Parabolic Springs

[Johnharris]

Rebuilt my 1973 roadster over the course of last year after purchase. New front and rear suspension included. The rear suspension fitted with parabolic springs and Gaz dampers. Very bouncy - low damping setting on Gaz dampers (3 to 5), very stiff and jittery when set higher ( 6-10 ). Really regretting this experiment. Terrible ride compared to my V8 on leaf springs and Gaz dampers. The rear end skits over bumps in a corner very badly.

First set of parabolics from one of the big suppliers - very different ride heights either side and when taken off, one spring with a very different curvature to the other.

Current set from MGOC - who when asked recommended upping the damping to control the bounce - which makes sense, but now very jittery.

Bushed correctly. Lower damper connection correct. Ride height correct. Double checked the part numbers for the car. It is not the front upsetting the rear either. The front is 350lb springs and leaver arm dampers with adjustable valves and 3/4 inch anti roll bar. The car has done 4000 miles since installation including a trip to the South of France. Rear suspension the only issue.

Any ideas before I revert to leaf springs.

I cannot say I was not warned in advance by two highly regarded MGB restoration and engineering establishments who have done work on the V8 for me.

[Not_Anumber]

I keep seeing references to parabolic springs and wished i could help. Are 'parabolic' springs basically an alternative leaf spring with a single leaf rather than multiple leaves. anchored at the same points as the originals ?

If so the classic Ford community has been using the things for many years where they are regarded very favourably so long as they are properly made and heat tempered and matched in pairs. If they are the same thing then the same rules would apply to them on MGBs

[Johnharris]

Indeed they are the same type of springs and generally they are will thought of on MGB's.

However, for whatever reason, both the pair from Moss and the recent pair from MGOC are both extremely bouncy, to the point of being bounced out of my seat, and very jittery/bouncy when more damping is applied.

At the moment I can only think that either, despite the part numbers on them being correct, they are really GT springs or the manufacturing process has gone wrong.

Without any obvious way forward or input from this forum I am returning to leaf springs.

[Ian F]

I had always understood that parabolic springs were more "compliant" than the standard.
They are often fitted to Series Land Rovers to soften the ride - which is very firm.
To be more compliant I would think they have to be softer, at least in the initial phases of bending, but then becoming firmer towards the end of the travel. I can see how this would detrimentally affect the ride of an MGB.
I have standard good quality OE springs on my BGT, and adjustable telescopic dampers - these are set at their softest setting. This provides an ideal compromise for me. If I set the dampers to a firm setting then the back end does become very "jittery" and the handling/roadholding suffers.
I believe the ideal for these cars, and similar, is a firm front, well controlled with an arb, and a softer rear. This can be achieved with standard leaf springs as far as I can see.

Ian F

[Johnharris]

Ian

Indeed, it was an experiment as I had noted comments that parabolic springs were better, so at the point of rebuild I thought I would try them. My V8 has leaf springs and Gaz dampers, set as you say, and it is great.

Back to leaf springs, failed experiment !

[Mrbenn]

It maybe a stupid question but are the definately roadster springs not GT ones? Friend of mine has parabolic springs in his roadster and they feel fine. I replaced the leaf springs on my other B last year but they were a lot firmer and I noticed I'd ordered some for a GT rather than a roadster.

[Johnharris]

I will go and check again, the part number on it corresponds to roadster springs.

Will report back later after a further check

[Johnharris]

Definitely C/B parabolic springs for a roadster - never ever again, just ordered a set of leaf springs