Differential problem ?

[yanni]

First hello to all
I'm not exactly new here but I've been very busy those last 3 years. I
was until this evening very happy with my Elan until I noticed a heavy
noise in the rear.
This came suddenly and to give an idea, I have a huge "clong clong
clong" noise heard only when I'm decelerating with a gear selected.
Something similar as a very loose center lock on a wheel or a very weak
transmission on an ordinary car. Accelerating does not make any suspect
noise, same as when no gear is selected.
This reminds me with an unplesant similar (maybe identical) noise I've
always heard when reversing, this linked with sometimes severe shakes..
I suspect something has gone loose in the dif casing as I have not seen
anything strange, any play in the rotoflexes, propshaft or half shafts
or in the suspension itself. Maybe also a broken bearing ? I have no
unusual oil leak but I have not driven more than 1km since the problem
has started.
I wouldn't swear it's not coming from the gearbox, but I'm 99% sure it
comes from the rear.
Your opinion and personnal advice will be much needed and appreciated.

Yann
7001030021G (Elan S4/SE domestic version Stromberg)
Pau, France

[elansprint71]

Yann Delcan wrote:


Yann,
First thing to do is get your car up in the air and check that rubber
"doughnuts"; differentials are pretty tough pieces of equipment and do
not wear, if well lubricated; doughnuts are not in the same league,
maybe one of yours is beginning to tear? This happened to me and I had
this noise when reversing, sometimes. Other things to check are the 4x
rubber mountings for the differential, if these are worn, or loose, then
you can expect some noise too.
I got rid of the doughnuts by fitting Mick Miller drive-shafts and this
has transformed the car.

Cheers,
Pete

["e s"]

donuts *generally* go without warning and violently:(

I vote for a broken upper diff mount; 2:1 on the passenger side[it is unloaded in reverse]

Number 2 would be very loose torque rods, or beat/missing rubber, again, they are under compression while going forward, tension in reverse.

Diff should be well suspended, shouldn't hardly move with a screwdriver as lever.

Earlier elans sometimes broke the ear clean off the diff housing
Chassis gets weak where the torque rods connect
Park8ng brake stuck



----- Original Message -----
From: "Pete Taylor" <***@***.***>
To: ***@***.***
Subject: Re: [LotusElan.net] Differential problem ?
Date: Fri, 29 Apr 2005 23:33:29 +0100


--
_______________________________________________

[Elan45]

The other thing to check, especially when you speak of lots of vibration, is the prop shaft u-joints. With the rear wheels in the air and the gearbox in gear, move one of the wheels forward and aft and FEEL the u-joint for motion between the two yokes while moving the wheel. You usually can feel wear much sooner than see it.

Roger



I vote for a broken upper diff mount; 2:1 on the passenger side[it is unloaded in reverse]

Number 2 would be very loose torque rods, or beat/missing rubber, again, they are under compression while going forward, tension in reverse.

Diff should be well suspended, shouldn't hardly move with a screwdriver as lever.

Earlier elans sometimes broke the ear clean off the diff housing
Chassis gets weak where the torque rods connect
Park8ng brake stuck



----- Original Message -----
From: "Pete Taylor" <***@***.***>
To: ***@***.***
Subject: Re: [LotusElan.net] Differential problem ?
Date: Fri, 29 Apr 2005 23:33:29 +0100


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[tvacc]

I had a huge vibration problem in an Elan. I took that propshaft out so many
times.that I could get it out in about 20 min.from the front of the car.



I took it to several driveshaft places and had it balanced.but it was only
until I took it to a company with a new computerized balance machine did I
find the solution. It was out of balance.but it was a son of a gun to find.



Tony V



_____

From: ***@***.***lto:***@***.*** Behalf
Of Roger Sieling
Sent: Friday, April 29, 2005 10:34 PM
To: ***@***.***; ***@***.***
Subject: Re: [LotusElan.net] Differential problem ?



The other thing to check, especially when you speak of lots of vibration, is
the prop shaft u-joints. With the rear wheels in the air and the gearbox in
gear, move one of the wheels forward and aft and FEEL the u-joint for motion
between the two yokes while moving the wheel. You usually can feel wear much
sooner than see it.

Roger



I vote for a broken upper diff mount; 2:1 on the passenger side[it is
unloaded in reverse]

Number 2 would be very loose torque rods, or beat/missing rubber, again,
they are under compression while going forward, tension in reverse.

Diff should be well suspended, shouldn't hardly move with a screwdriver as
lever.

Earlier elans sometimes broke the ear clean off the diff housing
Chassis gets weak where the torque rods connect
Park8ng brake stuck



----- Original Message -----
From: "Pete Taylor" <***@***.***>
To: ***@***.***
Subject: Re: [LotusElan.net] Differential problem ?
Date: Fri, 29 Apr 2005 23:33:29 +0100


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CopyrightC LotusElan.net and the author:

[elanz]

Hi
One other thing to check is a sheared donut bolt. This happened to me
last year cars runs OK but the unbolted section of the donut makes a
hell of a noise as it comes into contact with the mounting ear.
More easily fixed than most other possible causees so unliky to be the
culprit.
Re Prop shafts I also had one balanced several times it always came
up fine 'til I took it else where where I was told that the prop shaft was
infact out of tolerance on alignment and whilst it had been balanced as
the revs got up the out of alignment created the vibration. The shaft was
split and rewelded, rebalanced with much less weight and has never
shown a hint of vibration since.
Cheers
Tony Herbert
On 29 Apr 2005 at 21:53, Yann Delcan wrote:

First hello to all
I'm not exactly new here but I've been very busy those last 3 years. I
was until this evening very happy with my Elan until I noticed a heavy
noise in the rear. This came suddenly and to give an idea, I have a
huge "clong clong clong" noise heard only when I'm decelerating with a
gear selected. Something similar as a very loose center lock on a
wheel or a very weak transmission on an ordinary car. Accelerating
does not make any suspect noise, same as when no gear is selected.
This reminds me with an unplesant similar (maybe identical) noise I've
always heard when reversing, this linked with sometimes severe
shakes.. I suspect something has gone loose in the dif casing as I
have not seen anything strange, any play in the rotoflexes, propshaft
or half shafts or in the suspension itself. Maybe also a broken
bearing ? I have no unusual oil leak but I have not driven more than
1km since the problem has started. I wouldn't swear it's not coming
from the gearbox, but I'm 99% sure it comes from the rear. Your
opinion and personnal advice will be much needed and appreciated.

Yann
7001030021G (Elan S4/SE domestic version Stromberg)
Pau, France

[yanni]

Hi to all
I'm confused to waste your time as I have found where this noise was from :
A rotoflex...
Confident as I had them new 4 years ago and 10000 miles only, I had not
thoroughly inspected the outboard ones. The one hidden behind the disc
is badly shredded, and for sure is responsible of the loud noise I was
worried about.
It's the first time you will hear about someone pleased to discover he
has a dead rotoflex !
Thank you for your answers

Yann
7001030021G (Elan S4/SE domestic version Stromberg)
Pau, France

[denicholls2]

I don't have the garage space to own an Elan as well as a Europa, but
the symptoms suggest a failed U-Joint, which initially will make more
noise when not under load than under load. This is because the "slop"
is taken up under load, but when coasting it can flail about freely.
You should also feel a clunk shifting from forward to reverse and
back.

These can be extremely noisy long before you can easily feel slop. Any
play at all means they're gone.

Unless you have modified halfshafts, the only U-joints in the system
are in the propshaft, both of which set directly under the passenger
compartment. In my Spitfire, the hardest one to get at (tranny side)
failed first.

Doug Nicholls, 54/1822 Ma~

[elansprint71]

Yann Delcan wrote:


Glad that my diagnosis was correct! It seems that Rotoflexes are nowhere
near as good as they used to be; I understand that some of the chemicals
used in the originals are now banned. Pau can get pretty hot and I guess
this may have contributed to the problem, maybe worth you other
hot-weather guys thinking about checking on a more regular basis.
I have had the Mick Miller shafts for a year now and would not go back
to roto's.

Cheers,
Pete.