LD200 CV joit bolts/nuts/torque

[Rick Kirchner]

So a while back there was this thread on the topic: https://www.apexspeed.com/forums/sho...nut-life-reuse

Thought I'd get a little more specific and address a problem of my own making.

When I bought this car, it had the M8? bolts and they were inserted from the flange side, meaning that it was a PITA to line them up and install the joint (have to do that on the outside joints anyway and I've since figured out an easier way to do it). The other problem with this setup is that if for some reason you lose the nut the bolt will back into the case side plate and machine off a nice little groove. The upside was that whether one used 10.9 socket head cap screws or hex bolts, it was relatively easy to torque them up with a low profile hex on the flange side, one could get a box wrench around it or a shortened allen key.

Of course, at first opportunity, I tore into the trans, replaced the 8mm with 5/16 and flipped the bolts around to make it "easier" to change out the bolts if necessary..... which I needed to do too often.

And just like in the previous thread, the AN bolts were too soft for the torque required and I spent a lot of time re-torquing them at the end of every day because they'd loosen up at the torque you could live with. Last year I replaced them and maybe the AN bolts were at the soft end of the spec, but I pulled the threads out of about a half dozen of them and so I decided to try to address this for good.

My first attempt was with a mix of NAS and Grade 8 bolts (couldn't get enough of the NAS). I believe they were -32's on the inside and -34's on the outside. I was both guessing a bit and having to make do with what I could find in stock. The outer ones were fine, if a tad long. The inner ones required a couple of washers under the head of the bolt and one under the head of the nut to ensure the nut didn't bottom on the thread and to keep the bolts out of the transmission case.

This worked but for one thing - the joint needs 24 ft-lbs and at 20-22 I could not find an open end wrench that would not spread apart and round off the nut. the first pic is my collection of wrenches I've used for this task - the first is a flare wrench that was ground off here and there, and it would open up. The second one is a box that I tried to grind down with no luck, and the other two are craftsman open ends where you can see the damage to the wrench from torquing the nuts so high. Obviously I had to do something else.

So I took the joint apart, measured everything, and then figured out the min bolt length as I should have before. What I came up with was a -29 would be marginal depending on tolerance stack-up. A -30 would be better. Unfortunately, I couldn't find any -30s in stock at a reasonable price. So I gave the NAS6605-29S's a try.

The shorter bolts allowed me to buy a 6-pt box wrench and grind it down enough to sneak in there. Second pic is this wrench ground down: https://www.amazon.com/dp/B00T3M9638...roduct_details

Third pic is the comparison between the longer bolts and the -29. Fourth pic is the wrench in place. I have a thin stainless washer under the head of the bolt, nothing under the nut. There's about 1.5 threads showing.

I was able to get them to 24 ft-lbs pretty easily. I might grind the 1/2" socket down to get it to fit close on the bolt head so that there's less of a chance to rotate off the bolt head when applying that much force. And for once the wrench didn't torture my hands, although I ought to make a 3DP sleeve for it.

If I could have found -30s I'd have used those, maybe with a thicker hardened washer under the bolt, but the last set stayed pretty tight (only had to check them before the weekend and didn't have to touch them during) at 22 ft lbs so I feel pretty confident at 24.

With the NAS-30s though I could bite the bullet and tear apart the gearbox again and insert the bolts through the flange no longer having to worry about goobering up the bolts.....

[FASTDAD]

My Staffs box has studs, never had a problem coming loose. Could you use Time-serts installed from the gearbox side and use studs? Is there enough room / metal there to drill and tap for Time-serts? Put some loctite on the stud threads of the Time-sert and the threads of the stud and maybe good to go.
Todd

[Charles Warner]

This subject comes up quite often. It was dealt with (IMO) definitively decades ago. Here is part of Steve Johnson's missive about hardware.
If you don't want to read it all, get Grade 8 bolts, hardened washers, and a bag of high-temp jet nuts. Of course, the fitment of the bolts into the flanges and cv joints is critical. If there is any slop you will always wind up with a loose connection. Replace the nuts every weekend.




gentlemen....
lets get back to basics, ok ?
but having said that, the radial shock load into that hardware , while not exactly of great magnitude, IS enough to loosen things up if you make mistakes during that sub assembly... and those mistakes are:

1) you fail to use hardware where the shouldered portion is not long enought to pass fully thru the first surface and at least 75 % of the second. thru BOTH surfaces is best with the washer giving the nec thread clearence.

2) the holes are loose. the bolts rattle in them. while the hardware is 300 % better than it has to be in shear, the CLAMP load that you can generate w/ an AN 4 is very small and is in no way adequate to keep these parts from moving relative to each other if the holes are not the correct size or worn out. you should not be able to move the two parts relative to each other with JUST the bolts stuck in them with NO nuts on them at all. if you can, the repair is either dowels or resizing the holes and hardware or replace the component.

3) using junk hardware. AN hardware is not grade 8. its not supposed to be. BUT it is manufactured to tight tolerance. what this means is that a -4 bolt will fit properly in a .249 to .251 hole where as a 1/4 " sae bolt will have a shoulder that is loose. loose is bad. and will cause your problem 100 out of 100 times.

4) you use junk washers. AN washer are soft . they are made to protect the surfaces of nut and bolt combinations held in shear where the torque is used to preload the faster correctly so it doesn't fall out... NOT to create a large clamp load to keep things aligned. as such, when you crush the bejesus out of these things trying to keep them together all you are doing is cold flowing the washer and in a short period of time the bolt loses its preload and is now loose. for assemblies where you want hi clamp, you must use hardened washers.

5) reusing hardware. jet nuts are one time use hardware. really, no kidding. this isn't some lawyer language on the back of a paint can. on the second use they lose 75 % of their self locking ability and anything after that is the same as no lock nut at all. if you are using them more than once you are not being smart. if you are using them more than twice you are too stupid to be doing this work at all.

An bolts can be used indefintely as long as they haven't been overtorqued or that the shoulder has gone out of spec.

the bottom lines are these ....


so the real world answer was to replace the stub axel bolts w/ gr 8 ( 10 if i could get them ) one time, and then keep a big bag of hi temp jet nuts around and just replace and retighten them before every weekend. they would have gone two or three weekends im sure but i figured for the 5 bucks and 15 mins at the shop, it was one less thing to worry about at the track.

end of problem.

[DaveW]

https://www.apexspeed.com/forums/sho...l=1#post661399

https://www.apexspeed.com/forums/sho...l=1#post661472

And, BTW, using these methods and torque, I don't have an issue with CV's getting loose over an entire season. I do check them between each race weekend. Plus there is no such thing as a "clearance-free-bolted joint". If there was no clearance, you couldn't assemble it.

[problemchild]

The modified box wrench does not even need to be 6-point. Ours is 12-point and it does the job just fine. Often, removing the flashing from the end of the bolt helps too (just 10 thou may help).

We have metric hardware on our Mygale axles so the jet-nuts are really expensive. My crew checks them every session. Once they get so they need to be tightened more than once per day, we start changing out hardware. The metric jet-nuts are so good that they hurt the threads on the bolts, so they need to be changed out regularly also.

Tip: the used jet nuts when run over a tap, make nice hardware for use on the hewland transmissions.

[DaveW]

...The metric jet-nuts are so good that they hurt the threads on the bolts, so they need to be changed out regularly also...

Was this with GR8 (or metric equivalent) bolts? In my experience, GR8's stand up pretty well to jet-nuts. Anything softer will, as you say, be degraded by the harder nuts.

Of course, I use the clutch for every shift, which minimizes shock loads, and the resulting less frequent reverse-direction shock loading reduces the propensity for loosening the joint, and so retightening is not often necessary.

[Rick Kirchner]

Besides flipping the bolts around, the cost and availability of the metric jet nuts were contributing factors for my switch to 5/16 - and also a little more slop. I never had any issues with the Lobro joints on my FSV, but getting these tripods on the 6 constrained bolts (especially on the outside) would nearly bring me to tears. My steel housings all have marks from a dremel with a kratox wheel trying to take sharp edges off of them.

Since then I figured out that I should take the housings off, install them over the bolts, and then unbolt the upright, swing it out of the way, and slide the axles in. Soooo much easier.

[problemchild]

Was this with GR8 (or metric equivalent) bolts? In my experience, GR8's stand up pretty well to jet-nuts. Anything softer will, as you say, be degraded by the harder nuts.

Of course, I use the clutch for every shift, which minimizes shock loads, and the resulting less frequent reverse-direction shock loading reduces the propensity for loosening the joint, and so retightening is not often necessary.

The metric jet nuts from Brad are doing some major-league "locking". They are about the same drag on their 3rd use as a traditional AN jet nut on its first. At some point, we noticed that the new metric jet nuts were not locking really well and the bolt threads were deformed/dulled. Once we changed the bolts, the lock nuts were effective again. I use quality machine shop grade SHCS hardware which may not be the best but certainly not junk.

Keep in mind that these are fleet cars serviced by various mechanics over time. It is a different situation than a personal pride-n-joy race car. Over time, we have developed processes that balance cost, time, quality. quantity, documentation, etc that "racer Greg" would not have considered (although he would adopt much of it if starting over).

[BeerBudgetRacing]

Since then I figured out that I should take the housings off, install them over the bolts, and then unbolt the upright, swing it out of the way, and slide the axles in. Soooo much easier.

IIR isn't there a c-clip at the axle ends?

[Rick Kirchner]

to hold the tripods to the shafts, yes.

[BeerBudgetRacing]

to hold the tripods to the shafts, yes.

Okay - your description made me think you were assembling the tripods and bolting them together and then just sliding the axle into the boot and tripod.

[Rick Kirchner]

nope - I slid the boots to the center and then insert the axle with tripods into the housings. I use non-locking nuts with the bolts to hold things together until I can get hands free to assemble the real parts.