PDA

View Full Version : Spitfire Spitfire Mk1 Rear Spring Shape



britishcarfreak
01-06-2004, 06:43 PM
I'm in the process of a full rebuild and have recently removed the rear spring.

I saw in a picture somewhere that it looked almost flat when new.

Can anyone confirm how curved it should be - as in when placed on a flat surface - how high is the mid point compared to the floor?

I figure I should heat treat a few leafs and flatten it out a bit to get tighter lower handling. I am aware though that this may affect rear alignment and hence throw out the handling of the rear.

[ 01-06-2004: Message edited by: britishcarfreak ]</p>

Bob Claffie
01-07-2004, 02:55 PM
BCF: Flattening (dearching) of the rear spring was a standard modification on racing spitfires in years past. I don't see any adverse street handling effects but you WILL see seriously increased tire wear. Stock setting leaves wheels slightly tipped out at the top, I have seen racing cars (my own included) tipped in as much as two inches each! Was a thread here a while back detailing rear spring mods. Bob

piman
01-07-2004, 03:33 PM
Hello Glen,

it is not usual for leaf springs to be flat when uncompressed. If you wish to lower your Spitfire the easier way is to put a spacer between the spring and the frame. I would take care to ensure that the negative camber is not excessive as apart from wearing the tyres as Bob mentioned it does nothing for traction, braking or handling. This is especially relevant if you are planning wide low profile tyres as their potential will be totally wasted.

Alec graemlins/cheers.gif

britishcarfreak
01-09-2004, 09:59 AM
Yep - I've had a block made up from billet aluminium and look forward to fitting it.

The reason I made this post is I was just curious to see if anyone knew what the original curvature of the rear spring was when it left the factory. At the moment it's really curved and I can't work out if it's gone out of shape from sitting for years unused.

Does the rear spring go soft?

piman
01-09-2004, 12:38 PM
Hello Glen,

"Does the rear spring go soft?"

Springs lose some of their rate with use, but not from standing with no load on them.
There is an initial small 'settle' when new but generally they do not weaken significantly even with many years of use. Probably the worst are relatively softly sprung large cars, Jaguars come to mind as settling quite a bit.

Alec graemlins/cheers.gif

[ 01-10-2004: Message edited by: piman ]</p>

Bob Claffie
01-09-2004, 01:55 PM
When I disassembled the rear suspension of my MK2 with about 50K on it the free height of the rear spring was huge. As I recall it was something like 6 or 8 inches. My trick was to insert a second number two leaf UPSIDEDOWN and discard the bottommost leaf. Stack in this manner: ()(((((. Made the rear much stiffer and virtually eliminated wheel tuck except under the most extreme circumstances. Unless the rest of the leaves are dearched it will be very difficult to reassemble this type spring without some serious clamping and accompanying danger. Bob

[ 01-09-2004: Message edited by: Bob Claffie ]</p>

britishcarfreak
01-10-2004, 10:27 PM
My main reason for asking related to stiffness and ride height. I figured that if it was really curved when not on the car then it must be adding to the ride height of the car - hence the acquisition of a custom alloy block to raise the wheels in relation to the body - i.e. lower the car.

Inserting a block is easy when you've got one - and I didn't much fancy the idea of fiddling about modifying the spring with unpredicatble results.

Bob Claffie
01-11-2004, 01:47 AM
Block or no block, if you don't modify the spring the car will continue to corner like a 1959 Volkswagen Beetle with the bottoms of the tires touching in aggressive cornering. Bob