So the first thing everyone says when talking about removing/installing the IRS is that you need two burly assistants and a great deal of care because it can bite?. Well part of that is true, the IRS is heavy and awkward and needs careful handling, but tools and technique can help with that, replace the two burly blokes and make life a lot easier.
So I thought I would show the tools I use, fairly simply made by myself, which allow me to do the job, by myself with little or no problem. As with any large job, an assistant is helpful but not vital.
The two main tools are a jack pad and a special lever to manipulate the Metalastik mounts. Also useful are wooden blocks to raise the vehicle safely and squarely. Other tools include a bar which is used to support the rear of the car once the IRS is out, a wooden spreader block, used to jack the front of the car up under the picture frame and another wooden block to jack the rear of the car without removing the exhaust. Obviously, some of these tools are useful for other more common tasks, some may even have made these already. The wooden blocks are fairly easy to make, the others require welding, so if you can?t do that, you might need to approach someone with a welder and possibly grinding tools as well. Alternatively, you may be able to adapt my designs and make them without welding. The effort may not be worthwhile if you are not likely to use them again, although they can save you a lot of money and make things safer ? a fairly priceless result. Some of the tools can be used for other purposes too.
The first tools are the wooden blocks. You can use axle stands to support the car, but axle stand manufacturers recommend that you do not use two pairs of stands due to stability issues. You are removing a substantial percentage of the cars? weight, so the change in weight distribution is something to consider. I use a couple of pine sleepers, cut into lengths and with built in chocks, which are then placed under the wheels. These allow greater access under the car and more stability. You can build these fairly high, but I suggest that three sleeper thicknesses is enough, more than this can become a little less stable. This picture shows the car on blocks, only two in this instance and I have made the built in chock much bigger since this picture:
To raise the car, a good size trolley jack is recommended, with a large pad. I made a wooden block which fits into the picture frame, supporting the weight on both the edges and inside the frame, reducing the chances of distorting the frame. This is a well-known modification and some make it from hardwood, leaving it in place permanently, secured with tie-wraps. I chose to make it removable, so again used softwood, as that was all I had at the time. I won?t give measurements as it seems likely these will differ and I did not measure mine, rather made it to fit the car by a little trial and error. Here is the wooden block for the front (Picture Frame):
A block of different design does the same at the rear. To allow the jack to act directly on the IRS lower plate, the block fits between the exhaust pipes. To prevent slipping, holes are drilled to align with the protruding bolts on the IRS lower plate. These holes are 380 mm apart, at least, that is what fits my car, it would be advisable to check your own car in case there are differences. The block itself is made from a piece of 90 x 90mm fence post, again a piece I had lying around, again, check this is deep enough to clear your cars? exhaust. The jack used needs to be fairly low profile to go under the exhaust. This picture shows both front and rear wooden blocks:
Once up on the blocks, make sure the car is stable ? it is worth noting that as the suspension compresses, the wheels actually spread a little further apart, so tap the blocks out with a heavy rubber mallet as you slowly lower onto the blocks. Next remove the exhaust, then swap the pad on the jack for the plate which mates exactly with the lower plate of the IRS. This plate is made from a thick steel plate, with a central hole which mates with your jack. Each corner has a bolt welded through, which sit very close to the IRS central lower plate. The dimension between the bolts (across the lower plate) on my car is 294mm. When the plate is offered up to the central plate, the bolts pass very closely either side of the plate. Mine were so tight when I first offered it up I had to file a little out of the threads on their inner surfaces, but this did not interfere with the next stage, which is to fit large penny washers and nuts which securely clamp the suspension to the plate. With a good jack, it is now possible to balance the suspension confidently on the jack. This pad is also strong enough to support the car, allowing you jack it up, remove the blocks under the wheels and fit a steel bar between the studs which mount the rear exhaust hangers, then allowing you to place a couple of axle stands under the bar. This bar is 515 mm long for my car, again, measure and manufacture to suit your own. The car is now firmly supported and will not move when you remove the suspension unit. The pictures should make it clearer, though unfortunately I don?t have one of it all in place:
The jacking pad:
The pad fitted to the jack:
The jack and pad offered up to the IRS:
The bolts securing the IRS to the pad (can be seen below the discs in this view from above):
Next disconnect the prop shaft, handbrake, brake hydraulic line and remove the bolts securing the radius arms to the cups on the floor and lower them out of the way. Actually, this stage might best be performed at the beginning of the process, due to the fact that they often corrode onto the mounts. If this happens, it can be very difficult to separate them, options are to use a crowbar, cut the rubber, or if you have a long-wheelbase model, you can insert a small thick plate of steel inside the cup, when wind a bolt down onto the plate from above, literally jacking the cup off the mounting. This can?t be done on SWB cars because there is no access inside the cups from above, on LWB cars; remove the rear seat base and you will be able to see the cup from above and insert your jacking bolt. This section drawing hopefully makes this last option clearer:
Once all disconnections are complete, make sure the car is firm on the stands and the jack is firmly up against the IRS, then disconnect the four mountings from the car. My choice is to leave all four mountings on the car and remove the bolts to the IRS cradle. It?s not everyones? choice, but it works for me.
Carefully lower the unit out of the car. Unless you have the car very high, you will probably have to manoeuvre the unit on the jack a little to get clearance, but it can be done. The unit is taller than you expect and unless the car is high enough, it won?t come straight back on the jack, so a little careful steering is required with the jack. The advantage is that the IRS is firmly bolted to the jack and will not fall off provided you fitted your penny washers and bolts nice and tightly.
Lowered to the floor:
With the unit on the floor, you can either transfer to a trolley, or no major dismantling is required, leave it on the jack, making it nice and mobile. To avoid leaving pressure in the jack cylinder, lower the unit to rest on the ground when not moving it around, the jack will stop it falling over. This has the advantage of having the whole, very heavy unit stable and easy to move around ? believe me having spent years lugging my unit around during the rebuild, this would have been a godsend if I had thought of it earlier!
Refitting is a reversal of removal ? yeah, how often have you heard that?! Well, it?s basically true, but, when offering the unit up, you will have difficulty aligning the four mounting with the holes in the cradle. This is where the lever comes in. The lever is a length of steel bar, with two prongs welded to it, which fit into the two holes on each mounting through which no bolts pass. It?s easier to see on the picture:
It fits like this:
This allows you to manipulate the mounts and steer them as you insert the studs and bolts to the mountings. Don?t tighten any bolts until all are through the cradle and mountings. Use screwdrivers and awls to assist the manipulation of the mountings to align the holes for bolt insertion. Once all bolts are in, tighten them ? a ratchet spanner is useful here, as is a socket set- preferably 3/8 inch or 1/4 inch drive.
With all bolts tight, reconnect the brakes, handbrake and prop shaft. When fitting the radius arm cups, make sure they are clean of rust and paint and lubricate with anti-seize grease as well as you can to prevent corrosion in future. Also make sure the cups under the car are smooth and free from corrosion.
I hope someone finds this usefull - any suggestions to make life even easier?
Regards,
Simon
