Ride height

[p.mole1]

I can't seem to find what the ride height should be for my car. Its handling was terrible and it would dart all over the road, a proper handful on bumpy roads

Its a narrow track pre 96 with a rear anti roll bar and it was about 145mm all round on the drivers side 140mm near side, this was probably due to the fact the K series is canted over towards the near side and the damper bushes were shot.

I will be using the car mainly on the road with a few track days. I have just finished fitting the dampers and have it set 160mm rear and 150mm front and on the softest rear anti roll bar setting.

Does that sound about right?

[Dave J]

it depends on the tyres you are running, a good starting point is to aim for 75mm under the sump ( same as a can of beans) and then raise the rear by 18mm.

[elie boone]

STD setting is 140 mm at the front + 15 mm rake on linear rear springs and 35 mm on progressive rear springs. Then you add 2 turns on the rear driver side to compensate the drivers weight.

[Jonathan Kay]

What sump clearance do you want? Discussion from 2013. Similar to what Dave J says, but I went with:

"Traditional minimum is a free-rolling Coke can: 66mm diameter. Common recommendation for road cars is ≥ 80mm."

Jonathan

[p.mole1]

Thanks,

My car has the shortest dampers fitted by Caterham! so I need to run about 150mm to have any appreciable front suspension travel.My sump clearance is 85mm, I could run lower but I think it probably spoil the handling as I may be bouncing off the bump stops, it would be Ok if wasn't for the Third World road surfaces we have to put up with round here.

I am off round the the Scottish borders for test drive, I hoping for a vast improvement

[Mankee]

As well as ride height, consider front toe in and also raising the steering rack. Toe in can help with stability and raising the steering rack can help prevent bump steer.

[p.mole1]

Hi Thanks,

I set the car with toe in before I fitted the dampers to help with stability it helped.

The car is much improved I could probably drop the front to 145mm if need be.

With dampers set at the recommended damper settings the car is much more stable but a bit harsh so tried turning down the damping, more comfortable but less stable.I would rather have the car set up to under steer till I get used to it although I have not driven it hard enough it seems quite neutral.

Bump steer seems like it could be a problem as softer suspension seems to make it worse.I am sure I read somewhere that early cars had the rack mounted in a less than ideal position, I have seen somebody advertising rose joints to replace track rod ends with the ability to add or remove shims however I wouldn't know what the ideal position would be.

What sort of shim/ spacer thickness is needed to reduce bump steer?

 

[Jonathan Kay]

Can you add a photo from the front showing the angle of the track rods?

Typically 9mm, but also reports of 6mm.

Jonathan

[p.mole1]

That's quite a bit! I will endeavour to add a photo but that might be too much for my feeble computer skills

[p.mole1]

I have just read the articles about bump steer, I am quite surprised I thought these cars wouldn't require this sort of fettling.

I am beginning to think the rose joints would be an easier option it looks like the joint will be nearer to the steering arm which would be the same as raising the rack without having to open out the bodywork.

It looks like the steering arm may have to be drilled? will have to look into it.

[elie boone]

A DD chassis should have 0 degrees 25" +/- 0 degrees 10" toe out

[p.mole1]

I have about 15" toe in I think from memory it was awful with toe out.

I think I come up with an alternative solution to raising the rack it involves fitting a rose joint conversion steering arm from http://www.chv-engineering.com/online-shop then using a rose joint with spacers in place of the track rod end.

The pin may need machining to get the required drop. Another alternative is from compbrakemotorsport but I think this may need the arm drilling and I would prefer to keep the taper.

I am still surprised that the rack has been so poorly positioned that it could need 9mm of spacers! I have tried to upload a photo but have failed miserably 

[Jonathan Kay]

I (or rather Ian) can help with the photo. Do you want to upload it here or link to it on another server? Both are possible.

Forum User Guide

Jonathan

[ECR]

I seem to remember that a degree of bump steer is sometimes deliberately engineered in in order to tune the initial turn into a corner. The downside is lack of stability on a straight. All suspension settings are a compromise ....

[p.mole1]

Hi Jonathan,

Had a go at uploading a photo from my own computer but will not allow me as the file size was too large.

Does anyone know what the thread pitch and size of the tie rod is?

[p.mole1]

I forgot to ask is the front hub Triumph?

[Jonathan Kay]

Does anyone know what the thread pitch and size of the tie rod is?

Here (but I don't know if it's the same on all 7s).

Jonathan

[Jonathan Kay]

Had a go at uploading a photo from my own computer but will not allow me as the file size was too large.

What OS is the computer running?

Jonathan

[p.mole1]

Hi Jonathan,

Don't laugh, Windows Vista, I am not really a computer person!

 

[Jonathan Kay]

I'm sure it's possible to reduce the image size simply, but I don't know how either...

Jonathan

[Grandmaster Flatcap]

On Windows, Paint (start-> all programs -> accessories -> paint) will resize .BMP, .JPEG simply enough. You can resize by percentage. Make sure you have "maintain aspect ratio" ticked on the popup dialog box.

[p.mole1]

I found that my ride height had had settled and was lower on one side.

I reset the ride heights and fiddled with the damper setting and whet for a blast round the Borders,

Transformed,its like a different car, when I first fitted the dampers they settled quite a bit and the ride heights were all over the place. Bump steer seems to be almost eliminated!