Front Trunnion refurb questions

[siroldvolks]

Hi All,

Just in the middle of a front susp refurb and had a couple of questions on refitting front trunnion , as I can't find much info and want to double check its right  !

Had some recent new rattles from the front end, and as MOT time is due on my GT6 I thought best to give it a look over.  One of those jobs you end up doing more than expected...the top ball joints had split rubbers so needed done, so whipped everything off to give it a good clean.  Also found the front trunnion bushes pretty much fell out and past their best, and also 2 rear chassis mounts had worked loose....it's the first time i've had a good look over the front susp since ownership apart from oiling trunnions.

Anyways after cleaning and painting everything up, fitting new wishbone poly bushes (and removing all the old grease from the trunnions :( ) everything is ready to go back on

1) how tight should the metal sleeve be in the front trunnion bush?  The nylon bushes needed pressing in, however it was even harder to fit the metal sleeve and needed some force and it's set very tight - is this right for the fronts, or should it have some circluar moment ?  When I did the rear trunnions, I was able to just fit the metal sleeve by hand just about and was a perfect snug fit.

2) I can't find much info on where to set the trunnion on the vertical link thread, other than Haynes Vague description - should it just make contact with the rubber bush, or be a snug fit ?.  If I set it back on by the number of turns when I took it off, it seems a bit too loose and only just makes contact with the rubber seal - I can see the top of the trunnion rim through 60 degree turn one way each side.  if I set it up another turn theres some minimal resistance with the rubber, but the seal turns with the trunnion. which is better set ?

other than that the link threads look in good nick still, and looking forward to getting it finished - pics soon !

thanks

Andrew

[Velocita Rosso]

When screwing the trunnion on ,turn until it is tight at the top, then back off(unscrew) the 180 degs which allows the steering to go full lock in both directions
eg if you screw it to the top and dont back off, then the steering will lock and will be unable to turn
The metal sleeve should be a tight fit into the bush, otherwise there will be `chatter`

[CharlieB]

In my opinion the metal sleeve should not have to be pressed in tight, it's supposed to swivel, I rejected a couple of rear bush kits that were like that. I'd be interested in others' opinions...

[migntig]

The bolt is supposed to revolve inside the bush. Use pleanty of copper grease on bolt when you assemble to prevent siezing. I also pack the dust shield halves with grease and carefully peen edges over with a pin hammer.
Steve.

[drofgum]

migntig,
No, the bolt is supposed to bring the two sides of the wishbone together against the ends of the steel sleeve and lock them all together.  The nylon bushes are supposed to turn on the steel sleeve. That is why the sleeve is longer than the sum of the nylon bushes.  I agree, lots of copper grease to prevent seizing.
                                                                  Cheers,
                                                                  Paul

[siroldvolks]

cheers for the input all - I think based on the above, the metal sleeve is faaaar too tight which I didn't think was right glad I checked....there no way in hell it would rotate!  I've just spent the past 30mins trying to the one sleeve back out , a vice was a must here .

it must be the bushes are too big as if I it put the new metal sleeve with the old bushes, its very loose as it was when I took the old bits off.  Hmm I'll have to try another source for them thats gonna set me back a few days :(

[siroldvolks]

Well I got everything back together on Sunday ! I couldn't wait for the new ones, but the old bushes were in good nick with the new sleeves were a perfect fit, so I'll whip off the hub again and swap out with new ones once MOT is out of the way.

Annoyingly it didn't sort the front end rattle which I can't figure out what it is, but I can't believe how tight and responsive everything now feels !  Definately a worthwhile job done, so fingers crossed it gets through this week.

Heres a couple of pics of before , and after a bit of a clean up :







next job, propshaft recon and sort oil leaks  :(

Andrew

[mikeyb]

looks good , but is is just me or does the brake hose in the second pic look to be stretched a little tight?  :-/

[siroldvolks]

thanks! Yeah it does look it like !! Its just the way it curves (towards the cam) - theres plenty of slack but I'd like to adjust it so it sits slightly lower, one for the snagging list.

[Ceaser]

I thought that the brake line bracket went onto the rear bolt of the upper wishbone???

[Velocita Rosso]

3588 wrote:

I thought that the brake line bracket went onto the rear bolt of the upper wishbone???

Correct

[Velocita Rosso]

Sorry, for sticking my two peneth in.Is it the photo angle or are the trunnions at a funny angle?  

[thescrapman]

It has GT6 brakes so the bracket went on the front bolt I thought.

I can see a bit of copper pipe on the caliper.

A little bit of re-adjustment of the bracket should cure and stretchy ness.

[siroldvolks]

Yep GT6 brakes, so looks like brake pipe mounting on the front bolt from other references

hmm not sure about the angle or just the photo re. trunnions, I'll check that later !  As the old one sat exactly the same I assume normal ?  or should it sit straight up ?

[Velocita Rosso]

2513 wrote:

Yep GT6 brakes, so looks like brake pipe mounting on the front bolt from other references

hmm not sure about the angle or just the photo re. trunnions, I'll check that later !  As the old one sat exactly the same I assume normal ?  or should it sit straight up ?

Straight up, cos if you imagine when the wheels turn, if  they were both pointing inwards? So the vertical link should be at 90des to wheel
Just check its not a pic angle

[CharlieB]

michael_charlton wrote:

Straight up, cos if you imagine when the wheels turn, if  they were both pointing inwards? So the vertical link should be at 90des to wheel

No, they should point to the centre of the ball joint which is inboard of the trunnion. That's your "king pin inclination" which is 5.75 +/- 1deg as standard (unladen).

[siroldvolks]

the angle of the photo really does make them look angled badly, but no, slight angle as they should be towards the top !  phew got me worried there lol

well Ive done as much as I can do ready for it's test tomorrow, it actually feels good again to seem like you've made an effort it's as good as things can be !  fingers crossed

[don cook1]

I'm about to fit replacement trunnions and its been decades (1973) since I last fitted one. Looking at Siroldvolks' photos am I correct in thinking that the disc has to come off to allow for the trunnion to be screwed up; Haynes manual is useless on this subject. I know I could just get on with it and find out but, well my sofa is quite comfy, someone else is doing dinner and I'm at a loose end...

[Royboy66]

Yes Don Disc and stone guard off.

Whats for Dinner??
8)

[Velocita Rosso]

royboy66 wrote:

Yes Don Disc and stone guard off.

Whats for Dinner??
8)

....Probably not enough ! ;D

[don cook1]

Turned out to be some Greek concoction...following a holiday in Greece by No.1 daughter.

Hhmmm so its wheel, calliper, disc, stone guard, nuts and bolts, take off trunnion then reverse order etc. Dilemma: its not broke so do I do it now or on some lonesome mountain pass in the high Alps? I've had the car for 9 years and done about 40000 miles with just oiling every year or so...

[sparky_spit]

A bit late into this discussion but I too had trunnion bush metal sleeves that were very tight in the top hat bushes. After checking that there was no crud in the trunnion hole itself that was crushing the bushes, I measured all the new sleeves I had and found one was 1.5 thou oversized. I'm lucky to have a lathe and was able to correct this by turn-grinding (they are hardened so can't turn them down normally) and take the 1.5 thou off. If I hadn't needed them in a hurry I'd have sent them back.

And 100% agree with Drofgum, the sleeves rotate in the bushes, not the bolt in the sleeves.

[don cook1]

Mine came assembled so once the old ones were off the new ones went in perfectly, bolts went in OK as well. I cleaned out a bit of grease in each trunnion but the links were ok with no slop, glad I did it now. Will take old ones on the 10CR as part of my spares package.

[siroldvolks]

I think that was my prob too sparky, metal sleeves oversized !  Perfect fit with new metal sleeves in old bushes, or old sleeves in new bushes .  I've had another kit arrive so when I have some time I'll whip it off quick and try again, peice of mind an all having complete new kits on.  Have a show to go to next week so want to resist any tinkering before hand just in case something happens / breaks in the proces...!  everything still feels great, I always feel it quite rewarding with any work that like that where you can really feel the improvements, and learnt a lot !

cheers

[slapathy]

Hello.
In the middle of an MOT-enforced rebuild which involved amongst other things trunnion bush refitting. The old ones werent worn, in fact they were both so tight that the bolts were turning in the lower wishbones. Got some new ones from Canleys. Assembling the sleeve into the (unfitted) bush resulted in a perfect fit. As soon as the plastic bush is press fitted into the trunnion, the intereference fit between the two is completely transferred to the bore as the bushes are "thin walled".This results in the sleeve being an interference fit ie it doesnt turn. Not quite how a bearing is designed to operate. I measured the sleeve at 0.5665". The bore of the fitted bush is roughly 0.555", this results in an interference of 0.0115", or 11 and a half thou which is not a running fit. My solution is to fit the bushes then ream them 9/16" or 0.5625" in old money. Even this gives an interference of 0.003", but I am hoping that the reamer will cut larger as the plastic is fairly soft. Another solution would be to ream them 14.5mm = 0.5708", but this would give .0084" clearance which is probably too much. 37/64" is even bigger at 0.5781", no good either. I will post the results when the reamer arrives, what would we do without EvilBay eh?
The long term solution is for suppliers such as CANLEYS and PADDOCKS to supply components which actually fit (incidentally Canleys outriggers fit whereas Paddocks dont). The bush wall thickness needs reducing by 0.005-0.006" which will ensure an acceptable clearance when fitted.
Also, I was considering drilling and tapping the trunnions M6 for grease nipples, in the centre so that the bush/sleeve interface could be lubricated. I cant think of an engineering/material science reason why this is a no-no, but would welcome any views on the matter. Has anyone out ther ever done this?