TR6 Rear Hub on a TR6 5 out of 6 studs enough?

[SCguy]

Can anyone confirm for me how tight to tork the rear hub bolt/stud to the trailing arm? I don't want to end up like Tinster! Is it 16 pounds?

up-date: I kind of figured I was asking for trouble when I decided to change my rear axle gaiters.

As I began to tight up my combination of nuts/ studs and bolts that hold on the two rear hubs to 12 lbs. I had two (one on each side that didn't hold the 12 lbs and stripped or were in the process of stripping. So is there an easy fix? or will I be forced to take off both trailing arms and have them fixed?

 

[TR6oldtimer]

Re: Rear Hub tork on a TR6

The nuts should be torqued 11-16 lbs. I would go for the lower end. Tighten them in increments diagonally across the center of the axle.

 

[DougF]

Re: Rear Hub tork on a TR6

The fix can be made while the trailing arm is on the car. You will probably have to use a Heli Coil because they don't require as big a hole as some of the better fixes.
You can find the kits at better auto parts stores.
I'm thinking that is a 1/4-20 stud.
You will need a 17/64" drill bit. The proper tap may be included in the kit.
The most difficult part is keeping your hole straight. Just take your time.

 

[SCguy]

Re: Rear Hub tork on a TR6

OK, I used a couple of Heli Coils. On each side 5 out of the 6 bolts I was able to put about 14 pounds of tork. On each side I had one that felt a little iffy and I stopped at about 10 to 12 pounds of tork.

All this leaves me feeling like even in the best of conditions it hard to believe that these are safe. I used red lock tight for what it's worth.

What's the best way that these can be fixed?

 

[TR3driver]

Re: Rear Hub tork on a TR6

You will probably have to use a Heli Coil because they don't require as big a hole as some of the better fixes.
You can find the kits at better auto parts stores.

But they are typically cheaper at online places, like McMaster-Carr
https://www.mcmaster.com/nav/enter.asp?pagenum=3415

"Helicoil" is a brand name, but there are other companies that make the same thing. "Recoil" is another good brand.

Personally, I prefer Helicoils to other thread repair systems. Main disadvantage is the high cost of the kit, but once you have it, the repairs are good. Frequently you don't have to drill at all (especially in aluminum), as the drill is very close to the diameter of the stripped hole anyway, and the tap will act as a reamer to remove the remaining excess metal. YMMV of course.

But double-check the stud size first, as ISTR they are 5/16 NF rather than 1/4 NC.

 

[Tinster]

Re: Rear Hub tork on a TR6

Hey Larry!!

You want some very first hand experience with helicoil
inserts in a TR6 trailing arm?

My car had five helicols and one original stud.
DPO install not mine.

All five helicoils popped out going around a bend
in the road doing 40 mph with my wife in the car.

The wheel seperated from the car but did not come
totally off.

I would never knowingly drive a TR6 with helicoils
in the trailing arms. Too risky.

I torqued my new T/A studs to 15# into a good shape
used but structurally sound T/A that Paul kindly
got for me.

 

[DougF]

Re: Rear Hub tork on a TR6

The best repair is a Keensert. These require a larger hole be drilled.
Once the hole is drilled and tapped, the Keensert is threaded in. There are tines(two or four depending on which grade you get) that run parallel to the insert. These get driven into the threads of the trailing arm.
When in position, the insert will not move. In aluminum, it is stronger than original.
They were originally used for cross threaded spark plugs in aluminum heads.
They of course are more money and harder to find.

 

[70herald]

Re: Rear Hub tork on a TR6

The best repair is a Keensert. These require a larger hole be drilled.
Once the hole is drilled and tapped, the Keensert is threaded in.
They of course are more money and harder to find.

Very easy to get and only cost about $1 each.
https://www.mcmaster.com/ search for Threaded Inserts

I have used these for several repairs on my car, including the infamous Al sealing bar on the front of the engine which always gets stripped out. Very happy to recommend, and yes, done properly, these will be much stronger than the original.

The advantage of this type of insert as opposed to the Helicoil type is that you do not need a special tool to insert the insert. You need to bore out the original hole to a slightly larger size, re-thread it, and then screw the insert in ( I had to use a double bolt and wrench to get them in they were so tight) The thread is now a slightly larger diameter, and a course thread, MUCH better in an Al part.

Dale, Pedro did his usual screw up job on the Helicoils. If he had done the job properly, they would not have come out.

Yisrael

 

[piman]

Re: Rear Hub tork on a TR6

Hello all,

as someone earlier mentioned, there is not a lot of material around the stud. I would be cautious about drilling out to a much larger diameter. Certainly Helicoli or Recoils would be a more than satisfactory repair, done correctly.
Ensure that the studs are screwed in fully and torque up to the specified setting. If it won't torque up then the repair is not satisfactory.

Alec

 

[vettedog72]

Re: Rear Hub tork on a TR6

Keensert advertises that it will hold well enough to break #8 bolts. I wonder where the truth is with safety and the hub repairs.

 

[bunzil]

Re: Rear Hub tork on a TR6

Since we're on the subject. Can someone confirm the Helicoil size required? Two sizes were mentioned above: 1/4 NC or 5/16 NF. Which one?

 

[TR6oldtimer]

Re: Rear Hub tork on a TR6

Hey Dale,
I read on another forum where a guy used aviation grade epoxy to repair a pulled stud. <u>NOT</u> that I am advocating this method, but thought that given you have a useless trailing arm maybe you could give it a test. Mix up some of your magic elixir and insert a stud into the trailing arm with it. After setup, see how much torque it takes to pull the stud out or strip the threads. If the threads go or the stud breaks, then this guy is ok. Otherwise I might drop him a note of caution.

Only if you have nothing better to do.

 

[TR3driver]

Re: Rear Hub tork on a TR6

Can someone confirm the Helicoil size required? Two sizes were mentioned above: 1/4 NC or 5/16 NF. Which one?

The TR6 parts catalog shows P/N TD0812 for the stud. Unfortunately the standard hardware catalog doesn't list that stud, but usually the last two digits are the length, and a TD0809 stud has 5/16 UNF threads on both ends.

Also, the SPC shows P/N YN2908 for the nut, which is a 5/16 UNF nyloc nut.

 

[Tinster]

Re: Rear Hub tork on a TR6

Ray,

I can fairly accurately predict the pullout resistance
of the magic elixir holding a treaded steel stud in
my useless trailing arm. It would be very high.

I think the failure will occur from the shear moment
with possible subsequent shattering of the bonding
agent. And then the wheel falls off.

I may try filling the holes with aluminum weld and
then drill and tap new holes. I spoke with one alum.
welder who said he's give it a try.

Personally, after having a helicoiled wheel come off
the car while driving, I would not use helicoils, or
anything else that requires enlarging the existing
tapped holes. Up close, in your face, there just isn't
that much aluminum in the surrounding structure.

Would I put my wife's life on the line trusting a $1.00
make-do part? Nope. Lived thru THAT DPO Pedro supplied
experience. Once is enough for a lifetime.

d

 

[DougF]

Re: Rear Hub tork on a TR6

My only concern with the Keensert is the lack of aluminum to drill. The two tine insert has a thinner wall and may work.
As for any possibility of it falling out, it won't. The aluminum will crack around it and turn to dust before that insert would fall out.
I sell these things and I have broken Grade 8 capscrews off while the Keensert is inserted in aluminum. We mark the insert and the aluminum to show that that in Keensert does not budge.
As I said before, it is a better than original fix.
I said it was 1/4" trying to go from memory from 6 years ago. Sometimes the memory isn't what it was a week ago let alone 10 years ago.

 

[SCguy]

Re: Rear Hub tork on a TR6

Dale,

I've been looking for your thread on your rear hubs as I want to reread it. Do you know it's title as I can't find the thread?

Also, as I don't remember the thread, do you think it's possible that the heli coils were not at fault and that the bolts or studs just loosened up? Is seems like everything on my car just loosens up and falls (or comes close) to falling of all the time? Just today I also noticed that all my bolts which hold the axle u-joints to the differential were loose and about to fall off. Last week my fan fell off!

Thanks!

 

[Guest]

Re: Rear Hub tork on a TR6

Larry, all my u-joints are held together with grade 8 bolts and grade 8 all-metal locking nuts, and red Loctite. Whoever built your car just didn't have the right hardware or didn't but enough torque on everything.

 

[Tinster]

Re: Rear Hub tork on a TR6

Hey Larry!

Here are a few photos. The experts here can attest
I know almost zip about auto mechanics. I'm just
an architect trying to make enough repairs to get
a very dead TR6 back into driving condition.

So mabye there are some other guys like me who don't
know very much about trailing arms, wheel hubs, lever
shocks, torque settings and stud threads. The photos
will hopefully get the non-mechanic guys like me oriented
into this technical discussion.

I bow to the wisdom of the experts. Some facts I observed.

My wheel became unattached from the car while driving.
A fact

The helicoil's studs and nuts were not loose.
A fact

The helicoils stripped out the aluminum re-bore threads
and came away from trailing arm as single units combos
of helicoil/stud/nut.
A fact.

The aluminum thickness where the helicoils install is
not great.
A fact

I am making no statement concerning the viability of the
helicoil concept. Only some facts I observed myself and
took photos. Sorry but I threw out all the combo H/S/N
-no photo.

 

[TR6oldtimer]

Re: Rear Hub tork on a TR6

Dale,
No one ever had an argument that once a heli-coiled fix failed on a trailing arm, that was the end of it. The only recourse was welding the hole closed then drill and tap for a new stud, or do as you did, find a good replacement. At sometime in the future, welding will be the only solution.

What is being debated, is whether to use a heli-coil or alternative product to make the repair. I even, for the sole purpose of discussion, threw in the one guy that did neither, he used epoxy (now there is a car I would wonder about).

Most of us have no problem with a properly install heli-coil or other insert solution the first time around. The key word here is "properly installed" which given your car's history with Pedro may have been the cause of failure, or some neophyte King Konging (over torquing) them, or both.

 

[SCguy]

Re: Rear Hub tork on a TR6

Thanks to everyone for their imput! As I mentioned I retorked everything to 15 pounds successfully and put about sixty miles on curvy roads today.