Damper modifications...

topcatcustom · Post by **topcatcustom** » Mon Jun 01, 2009 10:36 am

Well after re-fitting the rear subframe into the mazda with sierra cosworth running gear (sounds good now!) I went to put the coil overs back on and the bloody things wont fit, due to the cossy shafts and CV's being fatter than the mazda ones. I think it would all be ok if the bush on the bottom of the dampers were moved over (about 30mm), the top mount flexes so shouldn't be a prob- I cant see it being used round a track anyway- just straight lines! However I am very dubious about welding on the dampers.

The sketch shows what needs doing on the left, I thought I would lower the spring mount by 25mm whilst I was at it as will want it to sit lower and should save me getting shorter springs. To get over the possible problem of welding the damper I thought I could make up a sleeve with a new spring seat on it at the right height and the new mount on the bottom, then literally just put the original damper (with mount and spring seat chopped off) inside, and maybe a couple of small tacks on the top so it is fixed rather than just sitting in there.

Any ideas/thoughts?

TC

kiwicar · Post by **kiwicar** » Mon Jun 01, 2009 11:28 am

Personally I would modify the mount to get the same effect (if you can), make a new mounting bracket 30mm longer that also lowers the bottom of the shock by the amount you want. otherwise if you need to replace the shock you have to modify it first. Also I really don't like the idea of choping and welding somthing that has momentry pressurs as high as a shock.
Mike

topcatcustom · Post by **topcatcustom** » Tue Jun 02, 2009 1:07 pm

Think I'm going to try and make up a socket (like on the right) that the damper can just slide into, then maybe put a grub screw near the top to nip it up so sits in there nicely.

I assume the standard dampers are oil filled- are they under much pressure? I thought they were basically like a hydraulic ram but with holes in the internal seal (on the inside end of the rod) to stop the rod moving up and down too quickly!

TC

kiwicar · Post by **kiwicar** » Tue Jun 02, 2009 2:06 pm

topcatproduction wrote:Think I'm going to try and make up a socket (like on the right) that the damper can just slide into, then maybe put a grub screw near the top to nip it up so sits in there nicely.

I assume the standard dampers are oil filled- are they under much pressure? I thought they were basically like a hydraulic ram but with holes in the internal seal (on the inside end of the rod) to stop the rod moving up and down too quickly!

TC

they are an oil filled tube with a plunger in and often a volume of compressed nitrogen above to prevent foaming of the damping medum. However when your car hits a bump that oil is effectivly stopping the wheel from going up through the top of the wing, it does it by forcing the oil to pass through very small holes in the piston (yes I know I am telling my granny to suck eggs) think of the necessary pressure to force half a litre of 20/ 50 through 4 X 1mm holes in under half a second and back again, the transiant pressures are BIG

Mike

topcatcustom · Post by **topcatcustom** » Thu Jun 11, 2009 9:28 pm

This is driving me a bit crazy, cut out the old lower coil over mounts and fabricated new ones, have tacked them in place about 30mm behind the originals, and about 10mm higher, now the subframe does not want to go in- the springs seem about 3" too long!!!! Will have to keep trying with a fresh head on saturday, and a couple of ratchet straps! Thought springs were easier to get in and out- shouldn't have to drop out a whole subframe to change them surely?!

topcatcustom · Post by **topcatcustom** » Sat Jun 13, 2009 6:08 pm

Done- phew. That has to be the worst bit of the build out of the way! Ended up cutting the springs by 40mm which worked out well as they locate perfectly in the cups at a slight angle which everything is now set at.

Using cosworth running gear has ended up causing me a few headaches... well, at least they shouldn't break!!!

Over and out.
TC