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MG MGB Technical - Rubber, Prothane, Poly or Nylatron?

Hello-

I'm rebuilding the entire front end on my 68 Roadster, for regular driving,not competition. I would like to install longer-lasting bushings than the rubber ones. I have the V8 A-arm bushings on my GT and like those and they seem to handle OK. I know there are a lot of ways to go as far as bushings but I know that some will give a busier/stiffer ride, some may squeak, and some may not fit out of the box requiring hand-fitting/mods. From all of your experiences, which type of bushings will last, not squeak, and give a smooth 'as original' MGB ride? This would apply to the sway mounts as well. Opinions/experience appreciated!

Thanks,
Sam
Sam Sullivan

On a related note, what are the polyurethane bushings that Brit-Tek sells? Has anyone used these bushings in there car? Do you like them? How about the squeaking?

Thanks

Zach
Zach

Sam-
I would suggest that you order a set of polyurethane bushes from Superflex over in the UK. To my knowledge they're the only company that will allow the customer to specify the shore hardness of the bushings. For front end components I would suggest Shore 90. This will provide good, tight handling without transmitting too much vibration and road shock, much like a very high quality rubber bushing. They have a website at http://www.racecar.co.uk/superflex/
Steve S.

Steve,

I like the V8 bushings since they hold up a lot better than the stock bushings but still give me a lot of flex as they are still rubber.

My worry about the "plastic" bushing is that it won't be very forgiving on the suspension components on these bumpy potholed Boston roads.

I drive my Bs year round racking up hundreds of thousands of miles, so I tend to develop problems that more casual drivers don't.

Would I be wrong in assuming that the polyurethane bushings would put extra stress on the suspension? I've had wishbone pivots bend before and I would think that the polyurethane bushings would exacerbate the problem.

Steve Lipofsky

Zach and Sam
I have the rubber V8 bushings in my front a-arms, and polyurethane from Brit-Tek in my rear suspension. They both do the job well. The V8's are softer but something in my front suspension is squeaking and I fear it may be them. In the back the ride is a tad stiffer, however, the bushings keep the axle in place and don't sqeak a bit.
Bill
69 B-GT
Bill Mertz

Steve-
I understand your apprehension. Most of the polyurethane bushings being offered in this country for MGBs use a sales pitch of "Race-Style Handling Improvements". They're fine for a track racer, but a bit harsh for a street machine. These are quite hard and transmit an excessive amount of vibration, road noise, and impact to the body and steering column of the car. Most people who install these are replacing worn out bushings which stopped cushioning long ago, and even they notice that these characteristics are actually somewhat worsened when these harder bushings are installed. They sigh and consider the harshness to be the price that goes with improved handling. However, read my last posting more closely. Shore 90 hardness polyurethane bushings have about the same amount of "give" as high quality rubber bushings, such as those used on the V8. However, unlike rubber, they don't compress over time, go oval, or rot. As a result, the steering doesn't slowly develop slop over time and they continue to give a "like-new" feel long after the rubber bushings have ceased to do their job. Unlike the El Cheapo brands of polyurethane bushings, Superflex doesn't injection-mold their bushings, they machine them to precise dimensions on CNC (Computer Numerical Control) machines and supply them with stainless steel sleeves to reduce abrasion. Because of their precise dimensions, you don't have to bludgeon them into place with a four pound hammer. Holding one of them in your hand and inspecting it tells a story of quality. I consider them to be The Best. Try 'em, you'll like 'em.
Steve S.

Thanks, Steve. You may have me sold.

I did read the reference to the Shore 90 hardness, but my lack of experience with polyurethane made it hard for me to imagine how the plastic could compress upon impact the way rubber would.

Steve Lipofsky

Steve S.-

Thanks for your comments. A few questions, though. Do they have 'off the shelf' Shore 90 MGB bushings? Can you get the Superflex in the U.S.? And last but not least how much are they?
I was thinking of using V8 rubber bushes for the A arms and poly for the upper trunnion on the king pins, and poly on the sway mounts. Good combo?

Thanks,
Sam
Samuel Sullivan

Bushings; Are "Prothane" bushings as advertised in Moss basically polyurethane? If so, are they advised for street use? Thanks.
Pat

Sam-
Good though the V8 rubbber bushings are as compared to the OE rubber bushings, why bother? Rubber is obsolete. As I said before, the polyurethane bushings that most MGB owners are familiar with are the hard ones meant for racing use, so naturally polyurethane has gotten a bad rap. Like anything else, finding a truly quality item suitable for street use takes some searching.

At this time I think that you'll have to order the Superflex bushings straight from the UK. That's not really a problem as they're light and small, so they can drop them into a small box and ship them to you for very little. Yes, you can specify Shore 70, 80, 90, or 95 material to suit your needs. The "Universal" section of the website will fill you in on just what the best applications of the different Shore hardnesses are. For prices, check their website as it lists just which bushings they make and what they cost. As to whether or not a specific bushing in a specific hardness is "on the shelf", just click on the URL in my first posting on this thread and please Email them yourself (Cheeeeez, I don't work in their stockroom, y'know!).

The use of polyurethane bushings on the stabilizer bar mounts is subject to some controversy. There's no point in going for the El Cheapo injection-molded hard bushings as they would only transmit more vibration while offering no handling advantages. I'd say go with Shore 60. They'll be soft and compliant, damping out vibration quite nicely. Superflex makes them for 7/8",3/4", 11/16", 5/8", and 9/16" stabilzer bars. They also make all of the other front and rear suspension bushings, and even the spring pads and axle pads.
Steve S.

OK Steve -

My Dad was a machinest but I took a different path, so I'm not up on my knowledge of industrial materials specifications. Am I interpreting correctly from what you said that the lower the Shore Hardness number, the softer the material?

Yes, I know I could e-mail Superflex and ask them, but it's late, and I'm lazy...

Jon Sjoberg

Thanks Steve I will check out the site.

Sam
Sam

Jon,

They are colour coded for us laymen. I've used Superflex on my midget, easy to fit and no squeaking. Most MG outlets in UK put a package together depending on use.

Paul
Paul

I used the poly bushings (based on hype) and knew immediately that they made the car too stiff and unforgiving on everything but the smoothest road. Now I've got to pull them back out and replace with the rubber......
Mike D

Mike,

What colour/shore and make did you use?

Paul
Paul

To everyone who is asking about bushes,
I have a 78 r/bumper mgb and decided to lower it to chrome bumper height and also fit better bushes front & rear. After reading all the hype i decided to fit POLYBUSH COMFORT which are a touring bush to quote "factory fresh ride and superb durability".I have had mine in for about six months and have found them to be superb, no squeaks,good feel & feedback,better roadholding and comfortable.They were a doddle to fit,i had fitted v8 bushes in the past but these were far easier to fit,they were also cheaper than superflex.if you need any more info e-mail me.

have a happy crimbo

vic
vic doughty

I went to the polybush site, a few questions. The lower link, is that the A-arm? The upper trunion? I have never rebuilt a B's suspension, but plan on completing the task this winter. Needless to say, I am trying to gather all the information beforehand.

Thank You
Zach

Steve-

I called Superflex and ordered bushings. I discussed the different Shore values and the bottom line is, for the MGB anyway, A-Arm bushes are 80, trunnion 90, because they bear a lot of loading I'm told, and 90 for the 5/8 sway bar. I asked why 90 for the sway bar instead of a lower compound and the salesrep said that you need 90 or the bar will tend to 'oval' within the bush and handling would suffer. Anyway, I'll update this foray into poly-land this spring when the car is done and I can test it out. BTW, a point he made was that you don't really know the quality of the aftermarket rubber bushes, which I have to agree with although my GT seems OK. Thanks for the tip.

Sam Sullivan
Sam

I used the Prothane bushings from Moss in my MGA. No difference in ride,and no squeaks.
Bob
Bob Swain

There is a Superflex distributor in the US. I know nothing about them. Web site:
http://www.geocities.com/carorphanage/
Clifton
Clifton Gordon

Sam-
I'm surprised that nobody has noticed my typographical error: I said "Shore 60"! There's no such a critter! That's what happens when I write late at night- I get dyslexic. "6" instead of "9", good grief! (11:14PM is late for me. I've still got kids in the house.)
Anyway, you're dead right about the Shore 90 for trunnions and leaf springs and Shore 80 for the A-Arms. Anyway, thanks for correcting me. I'd hate to think that because of me somebody tried to get something that doesn't exist! Mea Culpa, mea culpa!
Steve S.

Steve-

I figured that was a typo when the salesrep said they didn't make a 60!
But I'll tell you those guys really seem to know what they're talking about. And took the order without trying to sell me other bushings. If the bushings match their knowledge of the business I think these things will work out great.


Thanks again
Sam
Sam

I need to know if the nylatron bushing are a replacement for the brass trunnioin bushings and not for the rubber pivot A arm bushings. I can call Moss after the holidays, but I wanted to get some feedback. IU athink they are because they list them for the shock to trunnion and the A arm application.
fredh

I just replaced all my rear suspension bushings with prothane (the red ones). I haven't driven the car a lot yet but so far I don't notice harshness over bumps or any other negative affects. I does handle better.
Scott

This thread was discussed between 16/12/2001 and 26/12/2001

MG MGB Technical index

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