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Rubber bushes tightness
Posted: Wed Mar 29, 2017 12:45 pm
by Plymo
New member here, working on my 1968 saloon as a rolling project.
I've been replacing the front suspension rubber bushes and adjusting the ride height. Gone well so far but...
How tight does the eyebolt need to be? Should it be done up as far as it can go, or loosened slightly so the shoulders on the bushes aren't squashed?
And how tight should the lower trunnion fulcrum pin (bronze bushes with thrust washers either side and a rubber seal over the top) be done up?
I have a pdf of the BMC workshop manual but there doesn't appear to be anything about it on there
Cheers
Re: Rubber bushes tightness
Posted: Wed Mar 29, 2017 1:47 pm
by philthehill
The distance between the thick and thin arm at the eye bolt end is set by the shoulders on the eye bolt pin (Pt No: AAA1407 (MOSS)). Therefore the eye bolt pivot pin nuts should be done up tight. There is no facility for adjustment.
Again the shoulders of lower trunnion pivot pin (Pt No: AAA1481 (BSF threads) 21G4002 (UNF threads) (MOSS)) sets the distance between the thick and thin arms. There should be a 0.002" fore and aft play of the trunnion on the pin but in reality so long as the lower swivel is able to rotate (limited arc) all will be well. The nuts should be done up tight.
The only way you can get the correct 0.002" is either by grinding the pin or by pin selection.
Poly bushes fitted to the front suspension is a much better option than the BMC rubber bushes which are next to useless.
There are different ride quality bushes available if you search the web..
Give the poly bushes a light smear with red or white grease before fitting.
Re: Rubber bushes tightness
Posted: Wed Mar 29, 2017 3:04 pm
by Plymo
Cheers for that, I had suspected "Tight" would do the job.
I've already fitted the rubber bushes but I shall keep an eye on them and when (not if!) they need doing again I will do the poly or even metelastic bush instead
Re: Rubber bushes tightness
Posted: Wed Mar 29, 2017 4:30 pm
by philthehill
You mention the metalastic bush which was the preferred modification to the Minor eye bolt a few years back and before poly bushes became available..
Unless you already have them - the biggest problem will be finding the correct metalastic bush.
Much easier to fit the poly bushes and be done with it.
Re: Rubber bushes tightness
Posted: Wed Mar 29, 2017 8:31 pm
by MichaelBeckNZ
Further to this - How tight would everyone do up the rear shackles? Till the nut runs out of thread, Just touching rubber bushes, or "snug"
Re: Rubber bushes tightness
Posted: Thu Mar 30, 2017 7:40 am
by philthehill
The shackle pins at the rear of the leaf spring are the same pins (Pt No: AAA1407 (MOSS)) (even though sometimes given a different part number) as the eye bolt pin and the shackle plates (Pt No: ACA5251 (MOSS)) again should be done up tight against the shoulder of the pin.
If done up just snug there is a good chance that the nut will come loose and you could loose the shackle plates/pins with dire consequences.
To reiterate:-
Both plain nuts with spring washer and self locking nuts should be done up tight.