Damaged Chapman Strut

PostPost by: l10tus » Sat Mar 23, 2013 1:57 pm

Information please?

One of the steel octagonal caps on the bottom of my struts has been damaged - (looks like its been damaged by being dragged along the Tarmac, after loosing a rear wheel!)

There's an hole in it and the oil has run out a long time ago.

Question is;-

Do these unscrew from the aluminium casting?

Are they user replaceable?

What's their purpose?

Is the oil just to stop the shocker from rusting?

Which oil is used?

Where can I obtain a replacement?

I think whilst I'm working on the strut, I'll convert to 2.1/4 " springs, was it ever confirmed that the Burton Power or Rally design spring coil over conversion parts were suitable, and sized correctly to fit over the existing Chapman strut tube, etc?

All replies gratefully accepted,

Regards,

Philip.
Philip.

UK '72 Sprint DHC

Sometimes my Lotus makes me cry.
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PostPost by: elanman999 » Sat Mar 23, 2013 4:00 pm

Philip,
Yes they are replaceable. They are a shrink fit in the housing which means you have to heat the housing up and tap the old tube out. Inserting the new tube in is a little easier as with the housing hot and the tube cold (out of the freezer) it slots in.
TTR sell tubes with the threaded part for adjustable spring seat already on. They also sell the rest of the 2.25 spring kit. Not the cheapest but it all fits together. Paul Matty and Sue Miller may also sell the tubes
The oil is to aid heat transfer from the shocker.
Cheers
John
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PostPost by: Bud English » Sat Mar 23, 2013 4:20 pm

Just to clarify, that's not a steel "cap". It's the closed end of the strut tube that John describes above. It extends through the alloy housing.

If that's the only thing wrong with the tube it probably can be repaired by a competent welder once the strut is removed and disassembled.

That's a moot point if you want to replace the whole tube to change over to the adjustable spring set up. The adjustable perches can also be accomplished without having to change the tube. Parts to do that are available to make the changeover either way.
Bud
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PostPost by: l10tus » Sat Mar 23, 2013 8:04 pm

Many thanks for the replies, much appreciated.

I'll be on the phone ASAP, to order the parts.

On the same topic,

Do you know what the recommended 21/4" spring rating is on the rear;- travel distance, unsprung length, and poundage, etc. to replace the original larger springs, on a like for like basis - for normal road use?

What effect does the reduced diameter (21/4" spring) have on the rating, I need to achieve as near original ride, characterisics as possible? Or will this alter the feel?

Regards,

Philip.
Philip.

UK '72 Sprint DHC

Sometimes my Lotus makes me cry.
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PostPost by: ceejay » Sat Mar 23, 2013 10:23 pm

Hi Guys

This is what I have been running on my S2 elan for about twenty
years. It all works like a charm, ride and handling is excellent.

Lotus Elan S1- S4 Rear Spring Data.

Data for your spring manufacturer

Spring OD: 90mm. (3.54?)
Spring ID: 70mm. (2.75?)
Wire Dia: 10mm. (0.393?)
Free Length: 380mm. (14.96?)
Fitted Length: 292mm. (11.496?)
Spring Rate: 78-80Lbs.
Working Coils: 13.

Springs ride on adjustable platforms.

Info courtesy: www.elantrikbits.com
Australia.

Note:
Use the above data in discussion with whoever you choose to wind your coil springs.

Photo of strut below is for illustration only, spring height
has not been set, and nyloc nut on axle has not been torqued.
Attachments
strut-spring-caps-07 copy.jpg and
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PostPost by: l10tus » Sun Mar 24, 2013 8:48 pm

Super reply thanks, just the info I needed!

Regards,

Philip.
Philip.

UK '72 Sprint DHC

Sometimes my Lotus makes me cry.
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PostPost by: ceejay » Sun Mar 24, 2013 9:01 pm

My pleasure, glad to be able to help you Phil.
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