Rear Diff. LSD Locked up

[aston_jag_tech]

New concern: 275K, 535I Auto with LSD Rear Diff.

Poor acceleration/ Wheels off ground extreme effort required to spin wheels.

Vehicle on lift and spun rear tires-Felt as if the park brake was partially engaged. It was not, Rmoeved rear brakes-no change. Removed Rotors-no change.

Im questioning if my rear diff LSD is jammed up. No issues when turning at speed such as hopping of rear tires.Whine noise at 1st to 2nd but believe its transmission...

Conidtion of diff fluid is unknown as well as last service...

I need to replace all the rear bushings in the rear subframe so I will drop the subframe if the diff needs work...

Any suggestions or anyone had issues similar?

Thanks!

[Ferret]

New concern: 275K, 535I Auto with LSD Rear Diff.

Poor acceleration/ Wheels off ground extreme effort required to spin wheels.

Vehicle on lift and spun rear tires-Felt as if the park brake was partially engaged. It was not, Rmoeved rear brakes-no change. Removed Rotors-no change.

Im questioning if my rear diff LSD is jammed up. No issues when turning at speed such as hopping of rear tires.Whine noise at 1st to 2nd but believe its transmission...

Conidtion of diff fluid is unknown as well as last service...

I need to replace all the rear bushings in the rear subframe so I will drop the subframe if the diff needs work...

Any suggestions or anyone had issues similar?

Thanks!

Drop the bolts out of the propshaft to diff connection, see if the problem goes away - if it does you've probably got a seized centre bearing or gearbox fault!

[632 Regal]

cooked pinion bearing will be self evident once you remove the driveshaft and try to spin the pinion.

[sal_park]

Hi,


Wheels off ground extreme effort required to spin wheels.

What do you mean by this ? do you mean spinning one wheel while keeping the other still ? or do you mean spinning both wheels together ?
Also what is extreme effort ? can you turn the wheel by hand or are you using a socket/4ft extension on one of the wheel nuts ?

For reference my 525 has an LSD with no obvious issues / noise and I observed the following behavior:

Jacked up rear end, both wheels off ground. All brakes off, including hand/park brake.

Manual gearbox was in neutral.

It took alot of effort (2 grunts say) to turn one wheel by hand while the other wheel was held still.

It took next to no effort (1 finger) to turn one wheel while the other could free wheel.

This (I believe) is normal LSD behavior.


hth

sal

[Ross]

Unless you are holding one wheel the diff even if locked up tight won't offer resistance to the turning of both wheels.
A pinion, diff carrier, wheel bearing or even a driveshaft center bearing could be the cause but I would think a bearing failed that badly would have been very loud.
I'll be curious to see what happens with the driveshaft disconnected, wondering about some odd autobox failure

[aston_jag_tech]

Extreme effort with both rear wheels off ground - Two hands and a lot of muscle to spin one wheel forward with transmission in park.

Driveshaft has been rebuilt. When removing wasted driveshaft transmission was in neutral, and just ONE wheel was off ground...

I will jack up rear end, place trans in neutral and check resistance.

I dont think theres an auto box issue, Transmission shifts alright, fluids a decent red, no burnt smell. I do want to do a trans service on it though(drove around 50k on car since I bought it).

Thanks for the input and checks on your own cars, very much appreciated!

-Scott

[Ferret]

Extreme effort with both rear wheels off ground - Two hands and a lot of muscle to spin one wheel forward with transmission in park.

Doesnt this mean your propshaft is locked solid by the gearbox? And as it's a limited slip diff, doesnt this mean the behaviour is natural?

Drop the box into N and try it again...!

[sal_park]

Doesnt this mean your propshaft is locked solid by the gearbox? And as it's a limited slip diff, doesnt this mean the behaviour is natural?

Drop the box into N and try it again...!


100% agree with Ferret. With the prop locked and both rear wheels off the ground, turning one will cause the other to turn on the opposite direction - this is the case with any kind of diff, LSD or otherwise. With the LSD you will get alot of resistance aka:
Two hands and a lot of muscle to spin

btw, why do you think there is a problem aston ?

[Jon K]

so wait the diff is locked 100% lockup?

Sounds like a feature!

[Ross]

Not sure I understand now.
With thetrans in park, both wheels off tyring to turn either wheel will encounter the clutch resistance in the diff if LSD. What you decribe sounds normal as the driveshaft cannot turn so to turn one wheel you are overcoming the diff clutches.
Non-LSD rear will freely turn the opposite wheel in the opposite direction.
With the trans in neutral bothe rear wheels should turn in the same direction when turning one of them.
Hope this helps, I don't think you have a problem.

[aston_jag_tech]

With both rear Wheels off ground, trans in neutral, wheels spin with no major resistance and both wheels spin in same direction. Fact. spec states 25% diff lock up. Just curious of functionality. I know I did learn LSD operation at some point of my tech training..... :)

Thanks guys...

P.S. please excuse my mis-diag initially...