The ends of the springs have been manufactured such that the end coils are touching each other and then the ends are ground to give the spring a flat surface which bears on the spring seat. Cutting the spring would destroy this arrangement.
Modern cars tend not the have this arrangement but have the seat profiles to match the spring. In which case timming the spring would be effective.
Ulf, to put Andy’s reply in different words, the ground flat ends of the springs are critical in keeping the forces in line with the axis of the spring and shock. If you tilt the ends, the shocks will see higher side loads. The springs are also highly stressed and may fail with the extra bending forces. The Plus 2 springs also have a tendancy towards buckling because of the extreme length/diameter ratio. Any tilting of the ends will make this much worse.
Consider getting shocks with adjustable spring seats instead.
I think Mr. Chapman and Mr. Hickman decided that the ride height was fine the way they designed it. I would be very hesitant to try to improve on their work.
“Make the suspension adjustable and they will adjust
it wrong – look what they can do to a Weber carburetor in just a few moments of stupidity with a screwdriver.” Colin Anthony Bruce Chapman
Yes agreed, bear in mind that Chapman acheived his legendary handling with a combination of long travel springs and optimal damping to allow the dampers to achieve as much as possible while providing suspension to keep the geometry as accurate as possible. Not so revolutinary now but in those day, few cars had very good suspension geometry so spring travel was usually restricted giving a hard ride for sports cars.
OK, thanks. Cutting springs is not an option then. As I recently installed TTR shocks in the rear, without adjustable platforms I was hoping for another method of lowering the car. As my tyres are a bit to small, bigger tyres in original dimension will decrease the gap between wheel and body
/Ulf
Ulf, custom springs are not a big deal or very expensive. If you are going for extreme accuracy a shim of say 1cm thickness would help (could be installed later if springs settle a little). Faulkners come to mind as one UK supplier that should be able to help. I’ll check my records and dig out another name.
Bear in mind that you will bear the risk if results are not 100% predictable, but you need to weigh this against replacing you existing new shocks and starting again.
Just a thought, we are talking about the front coil-overs? The rear struts can be modified to allow fitment of 2-1/4" springs and adjustable platforms.
Plus 2 may be different but on my S2 Elan only the front springs have ground flat coils top and bottom, the rear coils are open and unground, so the rears could be cut down without causing seating problems. However, if you cut the springs to reduce height you will increase the spring rate, which is a function of number of coils, and so stiffen the suspension. Worst case scenario would be to cut down rears (or fronts) only, because that would stiffen one end and alter handling balance.
Do be aware the the late Plus 2s had 1" long spacers fitted on the tops of the shocks to limit the amount of “bump” on the suspension. Ride height was then increased to maintain the overall amount of suspension travel.
This I assume was done based on experience and to prevent the cars bottoming out as I believe the early cars were somewhat prone to do.
If you attempt to shorten the springs you could have a problem with the reduced length of suspension travel unless you also remove these spacers. Then you might find you’re back to the car bottoming out on rough roads and speed bumps when it’s fully loaded.
My +2 has adjustable spring platforms and at the moment it is set to MX5 (Miata) height. This is to allow my car to be used every day and not worry unduly about speed humps and the generally rubbish road surfaces we get all over the UK. It does look a little high, but can’t really be compared to a 4X4 as has been put about on these forums before.
Okay it’s a Spyder Zetec conversion but that doesn’t mean you can’t do the same to your original +2. I spent a happy hour on Monday this week lowering my car for a track day in the pit lane at Brands Hatch, apparently there are no speed humps around the circuit, although I did manage to scrape my exhaust a few times whilst hurtling down into the compression at the bottom of Paddock Hill Bend.
The only problem with this is that I have road springs, therefore it doesn’t really make a great deal of difference for handling on a circuit(although it certainly helps), but it really makes the car look great, there have been a lot of comments about Zetec and Spyder chassis cars looking like they ride a little too high and I generally agree with this as being a bit of an aesthetic problem. Unfortunately the exhaust where it exits the manifold at the front on Zetec cars seems to be the main culprit with grounding and i can’t see a real easy solution to this, mind you I remember literally ripping my exhaust off on a car park exit when I had a standard LTC +2 down at Hastings sea front caused by one of those cats claw devices, and yes I had paid!
You are correct in that the Plus 2 also only has the front springs with ends which are ground flat. However, at the rear, the end coils of each spring are wound much tighter than the others, so you still can’t really cut the springs down without affecting how they sit in their associated seats.