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MG Midget and Sprite Technical - Radius arm bush / poly bush

My radius arms need new bushes.

The radius arms themselves are only about 4 years old so I'm inclined to just replaces the bushes. I don't want to fir the original styles bushes because:

i) They are brazed / welded in
ii) They don't seem to last very long.

I see you can get replacement poly bushes from Moss and Minimania and Peter May do some Nylatron ones. Presumably these make use of the existing bushes outer steel sleeve.

I don't want to make the rear ride any firmer, just get the longevity of poly type material.

Has anyone any experience in this area? Recommendations or otherwise?

thanks.
Jeremy Cogman

Jeremy,

Are we talking 1/4 elliptic radius arm bushes here? If so they are metalastic IIRC and so have an inner and outer steel sleeve with rubber bonded in between. The bushes should press out and so are easily replaced. There should be a sleeve in the radius arm that they fit into, I suppose the poly bushes would fit into those.
David Billington

Yes, read radius arms on a mk2 Sprite.

I hadn't realised the outer sleeve pushed into another sleeve in the arm. I did wonder how you welded in a metalistic bush? (Quickly!)
Jeremy Cogman

Jeremy,
I don't know for sure as I've never used them but I thought nylatron bushes were more for racers and would make the ride harsher and need regular checking and maintenance(?)

the requirements of track/sports cars can be entirely different to a road car especially one that is used regularly and/or higher mileages
Nigel Atkins

I fitted Superpro bushes all round on my MK3 Sprite but that has 1/2 eliptical springs. They did firm up the ride a bit, but the car feels much more "planted" on the road now. On the 1/4 eliptical spring I guess the front bush is similar to the eye bolt bush on a 1/2 and would have to be drifted/ pressed out with a couple of sockets and the new one drifted/pressed in. I don't think doing just the rear spring bushes would make any noticable difference to the feel of the car unless you did use Nylatron ones, which as Nigel says are very harsh.

Bernie.
b higginson

Polybushes (note the capital) on the front did not degrade the ride and are lasting well.

I'm simply after:

i) not junking a completly servicable arm.
ii) greater longevity that whatever the standard bushes are (rubber, neoprene?).

No-one needs to firm up a mk1 or 2 Sprites rear end!!!

Jeremy Cogman

Jeremy,

Maybe you can find a supplier of a appropriate bush, a short search found these and they do others http://www.antivibrationmethods.com/Products/Bushes/TorsionBush/tabid/199/Default.aspx#BB
. Maybe one in the list is an appropriate size. I would have expected a quality bush to last much longer than 4 years so maybe they were a poor quality repro. Have you got the dimensions if the bush, OD, ID, width. I have radius arms on my frogeye but made new arms years ago when I couldn't get the bushes from BL so made new ones with TR6 inner wishbone bushes as that is what the parts guy came when with when I asked if they had anything similar. The TR6 bush doesn't have an outer sleeve and IIRC the ID is 1/2" rather than 7/16" but worked fine with a sleeve and arms made to suit.
David Billington

If you've used Polybushes before, and like them, they would be the ones to go for.
My standard rubber bushes were splitting and starting to creak and groan three years after being fitted new, rubber ain't what it used to be.
b higginson

Ah, Polybush don't seem to do one though I'll call on Monday to check. They do do a 1/4 elliptical spring bush so they are aware of the early car suspension.
Jeremy Cogman

Some time ago I too looked for 1/4 elliptic radius arm Polybushes and couldn't find any. Would be interested to know whether you find a source.

Simon
SA Wood

give Superpro a ring:
http://www.superpro.eu.com/

They currently have my radius arms (replacements from moss as ones on the car were dead) and are sorting bushes for them as we speak so I'm sure they can help you out.

Really nice guys. Can't speak for the sprite yet but the ones on the TR3A my dad has are great.

just a note: the reason they have my arms from moss is that the replacement bushes they originally supplied just slipped straight through! so need slightly bigger ones than standard it appears!
D Paul

Thanks for that folks.

D in Devon, do you have any information about how firm the Superpro are?
Jeremy Cogman

This thread was discussed between 26/05/2012 and 27/05/2012

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