dabiz7

Thought I was done working on this car, looked at the rear brakes while the wheels were getting cleaned up and...haicarumba! the pads were down to nothing and the rotors were toast!...so, looks like another week waiting on parts to get here.

My question...I noticed that one (1) wheel stud on each side had a HUGE amount of wear on the sides of the thread, like the wheel had been loose. None of the other studs had this kind of wear. Seemed strange to me. thoughts?

So this is an early 86, according to PET, I think the stud I need is a 928 341 671 02. I think this is a 50mm long, but can anyone confirm that this is in fact the length of stud I need? Have not diassembled the hub yet. Will another Porsche part number work? Can't seem to find this part number around, there are wheel studs on e-bay, but some are 45mm, some are 52mm....I'm thinking a 52 should work ok, thought I would ask for a recommendation here first before I pulled the trigger. Just have the regular manhole wheels, stock setup, so whatever will work, I would appreciate the heads up.
Thanks!

Shane

50 mm if you are using the closed aluminum lug nuts. Longer and you would need to switch to open lugs.

Your '86 should have the 21mm spacers which is why it uses the longer studs in the rear.

The wear you are seeing could be from someone drilling off corroded lugs nuts or a wheel lock. Check the radius of the wheel where the lugs seat and look for some marks left by a drill bit going a bit too deep.

Driving the old stud out could require a press or a serious BFH, see if you can't get a thread chaser on there to clean up the threads negating the need to replace it.

dabiz7

My 86 is an early VIN car, below the 1000 mark...there is no spacer on my hub.
Maybe you are referring to the later year 86.5 version?

dabiz7

Ok, you are correct, there is a spacer on the hub..I just took the spacer and the rotor off to inspect.
I don't think the stud can be saved, it is REALLY worn, threads smashed...my question is now, which stud am I supposed to use ?????????????
the stud I measured in the hub is 69.85mm from the stud flange to the end of the threads, 76.2mm overall length. Is this a 91 331 671 01 stud? No way is a 50mm the right one.

Also, anyone replaced one of these without removing the hub? I did not see a procedure in the WSM and it looks like you maybe can sneak one in the backside if you remove one of the parking brake shoes. Can anyone confirm this?

FLYVMO

The studs on my 86.5 were around 72mm, it had a spacer 21mm? I think. Pretty sure there is no way to press the studs out in place. As far as I know the hub needs to come out, which requires new rear wheel bearings. But if your car has over a 100K miles it may not be a bad thing to get those replaced anyway. Hopefully someone with more experience can confirm this.

Cheers!
Carl

jheis

I'd try to use a thread chaser to clean up the stud as much as possible. You can't replace the stud without pulling the hubs apart - which means destroying the rear wheel bearings - which means a much bigger (expensive) job requiring special tools...

James

terry gt

Yup . wheel bearings . studs are too long

dabiz7

Getting the stud out isn't a problem, cut it off and punch it out the back....sneaking the new one in from the back without pulling the hub, that's the question. Sure looks possible after removing a parking brake shoe. I will try it this winter while the car is in limbo. Will report back. Thanks for the info.

Bilal928S4

Do not bang on the hub with a BFH or you will ruin your wheel bearing.

jheis

Good luck with that.

Remember, however, once you cut the stud off, you're committed. It should be obvious, but if you don't have clearance to press the old stud out without cutting it off, there's no way you have clearance to press a new stud in. If you can't finagle a new stud in from the rear (and in my experience you can't) you're buying new rear bearings and buying or borrowing the Sir Tools installation tool as well.

It's also a days work for two, assuming you have everything you need when you start and don't find any other problems...

James

dabiz7

I've driven a LOT of wheel studs out of hubs over the years, from cars to Diesel semi's...a couple of whacks with a good hammer should be sufficient to knock the stud out. The wheel bearing is quite a chunk, if it can't tolerate a couple of whacks on the hub, well...

I haven't put a tape measure on it yet, but is sure seems like if you take the parking brake shoe loose and move it out of the way, you should be able to sneak a new stud in the back and pull it down tight with a M14-1.5 nut and some washers.

If you guys have already tried it and are convinced it can't be done on my '86 hub, I will take your word for it and just pull the hubs off this winter and do the bearings.

FLYVMO

For my 86.5 hub it took a 20 ton press to press out those studs, I doubt a hammer will do anything...other than damage your bearings. IF those studs are NOT the original 25 year old studs and have previously been replace, your hammer MIGHT loosen them, but on my hub with the studs required for the 21mm spacer, there is NO ROOM to press them out in place. Just do it the correct way and save yourself a lot of headaches down the road...