The best and believe it or not easiest way to work on the rear brakes is to drop the whole rear subframe. This might sound a daunting task but can be done fairly easily with a good set of axle stands and a jack. There are several reasons for removing the rear subframe.
First as the brakes are in board working on them whilst the subframe is on the car is very difficult. They are inside and at the top of the cage. The handbrake is right at the top and people have in the past cut a hole in the boot as an access panel to get to the hand brake calipers.
Secondly it will allow you to replace the subframe mounts either side and the trailing arm bushes which will give you a much better and stiffer ride.
Lastly it will also allow you to drain the rear diff replace any leaking seals and refill it before putting the subframe back in the car.

To remove the Subframe, jack the car up so you can get underneath supported the car with axle stands on the rear jacking points. You will have to disconnect the trailing arms from the floor of the car. These are set with the bush sat on a cone and the two tend to fuse together over time. Lots of penetrating fluid and a crow bar should get them off. Sometimes the rubber of the bush is so bad that the arms come away leaving the bush attached to the car. The subframe mounts have four bolts either side connecting the mounts to the chassis legs and the rear wheels need to come off to get at the bolts but once loose replace the wheels. The hand brake needs to be disconnected and I think I am right in that the 420 has two brake pipes going to the rear for its dual brake system whereas the S type only has the one. Lastly disconnect the prop shaft at the diff.
Once the subframe is all loosened off lower the car back onto its wheels and remove the subframe mounting bolts. Now jack the body of the car back up leaving the subframe sat on its wheels. Once the car body is high enough put the axle stands back under the jacking points and wheel the subframe out from under the car on its wheels. Be careful because the subframe is front heavy with the diff and it will try and rotate forwards as you pull it out.
Once out of the car the rear axle is a pleasure to work on and all though it sounds like a lot of work try working on the brakes whilst it is still attached to the car and you will quadruple the time it takes to do the jobs. You will get so angry and frustrated at the lack of room to work you will either wish you had removed the subframe or resorted to cutting a hole in the boot of the car.


My subframe on its wheels before I put it in the car during my rebuild.

Nose of the diff supported.

Rear subframe rolled under the car on its wheels ready to be attached to the chassis.

 

AWESOME! Thank you for this. I will pull the subframe and rebuild the entire thing while it is out. Same for the font.

 

Excellent advice by Cass & don't forget to wire the necessary bolts when you are finished.

 

AWESOME! Thank you for this. I will pull the subframe and rebuild the entire thing while it is out. Same for the font.

Steady, my boy, steady! Stick to Cass's instructions on how to drop the rear end and get the brakes working.
Complete rebuilds of front and rear ends is laudable but not at this stage of revival. I have done a few (Mk2 and XJ6) and it is not a couple of hours of work
Stick to the simple and basic things otherwise you may "bog down" (lose enthusiasm) and turn it into a "gunnado"
By the way do replace the brake flex hose going from the body to the suspension while you are at it. Old flex hoses are subject to "arteriosclerosis" ie they will expand internally and eventually block up.
The same goes for the front brake flex hoses.
​​​​​​​Cheers

 

Listen to Bill & Cass. ~ This is one side of the IRS from an E Type. They are all the same but P/Ns differ in places ~ use your parts manual. Only the width & spring rate varies between E Type, 420/S Type (in the middle) & Mk X/420G (widest). This is one complex piece of engineering (compared with the crude rear live axle on a Mk2). It's no one day rebuild. E Type had a sway bar. Optional on S Type & 420. All the mounting points are there with plugs in them. Remember the handbrake has it's own set of pads. The cage it's all mounted in is usually known as the Bridgepiece. The 4 Metalastic V mounts & Radius arms with rubber bushings mount it to the body. No metal to metal contact for NVH reasons. Both UJ's on both sides of the half shafts have covers with a plastic plug you remove for greasing.

Diagrams below this are S Type/420.


E Type to show complexity. The only detailed diagram I have.



S Type/420. LS Diff. Limited slip version dropped on some models. e.g. my S Type has the LS Diff



Main brakes



Handbrake.

 

The one thing I forgot to mention is the exhaust. Sorry but this might be harder to remove than the subframe itself. Seized joints and "U" bolts that are rusted up and will snap. The exhaust splits into two and runs to the rear with the last section going up and through the cage. I forgot because when I put mine together the exhaust was not in place and when I stripped it down the exhaust was cut off as it was going to be replaced with a Stainless steel version.
The joints on mine are now held together with band clamps rather than "U" bolt clamps and slide on and off easily. The "U" bolt clamps tend to crimp the joints together making it hard to get them apart. Band clamps that come in different lengths and are made of S/S so don't rust up.

 

Use SS band clamps as Cass advises.






Clamping & mounting diagram



Band clamp kit I used on my car. You can use wider ones like Cass has. On no account use U shaped clamps with two nuts that rust & distort the pipes. These ones from Barratts have caused zero distortion & I have no leaks without sealer on a Bell SS exhaust system shown above. Everything fits to perfection & rear pipes align with body indentations perfectly. And none of that unpleasant SS exhaust tinny rasp of older systems. It has been engineered out. They sound just like a mild steel exhaust.

 

Woah- all great advice- thank you. I will drop the rear, do the brakes, calipers and replace the hoses. When I start the metal work I can do the front and rear proper at the same time. Or maybe after paint.

 

The Rear end may need nothing more than painting, greasing & replacement of all rubber bushes, pads, shocks etc. Unless there is trouble, leaks or noise leave well alone. We did everything on my car right down to setting correct crownwheel & pinion meshing. Pinion bearing preload ~ the whole 9 yards & I have a dead silent axle but for the mileage I'm going to do I wonder if it was worth all the trouble. Shimming the hubs, as an example, is an absolute nightmare & we built a special jig to do it. If you don't have the correct Churchill tools you have to make an alternative plan. Excuse dust.

BTW ~ that little round thing on the hub is a cap you open to, in Jaguar terms "spoon in a little more grease" (to lubricate the bearings).

 

The next owner will appreciate it Glyn.

 

Sadly ~ Yes Jeff.

 

I rebuilt my rear hubs first time around but when I changed from steel wheels to wire hubs I sent them off to a specialist to rebuild. Cost £200 plus for both sides but that was bearings, correct shimming and they had to machine one of the bearing carriers as it was out of true.

 

Wise move ~ shimming is an awful task.

 

Sad to report no updates- it starts every time now though, so I can start to fine tune. I may work on the carbs a bit this weekend and perhaps put the electronic ignition in.

I can just mark the distributor and put it back the same way, right? Or do I need to re-time it with a gun?

 

Technically yes, in reality probably not.
There will always be a bit of wear on the old points meaning the rotation of the distributor will have been altered in its life time. Putting the new electronic unit in gives you a specific fixed timing point that will not alter through wear as long as it is tightened down correctly therefore the two timing points old to new will be different and you will have to tweak it to get it correct. Sometimes it can be done just on feel and sound of the engine with tiny movements of the distributor but timing with a light is obviously more accurate and better.

 

Mark the flywheel/damper with chalk so that you can see the timing marks clearly. If you are using a standard strobe gun with normal length leads you can time it on cylinder 6 i.e. the front cylinder. No 1 is the rear cylinder. They are identical.

Presume you are using similar to this as I did to get rid of damn points & condenser & setting Dwell angles.

If you hear loud bangs from the exhausts you know you are 180 degrees out. If you have not dismantled the distributor that won't happen. i.e. undone the centre screw & separated the shaft.

 

Don't muck about putting electronic ignition into the car at this point.
You have the engine starting and running. Leave it at that.
I am not sure what carbies you have on the 4.2 engine. They did vary from country to country due to emission requirements.
If you have HD8 SU carbs then don't even think of tuning the carbs until the diaphragms have been replaced. They will be old and hard and will split and cause an engine fire if you disturb them
Have you sorted out the brakes yet?
Just keep in mind the basic object at this time is to get the car running and driveable on a "NEED to do basis"
I classify those upgrades such as electronic ignition as "NICE to do" for some time in the future.
Cheers

 

We tend to quantify things as "Wants" and "Needs" as well. Needs are tyres, brakes, fuel system, electrics and so on. Things to get the car running and driving.
Wants are wire chromed wheels, leather interior, wooden steering wheel and so on. Things that make the car look pretty or are an upgrade on something that is already working but can be improved.
I would put electronic ignition on the wants list but would have to change it over to the needs list if the original distributor with points was causing problems and needed replacing.

 

Ya BUT. If I get the electronic ignition sorted, that is one thing less to worry about as I get things dialed in. This weekend is distributor and probably checking the SU pistons to make sure they drop at the same rate (are in correct side) Anything else I feel inclined to fiddle fart around with. I really should helicoil that stripped plug well.

 

I'm in total agreement with Bill & Cass on only doing what is necessary at first.

But getting that plug thread sorted I consider necessary or you will blow out a plug & damage your bonnet or worse & damage yourself.

If the snap off piece (tang) of Helicoil gets in the cylinder for heavens sake fish it out with a magnet on a piece of wire, 3 prong push & grip device or whatever. There is no guarantee that it will blow out of the exhaust valve and is as hard as hell & can do damage. Best to make sure it doesn't happen with a well placed cloth etc.