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MG MGB Technical - Suspension rubbers

I have a 1978 MGB GT rubber bumper model, running on standard springs front and rear with spax uprated shocks front and rear also. I currently have standard rubber suspension bushes fitted throughout, but have seen various aftermarket upgrades available, such as superflex, poly fast road etc. Can anyone tell me which is better, what impovements, if any, I could expect from fitting these throughout the car? I am considering fitting parabolic rear springs, but not decided on that yet, having read previous threads on the subject.Thanks
P Sorensen

No experience myself ... I found this on bushes last night-

http://www.netbug.net/blogmichael/?p=103
Geoff E

Obviously, there is no single Magic Cure-all for any cars handling. Only in fantasy are things that simple. However, a simple modification involving nothing more than a change of parts can produce worthwhile results. The rubber front suspension bushings from an RV8 model produce significantly less longitudinal flex, endowing the steering with greater precision. Be aware that these bushings are not a press-fit onto the inner fulcrum pin. Should the fit seem to be tight, clean the fulcrum pin to bare metal. The inner end of the stainless steel bushing sleeve should be mounted with its chamfered end matching the radiused inner end by the flange of the fulcrum pin. The large flat washers must fit over the outside diameter of the pin so that they will clamp the stainless steel bushing sleeve tight on the fulcrum pin. Should the hole in the flat washer prove to be too small to permit this, both rapid failure of the bushings and rapid wear of the fulcrum pin will result.

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 to steering input will also demand that you pay closer attention to what you are doing. Unfortunately, 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. Because they are harder, you will feel more vibration emanating from the suspension and steering wheel, hear more road noise emanating throughout the body of the car, and your hands will feel smaller pavement imperfections through the steering wheel. Hit a big pothole and you will know it! Even worse, the greater transmission of these forces means that associated load-bearing components (Steering rack and column components, tie rods, ball joints, kingpins, swivel axle bushings, dampers, etc.) will wear more quickly. The purpose of the original soft bushings at the top trunnion, the bottom of the swivel pin, and at both attachment points of the lower A-arms (wishbones) is to absorb energy. By absorbing energy, they prevent it from being transmitted elsewhere. In reality, there are better options for increasing steering response while avoiding most of these drawbacks. Sudden, outright failure of these components is highly unlikely unless they are of defective manufacture, but longevity is always desirable.

This is not to say that you should resign yourself to the use of rubber bushings. Whereas 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. In terms of their quality, some of these bushings are real bargain basement items. In my opinion, 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. 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 (wishbone) bushings (Original Equipment Part# AHH 7933 *, BHH 1123 **, SuperFlex Part# SPF0012) and 90 Shore-A bushing material when you order the trunnion (Original Equipment Part# 8G 621, SuperFlex Part# SPF0282), leaf spring (Front- Original Equipment Part# AHH 644, SuperFlex Part# SPF0181: Rear- Original Equipment 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), (Original Equipment Part# AHH 7927, SuperFlex Part# SPF0063/19), 11/16 (Original Equipment Part# AHH 7921, SuperFlex Part# SPF0063/17.5), 5/8 (Original Equipment Part# IB 4526, SuperFlex Part# SPF0063/16), and 9/16 (Original Equipment Part# AHH 6541, SuperFlex Part# SPF0063/14). I would recommend 70 Shore-A material for both the lipped upper and flat lower crossmember pads (Original Equipment Part# AHH 6204, AHH 6206, respectively; SuperFlex Part# SPF0015A, SPF0015, respectively) and the stabilizer bars.
*(MGB bushing) **(V8 bushing)

Prior to fitting any suspension bushing, remove all dust, previous paint, old grease, or bushing residue from all of the surfaces that can come into contact with the bushing. Be sure that any original outer shell is not inadvertently left in place. This is a common mistake whenever an old rubber bushing has unbonded from its shell. Do not fit new bushings to worn, rusty, or distorted fittings. All such worn components must be replaced. When preparing to install a bushing, lightly coat both it and the contact surfaces with CRC Sta-Lub Extreme Pressure Lubricant prior to fitting. In a very cold climate, immersing high-interference fit bushings into boiling water can facilitate fitting. Insert the stainless steel tubes (where applicable) after the bushings are installed into their housing. Before the final tightening, all of the suspension arms must be normally weighted at normal ride height and the car bounced up and down. When replacing original components, ensure that all nuts and bolts are torqued to original manufacturers specifications. Note that polyurethane bushings must not come into contact with alcohol-based solvents such as MEK, methanol, or methylated spirit.
Steve S.

About 2 years ago I replaced all my rubber suspension bushes (with the exception of the anti-roll bar bushes which are still rubber) with the Superflex Blue variant, which was I think a "comfort" model. Fitting them was easy and all four corners were done in about half a day.

I would not call myself a demanding driver (the oily bits is my thing)but I did notice that the overall handling of the car improved - it felt tighter and more responsive in cornering and just a little more sure footed. It is a very subjective thing but I am happy with the results of my upgrade.

hope this helps

pAul
P R Ives

Thanks everyone, some really useful information. My wife doesn't understand why I can't just leave my 'old' car as it is, but then for her a car is a box with a wheel in each corner that gets her where she wants to go! I love my MGB GT, and will slowly continue with various improvements. The Superflex bushes sound good, will enquire further.
P Sorensen

Hey P. Sorensen - bet you didn't expect a response as fast, detailed and helpful as that supplied by Steve S ! As a newby I am continually amazed at people's willingness to help the rest of us to keep the MG dream alive. I feel the same about my BGT as you do about yours. Regards, John.
J.P. Hall

P Sorensen,

Buckingamshire not too far from cambridgeshire.
You may have a car test at your disposal by MGOC. Contact them for a drive test if either it could be usefull to you.
Regards.
Renou

I have the blue grade, road use poly and think they are great. I went from new rubber to poly so the change was not just due to new.
The poly bush is on two halve with a staineless center so they locate very precisely, and lightly. They have more give than rubber, are less harsh, but have more return to center than rubber.
Squeaking- you need to use the lubricant supplied. I often go away from home for weeks at a time and for a couple of days on return they will sometimes squeak, then they stop this after about three hours of driving.

Conclusion- much better than rubber, even V8, but if you drive the car once a fortnight for half an hour be prepared to put up with squeaks. (and actually I don't care much you girly Sunday driver you!!)
Peter

I've got red in my daily drive GT. They make the steering very sensitive but a cat's eye feels like a brick. Blue should be good.
Steve Postins

I am rebuilding a 77 model B but when I put the back surpension together and istalled it the rubber straps won't connect as the body sits to high,what is wrong ?,I have assembled as per book.
Ian

Ian 2 types of straps one for rubber /chrome.just about finished my 1978 front rear rebiuld,fitted superpro bushes from moss
ian smith

Interesting addendum,
After posting the above we had a sudden cold change and all my poly bushes started to squeak in chorus, like someone had thrown a switch. Karma! What a din! The bushes are about three years and 50,000 km old. You wouldn't believe the noise and creaking
On the grounds that I had nothing to lose last night I pulled the front suspension apart and applied gobs of grease (molybdenum blue) to the outer edges of the bushes (the sides) and the center of the stainless tube that runs through them. 100% success. Deathly silent to day. Poly propylene is pretty tough and shouldn't absorb grease and swell. Petrol container are made of polypropylenes.
And anyway, the grease is only contacting the sides.
If your joints are creaking, try this.
Peter

Listen to Steve.

Except for MGB/GT V8 bushings installed many years ago, the rest of the car still rides on stock suspension rubber. The sway bars (front one is a 7/8") are in poly & I did add a panhard rod & very sticky tires.

This one is hard to catch:


Carl Floyd

I'd agree about the 7/8ths bar. I've ordered one up.
Currently using a 3/4th. A litle bit of over steer.
I've also got a 10kg tow bar fitted (sailing).
The original design of the mgb was brilliant, however they changed to a much heavier diff' (then tackd on 25 kg bumpers) and that upset the balance a little 8-0. I'm hoping 7/8th should be right on the money.
I've just changed to composite springs (30kg less) and the change is much for the better. Pleased as punch with them.
PETER

Ian Oz - is the car fully built? If not then depending on how much has been left out the car will be higher. A chrome bumper rebound rubber will also be too short for a rubber bumper, but I'd still expect to be able to fasten it in a fully assembled car. If, on a fully assembled car, with the weight fully on the cars' suspension, you still can't fasten the straps then the springs are either too hard, too arched or both. This is a very common problem from some suppliers, although I have had three sets from various suppliers in the UK - one set as late as last year - and not had any problems. What angle are the rear shackles with the weight fully on the suspension? They should be pointing almost fully downwards. I've read that on a rubber bumper the shackles can lock up against the chassis rails and need levering downwards as the weight is put on the springs, but having changed springs on both rubber and chrome bumper that hasn't happened to me.
Paul Hunt2

This thread was discussed between 24/04/2008 and 07/05/2008

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