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Trunnion bolt torque

Posted: Tue May 05, 2009 8:24 pm
by MightyMite
Just fitted new trunnion bush kit to my front suspension but I'm not sure how tight to do the nut. It's a castelated nut with split pin by the way.



Thanks, Adam

Posted: Tue May 05, 2009 8:50 pm
by lozzzzzz
I'll be interested to see what folks think here too.

I did mine up nice and tight so that the sleave moves within the trunion (that seened to be the way it was meant to work) but it made a horrible creaking noise over the bumps.

So I loosesned it a bit and now its quiet, but i'm worried it might be wearing in the wrong place.

Posted: Tue May 05, 2009 9:11 pm
by Roger Pennington
Hi, The trunnion bolt should be done up to 50 - 65 ft/lbs torque. What should then happen is that the assembly of washers and steel spacers sandwiches the trunnion, forming one solid assembly, carrying the nylon bushes on which the wishbone arms rotate. The through-bolt should not *under any circumstances* rotate in the trunnion, as the softer bronze trunnion will quickly wear to an oval hole if this happens. If when the bolt is tightened the whole assembly (including the wishbone arms) locks solid, then this suggests that the steel sleeves are the wrong length (or the top hat part of the nylon bush it too thick, and some corrective action will be required. A good test when assembling the trunnion/wishbones is to check that the upright falls under it's own weight if the top joint is not connected - if it does then that's fine. The longevity of the nylon bushes can be helped by drilling the exact centre of the wishbone eyes for a grease nipple, so that grease can be injected into the gap between the two bushes.

hope this helps,

....Roger

ps Jim, perhaps this info should be "stickied" as it is quite important?

Posted: Tue May 05, 2009 9:48 pm
by Poppy
An essential mod. if the steel and nylon bushes are to last is to drill from beneath each wisbone end, tap and fiT a greaes nipple, you can then grease the wlole assembly. This lubrIcates and stops water from getting in and rusting the bush and bolt. As has already been said THE NUT MUST BE TIGHT OR THE TRUNION WILL WEAR VERY QUICKLY[/b]

Posted: Tue May 05, 2009 11:24 pm
by Nick_F
If you're having trouble then loosen the bolts holding the damper mounting plate to the wishbone arms and free everything up so that the wishbone arms can be pulled a little closer together by the trunnion pivot bolt.

Posted: Wed May 06, 2009 9:43 am
by AllanI
Agreed this should be a sticky. It is vital that newcomers to the Scimitar should be aware of the correct procedure for assembling the trunnion. There have been too many cases in the past where people have left the bolt loose to rotate in the trunnion itself.

Allan

Posted: Fri May 15, 2009 11:53 am
by daleywhaley
I am intending to take a look at my trunnions in the summer, does anyone have a pic of where the grease nipple should be fitted?

Posted: Fri May 15, 2009 5:21 pm
by Poppy
If you look underneath the outer end of each lower wishbone, two per side, you will see that the centre area of the casting is slightly raised. Drill and tap, (With a well greased drill and tap to catch the bits) the center of this area. The size of drill and tap will depend on the gease nipples you have. Dont use too large a size. An angled grease nipple makes it easier to use the grease gun.
The idea is to find the gap between the two nylon 'Top hat' bushes so that grease can be injected and hopefully ooze between the nylon bushes and the steel bush and stop the whole assembly rusting solid

Posted: Fri May 15, 2009 5:24 pm
by Coupe Racing
Personally - I have never bothered in 28 years :P :P !!!!

I assemble everything with loads of coppaslip - just ask the MOT man :twisted:

Seriously - I rarely ever have to replace the bushes.

Cheers

Steve

Posted: Sat May 16, 2009 4:17 pm
by lozzzzzz
I've redone mine this morning, its given me peace of mind! The bolt now stays with the trunnion and moves relative to the wishbone. Gave the tracking a little tweak too.

Posted: Tue Jul 21, 2009 10:18 am
by Dennis Nicholas
Coupe' Racing wrote:Personally - I have never bothered in 28 years :P :P !!!!

I assemble everything with loads of coppaslip - just ask the MOT man :twisted:

Seriously - I rarely ever have to replace the bushes.

Cheers

Steve
: :

:shock: coppaslip is an abbrasive....best just used on threads!

Posted: Wed Nov 04, 2009 11:53 am
by JoeySully
should the Nylon bushes fit easily into the wishbone eyes or should the fit quite snugly?

I really can' t understand how, if the trunnion bolt is very tight then the whole assembly including the bolt cannot move together??

Posted: Wed Nov 04, 2009 12:11 pm
by mn757
The nylon bushes should be pressed firmly into the wishbones. Once they are fitted, the steel inserts will protude at either end very slightly. It is the steel inserts that lock up against the washers / trunnion, so that the only parts that move are the wishbone pivoting around the inserts. Everything else will be locked up solid.

There are still some trunnion bush kits around where steel inserts are the wrong size (they are too short) and therefore when fitted the wishbones are trapped against the washers and cant move.

It may be that your wishbones eyes have corroded slightly, and are not allowing the nylon bushes to be pushed fully home. If this is the case the steel insert will not protrude and the whole lot will lock up when tightened.

Posted: Wed Nov 04, 2009 12:15 pm
by Roger Pennington
Hi, The nylon bushes should be a snug fit, and movement then takes place between the bushes and the steel sleeves (the steel sleeves being sandwiched as a single unit between the bolt head/the washers/the trunnion/the nut).

cheers,

....Roger

Posted: Wed Nov 04, 2009 12:20 pm
by JoeySully
Roger Pennington wrote:The through-bolt should not *under any circumstances* rotate in the trunnion,
I see now - I misunderstood this part.
If I move the upright in and out when tight the whole mechanism including the bolt should move but the same amount as the trunnion is moving. so am I right in saying The Nylon bushes stay stationary but everything else moves ??