Rear Trailing Arm Hole Reinforcement

Last Updated on Sunday, 11 September 2011 20:38

When the rear trailing arm pin becomes loose in the subframe it can cause the mounting hole to wear and become oval'ed, allowing the trailing arm lateral movement and thus upset the rear toe-in and and alignment.Once the hole is oval'ed it can be hard to fix by just doing up the nut tighter as the forces in the trailing arm can be quite severe.

Bear in mind that this modification should not be necessary if you keep things nice and tight and in good order regarding the Trailing Arm Pin but this can can also fix the problem if you haven't.

A solution which has been around since Noah was tinkering with Mokes is to weld a thick washer over the hole to locate the trailing arm properly and thus remove the ovel'ed hole. In thinking about this not that recently i thought why wait for the problem, why not put the washer in there first to strengthen and prevent the problem.

Lucky I did, because I found my trailing arm pin was not as tight as it could be so left unattended it might have developed the problem i am attempting to prevent. The first part of the solution is to remove the nut and washer from the pin to make sure the hole isn't already oval'ed and to scrap away some paint for the welding that is about to come.

Next up is to fit a washer that is thick and just the right size to fit the thread of the TA pin and is large enough to protrud around the nut. Next up replace the nut, not the spring washer, to hold the new washer in place while you give it a couple of tack welds. Be careful to keep the welds to the side of the washer and not the surface as that may prevent the nut from doing up tightly.

Next remove the nut and replace the spring washer and do the nut up to the tension you would normally use. Although I dont' mind using Nyloc nuts around the car, the Trailing Arm Pin and Upper Arm Pin are two places where the Nyloc is more trouble than it is worth when it comes to undoing things.

Now before you get too excited and comment on my welding effort keep in mind this was done upside down under the car and with the rear tank and exhaust tank still fitted and there is barely enough room to gun the MIG gun in there. Obviously if you are renovating a Subframe and everything is on the bench there you should have a much easier time of welding it up, but for in car methods just hope the road gunk builds up under there before anyone sees it.

This is not a tried and tested modification and is just something I thought I would try to see if the welding made things worse or if there were any side affects from doing before the hole gets ovaled rather than after.

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