Front Caliper Overhaul

[iain1980]

Has any one here overhauled the front calipers?
In the past I have just put new on but as times are tight...........
To do the job I think requires 8 pots and a seal kit which looks cheaper, but I really cannot tell if it is worth the saving.
Some questions I have are;-

Does the caliper have to be split?
Is it as durable as a profesional recon caliper?

Any guidance on this would be much apprieciated

Iain

[kelsham]

Hi Ian, I have rebuilt several sets of calipers on my xjs cars. I have replaced the pistons and seals, It is not advised that you split the the calipers.

Special seals are required and the bolts are supposed to be replaced if you do.

Because the seal surface is between the pistons and the rubber inserts, a thorough clean up using wet and dry paper using your fingers is satisfactory.
Make sure you clean the calipers out and finish off with meths or use brake fluid.
You will find it best to use brake fluid on the seals as you push the pistons back.
I usually use rubber grease round the parts as I fit the dust seals.

regards Kels.

[boots1234]

3.6 XJS COUPE 1990

I'm in the process of overhauling the front calipers. Managed to get them off the car ok but having a devil of a problem to get the pistons out especially two that appear to have siezed badly. The car was pulling to the right.

I don't have an air compressor although not sure how that helps, since the free pistons would blow out ok but not the troublesome ones.

Question - how do you get the siezed pistons out?

Ive thought of drilling through the back and threading for a plug but not sure whether there is sufficient meat in the casting to hold a plug

Any help would be appreciated.

[boots1234]

PS just noticed a remark of yours - can you get low priced recon calipers and if so where?

[iain1980]

Hello Boots1234

In the end I went all out and replaced stub axles, bearings, discs, pads, fitting kit and calipers, I don't like doing things twice!

The calipers came from jagaxles, who mainly cater to the kit car lot, at £180 the pair. They were hidiously brightly plated!

I then overhauled mine and sold them on for £75.

A little hint is when you come to reassemble and put the little R clips in to hold than keep the pad retaining pins in wire them so they can't damage the dust boots, as this is what wrecked mine in the first place!

[ptjs1]

boots1234,

Without a compressor, you can get a stuck piston out by connecting a footpump to the caliper and just one or two pumps will pop it (but be careful!)

As you say, the free pistons will go first so just clamp them in using some wood and a G-clamp or similar.

Good luck

Paul

[boots1234]

Thanks - I'll have a word with them since trying to get the pistons out is going to be a bugger.

[boots1234]

Hi Paul

Thank you very much also - I'll have a go at that first.

Regards

Boots

[kelsham]

I must admit that I cheat by always making sure that the pistons are removed from the calipers before removing the caliper from the car.

Usually one piston is sticking, I use a G cramp to hold the loose piston back, and use the hydraulic system to force the stuck piston outwards. Once it moves I release the clamp on the loose piston and move that out a corresponding amount. Then I return to the tight piston and force it further out.

I am sure you get the idea, eventually the tight piston pops out.

Regards Kels.

[boots1234]

That's a very sound method - thanks

Boots

[boots1234]

Hi Paul

The foot pump worked a treat albeit at 9 BAR and after, eventually, knocking (bashing rather) the siezed piston inwards to break the rust seal.

I'll now have a go at the other side.

Thanks again,

Boots

[boots1234]

Hi Paul XJS 3.6 COUPE 1990 AUTO

Overhauled front calipers and fitted new flexible hoses plus repaired all four wheel arches, on the cheap with fillers and spray paint. The latter looks good.

Question - now about to bleed front brakes. Brake fluid obviously leaked out and reservoir almost empty.

My 1990 cat has ABS and appears to be more in line with the more uptodate 4.0 litre in the Jag manual including engine layout. Manuel appears to say that I only need to bleed the front calipers since the system is independant of the rear. Ive not touched any of the rear brake system - dont really want to either - a rather poor design to say the least. However access to the rear bleed screws appears reasonable.

The manual appears to indicate that the bleeding can be done without the engine running or switched on.

Your advise would be appreciated or from anyone else of course.

regards,

Boots

[PaulE]

The Coopercraft ad seems to suggest that their calipers are now available for thr XJS. Anybody tried them?