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MG MGB Technical - suspension bushes - again!

Once again I think I have suceeded in resurecting a subject which has long been a source for discussion in the board and the archives. So much so that I am having trouble seeing the woods for the trees.

My dilema is as follows: stock 1967 GT, original suspension setup(no modifications), maybe 3,000 miles per year max in the dry and for the fun (no racing). Suspension at the front is a bit "lifeless" so I figure rebuild (bushes,check springs etc). Now the issue I have is V8 rubber bushes or polyurethane? The archives are evenly split with personal experiences so I figure maybe a question about the expected handling differences may help. What can I expect from these two different setups?

What I want is to have a bit more feel at the front and sharpen things without giving a harsh ride.I still have the old dutch cobbled streets in my village! I am not so worried about longevity issues with rubber (this is my hobby right) and the cost is not a consideration either.

I realise this is the MGB equivalent of asking people if chrome bumpers are better than rubber bumpers (me, I am a chrome man, but thats just personal!!!) but some feedback from your experienced may help me out. Let battle commence - in the right corner rubber V8 and in the left corner polyurethane....


pAul
pAul

Paul,
I installed the poly bushings recently in my 67' GT. I have also used the V-8 bushings in a 72' roadster. The poly bushes are the way to go, plus they should last longer and are way easier to install than the V-8 bushes.
Steve
Steve Brooks

I'm with Steve on this one. The ride didn't become harsh at all and they were an easy fit. Its getting the old ones off thats a b$%#@*.
Luigi

I have just installed the superflex polyurethane bushes to th BGT and have now done about 500miles with them.

The ones i used were made, as i say by superflex, which seems to be the company of choice (lots of favorable reviews) and speaking to the guy from superflex, he is knowledgeble.

I had fitted new suspension exactly 6000 miles (6months) before the new superflex bushes were fitted, so i have gone from brand new rubber bushes all around with v8 bushes on the front to superflex.

There is definitely a difference, noticeable even with previously new rubber bushes. The car has firmer suspension slightly. When the road is of good quality surface it really is pleasant, there seems to be a better turn in and less movement from the rear of the car!! :->

However, IF the road surface is very poor, the new bushes seem to make this more noticeable. Its not unpleasantly noticeable, but you can tell. I currently have a problem where the tailgate moves about at the catch mechanism on bumpy surfaces making a horrible screeching noise. With the rubber bushes i maybe got this every few miles or so. Even on the same stretch of test road the small imperfections in the road and the loss of the slightly damping quality of the old rubber bushes means the screeching comes back more frequently (at least its prompted me to solve the screeching noise though ;-> ). The car seems to cope with cobbled streets ok (i live on one as it happens) if driven slowly.

So in changing to polybushes i believe you will notice a slight difference in ride but ultimately it will be for the better. I went for the polys for longevity (high mileage car) and for the slightly firmer ride to help my cornering! ;->

As a low mileage user polys maybe a bit pricey but you won't have to worry about the rubber perishing before you've put too many miles on. So i guess you'd save money in the long run as they should last very long time!!

Hope that helps ~PHIL
Phil

Paul-
As engineers are fond of saying, it's all a matter of finding a balance of priorities. In other words, you don't get something for nothing. Obviously, there's no single "Magic Cure-all" for any car's handling. Things are rarely that simple. Firmer bushings, such as those made from nylon, will reduce compressibility in the suspension component mounting points and make small steering inputs result in correspondingly small reactions in the steering. In other words, the steering will become more precise, but the greater reactivity will also demand that you pay closer attention to what you're doing. Unfortunately, because they're harder, you will feel more vibration emanating from the suspension, hear more road noise, and your hands will feel smaller pavement imperfections through the steering wheel. Hit a big pothole and you'll know it! Even worse, the greater transmission of these forces means that associated load-bearing components (Steering rack and column components, tie rods, balljoints, kingpins, swivel axle bushings, dampers, etc.) will wear more quickly. Hard bushings are also not only unnecessary for either the mountings or the attachment points of Stabilizer Bars, Panhard Rod ends, and Antitramp Bars as they offer no benefit in handling, but are actually undesirable as they will fail to damp out vibration and road shock. In reality, there are better options for increasing steering response while avoiding most of these drawbacks.

This is not to say that you should resign yourself to the use of rubber bushings. Rubber bushings wear rapidly and rot, Polyurethane bushings take a long time to wear and never rot. Sadly, almost all of the aftermarket suppliers in the USA offer only the harder varieties, being either of the "Racing & Competition" or of the "Fast Road & Rally" type. Some of these bushings are real "bargain basement" items in terms of their quality. In my opinion, Superflex over in the UK makes the best, and the price is quite reasonable for the quality of their product. They don't injection mold them (a sure sign of an El Cheapo bushing), they start life as a solid rod that 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. Superflex bushings are self-lubricating once installed. They even include stainless steel sleeves so that rust can't abrade them. If you want to purchase a softer set (like rubber) 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 (wishbone) bushings and 90 Shore-A bushing material when you order the trunnion, leaf spring, and stabilizer bar bushings. Superflex makes bushings for 7/8", 3/4", 11/16", 5/8", and 9/16" stabilizer bars. I would recommend 70 Shore-A material for the crossmember pads.
Steve S.

I think Steve S. is exactly right about the hardness
of most poly bushings.

I got some "Blue" bushings from www.polybush.co.uk,
however, which are claimed to have an appropriate
softness for street use. They sell "Blue" for
touring, red for fast road, green for racing.
(Don't know the Shore hardness figures, however.)
However, Polybush doesn't seem to have a U.S.
distributor for thus over here - I had to
order directly from the website.
Ronald

I'm a poly fan. They made the whole front supension just generally better, felt/feels like a new car. Not necessaraly harder, just tighter/firmer.
These were for general road use(blue). If you get them, do take care to lubricate them well with the grease provided otherwise they will sometimes make anoying squeeking noises. One of mine did for a while (in hot weather) but eventually stopped. Improperly lubricated I guess.
Peter

I replaced all of my '78 RB's with red poly bushings, when I replaced the entire front suspension. I can't distinguish between old metal parts and new bushings, because everything else is new, down to the nuts, bolts and washers. I can say that I'm thrilled with the new ride and responsiveness. It is firm and quick, but not harsh. I echo what Peter said, and if you install poly, insure you use the lube which is supplied.
Pat Hanrahan

Its time to replace the bushings on my '79B. I've checked all the manuals but they seem too vague - anyone have a site or text I could tap into?

Tnanks
Ed

Ed, Try this. Regards,Clifton
http://www.mgbexperience.com/service/front-suspension.html?PHPSESSID=daa9f5ca1057cb962fdf7a92dafbaea9
Clifton Gordon

This thread was discussed between 29/01/2003 and 01/02/2003

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