Blocking The Central Differential

[vivianM]

vM

I have had some very interesting conversations at main dealers. No doubt the are some knowledgeable people in some of them but for others using a generic term like "limited slip diff'" is an easy way of concluding a conversation.

I have all the drawings and maintenance info for a 4.2 including rear axle, transfer box and gearbox and there is not a limited slip diff' to be seen!!! In fact there are some disadvantages in using a limited slip diff which is why they are seldom used on what is essentially a road going vehicle. They are usually the domain of true off roaders or very high performance cars like your Jensen's. They use a spring loaded multi plate clutch or viscous coupling to resist what would otherwise be free to rotate planet wheels. In the case of one wheel spinning in the mud a torque equal to the resistance generated would be applied to the stationary wheel which is sometimes enough to ease the vehicle into motion. The downside is that they generate some "tight corner braking", excessive fuel consumption, tyre wear and drag. By their very nature they are a wearing part (designed to slip) and introduce a maintenance issue.

This explains a bit more;

http://auto.howstuffworks.com/differential3.htm

Thanks for your help, Anchorman, that makes it all clear now, very annoying that I had been told there was a limited slip diff. fitted to my earlier RAV

Best wishes

Guy

[shcm]

Thanks for your help, Anchorman, that makes it all clear now, very annoying that I had been told there was a limited slip diff. fitted to my earlier RAV

Well, they could be forgiven, when the 2002 brochure says this:

[anchorman]

It does indeed and yet here in their own workshop manual is a bog standard diff;

and a bog standard carrier;

It seems strange to list it in the suspension section!!!

[shcm]

It does indeed and yet here in their own workshop manual is a bog standard diff

I can't see what you've posted there at the moment, as work kindly blocks photobucket. (I can defeat the ****ing thing, but that's another story :) )

Anyway, for the moment, as I'm working (allegedly) and can't post pictures, have a look at manual RM777E - Rear Diff Carrier disassembly - should be page SA62 onwards. It mentions slightly different procedures for a torque sensing LSD.

Not trying to embarrass anybody here, just interested in the facts and you obviously have far more detailed knowledge in this area than me. Maybe I'm barking up the wrong tree (wouldn't be the first time)

Couldn't tell you whether it was a LSD on my old 4.2 VX. I just changed its oil and checked the seals for leaks from time to time.

It seems strange to list it in the suspension section!!!

Yeah, I spotted that too! :D.

Cheers

EDIT:

....and from the same bit of the manual, references to a LSD???

.....I'm going to incur the wrath of the grand master now?

[vivianM]

Thanks for your help, Anchorman, that makes it all clear now, very annoying that I had been told there was a limited slip diff. fitted to my earlier RAV

Well, they could be forgiven, when the 2002 brochure says this:

At least I was partly right as I was sure that I had seen the spec before I bought the VX about 5 years ago.Many thanks

Guy

[anchorman]

It does indeed and yet here in their own workshop manual is a bog standard diff

I can't see what you've posted there at the moment, as work kindly blocks photobucket. (I can defeat the ****ing thing, but that's another story :) )

Anyway, for the moment, as I'm working (allegedly) and can't post pictures, have a look at manual RM777E - Rear Diff Carrier disassembly - should be page SA62 onwards. It mentions slightly different procedures for a torque sensing LSD.

Not trying to embarrass anybody here, just interested in the facts and you obviously have far more detailed knowledge in this area than me. Maybe I'm barking up the wrong tree (wouldn't be the first time)

Couldn't tell you whether it was a LSD on my old 4.2 VX. I just changed its oil and checked the seals for leaks from time to time.

It seems strange to list it in the suspension section!!!

Yeah, I spotted that too! :D.

Cheers

EDIT:

....and from the same bit of the manual, references to a LSD???

.....I'm going to incur the wrath of the grand master now?

No not at all, I want to understand these comments as much as anyone - never to old too learn or too proud to admit being wrong.

I can't access SA62 from the menu tree but I have also found another reference to it by trawling through the individual pages;

Very frustrating that they don't seem to show any detail on that option but only make reference to it.

So! VivM - your salesman was right and that would mean that the rear axle only would provide some left/right assistance on a low friction surface. As I said above, there are LSD's and LSD's so how affective this version is would depend on the design. Also at this stage unless somebody like Moonstone Mart or Kingo can clarify, we don't know how or if this spec carried over to the XT series 4.2/2s.

[bothwell_buyer]

Interesting stuff - wonder what track it has and if its worth trying out on RAV number 1? The rear end is coming up for a major refurb soon anyway.

[vivianM]

Interesting stuff - wonder what track it has and if its worth trying out on RAV number 1? The rear end is coming up for a major refurb soon anyway.

Well, I had always thought the VX was very good on icy roads, I live on a hill which is not gritted very often and the RAV VX has always got me up it - it gets very icy as opposed to deep snow so I am not sure how good the LSD would be under those conditions as I am sure from my previous 4x4 2.9 Sierra that it was the depth of the tyre treads that was the most important feature in deep snow.

That was the most fantastic car, it travelled across the Peak District to Sheffield and used to pass cars stuck on the Winnats Pass whilst listenting to the radio saying the Pass was closed!

Guy

[shcm]

Very frustrating that they don't seem to show any detail on that option but only make reference to it.

Also at this stage unless somebody like Moonstone Mart or Kingo can clarify, we don't know how or if this spec carried over to the XT series 4.2/2s.

Just out of idle curiosity, I had a look in the parts catalogue. The part explosion diagrams look much the same as your post. This one was label up as the LSD (No, I haven't crossed these over, well not according to the catalogue :D):

and this one wasn't:

There are possibly some differences (over to you for a better interpretation), and the "*2 (- 0307)" on the top explosion, maybe indicates something happened at the 4.2 facelift changeover date (July 2003?), but that could just be some updated part numbers.

The factory manuals are also incremental (new editions only show changes) and there is nothing in for the diff for the 4.2 facelift manual increment. But as you say, Kingo or Mart would be definitive.

Well, I had always thought the VX was very good on icy roads, I live on a hill which is not gritted very often and the RAV VX has always got me up it.

I agree. Mine proved its worth in winter 2003/2004. The snow came in Brum in rush hour, grid locking everybody including the gritters (they hadn't got out quick enough). The snow promptly turned to ice. I remember grinning a lot going up hill passed a stationary BMW, who was just busy polishing the ice with his rear wheels. He had not a clue. The RAV never missed a beat. The only hint of any loss of traction was the following morning on one of the still iced over dual carriageways. The back end twitched a bit - I probably was going a bit to quick for the conditions. Then I watched from the mirror, as a car some distance behind, went over the same spot, did a full 360 degree spin and "parked" itself neatly on the verge.

You seem to have had a few interesting vehicles though Guy

[anchorman]

It just shows the diff as a sealed unit where the non LSD shows the planet wheels etc. I have found an ammendment to the manual but its rather vague.