

 

Hi Ian,

Petroleum-based greases should never be used on brakes because their liquifaction temperature is too low (around 500°F), so the grease soon melts and drips out, sometimes onto the brake pad friction material and rotor friction surface.

Purpose-designed brake parts lubricants tend to be silicone- or synthetic-based, sometimes with added ceramic ingredients, and have much higher liquefaction temperatures. The Permatex Ceramic Extreme Brake Parts Lubricant I use is rated up to 3000°F:




I am attaching the technical data sheet. Other similar products are available from Permatex, CRC, Loctite, Ate, Raybestos, ACDelco and other automotive chemical suppliers.

All the chemical companies instruct to use "a small amount of grease" and only on the key contact areas. I apply grease to the face of the caliper piston and on the faces of the caliper "fingers," and on any points where pad ears contact abutment clips or slide rails, or where the pad-retaining rods contact the anti-rattle clips.

I do not remember Brembo pads coming with steel shims, but the shims are probably correct. I would suggest cleaning away all of the grease you applied, checking the friction material for grease contamination, and reassembling with a small amount of correct brake parts lubricant.

Did you clean the pad-retaining pins of all corrosion and baked-on brake dust? If not, the new pads may not be retracting sufficiently.

Regarding the bedding-in process, it is critical that when you are performing your firm stops that you do not bring the vehicle to a complete stop. Doing so with the pads and rotors hot can leave a pad-shaped imprint of friction material on the rotor that will create a high-spot. The idea is to perform firm stops until the vehicle speed is reduced to 5 or 10 mph, then accelerate again to 45 mph or 60 mph or whatever your chosen speed is, brake to a slow roll, then repeat until the pads are quiet and braking properly. Then drive the car long enough for the pads and rotors to cool before coming to a complete stop. Plan your driving route accordingly.

Cheers,

Don

 

Hi Don, thanks for the detailed feedback. I will be purchasing the correct "brake parts lubricant" and use it instead of the grease I have previously used. I have always been very careful to make sure the pad surface does not get contaminated by grease, and as I say I have never had a problem previously. Back in the day standard grease was the norm. But I take the comments on board and realise things have moved on and there is now more temperature stresses on the brake pads.

All the brake parts were thoroughly cleaned as this is something I have always done when, removing or working on items.

My bedding in procedure is very much as you have indicated. There is a stretch of road where I can do this safely at approximately 80km\ hour.

My main concern was that the pads that I received were identical to the pads removed, except that, the new pads came with the shims, and the pads that were already on the back and front were without shims. So this made me unsure even prior to fitting the pads.

Thanks
Ian

 

The shims are there to insulate the hot pads from the piston to reduce the heat there. The grease goes between the piston and shim. From what I've learned that is where the squeaks and squeals come from. Hope this helps, TM

 

Thanks TM for the info. Yes makes sense to be an insulator, I suppose it was installed as an additional modification to the previous pads. I have reinstalled the pads again, now with the correct grease. I can’t see there would be a problem but I also put a slight smear of grease between the pad and the shim. I’m yet to take the car for a test run.

Ian

 

Well I just took the car for a test run and the squeal is much the same as it was. Mainly at slow speed in fact the car only needs to roll a meter to get a squeal when stopped.

I have tried bedding the pads in, cleaned every speck of dirt or grease from the callipers and pads etc., and used the correct grease on parts recommended in the Jaguar workshop manual, as well as the pins and metal shims.

I have done everything I could without getting the discs skimmed, mainly because I was trying the easy stuff first. So is the general consensus the discs need to be skimmed, it feels like the only thing left?
Ian

 

There is one more relatively simple/easy thing you can try before getting the discs skimmed - CRC De-squeak spray, see here: https://www.ebay.com/itm/19608593720...Bk9SR7TGk-DsZA
Many moons ago before I got into Jags my brakes used to squeal like a stuck pig until I used this gear, hey presto no more squeal!

 

Amazon has the same product for less, and without the $9.00 shipping charge (no shipping charge for Amazon Prime members)

just saying…. I’ve never had the occasion to need it, but am a fan of the CRC product line. They are uniformly the best. So I don’t doubt that it works.

https://a.co/d/hOQyfiB

All that said, it appears to be a bandaid, and skimming, or “turning” the rotors would be my normal course of action at every pad replacement.

Z

 

Hi Ian,

There are lots of possibilities.

Were the brakes squealing before the pad replacement?

When you retracted the caliper pistons, did they seem to move freely, or was one piston stiff?

Did you remove, clean and re-lubricate the caliper guide pins?

Is there any chance that the squeal is from the emergency brake shoes?

I'm assuming you did not remove the rotors and check for rust-jacking on the hubs?

Cheers,

Don

 

Once again thanks for the feedback, it’s much appreciated, I was certainly not aware of the CRC De squeak spray. I was having thoughts that I could drive the car a bit longer to see if the pads would bed in. This could assist with that if it works, I will purchase a can as I am also a fan of CRC products.

Don thanks for your enquiry, and to answer your questions:

· There was absolutely no noise from the rear brakes until I replaced the pads

· All the pistons retracted freely with no sign of binding

· In my picture you may be able to see how clean the pins are, and I also lubricated them during installation

· I have not disturbed the emergency brake shoes so I don’t think that could be a problem

· I have not removed the rotors but there is hardly any rust on the car at all (and I’m not sure what rust-jacking means)

Cheers Ian

 

Rust-jacking is the accumulation of corrosion on one part, such as a wheel hub, that "pushes" or "wedges" against another part, such as a brake rotor, causing it to move out of its correct location. On wheel hubs, rust-jacking often occurs unevenly, causing the rotor to run out of true, or with what is called run-out, as though the rotor was warped.

It might be worth removing the shims as an experiment, to see if the squeal is resolved.

If that is inconclusive, it might be worth purchasing a good inexpensive brand of pads, such as Wagner ThermoQuiet, and installing them to see if the squeal is resolved. It is possible that one or more of the new Brembo pads has a problem with its friction material or fit in the caliper. Rock Auto has good prices on brake pads - they currently have a set of Wagner ThermoQuiet semi-metallics for under $15.00 plus tax and shipping, but I prefer the ceramics. Another approach would be to purchase a higher-end replacement set of something like Akebono ceramics and send the Brembo's back as defective.

Cheers,

Don

 

Hi Don, yes I agree with you regarding the shims removal as a test. I have been toying with that idea from day one. I had concerns regarding the shims due to the fact there were none on the previous pads.

At this stage it’s not to say it is the problem, and I understand the shields are there as a heat insulator. Bearing that in mind I would only use them without the shield for a short time. The pads were purchased from SNG Barratt and I have found them to be very good, so I will see how it all turns out.

I have already purchased the CRC De squeak fluid so I will give that a try first as an initial test.
Cheers Ian

 

First, make sure they are genuine Brembo pads and not a knockoff.
Second, performance pads generally need some aggressive stopping to generate heat in order to bed & quiet them down. Try a hard 70 mph to 0 mph 2-3 times in a row and see if that quiets it down.