Lotus Elan

Ride Height (again)

PostPost by: vincereynard » Tue Apr 24, 2018 11:29 am

Toad is far too twitchy on long down hills. I have a set of adjustables supplied by my old mates Spyder but before I fit them I would like to check the front / rear and side to side ride height as I'm told having the rear to high also increases instability (and reduces castor I imagine.)

Before I consider cheating by filling the tank and put a couple of bags of sand in the boot, to see if it makes any difference, is there any general data / recommendations for wheel centre to wheel opening lip for a S130?

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PostPost by: JonB » Tue Apr 24, 2018 5:35 pm

The measurement is normally done from the front crossmember to the ground and I guess assumes you have 80 profile tyres. Another rough check is to see if your lower front wishbones are horizontal.

I have a measurement you can take between the shock absorber top and bottom that Wiggy gave me but it's at home. I'll post it later.
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PostPost by: JonB » Tue Apr 24, 2018 5:51 pm

Found it.

JonB wrote:Regarding getting the ride height correct, that is what the guy at Spider said but my car does not have the facility to adjust it. However, measuring it would perhaps help diagnosis (not tried it yet, but we're looking for 13.5" from the front lower shock absorber bolt to the bottom of the upper suspension mount plate, apparently).


That's on the Spyder chassis with standard suspension arms.
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PostPost by: Foxie » Tue Apr 24, 2018 11:33 pm

JonB wrote:Found it.

JonB wrote:Regarding getting the ride height correct, that is what the guy at Spider said but my car does not have the facility to adjust it. However, measuring it would perhaps help diagnosis (not tried it yet, but we're looking for 13.5" from the front lower shock absorber bolt to the bottom of the upper suspension mount plate, apparently).


That's on the Spyder chassis with standard suspension arms.


I have a Spyder +2 chassis with adjustable spring perches/ride height. I set the sills at 5.5" with driver load up. It works good.

I went over to Spyder to see the original Zetec prototype. As I remember, the Spyder Zetec needs quite bit more ride height because the Zetec exhaust runs under the starter and needs extra ground clearance.

The main reason I never went Zetec :o
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PostPost by: vincereynard » Wed Apr 25, 2018 8:37 am

Jon
Spyder suggest 13.5 " from the damper pivot to the underneath of the front tower. (bottom of the upper suspension mount plate.) Is that correct.

Foxie
Toad has Spyder double wishbone rear suspenders. I'm not sure if they have adjustable spring platforms.
At the moment it was set up by Spyder so each corner is a different height. :?
Doesn't 5.5" at the cills leave the exhaust very close to ground?
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PostPost by: JonB » Wed Apr 25, 2018 9:48 am

vincereynard wrote:Jon
Spyder suggest 13.5 " from the damper pivot to the underneath of the front tower. (bottom of the upper suspension mount plate.) Is that correct.


Yes, that's my understanding, but I have yet to measure it on my car. My lower arms are horizontal, pretty much, and so I attribute my low ride height to the 70 profile tyres I have (fitted by the PO, too new to discard!).

I do not believe I have 5.5" at the sills, by the way (if by that you mean the lower edge of the body between the wheels, where the strengthener bolts are). Happy to measure it though.
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PostPost by: Spyder fan » Fri Apr 27, 2018 3:20 pm

Foxie wrote:
I went over to Spyder to see the original Zetec prototype. As I remember, the Spyder Zetec needs quite bit more ride height because the Zetec exhaust runs under the starter and needs extra ground clearance.

The main reason I never went Zetec :o


After much head scratching I cured the Zetec exhaust manifold problem. On the prototype car the gearbox was an MT75 cable clutch gearbox that has the starter motor on the exhaust side which is opposite to the 4 speed gearbox. So the design of the exhaust manifold routed much lower and further forward actually passing under the ARB, the perfect sort of position to ground out and send sparks flying on any average bumpy road. Absolute murder on speed humps. The cure is to have a hydraulic clutch MT75 gearbox which puts the starter motor where it should be on the inlet side of the engine, luckily I had one of these boxes fitted, but Spyder still used the old design manifold. I bought a new manifold from Paul Dunnel that was based upon John Pelly’s design for his Zetec Elan, the result is a car that can run as low as the spring perches will allow and no grimaces when you go over the bumps, looks good as well!
6b6d9f42-0765-496a-a887-48d6bf1af43c.jpeg and
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PostPost by: Spyder fan » Fri Apr 27, 2018 3:26 pm

vincereynard wrote:Jon
Spyder suggest 13.5 " from the damper pivot to the underneath of the front tower. (bottom of the upper suspension mount plate.) Is that correct.

Foxie
Toad has Spyder double wishbone rear suspenders. I'm not sure if they have adjustable spring platforms.
At the moment it was set up by Spyder so each corner is a different height. :?
Doesn't 5.5" at the cills leave the exhaust very close to ground?


Vince,
I’m pretty sure your car has adjustable coil overs on the rear, I seem to remember seeing it up on the ramps at Spyder, no reason why the fronts won’t be the same. The quality of the springs seems to be questionable these days, they do seem to settle unevenly. Ground clearance is meant to be around 4 inches, so 5 inches at the sills doesn’t sound too low.
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PostPost by: JonB » Fri Apr 27, 2018 4:10 pm

Just to follow up on those measurements. I have:-
  • 13.5" at the front shock absorber (pivot bolt to tpo plate underside)
  • 5.5" between the floor and the bottom edge of the sill (on 70 profile tyres)
That last one surprised me somewhat and yes, my exhaust is very close to the ground but I think this is caused by the engine being slightly down on the exhaust side (which pushes the manifold down) - maybe due to mount rubber failing in the heat, I need to look into it; and the exhaust itself being a very poor fit.
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PostPost by: vincereynard » Fri Apr 27, 2018 4:54 pm

Spyder fan wrote:Vince,
I’m pretty sure your car has adjustable coil overs on the rear, I seem to remember seeing it up on the ramps at Spyder, no reason why the fronts won’t be the same. The quality of the springs seems to be questionable these days, they do seem to settle unevenly. Ground clearance is meant to be around 4 inches, so 5 inches at the sills doesn’t sound too low.


I think you are correct Alan. I checked by the simple procedure of groping about behind the wheel and it definitely feels like a castellated collar something. Hopefully enough adjustment to drop the rear a good bit.

JonB wrote:Just to follow up on those measurements. I have:-

13.5" at the front shock absorber (pivot bolt to tpo plate underside)
5.5" between the floor and the bottom edge of the sill (on 70 profile tyres)


I measured Toad. On the driver side the cill is 6.25", front and rear. Near side is just under 7".
This on 175/70 tyres which are 0.4" smaller radius than original. https://tiresize.com/comparison

So it is riding high, and leaning a bit. It should be tweakable. Then fit the adjustable A arms and orf we go!
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