Lotus Elan

Final drive noise

PostPost by: zeca » Fri Dec 18, 2015 12:41 pm

I install in my Elan S4 the TTR 3 bolt drive shafts, LSD, new lower diff bushes and top mounts. Everything seems ok when I ride straight foward, but in slow corners (or starting in first gear cornering) I hear o knock knock sound on the rear. The video is when car is cornering left almost stoped in first gear:

https://www.youtube.com/watch?v=c3xP76D ... e=youtu.be
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PostPost by: david.g.chapman » Fri Dec 18, 2015 1:27 pm

Hi Zeca,

The U-tube video was a good idea - so much better than trying to explain...

I has a similar sound when starting off from rest a few years ago. That turned out to be a broken diff mount - the ones above the diff then fit into the chassis. There was a crack from the centre hole in the mounting plate of the mount assembly.

Other things it could be:

1. Torque rods not tightened up, or missing rubber bush components.
2. Loose diff mounts (apart from them being broken).
3. Diff mounted too close to the chassis. Check that there is a few mm at least between the diff and any part of the chassis or other metallic item. Give the diff a tug in all directions, and check for a firm mounting position.
4. Have a look at the other items in your rear suspension and drive train. Check for security (tightness) and
clearance.

I am sure others will chip in as well.

Good luck!

Dave Chapman.
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PostPost by: patrics » Sun Jan 03, 2016 10:59 am

Hi Zeca,
I have had similar noise my car the two things I found wrong were

Diff torque rod bush - to check disconnect from chassis and pull rod backward and forward - I had play in mine with new bushes and torqued correctly. Turned out that bush supplied was wrong length.

Also check that the rear damper / shock absorber is fully tightened in to the housing - they do come loose.

Regards
Steve
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PostPost by: Lyn7 » Sun Jan 03, 2016 1:14 pm

Hi Zeca, I notice you have a LSD fitted. If it is a plate type maybe a Salsbury the plates can sound with a loud click when cornering. This is more noticeable when moving slowly and quietly. :D
Lyn...
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PostPost by: zeca » Tue Jan 05, 2016 6:40 pm

the LSD is a Kelvedon "with 30 pound of preload and a 40/90 balance on the ramps for a very progressive response that suits an elan"

I think it?s not a diff problem... or it?s a wishbone bush, damper/shock absorber loose...

top diff mounts and lower are new, everything is tightened... TTR drive shafts are like new.

have to wait for the weekend to check it out... again!! :(
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