Fulcrum pin torque at bushing end

[Hoghead]

The bushing ends of the fulcrum pins must be torqued with the car on the ground and loaded.
Standard procedure for most if not all cars, but I cannot find the spec in the manual.

One could use a common setting for a 1/2 bolt but what is the optimum torque?
I have urethane bushings and have seen these fail with too much torque - insufficient torque is not good either.

Same torque setting for stock rubber bushings?

 

[pfreen]

Does anybody know what the proper torque is for the lower and upper bushings? I have not found a spec either in the manuals.

 

[IvaTiger]

Does anybody know what the proper torque is for the lower and upper bushings? I have not found a spec either in the manuals.

I have spent a long time trying to find an answer with no luck. I think it is a guessing game since the nuts have a nylon insert which throws out any torque specs. As I see it the way the fulcrum shafts are mounted the more torque will give a stiffer suspension and too much will not allow the shaft to turn in the bushing and can then over stress the rubber or urethane I guess a way to test how they act is to drive over speed ramps and getting an even bounce to the car We can only go by whether any feedback from members give us as to their experience and maybe that is why we arnt getting any positive responses or maybe no one reads the CAT forum much

 

[0neoffive]

I have spent a long time trying to find an answer with no luck. I think it is a guessing game since the nuts have a nylon insert which throws out any torque specs. As I see it the way the fulcrum shafts are mounted the more torque will give a stiffer suspension and too much will not allow the shaft to turn in the bushing and can then over stress the rubber or urethane I guess a way to test how they act is to drive over speed ramps and getting an even bounce to the car We can only go by whether any feedback from members give us as to their experience and maybe that is why we arnt getting any positive responses or maybe no one reads the CAT forum much

55-65 ft lbs is fine for all bushing applications. The specific need is to torque those nuts ONLY when the car is loaded on the tyres at it's natural height. The reason for this (with steel/rubber bushings) is to capture the bushing center sleeve at it's neutral position. The rubber is then only mildly stressed up/down as the wish bone moves during road use. Amen

 

[Hoghead]

60 ft/lbs is my educated guess, and would make sense given the nut diameter, and similar car applications.
As Tony points out, the stock steel locking nut, or Nylock replacement nut throws out the wrench setting. That raises the Nylock fudge factor question if any factory spec exists.

Odd that the FSM makes such a big deal out of this, but does not give a spec.

 

[IvaTiger]

Thanks for the answers

 

[pfreen]

Thanks as well.

 

[Hoghead]

So no factory spec?

 

[HolyCat]

I spent some time looking in the Rootes Sunbeam ‘260’ and ‘289’ Workshop Manual, without any luck. I wonder if it might be in the Alpine shop manual, which I do not have.

Good luck!

 

[IvaTiger]

I spent some time looking in the Rootes Sunbeam ‘260’ and ‘289’ Workshop Manual, without any luck. I wonder if it might be in the Alpine shop manual, which I do not have.

Good luck!

maybe but doesn’t the Alpine use a different control arm and fulcrum pin ?

 

[0neoffive]

maybe but doesn’t the Alpine use a different control arm and fulcrum pin ?

The early Alpines had a worm screw fulcrum and king pin/trunion. Quite different.

 

[HolyCat]

The early Alpines had a worm screw fulcrum and king pin/trunion. Quite different.

The early Alpine is a completely different beast from the later Alpines and Tigers. If you look at the Rootes Parts List Supplement for the Sunbeam '260' and '289', no part numbers are shown for the upper wishbone, because the Tiger uses the same as the Series IV. It does list different part numbers for the lower wishbones, but it notes that the "Fulcrum pin, bush, etc." are the same as the Alpine Series IV. I do not know what are the differences in the lower wishbones (or A-arms) between the Alpine and Tiger. But since they do use the same fulcrum pins, I would think the torque settings should be close, which is why I asked about the Alpine workshop manual. The Alpine manual certainly would apply to the upper wishbone.

 

[Hoghead]

I had the brilliant idea of consulting the new Shop Notes:
Berkley 2004 gives 75 ft/lbs "in the torque loading table in the front of the manual"
He must have a different manual than my two copies

The Editor added a note to Heyman 2005 who could not find a spec either:
"We are recommending 40 lbs in Shop Notes". This statement is derived from two differing specs on aircraft 1/2 bolts at 40-55 and 30-60 ft lbs.

No clearer than when I began thinking about this