Lotus Elan

Dead Diff

PostPost by: Nercw1 » Tue Jul 25, 2006 8:51 pm

After sorting the aggravating misfire all has been well for some 500 miles. On my way home this evening lost drive. G/box ok (prop shaft turning!)Drive shafts ok no power through diff!! :cry:
Car has been running as close to perfection as I could wish. :D No noise, clunking whining,vibration or untoward behaviour, pulling away in traffic (gently) and all drive lost. I have never been inside a diff :shock: is it possible that a lock nut or similar in there has come loose??????????? :shock:
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PostPost by: types26/36 » Tue Jul 25, 2006 9:21 pm

Most likely a broken output shaft, see this thread:
http://www.lotuselan.net/forums/viewtopic.php?p=58043
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PostPost by: Nercw1 » Wed Jul 26, 2006 4:45 pm

Oh the ups and downs of lotus ownership. Visited the workshop entrusted with looking after the +2 to hopefully establish that the problem was output shaft related and sure enough with the car off the ground we have drive to the diff nothing thereafter. Spun one rear wheel off the ground no action on propshaft, spun the other wheel and also no action on the propshaft.
Is it possible, has it been heard of before, doing 2 output shafts at the same time?
There has been no noise, rumbling, grinding etc from the diff in all my driving of the car, some 2000 miles in 6 weeks. Drive was lost when releasing the clutch in first gear at low revs in a queue of traffic, nothing no bang apart from loss of drive.
Any thoughts would be much appreciated.
:?: :?: :cry:
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PostPost by: types26/36 » Wed Jul 26, 2006 5:16 pm

[quote="Nercw1"]. Is it possible, has it been heard of before, doing 2 output shafts at the same time?quote]

I have never heard of it and think it extremely unlikely but why would you think both are broken?
Its academic anyway as you will have to work on the diff weather you take the diff out or replace the shaft(s) in place.
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PostPost by: Nercw1 » Wed Jul 26, 2006 7:53 pm

Thanks for the thoughts, I think that if only one output shaft was sheared then at least one wheel being turned would result in motion on the prop ????
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PostPost by: types26/36 » Wed Jul 26, 2006 8:08 pm

Nercw1 wrote: I think that if only one output shaft was sheared then at least one wheel being turned would result in motion on the prop ????


Err, no,it does'nt quite work like that, if it were to drive through one wheel only it would be defeating the object of having a diff :roll: probably best to check the unbroken shaft as well as I have seen them distorted (twisted)
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PostPost by: denicholls2 » Thu Jul 27, 2006 12:54 pm

OK, NRCW1, you're to be excused for not understanding basic open diff mechanics. They are a bit confusing.

However, your shop's cluelessness in this matter suggests YOU SHOULD GET YOUR CAR OUT OF THERE FAST!!!
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PostPost by: Nercw1 » Thu Jul 27, 2006 7:33 pm

Ok thanks for excusing me. I am going back to first principles and anyone out there that feels I am an absolute donkey :oops: please feel free to say so.
If I jack a car up so 1 rear wheel is off the ground and I spin it, it will produce motion on the propshaft the diff sending all output to the wheel with least resistance?
If the output shaft had failed on this side of the car then NO MOTION ON PROP.
If I jack a good car up so both rear wheels are off the deck and spin one wheel then the other rear wheel will move PROVIDING output shafts are good on both sides.
My car with both wheels off the deck (ON lift) when I spin either wheel no motion on shaft or opposite wheel.
So would one failed output shaft produce this result :?: :?: :?: irrespective of which rear wheel is spun.
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PostPost by: john.p.clegg » Fri Jul 28, 2006 5:51 am

EEEE-AWWWW

The broken output shaft will always be the path of least resistance,so any input will turn the broken shaft....

ie. no output from any input...

John :wink:
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PostPost by: reb53 » Fri Jul 28, 2006 6:22 am

John and others are quite correct.
If an output shaft is broken then spinning either wheel will not turn the driveshaft. If you are turning the broken side then no motion will be transmitted into the diff and nothing at all will happen.
If you are turning the unbroken side then the motion will be transmitted to the broken stub on the other side which you won't be able to see anyway.
Bet when you get it out you'll see that one little bit of shiny metal in the break is all that has been holding the whole plot together for a while and the major damage was done at some other time.
As an aside , don't let your garage keep the car up with the suspension at full droop for any length of time while they decide what to do. Not good for the rotoflexes and I strongly suspect not good for the wheel bearings.
My car was on a jack for weeks without me knowing.BOTH sides at rear failed within a 1000 miles. They each had different miles up and both failed well before their time.

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PostPost by: Nercw1 » Fri Jul 28, 2006 11:38 am

Joy of joys, see owning an Elan can be an informative experience. Thanks to all you guys I now have a working allbeit basic understanding of the properties of differentials. Off to purchase (Ouch) two output shafts and hopefully have the vehicle in motion for the remainder of our hot spell 8) .
Once again many thanks to everyone who contributed with the educative process.(And whoever sent the bunch of carrots special delivery I'll be baking a cake tonight!!)
Cheers
Bill Crease :P
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PostPost by: reb53 » Fri Jul 28, 2006 10:32 pm

Don't get two until you know for sure, i.e. until you've got it out.
The chances of two breaking at exactly the same time are rather remote.
As explained in my previous post , the moment one breaks .......you stop.
No chance to break another.

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PostPost by: bill308 » Fri Jul 28, 2006 10:48 pm

It is my understanding the OEM output shafts are iffy from a structural standpoint. Upgraded billet shafts are available and a pair should be considered. I've replaced both the output shafts and axles on my S2. The output shafts were part of the Dave Bean CV-joint kit.

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PostPost by: Nercw1 » Wed Aug 02, 2006 6:53 pm

Well thanks a lot to you all. 1 output shaft sheared. Replaced both shafts and all 4 rotoflex couplings and the car should be running tomorrow night.
The advice was/is much appreciated.
Cheers :P
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