Lotus Elan

1973 +2 vibration problems

PostPost by: futuresports » Sat Aug 26, 2006 11:23 am

My 1973 +2 130/5 has vibration problems when I drive at speeds +60 mph. It seems as if the vibrations are coming from the prop. shaft ? The car has been totally rebuilt and everything seems as it should, it also has spyder drive shafts. Could it be that at the time the engine gearbox was instaled they forgot to balance the prop.shaft ,or that the shaft was incorectly installed ? The 5 speed gearbox was also rebuilt with new berrings etc ( it does not shift as smoothly as my 1968 +2 4 speed does) I would appreciate if anyone has any tips on what could be the problem. :( :( :(
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PostPost by: sgbooth » Sat Aug 26, 2006 12:55 pm

Might I suggest you search the archives using "vibration" or something similar? You should find plenty of material.

FWIW, I had much the same problem when I first bought my Sprint. On the two occasions I test-drove it prior to buying, the weather was really foul, so I stayed near the legal limit ...... only later did I discover the problem !

Here's what I discovered later, and IIRC, in sequence:

I had little/no vibration through the steering wheel, and therefore decided the problem most likely lay with the engine/gearbox/diff mounts, or the rear axle setup.

Wheels badly out of balance and 20 year old tyres - sorted with new Minilites and Michelin XAS's and vibration much improved.

Car then developed a rear wheel-bearing problem - changed the bearings, and in doing so found that the brake disk run-out was horrendous. Fixed this too, and now the vibration is acceptable but not eliminated.

I also changed all front and rear bushes (including engine, gearbox and diff mounts) to polypropylene (stiffer), and in doing so, made sure the diff was clear of the chassis.

I'm afraid it is a trial and error process, but much can be eliminated by careful inspection.

Again, IIRC, there is a post (on this forum, or elsewhere) giving a 'definitive' guide to sourcing the problem(s). If you need it, let me know, and when I have time I will try to find it for you.

HTH.

Regards,
Stuart.
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PostPost by: elans4dhc » Sat Aug 26, 2006 7:27 pm

Stuart,

Am I reading your response correctly in that you have fitted polypropylene engine, gearbox and diff mountings? If so, from whom did you source these mountings?

Regards,
Andrew
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PostPost by: 1964 S1 » Sat Aug 26, 2006 9:12 pm

Wheel balance and tire quality are critical, changing a set of tires can make an Elan feel like a different automobile altogether. Did your vibration come on suddenly or over a period of time? Remember, these are old cars and we now live in a vibration free auto society now. Some vibes are inherent, but something as simple as motor mount renewals can stop a lot of it. As mentioned, there is a myriad of information concerning this in the archives.
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PostPost by: sgbooth » Sun Aug 27, 2006 7:38 am

Andrew,

You're right to question me. More precisely:

Poly bushes were fitted to front and rear wishbones, front top shock absorbers, diff torque rods, anti-roll bar and drop links.

Uprated mountings were fitted as follows: engine mounts, gearbox and diff top mountings.

All parts from TTR.

Regards,
Stuart.
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PostPost by: wparslow » Fri Sep 01, 2006 1:49 pm

I have a rebuilt +2S 130/5 (Ken Miles rebuild). It has always vibrated so I have replaced - are you ready?:

Engine mounts, all wheel bearings, all wheels, all tyres, propshafts, driveshaft and CVs.

Stil vibrates :)
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PostPost by: john.p.clegg » Fri Sep 01, 2006 3:40 pm

Is your vibration road speed or engine speed related?

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PostPost by: wparslow » Fri Sep 01, 2006 4:37 pm

Road speed related. Annoyingly it starts at around 68mph and goes through to 90, after which I think it calms down a bit as the frequency increases and all the other sensations drown it out a bit.
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PostPost by: john.p.clegg » Fri Sep 01, 2006 7:48 pm

Can the diff cause this?

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PostPost by: wparslow » Fri Sep 01, 2006 10:09 pm

Maybe - but ceryainly not in my case as it's also new.
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PostPost by: sgbooth » Sat Sep 02, 2006 7:12 am

May not be the problem, but perhaps part of it ......... have you checked run-out on the rear discs (I'm assuming rear discs, since you do not mention feeling vibration through the steering wheel)?

The symptoms you describe are almost exactly those that I experienced, and we seem to have replaced much the same items.

Can only say that one of my discs was badly 'out', and that when sorted there was a significant improvement.

Two things led me to this discovery:
a) the car was not that easy to push on a level floor.
b) one rear wheel rim was significantly hotter than the other, after a good run.

Maybe of no help to you, but nevertheless, easy to check.

Regards,
Stuart.
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