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MG Midget and Sprite Technical - How tight should it be?

There are a few nuts for my suspension parts that I might not have made tight enough.

The lock nuts for the bolts that connect the lower control arm to the body (bolt that goes though the bushings and lower control arm:
If I start to make them really tight then it becomes hard to move the control arm up and down and the bushings start to look too squished. So I loosened them a little. A friend told me that they should be tighter. Is there a torque for these (could not find in book).

I have the same question for the nut on the top end of the kingpin. Should that be cranked on really tight or left a little looser so as to be sure that it swivels easily.

The lock nuts for the leaf spring u bolts. I could just keep cranking them tighter and tighter and tighter but even though I could still keep tightening, the bushings (in the sandwich) start to look too squished. Is there a torque for these?

same question for the shackle bolts and the bolt at the forward end of the rear spring as well?

Usually I am pretty good at looking up or determining torques but in the case where bushings are involved I need more guidance.

thanks,

(PS: just got my car back from the body shop. I had them tweak the left front geometry so that it is lower. I need to further evaluate. I think that it is much better. Also, I welded a re-enforcing 1/8 plate to bottom in area of anti-sway bar mount hard point weld. It is now indestructible I think. I will post pics soon.)
R Harvey

Rebecca -
No bushes are adjusted by leaving the nuts loose. There are (almost) always shoulders or distance tubes that you tighten against. Rubber bushes accommodate motion by torsion in the rubber, not by motion on the pivot or in the bore, and the degree of compression is critical. Poly or other non-rubber bushes will also have shoulders in some form to locate things.

LCA bushes must be tight, and they must be tightened in the normal operating position. The Spridget LCA pivots are especially critical. The large stepped head MUST be correctly located in the frame hole, and the nuts MUST be tight. Otherwise, they will come loose, flop around, and destroy the frame. The bolts are shouldered as a stop point to tighten against; torque is "normal tight with normal tools", about 25lbft.

If you are referring to the nut on top of the kingpin, it is dead tight, but endfloat on the pin is set by shims under the upper trunnion. Should be about .002 endfloat with nut tight.

If you mean the bolt through the trunnion to the shock arm, it has a shoulder and again is dead tight in normal operating position.

Front of rear spring is again dead tight against the inner sleeve of the bush in normal loaded position.

Shackle bolts same, bolts are shouldered.

The rear axle to spring perch are the exception. Since there is wide variability in assembled thickness, they count on "mechanic's sense" to govern tightness, and they require periodic retightening as things settle and wear. They rely on the Nyloc nuts to keep it together, or jamb nuts on earlier cars. Again torque is "mechanic's sense", a standard (NOT long) 3/8 drive ratchet with a deep socket is the tool. If the car changes direction when you get on or off the gas they are too loose, if the plate bends it's too tight.

Also, See this thread but hurry up as it is about to fall off the board into archives:
MGA board Thread: MG v-8 bushings - too tight!

FRM
FR Millmore

Hey reb

I knocked that post FRM mentioned on the MGA boards back to the top for you
Prop

Frm is completely correct

Just one addition
Most bolts for hinging points in the suspention should only be fully tightend when the car is on the ground.
In essence when the sping is compressed and the suspention is in "neutral" position
Onno Könemann

I am sure that I am already at least at 25 ft lbs but I am going to re-check everything today.

thanks for the tips. and the hint that it must be resting on the ground (not jacked so that I can get under it). I will put it on the lift.

thanks,

Rebecca
R Harvey

Rebecca, when in doubt, and when the manual fails to mention a torque, here are some standard torque values, arranged by fastener size, that might be useful.

ignore the shading, if you don't use anti-seize (I shaded it because I do, and needed an easy reference so I didn't have to look it up every time!)


Norm

Norm Kerr

Excuse me for asking something that may be obvious, but what does "dead tight" mean? I had the same questions as I recently installed new upper trunnions and could not find any torque value for the upper kingpin nut. There is a shim under the trunnion (BTW - what is the difference between a washer and a shim? Looks like a thin washer to my untrained eye). I was afraid to tighten the nut too tight as it might damage the shim, but want to make sure it is tight enough.
Thanks, Jack
Jack Orkin

shim is a washer of X thickness

Dead tight is tight.
So you keep turning the nut until you can no longer.
no need to put a lot of tension on it but do not leave it loose
Onno Könemann

Jack,

what FRM is referring to, when he says "dead tight" is that the nut contacts a shoulder and is torqued against it. The "tightness" in the kingpin assembly is instead controlled by the addition or removal of shims so that when the nut is torqued there is no freeplay, and the axle can still rotate without binding.

Even though the kingpin nut is a nyloc nut, it still relies on the proper torque to hold and the nyloc is only there for additional insurance.

I can't remember what size thread it is on the end of the kingpin, 7/16" perhaps? In that case, the torque should be 55 ft-lbs (dry), or 32 ft-lbs if you use anti-seize.


Norm
Norm Kerr

Thanks, all for the clarification. I was afraid if I tightened the kingpin nut dead tight, it would not only crush the shim but also prevent the axle from swiveling. I copied the nice chart from Norm and will check the nut now that I have something to go by.
Jack
Jack Orkin

This thread was discussed between 30/04/2011 and 02/05/2011

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