Ideal ride heights for 1.8 K on 15inch 195/45 's

[Ralph45]

Any wisdom would be greatly appreciated on a good ride height for my car.

its a 1.8 k with 15 inch rims with 195/45/R15 cr 500's

I currently have 75 mm between my sump and the ground (wet sump) but I have no idea of what I should be looking for in respect of how much rake front to rear measurements from just in front of rear wing to just behind front wishbone.

The car has adjustable Bilsteins front and rear now and any guides to front and rear height would be greatly appreciated.

it currently sits flat front to rear until I know how much to add to the rear ride height.

my intentions are road use only.

[SM25T]

Put equivalent of your weight on driver seat. You want at least 70mm under sump with your weight on seat. Then measure under chassis rails level with back of front cycle wings. Get this level across front. Then measure under chassis rails at front of rear wings .... aim for 15mm above height of front measurements. Do all the measurements with the weight on the seat.

[Ralph45]

Thank you,

And my wife said there was" nothing going on this weekend"......,thanks to you that's all changed,cup of coffee for me while I sit in my best friend as don't have 11 stone of ballast and the boss can run the measurements.

 

[rj]

Unique boss you have 

[SM25T]

I take the seat base cushion out and stand concrete blocks on the floor. It's a bit scary !

[rj]

I use plastic raw material in bags. Every man his tool.

Nothing beats Ralps though.

[Ralph45]

My raw material is a star .... She's put up with me for 35 years.

we've got about 75 under the sump still and have 145 level with rear edge of the cycle wings both o/s and n/s. on the back what we managed taken level with the front of the rear arch is 161 o/s and 162 n/s?...hows that?

we kept re'bouncing it and to be honest it kept varying by a few mm so we took the average after a few goes.

Going back to my racing days we tried to set the sag as best we could by bouncing the car as much as was possible to try and let it settle with just me onboard.......have to say we looked like a pair of pi$$€d chimps dancing in a seven!

I think we have a good result for a cold garage setup?

team work 

[SM25T]

Pretty good for a pair of drunk monkeys.

[rj]

If it does not settle in the same place you have a friction (presumably static) to address somewhere. This could be an excuse to upgrade the suspension.

[Drumster]

That'll be the all important 'safety' upgrade. Therefore financial justification isn't necessary 

[Piers300]

Last year on the way back from the L to B meeting, I hit a large stone. It cracked the sump and the replacement was £430 plus labour to fit. It was an expensive last Blat of the year.

Piers

[7 wonders of the world]

The OE suspension set up has stiction on every single metalastic bush - Spherical joints or Powerflex with eradicate this  

If your running wet sump have you considered making a sump gaurd / skid to dissipate the impact of items such as cats eyes

[Ralph45]

Sorry I'm late back to the thread and no I haven't considered a sump plate /bash guard.

to be honest wouldn't know how to fabricate or quite where or how to install it?

tonight I moved the car around and drove it up and down my drive a few times,when I re-measured the static sag/ ride heights they had all changed so much I'm not sure it's worth worrying about for road use really?

there was as much as 5 mm difference on some of the corners and it was done as accurately as we could get it.

I now have to much rake n/s 21mm and o/s 28 ? Any ideas or advice ?

I did panic a bit and double check the sump and I have 74mm clearance.

[SM25T]

Silly question ... did you have the same weight in the car when you measured yesterday ?

[Ralph45]

Yes and then tried measuring it it roughly the same spot on the garage floor.

[SLR No.77]

It could be worth loosening the wishbone and radius arm bolts and re-torquing them. If they've been torqued up with the car not on the ground, ie. sat on it's own weight on the wheels, they could be adding torsional forces that mess up your settings.

[rj]

Even if there's torsional forces in play the car ought to settle at the same level each time. There has to be static friction somewhere that need to be sorted.

Ralph, has your car "race washers" between wishbones and chassis? If so, are you sure the wishbones move freely? 

It may be worth having the shocks tested; if I were you I'd have a chat with Simon Rogers (raceshocks.uk), but beware that it's easy to be tempted to spend a fortune in his shop. You get what you pay for...

[Ralph45]

I'll have a go at backing off the bolts and re-torquing them to see if it helps.

rj my car doesn't have race washers fitted and I know what you mean about temptation when it comes to boingy bits ....they all ways look so trick the dearer they get  and its that time of year.

[Ralph45]

I've decided that time permitting I'm putting the car up in the air will double check that I do actually have sooth movement on the wishbones etc, drop down then re-torque it,and start again with the ride heights.

as a matter of interest how accurate are the shock mounting holes on a 98 arch chassis?

the reason I ask is if I take a measurement from underneath from the base of the shock collar up to the lower edge of the adjuster if one is wound up or down more than the other side is,per say 10 mm to gain the correct weighted ride height surely that will preload that particular spring or is it normal for one to be wound higher or lower than the opposite side?

[rj]

The unladen corner weights of a K-car are not very equal whereas I found that mine was almost spot on with myself in the car.

I would expect the chassis to be within a couple of mm if not better.