Lotus Elan and Lotus Elan Plus 2 Forums

Her's a theory to explore. Assumption: Your exhaust system is contacting
the body/chassis or your exhaust hanger is damaged/mis-aligned. Rationale:
If this is so, the engine is idling (ticking over) lumpily (rough) and that
movement is causing the exhaust system to bump the body at the rate of
engine "lumpiness". But, while motoring along, the torque action of the
engine moves the exhaust away from its contact point and thus, no noise.

Stan

Subject: [LotusElan.net] Deep vibration at idle problem

Here's hoping someone can point me in th right direction.

Well, I changed the one engine mount on my car that looked damaged in
hopes that this was the cause of the vibration I experienced on the
way home--of course it was not. The vibration is still there. The
only way to describe it is as a deep thumping vibration that feels
like it is coming from under the seat. When I rev the engine it goes
away and this was the case when I was driving home when it originally
ocurred. At speed it was driving about normal, but at idle something
is definately not right.

It has me and my mechanic friend a bit stumped. Anyone have an idea
of where to look?

David
+2S Helsinki, Finland

Here's hoping someone can point me in th right direction.

Well, I changed the one engine mount on my car that looked damaged in
hopes that this was the cause of the vibration I experienced on the
way home--of course it was not. The vibration is still there. The
only way to describe it is as a deep thumping vibration that feels
like it is coming from under the seat. When I rev the engine it goes
away and this was the case when I was driving home when it originally
ocurred. At speed it was driving about normal, but at idle something
is definately not right.

It has me and my mechanic friend a bit stumped. Anyone have an idea
of where to look?

David
+2S Helsinki, Finland

I would tend to agree. If it was a "bad" low vibration.I would think it
would increase with the increase in RPM. It would then just be faster.



That not being the case.If it is a slow (well.1/4 the speed of a fast
vibration).I would suspect a thrown weight on the flywheel.or a nut coming
loose on the crank(which I doubt),. A faster (double speed of a slow )
would be the cams.and then faster would be like the belts.



I still vote for a muffler rattle..



Tony Vaccaro



_____

From: ***@***.***lto:***@***.*** Behalf
Of Stan Aarhus
Sent: Saturday, September 09, 2006 11:32 AM
To: ***@***.***
Subject: Re: [LotusElan.net] Deep vibration at idle problem



Her's a theory to explore. Assumption: Your exhaust system is contacting
the body/chassis or your exhaust hanger is damaged/mis-aligned. Rationale:
If this is so, the engine is idling (ticking over) lumpily (rough) and that
movement is causing the exhaust system to bump the body at the rate of
engine "lumpiness". But, while motoring along, the torque action of the
engine moves the exhaust away from its contact point and thus, no noise.

Stan

Subject: [LotusElan.net] Deep vibration at idle problem

Thanks Stan--I'm going to look into this tomorrow. It does seem like
a probable cause especially since before coming home the night I had
problem I did "bumb" the bottom on a bad parking lot entry way. I
checked under the car before leaving and didn't see anything and
drove it about 30 minutes before any problems but it can be that there
was something and it just took time to shift into contact.

I'll let you know what I find.

Thanks again for the pointer.

David



--- In ***@***.***, "Stan Aarhus" <saarhus@...> wrote:

Checked out the exhaust system today and didn't find anything that
would be tuoching the chasis even when running. There is still a deep
vibration coming from somewhere but just cannot track down from where.
I'm just stuck as to where to look--something is not right but what
and where I have no idea.

Any other suggestions what to check out? Before this happened I had
planned to pull the engine this winter for a rebuild so unless someone
has some insight, it might have to wait until then.

David


--- In ***@***.***, "david_c_w" <david_c_w@...> wrote:

Check the trans mount. The rubber tends to get soft from the usual Lotus
oil bath and it collapses under load.
Eric
64 S1 comp

David,

No one has mentioned the tranny mount and this would have been my first
guess. If your engine mounts had perished and the gearbox mount was of
the same age, it would have a good chance of being suspect. Also, the
g'box mount brackets have a habit of fracturing, unless they have been
reinforced. I usually weld the crack(s) and then add the reinforcements
to mine.

Roger


would be tuoching the chasis even when running. There is still a deep
vibration coming from somewhere but just cannot track down from where.
I'm just stuck as to where to look--something is not right but what
and where I have no idea.

Any other suggestions what to check out? Before this happened I had
planned to pull the engine this winter for a rebuild so unless someone
has some insight, it might have to wait until then.

David


--- In ***@***.***, "david_c_w" <david_c_w@...> wrote:

David,

Try the u-joint in the drive shaft. It's not easy to remove if that's
the problem but I suspect it might be.

Rod Bean
S1 & S2 Elans

HI Rod,

Just wonderng would the u-joint be vibrating even when not in gear?

Also, how the heck do I get at it to check it?

Still haven't yet had a chance to check the other mounts so those are
also possibilities.

David

--- In ***@***.***, Rod Bean <rodbean@...> wrote:

Tony wrote:



I still vote for a muffler rattle..

Put me in the muffler rattle category. An internal bit would be more
likely to be heard only at low flow rates.

Any potential contact with the body should be easy to confirm and is
dangerous - your car body is cast out of fuel! Fix it now!



-- Doug Nicholls, 54/1822 Ma~

The only way the drive shaft vibration would not be felt is if the car is
not moving...and in neutral. Is is being felt when the car is NOT moving?



I had a very deep vibration on my Elan..tried everything. Got to the point
where I could remove the prop shaft in under 20 minutes. Had it balanced
many times.but it was only when I took it to a new digital balancer..that it
got fixed. It was out of balance.



Tony Vaccaro



_____

From: ***@***.***lto:***@***.*** Behalf
Of david_c_w
Sent: Monday, September 11, 2006 3:33 PM
To: ***@***.***
Subject: [LotusElan.net] Re: Stil no luck--- Deep vibration at idle problem



HI Rod,

Just wonderng would the u-joint be vibrating even when not in gear?

Also, how the heck do I get at it to check it?

Still haven't yet had a chance to check the other mounts so those are
also possibilities.

David

--- In ***@***.*** <mailto:lotuselan%40yahoogroups.com> ps.com, Rod
Bean <rodbean@...> wrote:

Tony,
What are your tips for such quick prop shaft removal?
Thank you,
Greg Tatarian
Elan S4

Tony Vaccaro wrote:

Now?keep in mind two things?this was well over 13 years ago..1992 or so..and
I do have a lift in my garage.



You first remove the 4 bolts holding the prop shaft to the diff flange. You
then take off the tranny mount. You can then jack up the tranny enough to
slide the prop shaft back towards the diff (you have to angle it up to clear
the diff)?enough to get it free from the end of the tranny extension?and
then bring it out the front. That simple. I don?t think that there was any
more to it. I don?t know if I had to remove the starter?but maybe. Don?t
know why you would?but something tells me I did. And then I may be getting
confused on the starter removal with my Seven Crossflow?which I had to
remove to take of the pan the 10 times I did so to weld the pan?It got to be
I could do that in less than ? hour.





Any more help?let me know. If you were near Buffalo?we could do it here.



Tony Vaccaro



_____

From: ***@***.***lto:***@***.*** Behalf
Of Greg Tatarian
Sent: Monday, September 11, 2006 6:32 PM
To: ***@***.***
Subject: Re: [LotusElan.net] Re: Stil no luck--- Deep vibration at idle
problem



Tony,
What are your tips for such quick prop shaft removal?
Thank you,
Greg Tatarian
Elan S4

Tony Vaccaro wrote:

Hi Tony,

Thanks for the reply. Just to clarify the situation with my car is
that the ibration is at its worst when it is in neutral and at idle.
At speed it seems to be about normal. So if I understand correctly,
this does not point to the prop shaft as the car would rightly need to
be moving for this to be a problem.

I guess I am back to looking at the mounts.

David

--- In ***@***.***, "Tony Vaccaro" <tvacc@...> wrote: