Bilstein - Coilover Conversion

[Mr. Untouchable]

looking good, I have a mate who has machined the bushes for me, just need to order the ISC tops.

good work djr

[simpletool]

Wow, glad someone ran with this. Nice work!

After finding out I had my first baby on the way this fell by the wayside.

After a lot of measuring I was going to use the 10" front spring (275lb/5kg) while using the Bilstein sleeves but turned upside down (like on the USA Supra forums). The sleeves then hang down off the circlip. I was planning to use another circlip below the top one to centre the sleeves, so they don't flop about at all (although the Supra guys don't seem to worry about it).

The Bilstein sleeves are required to be cut to slip over, but they are cheap and quality.

For the rear I was going to use 10" and 4.5kg/mm (250lb).

I went the Tein s-tech mediums instead and they are pretty good actually, noticeably firmer than the Kings.

[djr81]

Couple photos of the installed rears - just for the sake of completing the thread a little. You may want to mount the thread a little lower than shown. The shot with three dampers shows a stocker next to the one fitted with a sleeve.

Other shot is the bushes for the strut tops & the plates I had made that fit above the bump stop - I didnt use the ones ISC sent.

[Mr. Untouchable]

djr81,

quick question mate regarding the ISC strut tops, got mine today, and had a mate spin up some bushes ages ago from your diamensions, 15x10x32. just looked at the tops, before I go bashing away, did you tap the factory ISC 12mm ID bushes out and put yours in? or did yours come 15MM ID and just slipped yours in? cheers mate

[Mr. Untouchable]

all good, answered my own question, bit of WD40 down around the factory bush and away she went.

cheers

[djr81]

I just bashed mine through with the new bush and a soft hammer.

They pull up and align anyway when you tension the nut on the damper.

[Mr. Untouchable]

only got around to fitting the fronts ATM, but much better setup that standard tops, more travel - have yet to measure. very happy so far

[djr81]

only got around to fitting the fronts ATM, but much better setup that standard tops, more travel - have yet to measure. very happy so far

I changed my spring rates again as I wasnt totally happy with what I had. Went up another 25lb in rate front & rear.

The setup is such a massive improvement over how it was with the Nissan tops it just isnt funny.

I think I got about 30mm extra shock travel front & rear although the rears werent critical.

[Mr. Untouchable]

good to hear.

I have got the rears fitted up now too. Yeah same have yet to measure BUT, i'd say ive gone from about 70mm or so in the front to atleast 100. same for me, gained in the rear but wasnt that big of a factor. still havent had a chance to take it for a run and wont for another month or 2 but def worth the $400 or so to do it.

[simpletool]

I'm doing the front struts for now. Parts are being collected. Currently have Tein S-tech (medium) springs. ~4.1kg/mm front, 4.4kg/mm rear. Going to keep the 4.4kg rear Tein S-tech spring in the rear.

Have the ISC strut tops. Getting sleeves and springs sent. I done quite a few calculations and I think I can squeeze in a 10" 275lb front spring.

[simpletool]

OK so I finally completed the fronts on my R33 GTST. It was VERY easy to do once I had all the parts. I converted the original SK Bilstein shocks to coilovers with 5kg/mm springs.

Parts:

2 x Front strut tops to suit 2.5" spring (I used ISC R33 rubber mount strut tops)

2 x sleeves to suit bilstein shock (I used A1 racing, pn A1-12451)

2 x 2.5" lower perch to suit sleeves (I used A1 racing, pn A1-12460)

2 x 2.5" ID, 10" length springs 275 lb/inch (I used Hypercoils for $60 each)

2 x 10mm ID hardened steel washers (thick). One for under the strut top, one for on top of the strut top.

I got the sleeves, perch and springs from the USA and they shipped in a large flat rate US postal box ($60). I would have liked to go local but not for 220% of the cost.

Install:

You simply remove the strut top, take out the spring and perch and clean the shock body. Then place the circlip on the BOTTOM GROOVE. The slide on the sleeve with the internal square edge lip facing down. See the inner ridge in the pic.

This positions the sleeve very nicely about 3mm above the brake line bracket - pink circle.

This shows the sleeve and bottom perch before sliding over the circlip.

Then you put the strut top on and assemble. The bottom perch is positioned 11 turns up from the bottom (counting the top of the ridges on the sleeve). This gives a wheel to guard height of 345mm (recommended).

Installed on the car.

NOTE:

1. The strut tops from ISC have an inner diameter of 12mm as noted in previous posts. The bilstein is 10mm diameter. You will need to find a suitable reducer for this to mount properly.

2. Bump stops - I previously had a combo of 1 x superpro bush and cut-down SK/pedders bump stop. Since the ISC strut tops add another 30mm of bump travel (and reduce droop by the same amount) I added another polybush to space down the bump stops. This poly bush was ~20mm long which is what I wanted (I wanted to add another 10mm to the travel before hitting the bump stops as the previous ones were a bit too quick to touch). You might be able to see the 2 x poly bushes and the old foam bump stop in this pic. It worked well for me previously and adding a 2nd poly bush like that should help make them even more compliant. This gives me ~40mm of bump travel before the shock touches the foam bump stop at 345mm height.

This is them installed, you can see the old foam bump stop just slides around. You can also see the 1 x hardened steel washer (10mm ID) that I put under the washer supplied by ISC (12 mm ID), there is also another on-top of the strut top below the nylon lock-nut.

Ride/Feel:

With the 5kg/mm springs and ISC strut tops the ride is amazingly compliant. It doesn't feel any harsher than the 4.1kg/mm Tein springs I took out. However the front is definitely firmer when cornering and the balance of the car has shifted more towards neutral from oversteer.

Ride Height:

At 345mm height the spring is pre-compressed ~15mm at rest, then further compressed 60mm with the weight of the car. This gives 60mm droop travel for this combo, stock is ~80mm droop (limited by suspension arm movement - as the shock goes 90mm). Therefore with a 10" 275lb spring you could go down to 335mm ride height and have ~5mm pre-compression so the spring is trapped. Alternatively you go all the way up to and over stock ride height as the sleeves have plenty of thread left.

Edited August 10, 2012 by simpletool