Porsche Enthusiasts Club Forum

Just finished replacing the ball joints and came to refit the drivers side control arm and the two 15mm bolts that hold the rear of the control arm to the body of the car do not appear to want to tighten up, the ones on the passenger side are fine.
I guess the captive nuts have broken free, has any one encountered this problem before and if so what is the solution?

Shame really as it was all going so well

1985 944 lux

If by control arm you mean the front wishbone/bottem arm. The whole thing is only £17 from GSF for the early car. Not much more than a ball joint. Shame when yoiu've got so far.

This is one with a later ball joint and the problem is with the lower wishbone mounting to body bolts, their like a merry go round, they just keep going round and round.

These are the castor bush mounts, they are a captive nut welded into the chassis rail. This is not that usual but I've heard of the odd one.The only way to sort it is to get someone to cut open the chassis rail & re-weld the nuts into the chassis rail. This isn't a very DIY job so you'll have to get it to a garage. These bolts carry a fair load & are safety critical so I'd suggest getting a recovery co. to move it. You need to find someone who is competent as although welding the captive nuts on isn't rocket science, repairing the rails is.

At the risk of stating the obvious, the threads on the bolts have to be clean & greased & they need torquing carefully.

the captive 'head' inside the rail will probably only be tacked to the car. i'd run a weld round the bolt and the outer side of the rail then grind it smooth if the mount needs to be tight to the rail. failing that weld the thing in place

Glad I've not bought a car from you!!

Quite, especially something as safety related as this!

cars are held together with spot welds and glue , captive nuts/ fixed bolts are fitted to cars with 2 tack welds. welding the same bolts in position makes them stronger than factory and a properly welded mount would be alot stronger than factory bolt.

im glad im an engineer and fully trained in all types of welding in most materials and restored a good few cars from bare shell strip down back up to full running cars

one of which was mot'd today and i was told was in better condition than alot of 5 year old cars (this one is 23 this year )

No issue with completely welding the nuts in place, but the main issue is access it's inside the chassis rail.
But you suggested weldin the mount on, no way. As A. they need to be removed (normally) to adjust the suspension B.& more importantly the mounts are part rubber & wouldn't survive the heat,they are also around 50 quid each!

not seen them so cant say exactly i wouldnt cut out the rail though , getting it welded back in exactly right to keep the suspension geometery spot on would be a pain.

a properly done weld is stronger than the steel surrounding it.

Obviously. This is solid box section towards the back of engine bay. You have to open up one side so you can get access, weld the nut inplace then close the side up again.

I never got to the point where the torque wrench was required.
Bit surprised something that carries this load is not virtually bomb proof.

I had a cunning plan
Use something like a Dremel to cut a hole large enough to gain access to the captive nuts then tighten the two bolts up, weld the access panel back on and if the control arm needed removing for some reason, at a later date, it could be removed by unbolting the eccentric bolt, as per the procedure in Clarks garage.
Not perfect because in years to come when its next owner has to remove the control arm he is going to have a problem if he tries to remove these two bolts.

Welding the nuts from the outside then grinding sounds feasible if I can remove the bolts.

Did you loosen the eccentric, both sides whilst it was off? On mine I had the wishbone in the vice & me (17St) dangling off a 2 ft knuckle bar. When it went, I ended up in a heap on the floor & it made such a bang I thought I'd broken the vice or the bench. They seize up because of lack of use.
You can't weld the nut externally, it's hidden inside the chassis rail. Yes you can Dremel an 'ole, but if you're doing that it's worth tacking the nut back!
Obvious surgery to this area that isn't repaired to the satisfaction of an MOT tester will be an instant fail & probably a red ticket.

Never touched the eccentric.

Doesn't look like I have much choice other than to cut the hole and tack the nuts.