replacement tips drive coupling

[jimi hendrix 544b]

drive coupling replacement, what tips have you found invaluable in doing this .worse job is trying to line up and push u bolts into place. thanks in advance. steve

[Dearg1275]

Before you start grovelling under the car make sure that you pinch the U bolts in a vice until they are exactly the width for the holes in the yokes. That way they fly in.

D

[JohnA]

If the Ubolts have been used they will have opened out and won't be parallel
Nip them in a vice to align them
Fit them to the opposite side of the yolk and ensure they slide in freely before you fit try to use them
I keep an old yolk handy as it's easier to do it on bench

[JohnA]

Hadn't see Dearg1375 post

[Spider]

As the others have said to get the U Bolts in.

Also, don't tighten the nuts for them until it's back at normal driving height, ie, don't tighten them with the wheels in the air, otherwise, you'll chew them out in short time.

Ramps or a Pit is handy for this task.

[Peter Laidler]

And definitely DON'T OVERTIGHTEN the 'U' bolt nuts. The tightening torque figure seems stupidly low. That's how it';s meant to be. It's overtightening that kills the bonding of the rubber to the steel cross-joint. Annanuverfing too. Slightly radius where the inner/smaller dovetail part of the yoke meets the centre part of it. This sharp edge is said to friction against the bonded rubber/steel cross-joint, digs in and starts to separate the outer dovetail parts from the inner steel part of the joint. Not very well described I'm afraid and I haven't even got one to illustrate what I mean

[smithyrc30]

Drop the upper ball joint off, makes getting a new coupling in much easier. Also means you can raise the wheel to ride height so you can tighten the shafts in the running position if you do not have a 4 post ramp or pit handy.

[dklawson]

And definitely DON'T OVERTIGHTEN the 'U' bolt nuts. The tightening torque figure seems stupidly low. That's how it';s meant to be.

This has come up in previous threads on the QL-5000 joints along with a short discussions about the nut type.

What are your thoughts on replacing the distorted thread (or nyloc) nuts supplied with regular nuts and lock washers... with the addition of blue Loctite? Prior to the Loctite setting it should be possible to more easily torque the nuts to the specified torque.

[kit of bits]

This thread may help
D

viewtopic.php?f=3&t=23112

[Peter Laidler]

Yep, that's the thread kit-of-bits. Photo 2 on page one shows the sharp inner edge of the driving flange that needs rounding off slightly. Otherwise this edge gnaws its way into the rubber bonding between the bonded rubber outer and steel inner of the cross-joint. The same overtightening principle applies whether you're using QH's or bonded rubber. Tighten anything around a taper and the mechanics of friction tells us all that it WILL simply frees itself. Or in this case, OVERtighen and it will try until something fails. Basic physics

[jimi hendrix 544b]

thanks all for input, great help. fine line to achieve ,aged a few years but all in . nearly ready for Bicester scramble and then the best Blyton. see you all there

[dodge44]

Drop the upper ball joint off, makes getting a new coupling in much easier. Also means you can raise the wheel to ride height so you can tighten the shafts in the running position if you do not have a 4 post ramp or pit handy.

Not sure how it works with hydrolastic and is less useful if you are fitting rubber couplings as you will still need to release the top ball joint, but the old dodge for keeping the drive shafts at normal ride height when jacking the car up is to remove the rubber bump stop (Part 2A4267) between the subframe and suspension arm on both sides before lifting the car. Then drift either a hardwood wedge or a tape covered cold chiesel into the gap. The drive shafts then stay where they are when you jack the car up and you can still release the ball joints if need be. Use the same dodge of course when the ball joints just need adjusting.

Roger

[dklawson]

I was thinking about the need to have the suspension at ride height while the cross joint u-bolts are tightened. This makes sense to me with the rubber crosses as you wouldn't want to have them excessively stressed. However, is there any reason this would be required with the QL-5000s?

[iain1967s]

Hardy Spicer and Quinton Hazell [QL-5000] couplings use needle bearings. You can just bolt them up while the car is on axle stands, no need to level the suspension.

[dklawson]

That was my thought.

I removed the QL-5000s this morning as part of pulling the engine. I had a mix of distorted thread and nyloc nuts on the u-joints. When the engine goes back in I will be using regular nuts with lockwashers and/or Loctite.

[Peter Laidler]

I'm not so sure about that Doug! If I was being pedantic - as I would be with these tapered journals, I'd measure the torque required to turn a nyloc lock/stiff nut on a bit of plain thread. Say that it's 3 ft/lbs as a round figure. I would then tighten the same nuts onto the U bolts equally to 8ft/lbs PLUS the 3 ft/lbs. I just think that lockwashers are not the right thing at such minimal torque fuigure.

Maybe it's just me and all that with my physics teachers hat on.......

[iain1967s]

AKD3509 specifies LNZ205 Philidas (distorted thread) nut with no washers.

Superseded by GHF222 which is a 5/16UNF Nylock as the modern equivalent.

Personally I wouldn't trust plain nuts with lock washers on there, even with Loctite.

ps.
Quote from Roy Davies in the Simon Garfield MINI book, regarding torque for the rubber coupling nuts:
"The instruction on the assembly line when sandwiching them together was: Don't have more than a quarter of an inch of thread showing through the nut, otherwise you're pulled it too tight."

[Peter Laidler]

Wise words Iain.......

[smithyrc30]

I'm not so sure about that Doug! If I was being pedantic - as I would be with these tapered journals, I'd measure the torque required to turn a nyloc lock/stiff nut on a bit of plain thread. Say that it's 3 ft/lbs as a round figure. I would then tighten the same nuts onto the U bolts equally to 8ft/lbs PLUS the 3 ft/lbs. I just think that lockwashers are not the right thing at such minimal torque figure.

Maybe it's just me and all that with my physics teachers hat on.......

Peter, isn't your example ass backwards?

If we assume that the fixing is acting as normal i.e. 50% in thread friction, 40% in face contact friction and 10% clamp load, then in your example the standard fixing is using 3 of the 8 in 'locking' friction (which the plain nut does not have) which leaves 5 for the remaining and the important one is 0.5 for bolt clamping (the bit that will crush the rubber/nylon).

If we add the 3 to the original spec of 8, giving 11, that gives us 1.1 for clamp or over double what we had with the locking nut.

If the original 8 was for a locking nut with 3 consumed by the locking device, we would have to subtract the 3 from the 8 leaving 5 and then we would be back at 0.5 to clamp the rubber/nylon.

I never have understood why a spring type lock washer is used with a plain washer. The locking washer is designed to bite into the surface of the nut AND the part being secured to prevent rotation. Adding the washer means it bites into something that is free to rotate and thus will not prevent the nut or bolt from coming undone once the clamp load is exhausted because the plain washer will turn on the secured part.

If you need a locking device and the part being secured is soft or the joint is soft (example with a gasket or paint) then the locking device must be between the nut and the bolt/stud.

Another note when considering bolted joints is adding more washers increases the number of contact faces and each has its own friction to consider. If this is not considered when the joint torque is specified, the fixing will have insufficient clamp load and it will come undone without fail.

[dklawson]

Iain has posted reference document numbers for the QL-5000 distorted thread and nyloc nuts. In earlier threads the original lock washer and plain nut instructions have been posted so there are at least three possible fastener types. I concede that there must have been a major mishap with lock washers and plain nuts or Q-H would not have changed the nut type twice.

I have seen documents that say what Peter is suggesting... that when lock nuts are used you add their running torque to the desired final torque to determine what to set your torque wrench to. That makes perfect sense for the nuts accessible using socket extensions through the inner wing. However, what about the inner u-bolts whose nuts are closer to the gearbox? The only way I can see accessing them would be to have the car on a lift and use a crows foot wrench on your torque wrench.

Before leaving this subject I do want to address Loctite concerns. The products I designed and built over the last 20 years depended quite heavily on Loctite. Common blue Loctite-242 would be appropriate for this size fastener but one could opt for Loctite-262 instead. Grade 262 has a higher break away torque and once loosened retains a high running torque value. This makes fasteners assembled with grade 262 behave more like fasteners secured with nyloc nuts.