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Limited Slip part of a Sierra diff
smart51 - 15/6/05 at 06:23 PM

I removed the back plate of my diff today to clean out the swarf from where I accidentaly cut a hole in it. I was pleased to see that there was no real wear on any of the gears.
Afterwards, I thought about the limited slip part of the diff and how I hadn't noticed it.
Where is it and what does it look like?
I cleaned out the 4 gears in the planet carrier and the big crown wheel, so where's the limited slip bit?

mookaloid - 15/6/05 at 08:33 PM

The crown wheel is bolted to it,

Cheers

Mark

smart51 - 15/6/05 at 09:03 PM

Ah, the big black thing. How does it limit the slip? I managed to make it slip by hand quite easily, so that I could get to all the teeth on the "diff".

dnmalc - 15/6/05 at 09:06 PM

I believe its a viscous coupling ie it will have low resistance to slow movement but resists fast movement

dnmalc - 15/6/05 at 09:06 PM

its a viscous coupling ie it will have low resistance to slow movement but resists fast movement

smart51 - 15/6/05 at 09:10 PM

OK. how is it connected to each output?
The crown wheel is bolted to the planet carrier which has 2 small beveled gears fixed to it an small shafts. the 2 larger output beveled gears mesh with the smaller beveled gears and drive the wheels.
How does the viscous coupling fit in?

big_wasa - 15/6/05 at 09:23 PM

I may be wrong and often are BUT if its lsd Then I didnt think that you could see/touch the planet gears .ie that sounds like an open dif?????????????

The link below shows an rs2 lsd on ebay .does it look anything like that?
LSD link
Or can you see the planet gears like in the link below
open diff
?????????????????????????????//

liam.mccaffrey - 15/6/05 at 10:27 PM

a viscous lsd is just like a normal diff but with the addition of a viscous clutch consisting of plates very close to each other with a special fluid in between which when the plates turn at different speeds ie when a diff is fully slipping, change viscosity with the friction generated between the p[lates. this then turns the slower wheel transfering torque to the slow grippy wheel

i think

chriscook - 15/6/05 at 10:37 PM

The standard ford LSD (viscous as described above) looks like the attached picture - its hidden inside the bit to the left of the crown wheel. -identifiable because its thinker than the standard open diff.

Chris Rescued attachment dscf0044_small.jpg
Rescued attachment dscf0044_small.jpg

smart51 - 16/6/05 at 07:19 AM

It's funny, just looking at that picture I can smell gearbox oil. That is what my diff looked like inside. I just expected to see something that linked the two output shafts in some way.

Bob C - 16/6/05 at 11:24 AM

It doesn't have to link the 2 o/p shafts; the crownwheel is doing the average speed of the 2 shafts so it's equivalent - and MUCH mechanically simpler - to put the slippy bit between the crownwheel and one output shaft.
cheers
Bob

big_wasa - 16/6/05 at 09:59 PM

You learn sumet new every day

Liam - 24/6/05 at 01:39 PM

quote:
Originally posted by smart51
Ah, the big black thing. How does it limit the slip? I managed to make it slip by hand quite easily, so that I could get to all the teeth on the "diff".


The reason for that is that without the left shaft/flange plugged in, the left output isn't connected to the viscous coupling, so you can move the spider gears around as easy as an open diff. Plug the left shaft/flange in and this should be pretty impossible by hand.

liam

smart51 - 24/6/05 at 05:34 PM

My diff has bolt on shafts not plug in ones so it should work fine. My guess is that at the speed at which I was turning the shafts, the viscous coupling wasn't doing much, as if the car were going round an ordinary corner.