Trunnion-Kingpin wear limits

[DaveC]

Hello all
I'm going to replace my front bushes with poly in the next couple of weeks, and so doing will have the opportunity to check the trunnion wear. Could anyone advise me on what amount of play should I expect/accept as OK between the trunnions and kingpins?
Thanks
Dave

[bigginger]

IME, any free play/movement will fail the MOT when the inspector checks with his pry bar

[DaveC]

Okay thanks Andrew
BTW did your flashy bit turn up?:)

[bigginger]

Ooooh, didn't spot that it was you It did, and MANY thanks - must get the postage back to you...

[MoggyTech]

Hello all
I'm going to replace my front bushes with poly in the next couple of weeks, and so doing will have the opportunity to check the trunnion wear. Could anyone advise me on what amount of play should I expect/accept as OK between the trunnions and kingpins?
Thanks
Dave

Top and bottom trunnion to kingpin clearances are minimal on good units. With everything dismantled for poly bush fitting, check for any vertical or lateral slop, if you find any replace the entire assembly. Remember a few thou slop at the trunnion will mean much more at the end of the wishbone.

Worth mentioning that you can usually tell how the trunnions are doing while greasing them (Jacked up to remove trunnion loads), the greasegun lever should be fairly stiff to push as you put the grease in. Little resistance usually means wear.

I'm sure you will like the new suspension feel with the poly bushes. Did mine a while back, transformed the handling, and got rid of various squeeks and groans.

[bigginger]

The suspension sounded better as well...


Sorry
a

[MoggyTech]

The suspension sounded better as well...


Sorry
a

[bmcecosse]

" Remember a few thou slop at the trunnion will mean much more at the end of the wishbone "
The trunnion IS at the end of the wishbone!
And yes -expect to have at least some wear unless relatively ne units - just use your judgement as to how bad it is! Moly grease is always a good idea in here to help minimise wear.

[MoggyTech]

>>The trunnion IS at the end of the wishbone! <<

The top one isn't

[bmcecosse]

There is no top 'wishbone' - but the upper trunnion (which rarely wears much anyway) is certainly at the outer end of the top suspension arm. Therefore any wear apparent cannot be 'much more at the end of' anything.

[DaveC]

Okay thanks folks for that.
I didn't know if there should be any play at all, but I get the jist of it now, and yes moly grease-good idea!
Cheers
Dave

[DaveC]

Replaced the bushes, and 3 trunnions are OK, but I had to replace the lower LH trunnion/link assembly as the lower link fulcrum pin and bushes were shot. It was fortunate that I had a spare LH trunnion assembly in a box of bits, and also that I twigged that the pin has to be removed in order to screw the trunnion on otherwise I could have done some damage.

Anyway, as you all say, the trav is a new car with these polybushes, and drives completely differently. Very responsive.

I can almost over look the fact that my 2 month old oil seal on the rear hub has failed and filled my rear drum with oil again but on close inspection this time, I found a line scored to the underside of the oil seal running surface on the axle, which I think caused the seal to fail. Half a hour with some 1200 wet/dry got rid of it and fitted a new seal. Hey ho, off we go again

[MoggyTech]

Well done, enjoy the improved handling

[rayofleamington]

I can almost over look the fact that my 2 month old oil seal on the rear hub has failed and filled my rear drum with oil again but on close inspection this time, I found a line scored to the underside of the oil seal running surface on the axle, which I think caused the seal to fail. Half a hour with some 1200 wet/dry got rid of it and fitted a new seal. Hey ho, off we go again

first comment to that is make sure there is some oil on the seal lip when you assemble it - they can be damaged in the first run if they are dry.
next comment is that the 1200 may or may not have fixed it - you'll need to keep an eye out for leaks. The normal technique to work around the groove in the hub is to move the lip seal a bit so it runs on fresh metal.

[DaveC]

Okay thanks for that
Am keeping a daily visual inspection and have done about 300 miles so far so fingers crossed . I have a new back axle casing that was offered to me recently, and as the casing I have is rusted badly on the top under the bump stops, if the problem persists I will change the casing. I keep falling over it in my shed anyway

[MoggyTech]

Okay thanks for that
Am keeping a daily visual inspection and have done about 300 miles so far so fingers crossed . I have a new back axle casing that was offered to me recently, and as the casing I have is rusted badly on the top under the bump stops, if the problem persists I will change the casing. I keep falling over it in my shed anyway

You can repair the rusted/worn axle casings with a liquid metal/epoxy kit. Much quicker than welding them up or even swapping all the bits over.

[DaveC]

Hmmm hadn't thought of that Well I got the axle casing now so we'll see. Maybe it won't leak now so it'll be OK for a few years

[MoggyTech]

Probably be good for a few decades, you have to admire the over-engineering of the Moggy Backend.

[bmcecosse]

Don't fancy the plastic metal repair - if it was just to hold the bump stop would be ok - but that's where the rear springs are attached - definitely not a great idea.

[MoggyTech]

Don't fancy the plastic metal repair - if it was just to hold the bump stop would be ok - but that's where the rear springs are attached - definitely not a great idea.

The kit (as used by Mark Evans on the MG Resto) is an epoxy metal bondo, not plastic. It chemicaly reacts into the metal. Amazing stuff.
Araldite do a very similar epoxy putty, very strong. Obviously it needs a fair amount of sound metal to bond to, but for the Moggy Axle top where the bump stop causes rot due to trapped road crud, this stuff will do very nicely.