Guide: Coilover Conversion

[BradW]

This may be a dumb question or it may have been answered in another thread so if it has I apoligise but here goes.
Instead of cutting the struts to shorten them, is it feasible to leave the struts the standard length and take up the space left by the short stroke shocks with spacers. Now I realise if you use steel spacers you are adding to the unsprung weight so would alloy spacers be suitable. Would there be a huge amount of force on them from the shock ( I don't think there would as the spring is taking all the weight of the car and the spacer would be there to just keep the shock from moving up and down in the strut). Are there advantages to having shorter struts over standard length ( I'm talking strut bodies not shock stroke) or are they cut to help reduce ride height as well as accomodate the shorter shocks.

Sorry for all the questions but it is something I have been thinking of for a while.

[roadsailing]

if you just use spacers, the shocks will bottom out and the springs will not be captive. if you weren't going to shorten the strut then you wouldn't use short stroke shocks.

a spring might take all of the "weight" of a car, but a shock takes all of the "speed" of a bump.

[c2888]

If you don't go short in the strut body when you use a shorter cartridge, then you will loose shock travel. Imagine that you've put a 60mm spacer in a oem length strut housing and now lower the car, If you go really low (wheels tucked under the guards) you will be sitting on bumpstops, and the cartridge will only ever move in the lower part of it's travel.

You really need some diagrams to illustrate the point, there's a pic floating around the internet showing how this phenomenon works. google up short stroke club4ag.

And if you don't have a friend/family member to hold the steering wheel, pull the key out again, the steering locking is actually useful for once.

dan

[takai]

Just thought it might be interesting to add some more pictures.
Here is my simple setup, i did exactly the same thing as 45aken, except im using XT130 struts and a Fulcrum collar/nut kit rather than the Noltec one. Also im using T3 upper hats and camber tops.

Here is the strut as it sits with just the tender (helper) spring there:

Now, helper or tender springs can be useful to keep the spring captive. In my case im using 180mm high springs, so they wont normally be captive, as such the tender spring just holds the spring in place when not compressed. Doesnt change suspension geometry or rates at all, due to being 100% compressed when the car is sitting on the wheels.

And this is what is meant by a "normal" upper hat.

Maybe the entire debate about T3 hats and tops should be kept out of this thread for now.

And then completed:


Im using the Tokico HTS102s and using a 50mm shortened strut with a 20mm spacer. Works brilliantly.

Also if you have two rattleguns, or even just one and you want to have some fun with stock struts, you can play the "launching" game when you are removing the springs. *note* i take no responsiblity if you hurt yourself doing that.

[BradW]

Thanks for the replies guys.
I googled and read the club4ag article. From how I understand it the struts are cut to give the lower ride height without compromising shock travel ( when used with short stroke shocks of course). If the lower ride height was achieved without cutting the strut the shocks can bottom out.
The amount that the struts are shortened is then determined by the ride height you are trying to achieve and the shock travel needs to be matched to the spring travel, correct?

[phrostbyte]

Also if you have two rattleguns, or even just one and you want to have some fun with stock struts, you can play the "launching" game when you are removing the springs. *note* i take no responsiblity if you hurt yourself doing that.

Hahah, reminds me of one of the times I pulled apart an RA28 strut. Launched the top hat at a concrete wall, Took one hell of a chunk out of it

Kev.

[45aken]

never done that before, but trust me-cuttin springs with an angle grinder while there compressed in the strut is not as safe at it sounds after a few beers....

[Julz01]

Just to revive a dead thread would a 64mm spring be ok to use with the coilover conversion or will it depend on how thick the spring seat is? Ive gotten some coilover struts coming from an importer but unsure as to what spec they are? looking at getting some HSD springs.

[roadsailing]

64mm ID spring will be fine on a 63mm perch, will probably even fit on a 65mm perch.

are you sure its 64mm? id take the spring to a suspension joint and ask to fit it on some perches, or just buy 63mm perches and be happy.

my perches are 63mm (so i could use 63mm or 65mm springs) and im using 65mm ID springs. they are slightly loose when you jack the car up, but this causes zero problems.