Ride heights

[Gmg31]

Having been on axle stands for most of the last 12 months each corner of my car is at a jounty angle. Could members please suggest to me some measurements from wheel arch to wheel centre. I’ll have it professionally set up later but for now I just need a basic set up so she doesn’t look drunk.

[Stuleslie]

I’ve measured 30cm front and 31.5 rear. Wheel centre to arch. The setup Richard told me for a TC is 6in clearance at front chassis closing plate then what ever the front wheel arch height is add 1/2in to rear wheel arch.
Stuart

[EuropaTC]

Personally I'd wait a bit before doing anything, you've got a fresh rebuild and it'll settle down after a few drives. Yours is an S2 so although I've got lots of detail in my measurements, they aren't transferable to your car. But one thing you might look at is the data from the road tests which does give some detail on various heights you can measure.

Personally I'm reluctant to rely on body measurements. Firstly I don't have great confidence in the accuracy of Lotus mouldings and secondly you're assuming you have it perfectly settled on the chassis. I tend to take numbers of the chassis and hard points myself, but the road tests do give a reasonable starter

Brian

 

[Clifton]

6in clearance at front chassis closing plate

What is the chassis closing plate? Frame or body?

[Lotuswins]

Ah, ride heights, that old dilemma.

IIRC, its based on pivot points....front is to have lower a-arm outside pivot point at or above lower a-arm inner pivot point. 

For the rear, some like the lower links level/parallel to ground level, but personally, I've found that induced a vibration in the rear when I had a passenger, so I've found having the drive shafts level/parallel to the ground a better option. 

This way its independent of tire OD or selected measurement points on the frame or body. 

Jerry Rude
4005R

[Stuleslie]

“What is the chassis closing plate? Frame or body?”

The closing plate attaches between the front of the chassis and the body, underneath the steering rack.

Sorry Gmg31, I assumed you had a TC so my measurements are redundant.

[EuropaTC]

6in clearance at front chassis closing plate

What is the chassis closing plate? Frame or body?

The closing plate is the metal sheet between the front of the chassis (the "T" area) and the fibreglass section where the radiator and front wheel go.  I use the ground clearance at the junction of the T on the chassis as one of my datum points and mine's 6" or maybe a touch lower.  That gives a centreline between the  inner and outer lower wishbone bolts as pretty much horizontal.

Brian

[Gmg31]

I got round to fitting my new suspension today and I’m a bit confused.  When I finished the restoration my rear right hand side was way lower  than the rear left, a good 10 cm lower on the right.  I assumed it was the 50 year old Spax so I ordered some lovely new Protech.  I set everything the same and once I had finished I was amazed to see exactly the same problem this afternoon.  Clearly the new stuff is easy to adjust so I adjusted the Right hand side to level the rear but in order to achieve this the adjusting ring on the right had to be 6cmhigher than the ring on the left.  But surely my right rear spring is now under more load that the left so the car will be out of balance.  Really puzzled why one side sits higher than the other. 

[GavinT]

Don't know the answer but 60mm sounds like too much.

I'd start by measuring the chassis to ensure the front is parallel with the rear.
In my mind I'm thinking about possible accident damage has skewed the rear damper mounting point on one side.

EDIT to add:

It occurs to me it could be as simple as two different rear springs.
In any event, I think this is a process of eliminate thing so measurements need to be taken.

[buzzer]

Presume during your rebuild you checked the chassis for trueness. 60cm is a lot.  And check your front set up and if you’re using std bushes that they are all free and haven’t been tightened up as that would cause this type of issue.

[Gmg31]

10cm. Not 60cm.  Still a lot but a bit more manageable.  Yes the chassis was stripped down and measured and checked in every way.   New springs with the dampers. 

[jbcollier]

Hard to diagnose over the phone.  I set my springs to the same installed height on either side and set the ride height off the bumpers.  Everything was level side to side.

Don’t lift, support, pry or what-have-you in the middle of the rear lower tubular arms. They bend very easily.

[BobW]

Repeating the point that the car will often look cockeyed after you take it down off stands. I wouldn't make any adjustments before driving a couple of miles first.

[EuropaTC]

When I finished the restoration my rear right hand side was way lower  than the rear left, a good 10 cm lower on the right.

and

I adjusted the Right hand side to level the rear but in order to achieve this the adjusting ring on the right had to be 6 cm higher than the ring on the left.  But surely my right rear spring is now under more load that the left so the car will be out of balance.  Really puzzled why one side sits higher than the other.

To get my head around this, where are you measuring your original 10cm from, the body wheel arch centre, underneath the sill at the front of the wheel arch or from some point on the chassis ? Being old school and mentally converting that to inches, it sounds a heck of a lot out to me even if the body wasn't mounted squarely on the chassis.  If the chassis was 10cm out on the chassis legs where the damper crossmember bracket mounts then I think it would be very obvious and probably wouldn't go together easily.

The second point, again, 6cm difference again comes to me as a lot. My kit is the same as yours with just different spring rates and the difference side to side is very little. When I adjusted mine I would roll the car back & forwards to settle it between checks. Then I'd drive it round the block and do it all again because they do change a bit after you've driven them on our bumpy roads.

Going back to the 6cm thing, how much additional load you have there depends on what the free length of the spring is to start with. When I was researching my springs I found a survey from Phil Ethier (Yahoo group) for the S2 which gave a lot of detail. I've attached a screenshot here and you can see that if you have standard springs then according to his data you have roughly 400lbs static and helpfully he gives plenty of dimensions you can check against.   

If you've ramped up one side by another 6cm and still got the same overall damper mount dimensions (bush to bush centres) there's going to be something like 180lbs extra on one side (75lbs/inch compression rate). That sounds a lot to me and it's beyond my experience/reasoning.

If there's no obvious physical reason for the disparity (bent chassis/crossmember damper mountings/etc) then I'd start with the springs. You can calculate the approx rate from the formula in the second attachment and should be able to get the dimensions with a digital vernier without dismantling the assembly. I can't see how on earth you'd get a mismatched pair of springs but I'd want to rule it out before going further.

Any chance of a photo of the suspension from underneath when it's on it's wheels ? 

[surfguitar58]

Are we saying 10cm when we mean 10mm? 10cm is 4 inches, and pretty hard to fathom.