G'day,

Been exploring options for urethane bushes to replace the dodgy rubber ones I've had and I'd like to know if I should stick with my current straight bush arms or change to tapered bushes. I've got both in the shed.
I can get both Nolathane and SuperPro urethane bushes to suit both types of arms. From what I've found out so far, the Nolathane ones are rated 85A on the duro scale and the Superpro are 90 which makes the nolathane ones slightly softer.

Is there any advantage in changing to the tapered bush arms? Most mini places I've spoken to suggest changing but I'm not sure why. I've asked but all they say is it's better. A fellow member on this forum with the same issues as me has been recommended to go tapered (he had one of each and needed to change so upgraded to tapered).

My rocket is a 1963 850.

Thanks Rocky

The original Mowog tapered bushes with the steel sleeve were very dense/hard and I remember, very hard to fit - like an M&M, they didn't want to get in the bowl.
The earlier parallel, plain bushes were probably softer and flexed more ( I'm guessing here). Engines got bigger and the first style possibly chewed out a bit more quickly so needed more reinforcing.
The genuine tapered bushes also had a habit of splitting around the end bits that extruded past the arm and looked worn out. However the rubber on the inside was often still doing its job unless very old.
I have fitted a set of tapered poly bushes to the Mk2 and they seemed to improve the road feel of the steering. Not sure if they are Nolathane but are red. Since these didn't have a steel sleeve insert maybe it is worth trying a poly bush of some sort to suit parallel arms and see what you think.

Thanks Bill.
Red bushes may be nolathane brand as they seem to be the red coloured ones. I'm thinking if they're one grade softer they might be better.
Given I haven't got a power machine, it sounds like the straight bush design should be ok.

Cheers, Rocky

Hi Rocky, I guess the straight answer to your question is that the tapered bore lower arm is better... if only because BMC/Leyland saw fit to change the design. Although, this could have been a manufacturing decision rather than a performance issue...

You have to be careful with poly bushes as the material can vary significantly. I have had engine steady bushes crumble and basically disappear...

I have tapered bore adjustable lower arms that were made by Selby back in the 60/70s.. I used to use poly bushes but these didn't work well due to the non standard caster angle I chose. The bushes didn't crumble but became deformed (and loose) with not a lot of use.

I have since replaced them with Minispares UK rubber offset bushes and these seem to be working well. No problems after a few years use. Mspares bushes come in road and competition versions. I fitted the comp versions because they were all I could get when I needed them. I've since acquired some of the road version and they are noticeably softer (using the fingernail test). I will get around to trying them on the car some day.

The offset rubber bits definitely fit better than the "ordinary" poly units....

Yer pays yer money and takes yer chances

Cheers, Ian

Your comments about urethan bushes are interesting Ian.
I know the mention of urethane bushes create a reaction against them, but I've never been able to find out "why" in any detail before your comments here.
I recommended to 'the flying squirrel' (one of the best TV series ever) that he try the parallel bushes in Nolathane since he is already using the earlier lower arms and because my car, with tapered lower arms have their Nolathan bushes come without sleeves anyway so either tapered or straight urethane bushes should perform about the same.

Thanks for the info Ian. Not sure if you saw my other thread on the deterioration of brand new rubber bushes before I'd managed to re-fit the subframe into the car, but the only reason I'm looking for an alternative to the rubber ones is that the rubber seems to now be of questionable quality.

I've spoken to both nolathane and superpro and both went to great lengths to tell me that the older style urethane were in fact too hard and that newer manufacturing techniques now allow for softer materials without compromising longevity. Interestingly, I bought a set of urethane steady bushes from Karcraft because the rubber ones I got from minispares don't seem to fit too well. The urethane ones are relatively soft - you can squeeze them a bit by hand. Will be interesting to see how they go once I get the car on the road.

The straight bush arms I have are the originals and in really good nick. The tapered ones aren't too bad but have some minor pitting where the rubber bushes sat in them for years. I've cleaned them up with 400 wet/dry and there's no sharp edges so should be ok.

Thanks,
The flying squirrel

"Nothin' up ma sleeve..."