IRS. Clearance for removal.

[Rob.Brinkworth]

Hi All,

I need to refurb or replace my rear brakes as they are seized. Can anyone tell me how far the body needs to be jacked up so that the IRS assembly can be slid out? I'm not sure if my trolley jack and axle stands will provide enough height. I don't have professional equipment like a transmission jack but I do have a pit and the very sturdy boards that cover it. I'm trying to form a plan of attack and this info would be useful, to say the least! Perhaps I will need to invest in a transmission jack.

Any advice appreciated. Thanks, Rob.

[Brakebuster]

from personal experience, the rear of the car will need to be 1mtr off the ground to allow for the size of the cage plus the equipment you are using to lower the cage, i still had to slide it towards one of the wheel arches to manoeuvre it out from under the car



it is VERY heavy , and the weight is NOT CENTRED , due to the diff ,and it will want to topple off the jack........forwards.......

work safe,


BB

[davidr]

I have to admit that when I took the IRS out of my XJ-S for refurbishment I felt that trying to remove/replace it in my own workshop where I don't have a lift and would be working alone was probably asking for trouble. As BB says, these units are very heavy and unstable. My feeling was that there was a high likelihood that I would damage something and that thing was probably me!
So, although I'd did all the work on the IRS myself I used professional facilities to remove it and install the renewed one. Doing the job on a ramp was much easier and safer.
It is possible to renew the brakes with the IRS still in the car. Obviously it is much easier to do with the IRS on the floor but you have to factor in the issue of removing and refitting it which took me a day even with help and a 2 post ramp.
I've a feeling that the E Type has access panels in the boot for the brakes which also makes it easier?

[oldtimer]

Rob,
I agree with all that BB and David R have said and cannot overstate the bit a about weight, it is colossal and if it falls it will take the car with it if you are not very careful.

It's some years since I had an IRS out which I did on a hard concrete floor with a trolley jack. I made a double thickness ( 1 1/2 inches thick ) plywood jacking pad that fitted into the lip of the tie plate beneath the diff. Each end of the car was raised and two 10x4inch timbers (one on top of the other ) were placed beneath the jacking points with axle stands on top of the timber.

The trolley jack MUST BE A PROPER GARAGE STYLE one with the front wheels 12- 14 inches apart to give stability, not a crap little thing that can be carried around in the boot. The concrete floor needs to be smooth and in good order to allow the jack to roll and take the weight.

Disconnecting the propshaft, brake hose and hand brake cable is no problem however there is a distinct possibility of damage to the exhaust.

The jack has to be positioned well forward on the jacking pad as the assembly wants to roll forward when the V mounts are disconnected but this will become evident during the process of disconnecting . Then lower to the floor.

Well, that's what I did

Oldtimer

[oldtimer]

PS to above, it helps if you disconnect the radius arms - don't it.
In fact my very first job would to make sure the radius arms can be detached from the body **!!**??** , those that have been there will know what I mean

[Rob.Brinkworth]

Thank you all very much for the helpful advice.
My transmission jack idea is, of course, a non-starter as the hubs will not clear the edges of the pit. D'oh! it did look easy on the telly when Edd China did it with a proper lift and trans jack.
I've heard a rough estimate of the weight of the IRS assembly of 300 pounds. That's about the weight of someone that I couldn't pick up, so I appreciate you wouldn't want to get any part of yourself between it and the floor whilst moving it! As an aside, it appears to be about the same weight as a classic Mini engine/gearbox assembly, which I'm familiar with, having taken many out and put back when I was a youngster. It was a piece of cake with a tow rope, a scaffolding pole and four lager-laden blokes from my local (two on each end of the pole plus me tilting it). However, when we dropped one on my brother's foot from only a few inches, it quickly turned all sorts or sunset-oriented colours, so the warnings are duly noted!
The current loose-ish plan is to use the pit to disconnect what I can, cover the pit, get the car about three feet in the air somehow and then drop the IRS with a jack placed on a sheet of steel so I can roll it out.
Thanks again for your help.
Rob.

[Rob.Brinkworth]

Oh, I did have a look at the inspection holes in the boot but they don't seem to line up with the calipers in any useful way. I don't know what the purpose of the holes is but it doesn't appear to relate to the brakes. I couldn't even get to the bleed nipples - hence the seizure. I guess that's why people sell remote brake bleeding kits, one of which I intend to install.

[Brakebuster]

Oh, I did have a look at the inspection holes in the boot but they don't seem to line up with the calipers in any useful way. I don't know what the purpose of the holes is but it doesn't appear to relate to the brakes. I couldn't even get to the bleed nipples - hence the seizure. I guess that's why people sell remote brake bleeding kits, one of which I intend to install.

i think you will find the actual calliper inspection holes are behind the rear seat ( if you have one ) but in that location anyway.....

BB

[PhilBell]

While I second all of the cautionary tales above, I have successfully removed my IRS three times on my own. The key to making it safer the second time was to invest £120 in a big aluminium race jack with 0.5m lift and nice, widely-spaced wheels.

I did all of the loosening and all but the final subframe mount and radius arm disconnecting with the rear wheels on a pair of ramps, before supporting the rear of the footwells on large axle stands with large slabs of 1in thick hardwood (covered in thin carpet) to protect the floors from the stands.

I also placed stacks of wood in strategic places while I lowered the IRS in case it tried to fall off the jack. At this point it would be ideal to have an assistant stabilising the IRS while you lower the jack, especially while you're experimenting with the balance point. I used a 1in thick slab of hardwood to spread the jack load under the diff cage. For ultimate security it's best to make up a thick metal plate for this role, drilling it so that it can be bolted to the jack (in place of the cup), and again at points around its edges so that you can use long bolts and repair washers to clamp your new lifting platform to the edges of the diff cage.

The first time I did this it took me all day. The third time took an hour.

Refitting is more fiddly because you have to lift the IRS at an angle so that the subframe mounts will engage with the chassis rails/U-sections.

Best of luck