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MG MGB Technical - torquing up castlated nuts

I'm doing the torquing up of my front suspension and was doing up the top trunion pivit bolt. It should be 40ft lbs but the nut finished up with the hole half way between slots. Do I go back to the previous slot (reducing torque) or forward to the next slot (increasing torque). I have to do the bottom kingpin pivot also which is castleated. I'm using SuperPro bushes with steel crush tubes. Also, I can't find the torque figure for the castleated nuts on the end of the inner wishbone pivots.
Steve Church

Hello Steve, if you are tightening up a castlated nut you must never slacken to the previous hole, if you think it will be too tight if you go to the next hole you can always file the underside of the nut a little.

John
john wright

Never thought of that John, thanks.
Steve Church

Most torqued fasteners have a tolerance which should be enough to decide whether you go forwards or back. Nothing on these cars is going to snap going to the next hole, or fall off if going back. I've never heard of filing a nut to get an exact alignment between a torque figure and a split-pin hole, and I never would. For a start you would have to ensure it was exactly parallel and not sitting on a high-spot, and how many times would you have it off and on filing bits off to get it exact? If I were that fussy I'd rather use shims.
PaulH Solihull

Paul, I am surprised when you said you can slacken off to get the split pin in is against all I learned through all the years I spent in the motor trade. Would you do this on a main or big end bearing, I hope your answer is NO. So slackening off on suspension components is at the best bad practice and at the worse down right dangerous.

regards John
john wright

Gentlemen, surely it is a case of proper 'risk assessment?' I come across many instructions which as aimed at those with no knowledge at all, so specifics are quoted, (because often these individuals cannot think it out!). I think if a nut is torqued to the correct figure but the hole through which the split pin goes through does not quite line up, then surely a little forward or backwards is acceptable. But yes it depends on what is being torqued.In the case of supension joints, we are not talking of the components revolving against one another, like a mains journal, or a wheel bearing,( albeit a slightly looser wheel bearing may only be noisier!) But hey, how many castlatted slots are there in the nut is it 12? then backing off or moving forward 1/12 is going to have what effect on the torque figure??? Mike
J.M. Doust

Steve-
I have to agree with Paul. Removing material from the bottom of a nut while maining a surface perpendicular to the axis of the nut is possible only with a surface grinder, which is a tool available only in a machine shop. It the surface is not perpendicular to the axis of the nut, then your torque readinds will be inaccurate due to side loading. The best approach is to get the holes to align at the proper torque setting by using shims.
Stephen Strange

Stephen, I agree with you up to a point, but generally nuts are not precision items, so saying only surface grinding is good enough is a little bit over the top, using shims is a non stater also because you will only need quite thin shims and the will not last very long before they rust or are torn apart.

John
john wright

the vast majority of the castled nuts on the suspension are used to press against the suspension bushes, so a small thange here and there will make next to no difference. all i've ever done is tighten or slacken whichever way is closest to the gap for the split pin. I put my car on the track quite often and have never had a problem.
A P New

John-
The general-purpose nuts and bolts that are sold through hardware stores are not precision items, but machine nuts and machine bolts are. As a general rule of thumb, only machine nuts and bolts should be used on an automobile. Shims that are exposed to the elements should be stainless steel.
Stephen Strange

Or try one or more new and/or used nuts.
P.Y.A. De Rouck

You are getting too anal. Yes, I would back off a smidgen, but increase torque if it was half-way between slots. I can't say for all situations but for things like hubs there are two holes through the shaft, so if one is between two castellations the other will be exactly in line with another two, making any adjustment to get one or the other in line minimal. I've not done 4-cylinder mains and big-ends but the V8 only uses torque and thread-lock, not split-pins. Anything with split-pins isn't going to come undone anyway.
PaulH Solihull

This thread was discussed between 17/03/2011 and 25/03/2011

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