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MG MGB GT V8 Factory Originals Technical - Composite Rear Springs

Can anybody tell me if there is a distributor for good quality composite/fibreglass rear springs in the UK?
Thanks,
Stainzy
Stainzy

AFAIK, no. The only source is Doug Jackson at British Automotive in California. There was talk of the MGOC stocking some sets from him, but I don't know if anything came of that.
Dougs site URL is http://www.mgbmga.com/
HTH
David Smith

I noted a passing comment in one of the boards, about using a mono leaf steel spring from the rear of some Japanese mini car. Perhaps some time exploring in a wrecking yard (a breaker is it?) could be rewarding.
Barry
Barry Parkinson

I also heard about the MGOC stocking the BA springs-I also heard that they were going to be pretty expensive-like more than than the US price in pounds -I dont belong to the MGOC any more and haven't got their latest spares cat.

Cambridge Motorsport are marketing a steel competition single leaf spring-it appears to be a non-tapered leaf from the photos in their catalogue which must mean that it is not very progressive at small displacements.

I'm running Single taper leaf RV8 springs-these are forged to a tapered section so are progressive-they are longer than standard and need some special shackles-the shackles bushes are the same as the std springs.I am currently running them slightly modified to give circa 146 lbs/in with a pair of specially made LEDA shocks.(+my own design of panhard rod and tramp bars)
I think that the BA springs do look very good and would love to try a car out with a set of the 135lb springs fitted. My only concern is that they might be too soft to transmit V8 torque without excessive tramp.

BA are currently developing a tramp bar kit which is a variation on the Moss underslung tramp bar theme. Theirs is better because it uses rose joints-but I still think that it will cause the rear suspension to bind up as it is a fixed length link parallel to the flexible front half of the leaf spring.

Regards

John Bourke
John Bourke

I just checked with Doug and a set of 135 lb springs would cost $700 shipped to me in Florida.
BobP
robert pulleyblank

I assume the 135 lb composite springs are not Doug's standard issue - as I think I paid around $250 for a pair, collected, last May.
David Smith

Thanks guys, I will chase it up. The composite springs seem to have a good reputation.
Stainzy
Stainzy

David,
I am waiting with bated breath to hear your experiences with installing and running the Doug Jackson springs - I will assume you will publish a full report for us after you put them in?

Cheers,
Paul Kile
Paul Kile

Paul, you're not going to put composite springs on that ultra-cool factory car, are you???? For the love of God, my good man! FWIW, I went back to steel springs on my gtV8 converion as I felt the British Automotive composites were much too soft (I had the 135#-ers) and they REALLY wound up under the V8's torque. You could certainly add traction bars to counter that, but doing so would IME likely compromise the suppleness of those springs altogether ... never seen a traction bar install that didn't end up stiffening the springs to some degree. (Plus IMHO one would simply be out of one's mind to weld any extra stuff onto a factory car.)

I also had some misgivings about having the plastic springs right next to my exhaust system, which gets hotter'n a Texas tornado since I've got the headers coated and all that heat gets flushed down the exhaust. Lastly, the composites squeaked to high heaven after a bout of damp weather -- although this climate is surely damper than yours, so this may not matter. So now I'm running new stock steel 7-leafs, rear Spax and a Hopkinson sway bar kit, with 195/60/15 tires, and it all seems nearly optimal -- it all may sound like a recipe for a slightly harsh ride, but not so at all. No traction bars, Panhard rod or fancy x-member at the moment.

Please post pictures of your car as it progresses; it just sounds altogether happenin'!
Harry

An addition to Bobs $700 price. This was for two sets so one pair is $350.

David, there are two specs available 100 and 135 depending on vehicle weight more than anything else.

Rog
Roger Parker

Yes of course- - now I remember Doug asked me if it was chrome or rubber bumper......
David Smith

He used to sell a regular arched spring and a dearched spring, but apparently now sells only regular arch spring. The roadster is 100 # nominal rating and the gt 130. However there is significant mfg variation and he sells them in matched pairs. The earlier lighter model get the softer sets, the rb the heavier. The springs for my 67 gt are 118-120# and resulted in a 14" rear height for my gt which weighed in at 2115 lbs with 3 gals of fuel. The springs have little increase in resistance as they are depressed. i.e. the last inch and the first inch of compression both require 130 lbs of pressure. Leaf springs are progressive in nature. The further you compress the more leaves come into play and the more friction between the leaves. The initial rating on a leaf spring is probably substantially less than 100 lbs, the last inch is probably over 200 lbs. With a heavy car and large bumps the plastic spring would be more prone to bottoming out. The rear rides much better but over large dips does in my judgment fell like it is allowing more up and down movement than the stock springs. The rear seems more secure in hard cornering, proably the result of a more compliant low friction spring keeping the wheels on the road better and probably because of lowered rear roll resistance in hard cornering. Doug claims the mono construction is superior to the leaf construction in preventing spring wind up under heavy acceleration. With my 1800 cc's I haven't tested that feature.
Barry
Barry
Barry Parkinson

He used to sell a regular arched spring and a dearched spring, but apparently now sells only regular arch spring. The roadster is 100 # nominal rating and the gt 130. However there is significant mfg variation and he sells them in matched pairs. The earlier lighter model get the softer sets, the rb the heavier. The springs for my 67 gt are 118-120# and resulted in a 14" rear height for my gt which weighed in at 2115 lbs with 3 gals of fuel. The springs have little increase in resistance as they are depressed. i.e. the last inch and the first inch of compression both require 130 lbs of pressure. Leaf springs are progressive in nature. The further you compress the more leaves come into play and the more friction between the leaves. The initial rating on a leaf spring is probably substantially less than 100 lbs, the last inch is probably over 200 lbs. With a heavy car and large bumps the plastic spring would be more prone to bottoming out. The rear rides much better but over large dips does in my judgment fell like it is allowing more up and down movement than the stock springs. The rear seems more secure in hard cornering, proably the result of a more compliant low friction spring keeping the wheels on the road better and probably because of lowered rear roll resistance in hard cornering. Doug claims the mono construction is superior to the leaf construction in preventing spring wind up under heavy acceleration. With my 1800 cc's I haven't tested that feature.
Barry
Barry Parkinson



I'm interested to read the comments of somebody who has actually fitted and driven a car witht the composite springs-esp with V8 torque.

I can't from experience of actually having handled a set of the BA springs -but I would have said from the basic design of a monoblock spring that you can give it exactly the same characteristics as any multi leaf spring by changing the thickness profile of the tapered section to give the right amount of resistance for a given deflection. The advantages are that the spring has no interleaf friction so that the damper is able to be fine tuned to the characteristcs of the spring.The spring should also last longer than a multileaf spring and also be stiffer in sideways deflection.
I'm interested in the comment that the car feels too soft-the main aim with a B is to get the rear as soft as possible to keep the rear wheels on the ground and to use minimum damping forces. The front should be set up relatively stiffly to counteract the soft rear. if the car is bouncing then there is not enough damping. If the car is bottoming out too frequently(crashing onto the bump stops)-then this is beginning to show up the lack of basic travel built into the original design -nominally 3" either side of static ride height-radical springs deserve something other than hard black rubber bump stops-time to remove the lever dampers which might become damaged by over travel and invest in some slightly longer travel tube dampers and some progressive silasto(closed cell foam) bump stops to poach out the suspension travel and give the effect of a rapidly stiffening spring at the end of the suspension travel. I think that I may have sorted out the tramp bar question.... but that is another story.


Regards

John Bourke

John Bourke

I have run Doug Jacksons comp. springs on 3, yes 3 of my own V-8s. I have 150,000 miles on 1 set under my 2-74 G.T & 120,000 on 10-74 G.T. & 30,000 on my 7-72 roadster & I will not have anything else!!! I have sold this spring for Doug since the moss spring dose not have the right arch & then in 5 years thay have NO arch!!!! I tell people to put the 135+ spring under them all, my roadster had the light springs under it & it bottomed out very easily & I sent them back & got the 135s & thay are fine. I put tork arms under ALL of the V-8 I do to take the load off the springs (spring wrap) for if thay were to break it would be law suite time hear in the U.S.of A. I put these under my car for the better ride & I got that. I put the 1" sway bar up ft. & the 5/8" bar in the rear & it now GOES around the turns It isn't how many states you go through in your M.G.V-8 but how many TIME zones!!!!!!!!!!!!!!!! Glenn
Glenn Towery

This thread was discussed between 09/10/2000 and 24/10/2000

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