Hello again world of Jaguar lovers and experts.
So I have my rear-end out of the 420. I have removed many parts and now trying to get the Caliper off. I have not removed the differential from the cage just yet, I didn't plan to do that.
My issue is access to thes 5/8 bolt heads. The closed end of the spanner does not fit. It is blocked by the differential housing. Cannot get either bolt to move with the open end of the wrench. Tried a torch, penetrating oil , etc etc . It does not move. On my car there is another bolt which I learned you can access by a hole in the rear disc. These bolts connect to a bracket which are shared with the other caliper bolts. It figured that once those were removed the caliper would be loose. But that was not the case.
So my question is which bolts have to be removed, and if it is the ones squished to tight to access, how the heck do you access them. If it is the others that can do the trick, why wont it come apart now. I am thinking that the aluminum caliper is fused to the metal other components. I will take a photo in the morning and add to the post.

Getting closer , one day , one week, and one month at a time
Thanks
Jimmy

 

Yes Jimmy, often a thousand words will confuse where a simple photo can explain , , , especially if you use MS Paint or Photoshop to arrow or number the bolts in question.

I say this not to offend, but my memory of tackling the same task on a series of S Type, 420 and 420G (all the IRS) is now 40 or more years past, and leaves me with little but the certainty that it's doable. Not to say we liked rear pad changes on these models, but we did lots of them. The challenges I recall as nightmares were to do with getting starter motors out of the early compact saloons or trying to shoehorn triple SUs into those tapered engine bays.

Nor did we pursue the luxury of dropping the entire IRS which you have already done. Hit us with pictures.

Cheers,

 

The bolts holding the calipers in place are very difficult to get to if the suspension cage is on. You probably have the same rear end as my 66 S Type. I did a complete tear down of my rear suspension to rebuild what was necessary and to sort out some really bad previous repairs to the brakes. Of note the bolts on my brakes were not safety wired in like they are supposed to be. I know its more work to disassemble the wholes suspension but it is worth the effort especially since the calipers need to be centered on the rotors. To do that they need to be shimmed between the mount and the caliper which is almost impossible to do if the cage is on.


This will also help as well. I bought a 16mm box end wrench and ground down the outer end so it would fit between the bolt and the differential. The wrench is also nice and long which helps provides some leverage.

 

Hello,
I seem to have the same design as you and will need to get to those bolts. I just don't understand what the other two bolts are for, it looks like a bracket that connects to the caliper.

I would not say that it is a luxury to remove the entire IRS, rather a giant pain in the butt. I have no idea how anyone could afford to have a mechanic do a brake job back in 60's and 70's.



I have removed 2 bolts which I accessed thru the holes in the disc. What are they for, looked like that would permit the caliper to be removed? I know to remove the other bolt shown that I will have to do the same thing you did to the spanner.

Hole gives access to bolts.



worth all the effort, the rubber is finished!

 

It looks like you've removed the bolts from the caliper mount plates to the differential housing. You need to remove the two bolts on the inward side with the holes drilled in them for safety wire. Those are the bolts that hold the caliper to its mounting plate.


These are the bolts you've removed.


These are the bolts you need to remove to get the calipers off. There should be some shims between the caliper and its mounts that these bolts pass through. They center the caliper on the rotor and they are a pain in the *** to reinstall but are essential for proper brake alignment. Take caution when you finally gets the bolts out and start to remove the caliper because the shims will probably fall out and you need to keep them in order for each bolt so you can replace them.

Before you do remove the bolts check and see it the caliper is properly centered. Here's a great tutorial on how to check their centering and reassembly of the brakes


If you have a coventry manual for your model it will explain the whole brake repair procedure. If you don't have one get one immediately. It will save you a certain amount of frustration but not completely. You are working on a sixty year old Jag. Somethings are brilliantly designed while are others - like this set up, are really confounding and frustrating to work on. It would be impossible to do a complete brake job on these rear ends without a complete disassembly.

 

I just noticed that you removed the half shafts. You should remove the differential from the cage. I makes working on the brakes so much easier plus it needs to be removed to work on the parking brake!

 

Hi.
Still working on it.
I need to find a tool that will fit. The gap I have seems extremely small. I will look for a tool that is thinner. Started grinding my 16 mm wrench, but I do not think it will.

Yes I removed it from the so called cage . I feel like I am in the cage!

Jim

 

Ha! I know the feeling!

The rear brakes were possibly the must frustrating thing to work on besides removing and reinstalling the engine and gear box. Once you finally understand how it all goes together it's a little less daunting!

 

Even ground down you will only get short turns of the bolt. I ground just a small portion of mine so it still had some strength to it and not break. I removed just enough so it would fit snugly between the bolt and the differential.

 

Hello,

So using the ground down key worked for the first bolt. The second required more grinding down. It worked eventually but the wrench is toast and actually broken at the ground section. With the calipers off, you can see the bracket that supports the caliper. There are 3 bolts that hold the bracket to the differential. All 3 can be accessed thru the disc. I think that the correct way to remove the calipers is to remove the 3 bolts on the bracket. And then the whole think will lift out. Then you have easy access to the bolts connected to the bracket and the caliper itself.
I will do that in the morning and get back with photos if it works as i suspect.
Thanks
Jimmy

So i did remove the other caliper simply by removing the 3 bolts for the bracket. That makes a lot more sense!

 

Bingo Jimmy,

Between your own observations and input from Felix, it all comes rushing back.
You chaps are dealing with 30 or 40 more years of rust and crud than our work in the day.

Observation of the caliper bolts having holes for security wires is important, as is yours regarding "pass through: holes" to access the bracket bolts. Even more critical is advice from Felix to check centreing before dismantling so you can reassemble with correct shimming. Only thing worse than doing this job, is repeating it 2 or 3 times to correct it afterwards!

Cheers,

 

Coming soon photos of the restored brakes !!