Lotus Elan

rust hole in damper unit lower spring mounting

PostPost by: bob_rich » Wed Jul 14, 2010 1:05 pm

Hi Folks

On the rebuild have started to clean up the rear suspension parts. I have cleaned up the rear damper assembly all bearings and damper removed. The lower spring mounting has two small corrosion holes just a little smaller than the drain hole that is drilled in the unit. Otherwise the metal looks sound was thinking of just drilling it out (so water could drain) but could fill in the hole with a bit of braze. Picture attached shows the hole. By chance the holes are virtually spaced at 120 degrees. from the existing drilled hole

would welcome comments did not really want to change all of this assembly
car is for road use only not track or racing

picture of one of the holes attached

welcome comments

cheers

Bob
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PostPost by: john.p.clegg » Wed Jul 14, 2010 1:53 pm

...extra drainage..

John :wink:
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PostPost by: oldelanman » Wed Jul 14, 2010 2:51 pm

would welcome comments did not really want to change all of this assembly

Hi Bob,
If they are not serviceable you don't have to change the whole assembly, you can get just the damper tube and spring seat which is pressed into the alloy hub carrier. All the usual suspects do them I think. While you are at it you could go to smaller diameter springs and improve your wheel/tyre options !

Regards,
Roger
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PostPost by: david.g.chapman » Wed Jul 14, 2010 6:24 pm

I had the same thing on my +2 about 8 years ago, on one side only. I found rust on the inside of the spring cup, and after heavy poking with a screwdriver managed to break though the steel to form a couple of small holes 3mm dia.

There then followed a great deal of soul searching as to replacement or not. I ended up fabricating a splint in metal to support the cup, using 1/8th inch steel plate and steel bands around the body of the shock absorber. Spring force would be transmitted directly into the alloy hub casting in the event of cup failure where it meets the tube. See attached sketch.

No, I did not have access to welding equipment.

This bodge (and it is a bodge) will not work unless corrosion is limited to small perforations in the cup (a couple of 3mm holes). The rim of the cup has to be in good shape.

I then derusted the cup. painted it and then filled it with grease after assembly. I replace the grease every 5 years or so and poke a screwdriver though it to keep the drain hole clear. No problems so far!

Dave Chapman.
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PostPost by: kstrutt11 » Fri Jul 16, 2010 3:03 pm

I wouldn't risk it, if it has holed there it will be thin elsewhere and liable to crack.

I woudl repair it by welding in new metal.

Another option would be to fit adjustable spring perches and coil over springs, this allows easy adjustment of corner weights and ride height, a cheaper wider range of springs as well as better clearance for the tyres.
If I remember correctly the strut is the same diameter as a escort front so a kit intended to convert these can be welded on.
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PostPost by: bob_rich » Thu Jul 22, 2010 9:33 am

Hi folks

thanks for the posts. I decided to braze in metal plates over the holes. Brazing get the metal red hot and I have found this tends to highlight any other weak points if the metal is thin the brazing temperature usually holes the metal further. After brazing over small steel plates over the two holes the whole assembly seems sound and vigorous poking around has not shown up any other weak points.

will de-rust and then paint and then grease up in the water trap areas and keep an eye on this during services.

cheers thanks for help

Bob
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