Rear Brake Calipers

[JC]

..it all started with an MOT advisory - rear brake pad badly worn!!

...armed with new pads I borrowed a friend's pit. Unfortunately, poking around revealed that the dust seals were shot and that pistons were so tarnished that they would never push back in to accept the new pads. "That'll be fun" I thought So here are my queries

1. I guess there's no alternative to dropping the rear suspension to extract brake calipers?
2. Am I correct in supposing that to drop the suspension I need to drop the exhaust, disconnect the radius arms and then unbolt the suspension unit?
3. Is emery paper and a seal set frankly a waste of time i.e. should I be sending the calipers off for a professional refurb?

Cheers

JC

[MarekH]

Dear JC,

1/ You guess correctly
2/ You need to also unbolt the rear driveshaft where it joins the differential and disconnect the rear brake hose.
3/ It is likely that the pistons are rusted, so you'd probably need four new rear brake pistons and some red grease to help ease them in with.

Have a read up about the dangers of having a 300lb IRS drop on top of you before wading into the job.

Expenditure will probably escalate if you look at the condition of the rubber parts (IRS mounts, rear brake hose, bushes) plus the handbrake mechanisms as you won't really want to be dropping the IRS again if you can possibly avoid it.

kind regards
Marek

[vee12eman]

Hi JC

In answer, yes to both of the first questions - you have to do all you said. As to the third, it depends upon condition, I have had great success with resealing all sorts of calipers, including my own Series III rear calipers - identical to yours. I guess many will warn you off this approach, but it is possible. However, although it can be done, you need to be confident the bores are genuinely clean, any scratches mean they are scrap unless you have stainless liners fitted. Also check the threads at the inlets are good - remove all unions and the brake nipples to check.

Unlike other calipers, you can split these - they have no internal drillings. You should replace the bolts if you do this - ensure they are the correct grade of bolts if you do this. Consider replacing pistons with stainless and while it is all out, add a couple of remote brake bleeders for future ease of maintenance, several posts on this here.

Also consider new brake lines in kunifer (cupro-nickel - available from Automec), new flexible brake hoses and finally, with the suspension out, look at the bearings, u/j s, handbrake pads and suspension mounts - all in all, could be a bit expensive, but worth it in the end!

Regards,

Simon

[D COUPE]

Sorry if this seems a little brutal but 'do it once do it right'.

I have removed 3 IRS units in the last 12 months and they are heavy, dirty and if You dont have the right support they can bite You!

[vee12eman]

I agree with the previous post, these units are heavy, awkward and potentially dangerous. Fairly simple tools can be made to remove and refit safely, but it does require careful consideration. From this point of view alone, it is worth replacing all components that may be suspect or have a likelihod of failure and if you are not confident about the suitability of units for repair or reconditioning, best to replace them and avoid repeating the procedure.

If you are considering keeping the car and maintaining it yourself, the removal tools are a worthwhile investment in either time or money. You will need a large, stable jack, a transmission adaptor (I use a plate which bolts securely to the lower central plate under the IRS - home made and custom fitted to my own jack) and a good range of sockets, spanners, universal joints and an awl for aligning holes on refit. I also made a lever allowing me to manipulate the mountings to align bolts when refitting. I can post photos if you wish.

It also helps if the car is raised both front and rear and the best way to do this is to lift the front wheels onto ramps (I would not advise driving onto ramps, use a jack) or my own preferred method, which is with large wooden blocks or sleepers. Make sure the car cannot roll off the blocks. I don't recommend axle stands, as they can be unstable, also often get placed too far back. When removing the IRS you are removing a substantial amount of weight from the rear of the car and more than one car has toppled forward because the axle stands were too far back.

That said, I stand by my belief that with preparation and good tools, removal of an IRS is relatively straightforward barring problems such as major corrosion etc.. Also the calipers can be successfully reconditioned. I did this and have now removed my IRS several times during the restoration and maintenance of my car. You do need to be fairly competent as a mechanic to undertake this scale of work.

Regards.

[JC]

Thank you all for your advices - I'm now a forum convert. Over a pint, my friend (the one with the pit!!) and I have decided to (carefully) tackle dropping the IRS in late November, but to get a local brake specialist to refurb the calipers.

vee12eman - the reason it's a late November start is that my wife and I are visiting Oz. We'll be in Melbourne on Oct19/20 and the evening of Nov 13 - we'll keep a look out for a SIII. I don't suppose there are any classic car meets on these dates?

Cheers

JC

[vee12eman]

Hi JC,

Hope you enjoy the trip.

13 Nov is actually the AGM of the Jaguar Car Club of Victoria (JCCV), which is held at the clubrooms. There are normally afew cars on display in the clubrooms and the bar and library will be open afterward. I don't often get to meetings as it is a bit of a drive and not always that pleasant a drive, but I might go to this meeting, haven't decided yet and will see how I feel on the day.


Regards,

Simon.

[abowie]

Everyone's scared of removing the IRS but really it's not that complex a job.

Make sure you have a good plan of attack and understand what you have to do. Think through how you're going to separate it from the body; jacking, wheeled trolley etc.

Have at least 2 burly mates present.

In reality though; it's not particularly hard and once it's out you can access the whole thing easily.

[1954Etype]

Agreed. The trick is to get the centre of gravity right or the unit rolls out of control. The fore and aft position isn't where you think it is - I got it wrong once and the unit rolled forward. Luckily no damage just massively increased heartbeat!

[Smeg999]

Re. the condition of the calipers, the critical surface is the one that slides against the seals. For my S2 that was the piston as the seal fits inside the caliper bore. When I dropped the IRS last winter for a diff change, I cleaned up my bores and fitted stainless steel pistons - job done.

I concur that you should also go over the handbrake linkages - mine now works really well.

[JC]

Thanks again for the advice - and yes, the IRS is indeed a heavy lump of metal.

It took a day and a half to dismantle and a day and a half to re-assemble with refurbed calipers (refurb undertaken by a local firm in Worcester). Unfortunately we didn't pinch the brake pipe connections to the calipers tight enough and it took another half day tightening these in situ - very awkward job.

This photo was taken after we'd inserted the calipers back into the IRS


E-type 3 post by JohnC's Photos, on Flickr