useable diff or not?

[dan_g8]

i have been offered a lsd diff and the person has sent me a few pics through of the internals. i would like to know if the diff is ok or not pics and his email are below......

Thanks!

"Initially I was encouraged as the internals looked very tidy. However, after I turned the driveshafts through 180° I could see surface corrosion on the outside edge of the crown wheel and spots on the pinion gears. I can only assume this aligns with the breather where it has been sat. The diff turns over without problem.

I wouldn't expect this to be a problem (I would hope the increased surface texture roughness would retain an oil film better) "

[Big Vern]

That ain't no LSD it's just a normal open diff and not worth much. DONT pay LSD prices Either seller dont know his a8$e from his elbow or he's rippin' you off.

BV

[dan_g8]

hmmmm thanks for the heads up guys!!! the bloke said that it was from 1990 4x4 Sierra v6 and that it locks up correctly. i dont know much about diffs, ill question the person on it and see what he says.

[dan_g8]

right, now im confussed! i asked the same question on locost builders and a couple of people say it is lsd!

viscous LSD????

http://elworth.info/html/differential.html

[londonsean69]

Originally Posted by AdrianH

Hope the above works taken from a thread http://www.projectpuma.com/viewtopic.php?t=2519

Standard internals on right, LSD on left.

Adrian

I have a cosworth LSD, and the pinion looks like the one on the right.

Originally Posted by locostbuilders

To check if it is an LSD hold one of the output shafts so it cannot rotate, turn the input shaft, if you can still turn the input shaft freely without the held output shaft moving it is open, if the output shaft cannot be held in place whilse rotating the input shaft it is an LSD

Dunno if the check is right or wrong, off down to the garage to find out.

Well, assuming my diff is an LSD (and I have no reason to currently doubt it) that test works. No way I could hold either output shaft whilst turning the input shaft

[Davey]

My diff from a Granada Cosworth is LSD and I cannot turn the input shaft without both outputs turning, even if I try to hold one output still. It doesn't look like a LSD to me either, if I get time today I'll pull the rear cover off mine and photo it.

D.

[dan_g8]

thanks for the replys guys, think ill trust that it is an lsd. Do you think that the rust will be a problem?

[RAYLEE29]

HI, it looks like a viscous lsd to me, the giveaways being the plate between the crownwheel and the crownwheel carrier,
and its a 3.62 according to the writing on the crownwheel which is also an lsd ratio and normally go for good money.
as for the rust you dont want any pitting on the gears as they will wear quickly what the guy says about holding oil is total b****cks!
if it cleans up ok all well and good if not it wont last long.
out of interest is this for a track car as general concencus is you dont need one for the road.
Ray

[dan_g8]

the car will be for mainly road use, the reason that i wanted a lsd is because im using a v8 for the engine so probably will need a lsd to help get the power down?

[Big Vern]

The pictures you supplied in your original post show a normal open diff! At a pinch it could be a viscous coupled diff as was used in the Sierra 4x4 I had many years ago. (though I don't see the Viscous part only the planet gears and sun wheels) The viscous coupled diff is NOT an LSD and doesn't work in the same way as an LSD!
The 4x4 I had many years ago also had a Turbo nailed to it so it went like stink BUT all of the viscous drives in the system could be made to slip during a hard launch causing embarrassment and not a lot of go....
The rear wheels could be made to turn in opposite directions though with more resistance than a fully open diff. A true LSD this would be almost impossible!
The viscous diff will probably ok for what you need but repeated overheating will kill it and I once had quite a graveyard of dead viscous diffs!!!