Lotus Elan

Slipping clutch wasn't - differential is the problem

PostPost by: Rob_LaMoreaux » Sun Aug 02, 2015 2:51 pm

Well I have now replaced everything to do with the clutch and the car still barely tries to move. So I pushed it by hand with the transmission in first and while my daughter watched the crank pulley, then the driveshaft. The car moved, but the driveshaft did not.

It seems my differential is gone.

I hope to pull the diff next weekend, but in the mean time any guesses as to what failed?

I suspect the ring gear is spinning, so it could be the bolts backed out or broke. My guess is some bolts backed out (I did locktite and torque them) and then one or two broke. I never felt a sudden jolt of any sort, so I am not sure about the bolts breaking. It just seemed to slip more and more as if the clutch was going.

When I do get it out, what's the best source for parts for it these days, on the US side of the ponds
.
Rob
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PostPost by: StressCraxx » Sun Aug 02, 2015 3:24 pm

Hello Rob,

If the drive shaft didn't move with the gearbox in 1st, there is something wrong within the gearbox. If the drive shaft (propshaft to our friends in the UK) turns, then it is likely a broken differential output shaft.

I would raise the car, try turning the driveshaft by hand with the transmission in each gear, just to make sure.

Then block a rear wheel, turn the propshaft, and the other wheel should turn. Do the same for the opposite side.

Regards,
Dan
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PostPost by: TroonSprint » Sun Aug 02, 2015 3:45 pm

Dan, I think you have misunderstood Rob. He wasn't turning the engine over, but was pushing the car in 1st gear. If the prop (drive) shaft didn't turn when doing that, then the fault must be in the diff - mustn't it?

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PostPost by: rgh0 » Sun Aug 02, 2015 8:38 pm

If you have the original diff output shafts it is most likely one of them have failed.

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PostPost by: cusword » Mon Aug 03, 2015 8:44 am

Diff output shaft broken...........

dwc
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PostPost by: Elan45 » Mon Aug 03, 2015 1:25 pm

Another vote for broken diff output shaft

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PostPost by: Rob_LaMoreaux » Mon Aug 03, 2015 4:24 pm

I have a limited slip differential in the car so I would have expected more thrust with just a broken output shaft. I guess I can check the shafts tomorrow by jacking one side and trying to turn the wheel.

If it is a output shaft, I may bite the bullet and go with CV joints. Otherwise I may consider changing from the 3.77 to a 3.55 to get lower RPMs on highway.

Rob
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PostPost by: rgh0 » Mon Aug 03, 2015 8:35 pm

Hi Rob

What sort of LSD do you have fitted ? The Quaiffe only generates limited lock up at low engine speeds. Also possible with the quaiffe that the crown wheel bolts have failed like they did on mine I guess but this failure should make a lot of noise!

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PostPost by: Rob_LaMoreaux » Tue Aug 04, 2015 3:25 am

I actually don't know what brand the LSD is since I bought it used from a racer who had gone too spools for all his ratios. It is a clutch style, not a Torsen. Tonight my father in law pointed out that many don't give much limiting until the torque is high enough so that may be the case. I'll lift each side and try rotating with the car in gear tomorrow and see what I find.

Rob
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PostPost by: Chancer » Tue Aug 04, 2015 7:30 am

I am still perplexed by how your daughter would be able to see the propshaft (not) moving while you push the car, was she lying on her back underneath, in a pit or have I misunderstood?
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PostPost by: Rob_LaMoreaux » Tue Aug 04, 2015 10:29 am

She was lying down next to the car looking across at the bolts on the pinion flange. It was nicely silhouetted so any movement was visible.

Rob
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PostPost by: rgh0 » Tue Aug 04, 2015 11:00 am

Clutch style LSDs are locked at zero torque / slip and start to slip at a preset torque level maintaining toque to the other wheel by the amount of load required until they slip. So you should have drive a low speed with one output shaft broken with a clutch style LSD unless the LSD itself is not working or sometinhg has gone wrong with the crown wheel and pinion

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PostPost by: Rob_LaMoreaux » Thu Aug 06, 2015 1:44 am

Well tonight I jacked up the left rear put the car in gear and tried to turn the wheel. It turned very easily....and wobbled. Removing it I found the hub was loose, really loose.

So now I need to try to figure out if the shaft is usable. I am pretty sure the hub is not since the key is welded to groove in it.
Hopefully the pictures come through:

Rob
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Last edited by Rob_LaMoreaux on Thu Aug 06, 2015 1:55 am, edited 1 time in total.
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PostPost by: Rob_LaMoreaux » Thu Aug 06, 2015 1:46 am

Since the pictures didn't go through try this link:

https://www.flickr.com/photos/rob_lamoreaux/shares/t0k29x

Rob
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PostPost by: StressCraxx » Thu Aug 06, 2015 5:28 am

Rob,

I think you are very fortunate. This could have been a most unfortunate failure on the road. A few new parts, careful inspection and you will be back on the road in no time.

Regards,
Dan
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