G'day,
Not quite ready to put them in yet but have been thinking about how I can best judge 8lb torque while I'm laying under the car with a ring spanner in my hand.

Need a sanity check on what I've been playing with please.

I grabbed a bolt and old worn nyloc nut of the same diameter and thread as the U bolts for the QL's. Whacked a few spacers on the bolt shaft and then screwed the nut on by hand until it was just touching the spacers (about finger tight).
I then marked the spacer and nut with texta in that position so I could see how much rotation of the nut = approx 8lb (just shy of the 10lb marking on the wrench).

What I found is that the nut only rotates about 1/4 of a turn. Does this sound right to you blokes?
I'm thinking that the hard rubber casing of the QL might compress a bit and it would be hard to get all the nuts just right on the u bolts before torquing them up, but it would seem by my best guess that somewhere between 1/4 and 1/3 of a nut rotation would be sufficient.

Having read about the failures of these when the nuts are too tight, I'd like to try and get them ok first up.

Cheers, Rocky

While I admire your intension to get this right, I feel you may be "overthinking" it. It has been a long time since I've used the rubber couplings or the QH type so I bow to others with better advice.
But judging 8lbs/ft on nyloc nuts is not easy. The important thing is to get the 2 nuts on each U-bolt to pull up evenly - judge by the number of threads showing past the nut - and just enough to pinch the spider (knob) with the U-bolt so it doesn't move in the U-bolt.

Because the car is jacked up and the wheel is hanging down at a greater angle than it would normally drive at, you sometimes get exaggerated twisting of the universal joint while fitting it, making it harder to judge if it is tight enough. Before jacking the car, you could remove the little "L" shaped rebound rubber and replace it with a large nut in the gap between the upper control arm and subframe so as you jack the car, the upper control arm holds the hub and wheel and drive shaft in a straighter line.
When people talk about "overtightening" it is usually by 6 or 8 threads past the nut. I doubt that 1 or 2 threads either way is going to make an impact.

Others may have better suggestions.

Tighten them up when under load, IE car is on ramps.

_________________
The bitterness of poor quality (or Crappy Workmanship) remains LONG AFTER the Sweet Taste of Low Price is forgotten.

I agree. I was trying to come up with a procedure that simulated the driveshafts being horizontal. With ramps, you can only tighten 1 or maybe 2 U-bolts at a time before repositioning the car.

Thanks Bill and TK.

I seem to recall reading that with the QL's being more like a standard uni joint that the old rubber ones, there was no need to tighten them up under load. I think it mentioned that if the wheels were hanging in the air with the old rubber ones, there was undue tension on them - bit like the lower arms bushes on the front end if you do them up with the arm hanging right down.

Not sure if that's correct though. I may have things mucked up. It would definitely be easier if I could fit them all up without moving the car.

I've also read somewhere where you should have no more than 1/4" of thread showing past the nut. I did measure the length of thread past the yolk and the nut thickness but can't remember the measurements off hand so will check again tomorrow and let you know. I'll also measure the distance that 1 complete turn of the nut travels in order to maybe have a reference to how many turns are required to have 1/4" of thread.

I agree with you Bill that I'm over thinking it but I don't want to bugger it up if I can help it. Give me something to think about during lockdown.

Rocky

This is the sort of extreme overtightening I was referring to.
Photo Courtesy of mk1-forum.net

If you haven't done this, you are probably OK! That's all I meant by "overthinking". I'm sure you aren't anywhere near this!!!

No Bill, mine are still sitting brand new on the bench so all good. Finalising colour for paint job and getting everything ready to re-assemble.
Jeez they've been screwed down hard though. Obviously the cups? squash down a bit before giving out.

That is the point I have been making. You can see what the obvious problem is and so long as you are a long way off that extreme, you will be OK.

G'day Bill. I measured a few things this morning just out of curiosity. All measurements approx.

The length of thread on the u bolt past the yolk ready for the nut to go on is 13.3mm. This is with QL and u bolt firm fitting by hand.
The nuts are 8.7mm thick.
If the nuts were screwed down to just touching the yolk, that would leave about 4.6mm of thread past the nut.
Each rotation of a nut on the u bolt = 0.9mm
Working on the theory of having no more than 1/4"or 6mm of thread past the nut, this would mean tightening the nut about 1.5 turns.

In our previous discussions on these joints, we mentioned 1 to 2 turns as a gut feel.

In the pic you posted, assuming the nuts are the same thickness at 8.7mm, it looks like there's at least 10mm of thread past the nut. No wonder they failed!

Rocky

With the original rubber universal joints the tension on the nuts was more critical to allow the rubber to flex slightly with each wheel rotation. Too tight and the rubber was quickly torn from the steel centre. But these joints are needle roller bearings that are intended to allow movement without damage to the joint, so tension needs to be enough to hold the cups to the yoke firmly.

The number of threads protruding past the nut will obviously vary according to manufacturer. The rubber ones were all made by Dunlop originally so their U bolts were a standardised length.

Years ago I got a quote to make cups from steel not nylon for a Sydney Mini parts supplier, and to use the same U/J inside. To be made on an automatic lathe.
But by the time U bolts and nuts were included, the price wasn't nearly competitive with a QL5000, so it didn't happen.
Tighter nuts wouldn't have been a problem.

_________________
DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I do remember steel cups being on one of my early minis. You're right Kev wouldn't have been a problem

_________________
The bitterness of poor quality (or Crappy Workmanship) remains LONG AFTER the Sweet Taste of Low Price is forgotten.