Messing with leaf springs

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steveshaw
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Joined: Tue Apr 14, 2009 8:32 am
Location: Driffield - East Yorkshire

Messing with leaf springs

Post by steveshaw »

I had never been happy with the rear leaf springs on my BRA289, I started with 6 leaf GT springs which gave a ride height way too high.
Next I took out the 3 lower leafs, good ride height but too soft and gets spring wind-up on acceleration (that gets your attention!!)
So I've been running with the two smallest leaves removed for 4 years, this is ok for wind-up but still a little soft and still too high.
After reading an article on Rat rod transverse front leaf springs being used "upside down" it set me thinking, so I have taken the lower 3 leafs and mounted them on top of the main leaf but upside down so the curve is opposite to the main leaf.
This has resulted in the perfect ride height (the tire is centred in the arch) and the stiffness is about right.
I had no trouble in assembling the spring, even the centre bolt was long enough to get a nut on, although I think my springs were pretty old and flat which helped.
So far no problems (apart from the exhaust now catches on the driveway) If anything bad happens I'll post again.
Frank289
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Re: Messing with leaf springs

Post by Frank289 »

Will follow your posting with lots of interest.
My BRA i mounted MGB GT axles front and back, back i could also do Jaguar but t that time i thought MG is easyer to buy lots of spare parts and many tested racing parts in the marcket. in the front i ordered lower springs instead of the original ones, no the car is nicely in line and wheels fit perfect, in the back i still hve the original armstongs, but the car isnt running jet. so in very curious how the car will respond on the street.
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peterc
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Re: Messing with leaf springs

Post by peterc »

Try looking through the Clubs tech articles for leaf spring mods as I think Dave Pilbeam used composite items with only one leaf. He rated them highly but I thought it a bit dodgy having only one leaf.
Peter C
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StewbieC
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Location: out in the sticks, Shropshire

Re: Messing with leaf springs

Post by StewbieC »

I too have been looking at ways to firm up the rear springs. I worked out that the best fix would be to add an additional helper leaf to the AHT 20 competition lowered springs. Unfortunately I never got round to testing the theory but I'm pretty confident it would work.
My latest solution is on the bench ready to install. A Jag IRS with 3.54 power lock diff and external disks. Should sort the spring wind up out.
________________________________________________
Stu
Hawk 289, 66 Mustang Fastback with a 289 maximum smiles per mile..
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peterc
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Re: Messing with leaf springs

Post by peterc »

Stewie, is the assembly supplied by Ward and follows the design as sorted by Roger K.
Peter C
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StewbieC
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Re: Messing with leaf springs

Post by StewbieC »

Hi Peter,
Yes, XJ40 outer carriers with external disks and shortened XJ6 lower wish bones and driveshafts all supplied from Ed at Ward Engineering. The Diffs are getting extremely rare now (especially 3.54) and Ed is asking customers to locate their own.
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Stu
Hawk 289, 66 Mustang Fastback with a 289 maximum smiles per mile..
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David Large
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Joined: Tue Apr 03, 2007 7:28 am
Location: Walsall

Re: Messing with leaf springs

Post by David Large »

My BRA 289 has been on the road for almost 30 years.
For the first 10 of them I struggled with the rear springs. I tried different leaf spring sets, different spacer blocks none of which really worked. The exhaust also hit the ground more than I liked - I used to pull the system off driving through the channel tunnel train on the small protusion between carriages!
I eventually took my car to a local spring specialist. He looked at the car and then I took the leaf springs off and took them to him. He reprofiled them and retempered them and transformed the car. It looks good and rides well.
I then took the car to a local stainless steel exhaust system manufacturer and discussed with him what I wanted which he achieved. The exhaust has only hit the ground once since this was done about 15 years ago.

All is well.

I don't think (although I will be happy to be proven wrong) that single leaf composite leaf springs are still available, but if they are beware - they will be made for an MGB which has a different weight and a different ride height to a 289 Cobra replica.

David
David Large
Bald surfer with a BRA 289, Porsche 968 Coupe and a Radical PR6!
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