KuHL 951

We did struts yesterday on a friends 86 N/A. He had an alignment done a couple weeks ago. It appears the shop severely stripped the threads on the receiving end of the caster block mounting bolts. What would be the best way to repair this and is it a captive nut inside there or what? Right now he has only one bolt to bite and it's not that straight, looks like it cut new threads because it looks crooked. Any help would be greatly appreciated.

HY M8NC

I did the same thing when I did my motor mounts a couple of months ago. I borrowed some "Time-Sert" inserts from a friend, and have had no issues. He uses them to repair 911 cases, and had some for these bolts. Oh, I also bought new bolts, obviously.

Anyway-works like a helicoil, except that the sleeve expands on the end, making a permanent fix. It is not a captive bolt, but I think the frame rail is tapped.

It was a simple gig. The kit came with a large drill bit that was turned by hand, a tap, and the inserts. Took about 1/3 hour...

Jim @ EuroWerks

How did they do that? You don't touch those bolts for a caster adjustment on an 86

Jim @ EuroWerks

Ditto on the time sert.

KuHL 951

The alignment was part of a control arm replacement from a bad ball joint. The Time-Cert sounds good, any idea where to buy them? Do you need to ream out the old hole first and what size did you end up using? Thanks for the info, it really helps.

Jim @ EuroWerks

It comes as a kit we buy ours from winzer( nut & bolts) Ck them online, no I don't have an address but if you can't find a supplier for these. Let me know and I'll give you our contacts #. You will have to buy it as an intalation kit and everything is self explaining. Once you use them you'll think less of heli coils. The only thing is making sure you have enough metal to work with. You might want to explain to your mechanic how a bolt works. Maybe he's used to nailing everything.

RedlineMan

Hey;

That is a problem when folks work on these cars that don't know them intimately. If you look at the original bolts, you will note they are tapered- self- centering with a groove in the end? They are Thread Forming bolts and cut their own thread when they are run in at the factory. These type threads do not have the depth of a true machine cut thread, and so will not take the torque either.

Also, the metal they are threaded into is not thick like a nut. It is quite thin as a matter of fact, and so there is not a lot of meat there for lots of thread engagement. Both of these points conspire to make it pretty easy to strip them out unless you DO NOT OVER TORQUE THEM, which most people invariably do.

Yeh... so I learned this years ago by stripping mine! I fixed it by using a longer, standard profile bolt. It apparently found enough good threads to hold pretty well. Still, I take it very easy when I tighten that one.

The Thread inserts are a good solution too. Either that or tap it to the next SAE size and use a different bolt. I think they are 12mm bolts, so that would be 1/2" if I am thinking right. Simpler!

Serge944

Looks like inserts is the way to go! Thanks guys. Btw steve, youre not gonna post the sexy knees? Haha.

jonnybgood

Serge, did the threadcerts work? I was installing 968 caster blocks this weekend and could not get one bolt to click on the torque wrench. Before I realized what was happening I stripped it. Seems like Porshche should have put some captive nuts in there.

Mike C.

I used a heli-coil on one several years ago. No problems since.

Mike S

I'll post some pics later tonight. I took the more drastic approach since one of mine was stripped and spinning around inside the frame rail.

I carefully, took a cutter and cut a rectangle out about 1" outside of where the caster mount sits. Once you open it up you'll see two nuts welded together on the back side of that plate. I ground both of those off and replaced them with some new grade 8 hardware and spot welded them in place. After doing that I welded the plate back in using a series of spot welds to make sure that I didn't warp or burn through the plate. It's time consuming, but it looks good now.

fezz

i glad i read this thread as I'm getting ready to upgrade to 968 caster blocks. If I understand correctly, we are talking about the mounting bolts that go through the caster blocks ( 2, I think) and thread into the underside of the chasis. Thses bolts are not to be overtightened, right.

Is there a torque set in the manual or is that to be ignored. Sounds as if the bolts just need to be snug down, maybe with some loctite?

joseph mitro

wow, i didn't know these were so sensitive to overtorquing. good thing i found this out. wouldn't have helped yesterday as i just reinstalled the 968 blocks anyway, but good info for later.....

jonnybgood

So Mike what you are saying is that there are captive nuts on the inside of the frame rail. If that is so I will use a helicoil. From the previous discussion it sounded like the threads were just placed in the wall of the frame rail without any captive nuts.

fezz, I was going by memory and had the torque wrench set at 55lbs. That might have been my mistake. I will look up the correct torque in the manual tonight.

IceShark

Humm, I've had those bolts in and out a couple times, glad I didn't strip the threads.

If you are doing the 968 castor block upgrade make sure the inner bearing diameter is correct before you find out the hard way. It should take an 18mm stud. Some of them are undersized, I had one undersized by 0.025" so no way it was going to fit. And it is hardened steel laminated to the rubber insert. Sort of a trickey situation when boring that out to proper size. I had five machine shops decline to do it until I found one that reemed it in stages by hand. Five minute job turned into 3 hours of running around.