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MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Suspension Bushes

Many people seem to opt for Delrin or other solid plastic A arm bushes for street use. I though this comment from a guy in the business might interest some:

"THE hardest and most
long lasting bushes is a "Metalastic" type.
Steel core outside and inside with rubber in between."

In other words, the MG V8 bushes are going to be the longest lasting option. And they are, from personal experience, also amply stiff.
Bill Spohn

Bill. That does not seem to be true here in Arizona. Two year old V-8 bushings are already beginning to show deterioration of the rubber section. The car I am working on now has just had poly bushings installed and I will be testing them to see how long they will hold up in this environment. Hopefully, more than two years.

Les
Les Bengtson

I can't agree, either.

Poly, Derlin, etc. are harder than rubber and have steel on both sides, too (there are installed between the a-arm & the trunion pivot).

Disclaimer: I have had the rubber V-8 bushings for many years in my '79 B, but have installed poly in my '55 TF.
Carl Floyd

The biggest reason for deterioration of the rubber is the quality of the rubber itself. With small batch run specialty parts no one seems to be spending the little extra in cost it would take to get top grade material. Go check out the rubber components in a twenty year old car, you will find that much of the rubber is in good shape yet, while the rubber parts we are getting for our cars give up in 5 years or less. You will find the same if you compare some of the thirty or fourty year old original MG parts, after all these years some of the originals are in better shape than todays brand new parts.
There is noting wrong with using the plastic type bushings except that it will stiffen up the ride compared to equivalent rubber parts.
John H

Ditto for hoses in terms of quality. I've had my roadster 16 years and done 40k miles and it still has the same bottom hose it came with which shows no cracking. I've had to replace the top hose twice, and I'm just about to replace one of the heater hoses for the 2nd time as it is quite badly cracked. The V8 needs a new bottom hose as a precautionary measure for slight cracking, after only about 3 years and 6 or 7k. I did replace the top hose (along with all the others) when doing a top-end rebuild but kept it as it was still supple and shows no cracking even after about 70k miles. The first replacement top hose on the roadster started cracking after a few years, which again I replaced as a precautionary measure a few years ago. I used a Kevlar cored item and so far that shows no cracking.
Paul Hunt 2

Delrin is a hard plastic and therefore has basically no compliance - that means it is being used as a rotating bearing rather than a bush that squashes. That is why the ride is so harsh, the hard plastic 'bush' does not absorb any vibrations.

I've tried using them on my GT and they're a nightmare to fit (properly), you get lots of vibration and then they crack. Took all of mine back to Moss and they gave me my money back!

IMO, Metalastic bushes usually fail because the rubber comes away from the metal. Obviously you don't get that with poly bushes as the plastic isn't bonded to the metal...

Neil
Neil

15 years ago I installed V8 bushings in my '67 roadster and they have not deteriorated at all. I am very satisfied with the handling. Having owned the car for 34 years, I have made many subtle improvements and this is noticably one of the better ones. Ray
RAY

Neil, the rubber breaking loose from the metal is another sign of the manufacture taking a shortcut. In most cases a bonding agent is applied to the metal and must dry before the rubber is molded on, properly done the rubber should tear before coming loose from the metal. The sad part with the rubber parts is that they are being penny wise and dollar foolish. I used to work in a rubber molding plant, we used top quality rubber compounds,12 years ago the rubber material ready to mold cost us $1.50 per pound. That amounts to pennies extra to use top quality material to make a rubber bushing. I had a vendor of british car parts tell me people didn't want to spend the little extra, I think they are wrong.
John H

Carl

I believe that Superflex Polyurethane bushings come in a range of hardness. One is basically the same as the original rubber.

FWIW

Larry
Larry Hallanger

I fairly recently did the bushes in my front suspension and used V8 ones. No idea how they drive yet though since the car isn't on the road. One thing we (well, Garth Bagnall) had to do though was turn down the metal part of the upper bushes ona lathe. The tube was too long so when you had them both in you couldn't get the top arm attached to the shock over them. We measured to some original ones and the tubes were a few mm longer.
Simon Jansen

Neil and John - don't forget that one all too common reason the V8 style bushes give up early is improper installation.

I have seen several people install them with the car on jack stands and wonder why they break down. Proper method is of course to fit them loosely and then weight the suspension before tightening, or you will wind up with the bushes already partially torqued over when the car sits at rest height.

It is certainly possible that improper manufacturing (ie bonding to the steel) might be a player too.

And yes, urethane are a lot nicer than Delrin for the street - some compliance softens vibrations.

Speaking of fitting problems, I had a friend that raced Bugeyes. Said every A arm set up he had tried was so out of whack from new that if you fit solid bushes the suspension seized up......
Bill Spohn

I have the red poly bushings in both my BGT and midget. I've had them for a couple of years now and am very pleased with them. I get a slightly harsher ride, but no squeaks, no vibration, simply no problems at all.

You must understand that when Les says "That doesn't seem to hold true in Arizona", we will average 105+ degrees with single digit humidity for the entire summer. Anything made of rubber with exposure of that kind will only last for a few years at best.

When I did my suspension rebuilds that was the primary reason I went with the poly and I'm very glad I did.

Cheers,
Dennis
Dennis

blue poly for street use. Gives a bettter ride than rubber I think. Less harsh, more precise.
Peter

Hi Folks:

Used the V8 bushings for a few years, clunks; then they were thrashed. Presently using Moss poly bushings, also had clunks; until I realized the shoulders of the Moss bushings were not the same thickness of the original rubber bushing. I bought another set of flat washers and opened the center hole to the full diameter of the trunion. They now function correctly. I assume that the larger hole diameter should be used with the V8 bushings, since there is no shoulder. Next refit, I will try it.

Good luck: Rich Boris 67 B roadster
Rich Boris

Red polys here, I find I get some rattle and shake when I drive over a broken up road surface but otherwise they are wonderful - I'll never fit anything else again.
The Wiz

I used V-8's on the GT I did 22 years ago. We didn't carry them here, so I went to the Jag dealer and had them ordered out of the UK. I got genuine Rover and they were excellent. I'm running poly on my TD now, and will never use anything else. They are great.
Craig Cody

This thread was discussed between 17/05/2006 and 25/05/2006

MG MGB Technical index

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