IRS Cage fitting

[chrisvine]

I'm trying to install the suspension and engine this weekend but are struggling to get the cage bushes aligned with the mounting holes on the chassis.

When both bushes are mounted to the cage, the horizontal hole centres are 6mm wider than the chassis holes.

I think the rubber thickness might be too large and there isn't sufficient weight to compress the rubbers, causing the C2C distance to be too large.

Would anyone be able to confirm the correct distance shown in the picture below:



Thanks,
Chris

[neil4444]

Hi Chris,

Probably no help to you but my brackets (from Hutsons) measure exactly the same (68mm) from base to bolt centre.

Would heating them give enough flex in the rubbers ?

Regards,

Neil

[christopher storey]

When you say the holes are 6mm too far apart, do you mean the distance between the two holes on each mounting,( in which case fettling with a rotary file is the answer ) or the overall distance apart. If the latter, you are probably trying to offer up the IRS unit with all 4 mountings attached to the IRS unit. This will not work. You need to have 2 on the IRS unit, and 2 on the chassis, all loosely fixed. I cannot of course remember whether it is the front pair or the rear pair which needs to be on the IRS unit, but I suspect it is the rear pair

[chrisvine]

Thank Neil & Chris,

We thought the 68mm might be too large and, due to their mounting angle, had pushed out the overall C2C distances between the mounting holes of the front and rear mounts. Just the weight of the chassis wasn't sufficient to compact the rubber which would reduce this distance to get the bolts through.

The rear mount was initially fixed to the chassis and the front mount to the cage but subsequently both mounted to the cage just to measure C2C distance of mounting hole on cage and compare with those on the chassis. In the end it was just possible to align the holes by inserting a screwdriver into one hole and using leverage to draw the other bolt hole in-line. But it was a struggle. Everything has been nipped up and then backed off to allow it to settle.

It was also necessary to use a tourniquet between the roll bar and the wishbone to draw the IRS cage forward to engage the radius arm. I slightly concerned everything is under quite a bit of tension to get it to fit - is this normal?

At least it's now fitted:

[Cgarside]

From memory, the rubber mountings are attached to the body first (if you fit these to the cradle first, access to fit the nuts on the back the rear mounting is very difficult). The rubber mountings should be fitted with spacers either side to centralise on the rear chassis leg (the spacers allow the cradle to be centralised relative to the body). You will find that the steel cradle has a hole for the stud of the rear rubber mounting and slot for the forward rubber mounting. When lifting the rear suspension, the trick is to engage on the rear rubber mounting stud first (fit nuts as soon as you can) and then rotate the front of the cradle slightly upward by lifting the front such that the front rubber mounting studs move through the slots to their final position.
Easy writing this down, but get trusted friends around as this is a job that requires multiple sets of eyes.
Regards
Chris

[Cgarside]

Replies crossed, but great to see you now have the rear suspension fitted.
In terms of the arms, I had to resort to a tourniquet to get everything in place when I put my DHC together. Twenty years on, I replaced the rear suspension rubbers and all went together without any problem so never got to the root cause of the problem.
Regards
Chris