6 replies to this topic

[oliver122]

hey guys , so ive stripped my radius arms down to find that one had got 2 roller bearings in and the other arm has one bearing and bush . luckily for me we have a tool room at work that can easily knock me up anything i need . now i have been looking round and come across a couple of post that suggest that using 2 bushes is better than using a roller and a bush , if this is true is it work having some bush's made up to replace the rollers ? if it isnt true is it worth having an over sized bush mate to turn it back into a 1 bush 1 bearing arrangement or would it be better to have a steel insert mate that went into the radius arm and then the bush into that ? any help would be appreciated 

[Swift_General]

I belive very early cars had 2 bushes, however you should have a bush and a needle bearing as your other arm. Replace the needle bearing on the outer side of the arm with a bush. This will need reaming to size with a long reamer (13/16") so that it's inline with the bearing.

[MRA]

You should have one bush and one bearing, the old 2 bush system was never very good as they easily siezed up and then you lost suspension travel and reaction time increased, 2 bearings is also not marvelous because the bush can support more load (more surface area) than a bearing) like all things engineering based it is a compromise.

 

The reamer needs to be supported at the end that would have the bearing fitted (but not with the bearing fitted for obvious reasons) otherwise you get 2 high spots that very quickly turn in to 2 worn away high spots and the resultant extra clearance that means a fail at next MOT.

 

If you have a tool room can you make and grind your own reamers ?  also you will need a sleeve that fits in place of the bearing, both should be a sliding fit, 25 microns maximum on the outer of the bush. 12 to 25 microns on the inner to reamer shank,

 

because the straighter the tooling can be maintained whilst in use the tighter you get it and the longer your radius arms will last till next strip down and rebuild.

 

Also on your bearing to bush convertion, I would want them both to be the same, as you could get an imbalance, making a sleeve would be my preference, simply make it 20microns oversize (ground finish) and then heat up the arm in an oven, coat your new sleeve in loctite (I use 638) and then in it goes.  Concentricity would be assured if you grind the bore and the outer diameter on the same set up, and then cut to length.

Edited by MRA, 31 March 2016 - 05:49 PM.

[Spider]

The early cars did have 2 bushes but these were a sintered material on a steel backing, lubrication was an issue and there was even a Factory Technical Bulletin showing how to fit a 2nd grease nipple to the inside (what a PITA!).

 

They subsequently (from about 1961) went over to the bearing on the Inboard side, I guess it was a cheap easy fix at the time and stayed that way.

 

Our Big Wheel Mokes, which have a longer Trailing Arm than the Mini has Bearing inboard and outboard from the factory. I will say that unless grease is administered very often, they will give trouble and chew out not only the pin but also the tunnel in the arm.

 

On the Missus's Moke I fitted Phosphor Bronze Bushes to inboard and outboard sides, replacing the bearings some 25+ years ago. I also put a spiral in to them to allow the grease to get in where it's needed. They still need regular greasing but give no trouble and instead of a bearing that can fail with little warning and do subsequent damage, the bush itself will wear and even if worn, won't damage the arm, though they haven't shown any signs of wear yet. The bushes have a higher load capability in this application that the bearings and there's no need to run pins with hardened ends as there was a spate of soft pins getting around a while back (at least in these parts). The bush has around 60 degrees + of 'contact' on to the pin, where as with the bearings there's only about 4 or maybe 5 fine lines of contact to the pin.

[oliver122]

 

If you have a tool room can you make and grind your own reamers ?  also you will need a sleeve that fits in place of the bearing, both should be a sliding fit, 25 microns maximum on the outer of the bush. 12 to 25 microns on the inner to reamer shank,

 

Also on your bearing to bush convertion, I would want them both to be the same, as you could get an imbalance, making a sleeve would be my preference, simply make it 20microns oversize (ground finish) and then heat up the arm in an oven, coat your new sleeve in loctite (I use 638) and then in it goes.  Concentricity would be assured if you grind the bore and the outer diameter on the same set up, and then cut to length.

sadly they carnt , however they have said that they will order me a long 13/16" reamer in if i need one.  so if i get the dimension of the hole that should be a bush spec that it needs to be over sized by 20 micron that should be fine and then i can fit a bush like it should be 

[AlexMozza]

I've seen a few where the bush gas been badly worn, and the same for the casing.
As a fix the arm had been machined out to take the bearing.

[nicklouse]

The arms with twin needle rollers are just later recon arms.

Which are basically the same as the Metro had.

Needle rollers easier to change as no reaming required.