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MG MGB Technical - polybushes

Firstly happy New Year to everyone.

Now I have the front suspension in bits I'm thinking about replacing the bushes. So some questions.
1. Are polybushes a good idea for a road car?
2. If so, what sort? Are there different manufacturers? If so is one make any better than others?
3. Best place to obtain them in the UK?
Steve Church

Mostly personal preference! I have and like Superflex blue. The car is mostly street use, touring and the occasional track day. I have not tried "race" bushes -often red, but I suspect they are too harsh for my use. Remember anything new is better than the tired old rubber ones you replace -including new rubber ones!
Michael Beswick

Steve-
Sadly, almost all of the aftermarket suppliers in the USA offer only the harder varieties, being either of the “Racing and Competition” or of the “Fast Road and Rally” type. In terms of their quality, some of these bushings are real “bargain basement” items. In my opinion, the Australian company SuperFlex makes the best, and the price is quite reasonable for the quality of their product. They do not produce them in molds (a sure sign of an El Cheapo bushing), instead they start life as a solid rod that is actually precision machined to size and shape on computerized machines. As a result, they will slip-fit into place. This is not often the case with molded bushings. Sometimes you have to pound them into place with a mallet, which will result in their bores being distorted or compressed, which in turn will cause them to squeak. The SuperFlex bushings are self-lubricating once installed. They even include stainless steel sleeves so that rust cannot abrade them. If you want to purchase a softer set (that is, soft like rubber bushings) for use in a daily driver, go to http://www.racecar.co.uk/SuperFlex/ and specify 80 Shore-A bushing material for the A-arm bushings (BMC Part # AHH 7933*, BHH 1123**, SuperFlex Part# SPF0012) and 90 Shore-A bushing material when you order the Trunnion (BMC Par t# 8G 621, SuperFlex Part# SPF0282), Leaf Spring (Front Spring Eye- BMC Part # AHH 644, SuperFlex Part # SPF0181; Rear Spring Eye (BMC Part # 2A 5176, SuperFlex Part # SPF0014), and Stabilizer Bar bushings. SuperFlex makes a product line that even includes stabilizer bar bushings for 1” (SuperFlex Part # SPF0063/25), 7/8” (SuperFlex Part # SPF0063/22), ¾” (Original Equipment Par # AHH 7927, SuperFlex Par # SPF0063/19), 11/16” (BMC Part # AHH 7921, SuperFlex Part # SPF0063/17.5), 5/8” (BMC Part # IB 4526, SuperFlex Part # SPF0063/16), and 9/16” (BMC Part # AHH 6541, SuperFlex Part # SPF0063/14) stabilizer bars. I would recommend 70 Shore-A material for both the lipped upper and flat lower front crossmember mounting pads (BMC Part # AHH 6204, AHH 6206, respectively; SuperFlex Part # SPF0015A, SPF0015, respectively) and the stabilizer bars.
*(MGB bushing) **(V8 bushing)
Stephen Strange

Stephen, You are, indeed, a wealth of information. RAY
rjm RAY

RJM-
I try to be. Still learning, though.
Stephen Strange

Excellent Stephen, thank you. I've just printed off the page and will put it (with the appropriate numbers highlighted) aside.
I've already used the Superflex poly bushes in the rear of my MGB, with the front of the MGB and the MGA next on the list.
Luckily for me, I can just duck down to my local auto parts shop, 10 minutes from home, to get my Superflex bushes.
T Aczel

Most appreciate that information Steve. I am redoing the bushings in my B as the V8 rubber ones only laste about 4 seasons. I will get these ordered up right away.
Bruce Cunha

Bruce, Your V8 bushings only lasted 4 seasons? I installed a set in my '67 over 20 years ago and they look like brand new. Whatever happened to quality? RAY
rjm RAY

I think the information Stephen listed is part of the problem. Some of the manufacturers are just turning out junk. These were very hard to install. literally had to press them in with a hydraulic press - and that was after putting them in the freezer to get them as small as possible.

Could be a bit of it was that it was the first time I had installed these on a B. I do remember that it was not nearly as hard putting them in my TD back in 74. Those are also due for replacement but 36 years I can live with.
Bruce Cunha

I've been looking at the various Superflex bushes. I see there is no bush for the bottom trunnion (outer end of the wishbone). Is there not one required? I'm sure I saw a rubber bush there when I took the suspension apart.
Steve Church

Ok. I've found out its a phospor bronze bush. I guess I was looking at the seal.

Has anyone used Motor Sport World in the UK for Superflex bushes?
Steve Church

I replaced all bushes on my 80 LE with new poly ones from Energy Suspension (www.energysuspension.com). I ordered them from Moss. I had no difficulty with fit, but I dropped the entire front crossmember, thoroughly cleaned and repainted it so no dirt or grease to affect the fit. Poly bushes require a special grease and following the instructions about where to apply. My bushes came with a few tubes, but you can buy Energy Suspension brand grease through auto stores. Also, when fitting poly bushes, install them, but don't completely tighten until the car is on the ground. I can't add much about performance since the car hasn't been moved since with lots of other restoration going on. I've replaced all of the rear as well with poly bushes from Energy Suspension.
Rick Penland

I've just been speaking to Superflex here in the UK. They state that the parts they offer for MGBs are all 90 shore apart from the leaf spring plates which are 80. Has anyone in the UK used Superflex? What difference am I likely to feel over the hardness ratings that Steve is recommending?
Steve Church

Without wishing to sound rude, I think we are beginning to split hairs! The rest of the car is maybe 40 years old, and was hardly at the cutting edge of design when built! Superflex have been supplying bushes for Bs for many years. I think you will be well satisfied!
Michael Beswick

JUst to add, that is also my next job on the list of things to do, that is re-bush the front on a 1972 MGB GT. I am doing this in stages, due to necessity rather than design. I replaced the rear in supeflex as suggested and new lowered and uprated springs, but also took the line of a telescpic damper conversion. The old dampers I think were working well but, what the hell! Anyway, do you know the back really feels good and no noises or squeaks!
The front now has uprated lowered springs and a telescopic conversion. There are a new exchange rebuilt stub axle assemblies to be fitted, together with a new King pin and the new bushes will be placed at the same time. But just to point out having replaced parts in bits, it helped to highlight the next weakest link, if you see what I mean! The car at present feels very nice just with the springs and telescopics. But over rough ground I still get a rattle and shake, I guess bush wear and swivel axle wear? I should stress also that I am running on 185X65X6 yokohamas on superlite wheels. My track rods may be suspect but steering seems quite predictable and precise. Thanks for your thoughts. Mike
J.M. Doust

I've used Superflex on a coupe of MGBs with excellent results. I agree that they are the best bushings available. The standard shore rating is fine for street use unless ride comfort is your number one priority. They do stiffen the ride slightly. The increased steering response and handling more than makes up for it however.
Steve S

This thread was discussed between 01/01/2011 and 10/01/2011

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