Lotus Elan

loss of drive

PostPost by: rocket » Mon Jan 03, 2011 1:29 pm

Hi all,

Being a nice day today i decided to take plus2s a spin.As i reversed from garage i lost drive after about 10 yards,selected 1st car went forward fine.reselected reverse and she just about made the 30 yards required tho not smoothly.Put her into 1st and drove off ,shifted to 2nd and then into neutral at t junction.Into 1st and no drive,just a kind of faint feeling of trying to move,tried reverse with same result.Engine fine,clutch appears to be working and gears swopping smooth as usual.Looking at propshaft with car being put into gear and attemting to move there appears to be a slight movement at diff but doesnt turn.Ideas please?

Regards,

Ian.
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PostPost by: garyeanderson » Mon Jan 03, 2011 2:58 pm

Hi Ian

That's a drag, what about 3rd or 4 th gear? Will the car stall if you let the clutch out in either of the top gears? You need more info on this but you certainly have a problem. It may be in the gearbox (probably) or diff (not as likely). If the prop shaft spins the gearbox is fine if not well it seems box or clutch related. When I broke a diff output shaft I could coax no movement out of the Elan, I could shift through all 4 gears as fast as I could without the clutch being touched.

More info please!

Gary
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PostPost by: ken ob » Mon Jan 03, 2011 3:00 pm

Do you have the original type 'rotoflex' couplings fitted? If so that would be the first thing i would check.

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PostPost by: rocket » Mon Jan 03, 2011 3:31 pm

Hi again..more info..with engine running you need to depress clutch to select any gear,when in gear,any gear you choose you can release clutch but car wont move,kinda feel it trying tho and you can see prop shaft tho not turning it appears to try to turn diff...with engine off and in gear car can be pushed prop still not turning..Doughnuts replaced 3 years ago with miller shafts which turn fine when car is pushed..Im thinking diff broken and allowing wheels and miller shafts to turn but jamming prop shaft causing clutch to slip???
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PostPost by: alexblack13 » Mon Jan 03, 2011 3:44 pm

Prop' shaft not turning means either flywheel bolts sheared.Clutch driven plate failure or a problem within the gearbox. All of these issues are very uncommon.

Are you sure the prop' shaft was not rotating when in gear and motor running normally?

Keep us posted. I do you you find it soon. :?

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PostPost by: rocket » Mon Jan 03, 2011 3:49 pm

Alex,with you on those points but dont you think the prop should spin when car is pushed along.i.e driven from rear wheels..?
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PostPost by: alexblack13 » Mon Jan 03, 2011 3:53 pm

Second read!! You say pushing the car does not turn the prop shaft either? Hmmmmm! With the engine running and the car in gear clutch up and the prop shaft is not rotating point to a fault as stated above. However.. when pushing the car if the props not turning then, well that points to another issue again..... IE diff or drive shaft failure. I doubt you will have both.

Can't wait to find out what it is....Keep us posted.

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PostPost by: rocket » Mon Jan 03, 2011 3:57 pm

Quite keen to find out myself to Alex....do you think it possible for diff to jam so prop cant turn causing clutch to slip whie miller outputs still turn freely?
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PostPost by: JJDraper » Mon Jan 03, 2011 5:00 pm

Engine off, chock the car and jack one rear wheel up. Put the car in neutral. Grasp the road wheel and try to turn it. Does the wheel turn? If so, does the propshaft turn (solidly) as well? If the wheel turns easily, but not the propshaft (or only slightly), I suspect that Gary gets the biscuit - snapped drive shaft. If the prop turns - but with difficulty, problem lies in gearbox land. I don't know enough to even try and diagnose the fault here! Possibly a faulty CV joint, but unlikely, and you would see the wheel turn, but not the miller drive shaft. Repeat for the other wheel. If the CV or drive shaft has gone, one wheel would turn the propshaft, but the other (with failed shaft) would not. I had a failed CV earlier in the year, but that was a freak mis-assembled unit in the factory (I'm told). It is also possible that an outer drive shaft has failed, also rare.

If the engine starts on the starter, the problem is not crankshaft bolts. If the starter makes a horrible noise, or spins really fast, while not turning the engine over, then you have snapped crankshaft bolts.

It is highly unlikely that the clutch is slipping and spinning, unless the centre of the clutch is broken - also with a horrible mechanical noise. The smell of burning clutch would be enough diagnosis if it was!

If it is a snapped drive shaft as per Gary's picture, it can be replaced with the diff in situ, but difficult at the side of the road!

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PostPost by: rocket » Mon Jan 03, 2011 5:07 pm

Hi Jeremy,the car rolls fine so why jack it up to see if wheels spin?
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PostPost by: Higs » Mon Jan 03, 2011 6:39 pm

[quote]Hi Jeremy,the car rolls fine so why jack it up to see if wheels spin?[quote]

Because it is much easier to see what is happening (for example, it is quite difficult to see the propsahaft when the wheels are on and the car is being pushed.

To summarise, the symptoms you describe i.e. the propshaft does not turn when engine turning and car in gear and also won't turn when engine off and car being pushed, suggest a failure in the clutch or gearbox and also a failure in the diff or driveshafts. This is most unlikely - two major failures at the same time.

So Jeremy is suggesting a careful, observable, checkable and safe test to try to double check things.

Let us know what you find!

Richard
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PostPost by: JJDraper » Mon Jan 03, 2011 9:20 pm

Jacking up one wheel at a time will show if, and which drive shaft has failed. If both wheels are turning, as in just pushing the car along, the wheel with no broken shaft will turn the propshaft. If you jack up both wheels, with good drive shafts and try to spin one wheel, the other will go in the opposite direction. This is how a diff works, but is difficult to explain without pictures!

Jeremy
PS this may not work with a limited slip diff..
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PostPost by: alexblack13 » Mon Jan 03, 2011 9:26 pm

You have us hooked here Rocket.. We are all very keen to find out what has gone Phut!

Bad luck but it will fix ok.

Let us know. :wink:

We will help as much as we can...

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PostPost by: jimj » Mon Jan 03, 2011 11:39 pm

I may be confused, I often am, but if you jack up one wheel with the other stationery, surely the wheel and drive shaft will turn without turning the propshaft UNLESS it`s an LSD. It`s not difficult to get someone to roll the car forwards a bit and see if the propshaft UJ (the easy to see bit) is turning. If it is then it`s the clutch or gearbox, if it`s not then see if the driveshafts are turning at the diff. end. If they are it`s the diff, if not it should be easy to see if it`s a drive shaft, otherwise it`s the hub to outer drive shaft.
The diagnosis should take about 2 minutes.
Jim
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PostPost by: Higs » Tue Jan 04, 2011 12:51 am

Jim wrote:

I may be confused, .....


Trust us, Jim, but you have got yourself confused :)

Spinning one wheel will cause the propshaft to spin unless one of the drive shafts; the output shafts, or the diff internals are broken.

I tried to start writing the explanation but then realised that there would be a better explanation of the net somewhere....

Richard
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