CSR ride height help (for CC Bilstein 'race' suspension)

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vertew
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CSR ride height help (for CC Bilstein 'race' suspension)

Update 01-May-21 >> I've edited the title to include 'race suspension' in case anyone else has this issue, vanishingly rare though it probably is.
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Hi all,

I've had the dampers on my CSR 260 reconditioned and I'm attempting to set the ride height.   I'm aiming for what seem to be the generally recommended settings: 140mm front / 155 rear / 15mm rake.

Adjusting the spring platforms, I've set the front at 140mm no issues.

But ... I've got stuck trying to set the rear ride height as I can't get it higher than about 150mm.

Raising the spring platforms further doesn't seem to increase the ride height.  At these settings, when I rest the car back on its wheels, there's little or no suspension droop/settle.  So, not surprising I can't get it any higher - the suspension is fully extended when up on stands and is hardly compressing when resting on its wheels.

Some other info: the car has caterham 'CSR Race' springs fitted front and rear.  The rear are 300lb rate.  The car is on a flat / level floor.  The pre-adjustment ride height was quite low at the back, around 137mm, so rake would have been close to zero.

So the question is, what ride height / rake should I be aiming for with a CSR 260, with 'race' springs and dampers?

  • Should a CSR 260 with 'race' springs run lower than the usual 140mm/155mm heights?
  • Am I measuring from the right point ... I'm using a point just in front of rear wheel arch, at the edge of the chassis rail and corner of vertical side panel.
  • Something else ?

Pic - my rear ride height measurement location...

Ride  height measurement point.

Any advice on this gratefully received - cheers!
Andrew.

David Brown
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My CSR, I started with getting the sump clearance right as it is primarily a road car by the "rolling a coke can underneath" method. This also results in the lower wishbones and steering track rods being horizontal. My rear sits at 180mm where you are measuring it to give the correct rake. Can't help you with the platforms running out of stroke as I had no problems. Normal dampers usually have several circlip grooves that mean you can adjust the platforms. My car is a Superlight and came fitted with different dampers and I don't know whether it has different grooves or if yours are the same. 

James B
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I can't speak about race springs on a CSR but when I was setting mine up last summer (now sold and enjoying a new life 'sur le continent') I got frustrated about the lack of set-up data for these cars, compared to the S3 where data sheets are to found on every street corner.  I found that some Caterham specialists (no names, no pack drill) were oblivious to the nuances of the CSR and would assume that S3 geo was the way to go.  Err... no!

Anyway, salvation was at hand through Simon Lambert (CTO at Caterham Cars) who helped me with the details below for a CSR with standard springs.  Maybe they will help.

James

vertew
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Hi both + thanks for the responses!

@Dave Brown - yes, I've heard same about horizontal wishbones for correct suspension articulation.  I'll check on the damper stroke and whether this is adjustable for my 'race' dampers and springs. 

@JamesB - thanks v much for that ... yes OEM info is fairly scarce on the CSR.  I've added your info to my own personal CSR wiki on onedrive!

Agh, I was pretty desperate to get my 7 back on the road this weekend with the 'sun' (remember that?) finally appearing in SE England and given quite a long period of dormancy while I did a refurb on the rear suspension and dampers.  Thought I was nearly there, just needing a tweak on the ride height, then another area of complexity opens up.  Deep breath + cup of tea.  All part of the fun.

cheers.

Current: CSR 260 | Silver / Matt Black Stripe
Previous: Roadsport SV 165bhp VVC | Yellow / Green Stripe
Arriving: Toyota GR Yaris Circuit | Scarlet Flare

adrian.britnell
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Hi Andrew

just popped out into the garage and measured mine ..... at your measure point I get 160mm (approx)

Regards Adrian

Toughie
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#3, James,

Thanks for that, James.  I didn't have that, so I'll put it to good use ready for the next time you drive my car.Yes

Alan

Commercial Lead

vertew
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@Adrian - thanks, 160mm would be about right according to settings from James and general advice.  I'm 10mm less than that at the moment.  My rear tyres are nearly toast though, so can probably take off +5mm.

@Toughie / James - re. the settings info, what stood out for me is how little negative camber seems to be recommended for CSRs.  I'm running around -1.5 at the moment, which I think is not unusual for s3/sv cars.  I might try winding camber back a bit.  Of course a lot depends on how the car is being used for, balance for track / road use, etc... 

Yet to find the time to have another go messing around with the spring platforms to get to a reasonable ride height ...

cheers.

Current: CSR 260 | Silver / Matt Black Stripe
Previous: Roadsport SV 165bhp VVC | Yellow / Green Stripe
Arriving: Toyota GR Yaris Circuit | Scarlet Flare

adrian.britnell
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Andrew

have you seen Steve Marsh's web site/page :-

http://www.sjmmarsh.f2s.com/

There is a lot of very useful CSR stuff on there...... including suspension details

Adrian

MarkTheGoose
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Funny I just logged in to post a question about raising the engine in the chassis of my CSR, to stop the sump hitting the ground quite so often, which I'll do in a new post.

A couple of weeks ago, I went down the route of getting all my suspension aligned correctly on a Hunter. My ride height is right at the top end of the settings that James provided above 147mm front, 166mm rear, however, it drops to 145 & 163 when I lower my 80kg into the driver's seat. I decided not to go any lower as I wanted to keep the 18mm rake and the lowest point of the sump is only 75mm off the ground at this ride height.

Got most of the other settings right now, mine was running 2 degrees of camber at the front and only 4 degrees of caster, now set to zero & 5.5 - couldn't get the caster any further, I now have all the washers behind the lower wishbones. I also had toe out at the rear, and it's more stable now that's gone...

Mark, Orange CSR 200, Stack dash

James B
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"I also had toe out at the rear, and it's more stable now that's gone..."

Blimey, I bet it is!  Glad I haven't been your passenger yet!

James

James B
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"@Toughie / James - re. the settings info, what stood out for me is how little negative camber seems to be recommended for CSRs.  I'm running around -1.5 at the moment, which I think is not unusual for s3/sv cars.  I might try winding camber back a bit.  Of course a lot depends on how the car is being used for, balance for track / road use, etc"

Yes, the CSR is a different animal to the S3 or SV.  If you haven't previously seen it, the SV-R development paper by Multimatic provides some interesting insight.  There's a link to a version of it here (there are probably better links to be found, but this one seems to work):

http://fdocuments.in/document/caterham-new-susp.html

James