Ray Evans
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| posted on 15/9/09 at 08:15 AM |
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Front Spring Rates Clamshell wings
My car has Caterham Clamshell wings and coil over springs. On full lock there is just 30mm front tyre clearance and this often reduces to nil causing
Wing glassfibre damage. The front has 10.5 in long 185 lb springs compressed by 4 inches stationary.
The ride height reduces by 84mm for 50mm reduction in coil spring length. Any ideas as to the spring rate to keep the wings off the tyres?
 
Rescued attachment Ray with Locost.jpg
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MikeCapon
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| posted on 15/9/09 at 09:18 AM |
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Hello Ray and welcome
Your question is a tricky one with an element of the "How long is a piece of string" within.
My advice would be as follows:
First off, it's not the spring's job to prevent contact between components on bump, or droop for that matter. The shock should be fully
compressed, including the bumpstop, before any contact takes place. So it would seem that either the shock has too much bump travel or the clamshells
are fitted too low.
The best way to figure this one out is to remove the shocks and lower the car until it is at the minimum height you want to see at full bump. Turn the
steering from lock to lock and check for contact. If you have contact you will need to move the clamshells.
With the car at the full bump height now measure between the shock fixings. Compare this with the closed length of the shocks. If the shocks have a
shorter closed length you need to fit a spacer on the rod between the bumpstop and the end fitting to prevent over travel.
Once you've got that all sorted then you can (if you still need to) look at the spring rates.
Good luck,
Mike
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JeffHs
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| posted on 15/9/09 at 10:05 AM |
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I would suggest that you move the clamshells further forwards so that the highest part of the curve is over the wheel centre.
In my opinion, where they are fitted would not pass current British regs (admittedly not an issue in NZ). I think there is insufficient coverage of
the front of the tyre to meet SVA/IVA.
Looking at the pic, it looks like it might be possible to move them as I suggested leaving only the rearmost hole uncovered, so you wouldn't
leave much mess in that very tidy body.
See pic in my archive comparing my installation with Lotus. I suspect the link below won't work
http://locostbuilders.co.uk/upload/Compare 7.jpg
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rgrs
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| posted on 15/9/09 at 10:32 AM |
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try this
[img][/img]
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Bluemoon
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| posted on 15/9/09 at 11:57 AM |
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You need to remove the springs and still fit the dampers then work out where the wheels end up on full bump.. You can then move the shells to suite..
Changing the spring rates is not the answer..
Dan
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nick205
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| posted on 15/9/09 at 12:03 PM |
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Hi Ray and welcome to the forum - nice looking car you have there.
I'd agree with the above comments and suggest moving the clamshells forward to get the clearance you need.
However I suspect (difficult to see in the photo) that leading edge of the clamsheel is already fairly close to the rear of the upper wishbone? I
guess you may need to cut a hole in the clamshell and then refit the wishbone through the clamshell once it's in place.
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britishtrident
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| posted on 16/9/09 at 07:53 AM |
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Fit colars to the rack to restrict steering lock ---- this what Lotus did on several models back in the 1960s.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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Ray Evans
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| posted on 17/9/09 at 10:16 AM |
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Over the hills and far away!
There is was, thinking I was all on my own with no one to talk to who would understand the question I faced, when lo and behold I receive a set of
very helpful, reassuring suggestions that sound like the right solution and stopped me going off in the wrong direction. Life gets good sometimes,
very good. Thanks chaps.
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Ray Evans
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| posted on 22/9/09 at 04:15 AM |
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And There's Another Thing
The wings are supported by Caterham supports. To move the wings forward would require moving the supports forward which are located by means of a
recess in the nose cone so another recess would need to be cut. (see photos).
There was also mention of fitting Landrover bump stops, but I can't see how these would be fitted. Do shocks dismantle (mine are Nitron)
.
 
Rescued attachment P1000553 reduced.JPG
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