Rear suspension upgrade

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blodween
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Rear suspension upgrade

Post by blodween »

I have started to upgrade the rear suspension on my 1963 Tourer as it seems that every pot hole you hit really gives the car a good shaking.
I have looked at the clubs suggested list of mods and decided to go ahead with using the front dampers from a Mini. "BOGE" gas dampers.
I modified the rear spring brackets (where the shackle bolts fit into), manufactured the Special Bolts & made the additional top support brackets ( which give extra support to the top of the new damper arm & special bolt) all as per the instructions.
My problem is that when I restored the car 7 years ago, one of the things that I did was to replace the part of the chassis leg that the support pin was fitted to for the arm of the original damper unit, I now fin out that the thread on the replaced unit is 3/8" UNF & not 5/16" UNF as the original ones were. That's not much of a problem as new bolts can be made.
I offered the new unit up to the modified spring brackets and the existing top support for the original damper & because of the diameters of the new dampers, this meant that the unit was set at an angle of about 20deg.
This does not seem correct, so I have drawn out the area that the modification was to be & in order that the new unit can be fitted I will have to extend the top pin (on the chassis leg out by 40.0mm.
If any one has carried out this same modification procedure I would be grateful to have you comments & advice.
Last edited by blodween on Sun Oct 01, 2017 12:22 pm, edited 1 time in total.
philthehill
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Re: Rear suspension upgrade

Post by philthehill »

This is a similar modification to what you described.
The original kit was provided by Leadbetter's of Lancs and I have slightly modified the kit to suit my purposes.
Extending the top pin will put extra loading on the chassis and the pin may break out of the chassis leg.
Because of the diameter of the dampers at the top a champher was cut out of the damper shroud where it fits against the chassis leg and a plate welded in.
Even though the dampers are angled rearwards at the top they work very well.
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millerman
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Re: Rear suspension upgrade

Post by millerman »

Phil

Very good work around with excellent photo, seems much easier than that recommended by the MMOC Tech Adviser but is there a possibility that the damper body could contact the bottom of the chassis leg?

Blod take note :wink:
philthehill
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Re: Rear suspension upgrade

Post by philthehill »

Millerman
The possibility of the damper shroud hitting the bottom of the chassis leg is removed by a very small modification to the damper shroud.
That very small modification is to cut and adjust the top of the shroud to clear the chassis leg.
The modification does not impact on the damper operation.
The modification to the damper shroud was carried out by Leadbetter's of Lancs making the kit a ready to fit modification.
I do not know if the rear damper kit is still available from Leadbetter's of Lancs.
Leadbetter's of Lancs also made a very good front tele damper conversion kit which placed the damper bottom mounting directly over the centre of the lower suspension arm.
I would have bought their front kit but already had uprated lever arm dampers fitted.
My rear suspension is lowered by 2" and the damper still works well even with 2" of less travel.
When I take the dampers off to fit damper poly bushes I will take and post a photo of the modified damper shroud.
Phil

millerman
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Re: Rear suspension upgrade

Post by millerman »

Phil, thanks very much for your explanation.
Looking closely at your photo I can see that very little needs to be removed from the damper shroud
blodween
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Re: Rear suspension upgrade

Post by blodween »

Conversion now complete and reasonably happy with the result. tested the car over several bad pot holes and bumps and there has been a vast improvement.
I am a little concerned at the slight angle that the units are set at as this will put a strain on the bushes at each end of them.
I am looking at an alterative fixing for the top pivot in order to try and eliminate this slight angle. :P
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philthehill
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Re: Rear suspension upgrade

Post by philthehill »

Thank you for posting the photo of the revised damper set up.
Well done.
I have a couple of comments:-
You are right about the damper bushes - it can be seen that the damper is not in line and the bushes are distorted.
You will note that the bottom mount (which is a separate bolt on item) on my set up is cranked so as to keep the damper in line.
You could bolt a piece of angle (same thickness as the spring plate) on the outer face / wheel side of the spring plate / damper mount and attach the bottom damper pivot pin / bush to it - it will help keep it all in line.
I would advise that the bottom spring plate / damper mounting is trimmed so as not to foul any bumps in the road.
Phil

blodween
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Re: Rear suspension upgrade

Post by blodween »

Hi Phil
Thanks for the comments, I agree that the bracket is a little to low so I think that it will have to be reduced in size.
Also I am looking at getting the damper into a more vertical attitude in order to take the angle out of the bushes. :wink:
Regards
Dave
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