S3 Suspension & ride height

[UAB807F]

Hi folks.

I'm having a senior moment and could do with some advice, comments or even just sympathy would do

Ok, I've started to fit new suspension to my S3, comprising of Kelsport Fast Road springs & dampers all round. I'm doing the front now because I thought it would be a cinch.... well that was Friday and now I'm not so sure.

I photographed the front before starting and include the pics for comment. I'd always thought the front rode high, but it was genuine Lotus spring/damper/bushes and not adjustable, so I'd assumed it was right. Since reading the other threads here, looking at the manual and starting this project I've gone more towards the "horizontal wishbone" concept. The first pic shows the car unladen, but even with someone in the car the wishbones stayed in a similar inclination so I thought with Pat's new kit, this would be easy.



I've read the manual & it refers to using 15.5cm wooden blocks to set the height of the front wishbones, so I made some. I left the roll bar loose & set the platform height to the block height which more or less puts the wishbones horizontal (checked with spirit level on each side)

But the manual also refers to a ground clearance of 6", and this is where my first question comes in. If you set the wishbone height to 15.5cm laden as in the second pic, then it's not possible to get 6" clearance. So how does this work ? Is it wrong data and if so, which is wrong, the 15.5cm block or 6" (15.2cm) ground clearance ?



I'm thinking I should set it up for horizontal wishbones when laden but this won't give me the stated ground clearance. What do you guys do; 15.5cm to the wishbone bush, 6" ground clearance or just set the wishbones horizontal and disregard the rest ?



The third shot shows wheel arch clearances before & after. I'm aware of the problems with this approach, body mounting issues and the like, but it does look significantly tighter now. Is this how your cars look ?

Finally damper settings. I've set to half way on both front & rears as a start point. It's just a road car, does this sound right, too hard or too soft for the 2 seater Elan ?

TIA, Brian

[billwill]

Is that a Lotus chassis? In the photos the vacuum crossmember looks rounded and appears to have a drain-plug.

If it is non-lotus the requirements may be different.

[collins_dan]

Go with horizontal wish bones, then measure height front and rear and make sure they are the same. If front is lower, the handling gets heavy. Front fender clearance looks fine, but try a full lock rising turn ver carefully and check in that position as that is where the trouble will be, if any. If tires are different size than original, then shop manual recommendation will be off. Cheers, Dan

[UAB807F]

Thanks for your comments guys, it's appreciated.

Bill, it's an old style Spyder chassis which has a tubular cross member. I'm not so bothered about the drain plug affecting the ground clearance, it was the cross member base.

As it stands, if the wishbone eye is 15.5cm then there's no way ground clearances can be the same, as you can see in the shots there must be an inch of metal below the bottom of the wishbone eye. The senior moment bit comes in because I can't remember if the OEM lotus chassis was different and the base of the wishbone aligns with the base of the cross member ?

Dan, the tyres are 155/80 vs 145/80 as standard but I'd gone to the tyre calculator on the net to find the allowances I'd need to make. It's not much really, but even taking them into consideration I can't meet all the settings in the manual.

I took it round the block today to settle everything in, a quick check underneath gave no indications of rubbing but as yet I haven't gone over the measurements again to see if anything's moved.

Thanks again folks, any more ideas just chip in please, it's all appreciated.

Brian

[Galwaylotus]

With different tyres, new vs old bushings, etc., etc., etc., I wouldn't worry about the ground clearance. What's important is the suspension geometry and The factory shop manual, Section C, Page 5, Fig. 1 shows the lower front suspension arms horizontal. That's what they should be with the suspension settled, i.e. normal weight and rolling the car back and forth.

[billwill]

This photo from when I repaired my turrets, shows the position of the bottom suspension pin relative to the bottom of the cross member on a standard Lotus Chassis.




I seem to remember that there is a very good diagram in the workshop manual, but mine is not on hand.

[Galwaylotus]

After nearly a year on jack stands - Progress!

I know there's still a lot of work to do (suspension setup, carburation, etc.) but at least I got it back on four wheels and the engine ran after just a few attempts. The fine weather helped in the latter I'm sure!!

[UAB807F]

Thanks for the picture Bill, it looks like the pin is closer to the bottom of the cross member than it is on my chassis.

I know the workshop manual diagram you're on about, it is very helpful with measurements for the overall spring/damper lengths at droop/normal & bump height. I can get the dimension for normal ride height with horizontal wishbones and on reflection I think I'm going to go with that.

As an aside, I bought a cheap laminator the other day, scanned in those diagrams for front & rear suspension & marked them up with notes from the manual then laminated them in plastic. It's quite handy having a single sheet that's wipe-clean to work alongside.

Brian

[Galwaylotus]

Ok, folks. I just checked my front suspension after fitting new polyurethane bushings at the upper and lower spring/damper mounts. They're riding high and short of shaving the bushings I can't see how to lower them to bring the lower arms horizontal. I haven't checked the manual yet but does anyone have any ideas? The car is on a slope (see two posts previous) so I can't measure how far off horizontal they are yet but it's very noticeable. Might get a photo later.

[Galwaylotus]

Just thought ... I haven't rolled the car backward and forward much so that may contribute but probably doesn't take out all the rise.

Here are the photos. The car is altogether - no missing mass!

[UAB807F]

That's pretty much what mine was like with the OEM dampers/springs. As you've just fitted new bushes I'd be tempted to run it round the block and then up and down the drive with everything slackened off to see how much it moves.

Other than slicing the top bush in half I can't see what else you can do, in true Chapman tradition there's nothing you can adjust is there ?
Brian

[gjz30075]

Did you tighten the bushings with the car on the jackstands, ie, full droop?

[Galwaylotus]

Did you tighten the bushings with the car on the jackstands, ie, full droop?

The spring/damper mounts - yes - but the suspension arms are still loosely assembled.

[UAB807F]

Hi folks,

Just to wrap up the thread and post the outcome as info for future use. In the end I decided to ignore the ground clearance options and go for the horizontal wishbone theory. This has resulted in less than 6" clearance under the front crossmember but of course I have a Spyder chassis so that may account for it. At the rear, which is OEM design, I do get the clearance specified in the book so again it points to the tubular crossmember as being the problem.

The measurements I used were the "normal ride" measurement given in the manual for the spring/damper assembly lengths and the pin heights as starting points, then adjusted as needed to get horizontal wishbones.

I found this piece of kit very useful and if you've not seen it before, it's certainly worth considering. It's a DIY laser level which produces either a dot or line, comes with a small tripod and 2 spirit levels to set it up accurately. Bought very cheaply off Ebay a year or so ago originally for some tiling DIY.



It doesn't photograph too well in use, but if you have a very good imagination you can just see the red line on the chassis pin and in practice this makes it easy to check the outboard bolts are in the same plane.



I wasn't happy using measurements from the floor because although it's a good level surface it is concrete, so it's rough. Fine for measuring to +/- a few mm, but not for what's required here. I was all set to make a platform then I remembered having this level in the toolbox so gave it a whirl and it does work well on both front & rear wishbones.

Brian

[Galwaylotus]

Ok. I drove it around a bit (two trips - maybe 8-10 miles total) and the suspension settled a little but still not level. I then tightened the attaching nuts and bolts per the factory torque specs. With the car loading the suspension it's a bear to get the rear upper inner links torqued. I had to guesstimate as my torque spanner and socket wouldn't fit into the gap between fibreglass and nut!
The two photos were taken at the same time - just with wider zoom on one.