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MG Midget and Sprite Technical - Torque settings

Dear all,
I've recently bought a '75 1500 and posted on the general thread. I'm starting to go through the list of jobs and I've got to the rear axle U-bolts. One of the issues/problems/quirks is that the car rises to the right on the throttle and dips to the left off the throttle, it's only very slight and the answers I got in that thread described it as rear axle squirm with the recommendation to tighten the axle u-bolts and replace worn bushes.
I'm starting with the easy (cheap) option of tightening the bolts/nuts.
I think that could very well have been the problem because I'm guessing that finger tight is not good!
Ok maybe a little more than finger tight but not much.
I've tighten them up to 20ft/lbs to start with (I didn't want to shear a bolt too early in the game) but my question is...
What should they be tightened to? I see there is a rubber pad that is flattened and needs replaced. I have gone with 20 at the moment and equal amount of thread outside of the nut.
while I'm here I have another question...
Where can I find a list of torque settings?
Thanks in advance
Nigel B
N Broomfield

The BMC/BL workshop manual covers most things, depending on which version you can find.

For the 1500 engine, I find a Triumph manual is invaluable. I've attached an excerpt as a PDF, although the gearbox is likely to be different.
Dave O'Neill 2

ETA: Dave posted as I was typing (as usual) but I don't think the WSM has a figure unless I've missed it.(?)

NB,
20, you've got a torque wrench that reliably goes down to 20. 😃

The U-bolt torque subject is covered in the Archives here but I can't remember if there is a figure and with torqueing it depends on a lot of factors so for many things it's just a guide.

I can't remember the size of the nut/spanner/thread there but generally, as Guy has pointed out before, a standard sized spanner for the nut should give you the leverage, of course this discounts mechanics' forearm and upper body muscle strength, hence perhaps the need to rein them in with figures.

The 8 nuts want to be tight, not murder, Billy-big-bollocks, tight, but tight. Normally if each U-bolt has been tightened evenly and as a pair then follow this pattern. If not loosen off and retighten them evenly.

It (ETA: does) matter with the u-bolts, generally with this sort of suspension stuff once everything is alighted up and tight enough to hold position final tightening is done with the car sitting on its weight.

As nuts, bolts and fixings tightness tends to vary with hot, cold, vibrations, where the oon is during daylight hours you want to check and retighten if required before and after the first and second proper runs with the car (not just rolling down the drive or dribbling around like a sunny Sunday, no hint of precipitation, classic car off to the local annual show).

HTH.
Nigel Atkins

I've never torqued the axle u bolts nuts. Just do them tight with a ring spanner --- 9/16ths -- until you compress the rubber pads.

As it hapens, I've just swapped my axle and hence tightened my u bolts. I'll bung a torque wrench on them tommorow and see what it registers.

Edit. I never knew billy's had big bollocks. 🤣
anamnesis

Just checked the torque on my axle u bolts. Done up with a ring spanner. Register 15lbft on my 3/8 torque wrench.
anamnesis

Cheers folks, thanks for the replies.

I found these pages on internet that suggest 30. I haven't measured the bolt rod diameter but my guess is it's closer 3/8" than 7/16" and I don't know the metal grade but I'll assume the lower grade 5.

https://www.eatondetroitspring.com/how-to-properly-torque-your-leaf-springs-u-bolts/

https://www.suspensionspecialists.com/techinfo/Ubolt_Information.pdf

The danger is the condition of the rest of the bolt, great having a torque setting for a new bolt. After torquing them to 20 and taking it for a spin round the block it has sorted the torque steer at least, so I'll leave it at that and recheck. It doesn't take anything to recheck.

btw - a quick spin round the block is 21 miles with some town, long straights, some swift combination corners, good & bad surface, fast off camber, roundabouts, even a humpback bridge. For those with Google maps through Abingdon to Marcham, take the A338 to East Hanney left onto Steventon Rd, right at Steventon up the the A4130, down the hill to the A34 junction, watch your speed down the hill to time the lights at green into Milton Park, through Milton Park round past the power station (big space now) left at the roundabout onto the Didcot bypass, left at next 2 t-junctions to Appleford, slowly though the village, towards Sutton Courtenay, right over the bridges onto the A415 and back into Abingdon before the missus realises you've left. No dribbling.

Take car, have fun
NIgel B
N Broomfield

Well done on getting it sorted and test run.

In the factory parts catalogue the nyloc nuts are listed as GHF223 which show as 3/8" (thread) UNF which uses a 9/16" spanner (or sometimes 11/16").

Torque for that is whatever you want to believe or feel comfortable with.

20 miles just about enough to put the charge back into the battery from starting, at least in this weather the engine and oil would get warm enough. 😊

You would have of course been allowed a stop at the North Star and it'd be safe to go in the village on a Sunday as it's unlikely the stacks-of-sh*ts "specialist experts" will be doing their dark deeds there.
Nigel Atkins

Axle U-bolt nut torque is subjective, and I suspect may depend on whether using rubber or poly for the bushes. Frankly, I would replace any rubber pads/bushes for poly every time but personal choice.

As for tightening the nuts, finger tight is indeed hopeless, and quite possibly dangerous. My method is to tighten all 4 to a similar torque setting - around 10lbft or so, also trying to obtain a similar amount of protruding thread for each. Ensure they are also Nylocs or similar.

Drop the car and take it for a spin. On your return, tighten them up some more - as Anam says tight by a ring spanner.
Oggers

This thread was discussed between 17/07/2021 and 18/07/2021

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