Last years cars diff looked like this:
Mind you, having said that it leaked a bit around where the sprocket was bolted on, but thats a simple fix.
David
Oh no, yet more chainy stuff!!!!
Just a quick one!
I have seen, and been told about several diffs, modified to run in block mounted bearings, with a sprocket on the crownwheel location, in chain drive
applications.
These have all been fitted with an enclosure over the diff carrier, to contain oil/grease etc.
How does this work????
I understand the obvious, but there appears to be no seal between the output shafts and the "enclosure".
There are a number of mentions of sealing the enclosure to the carrier, but that is the easy bit!!! What about when the diff is "diffing"
and therefore the outputs are not rotating at the same speed as the casing, surely the oil/grease can leak round the back of the output gears, along
the output shafts and out into the open air!?????
I know that it will "tend" not to as the output shafts are a reasonable fit in their splines, and the output gears usually sit on bronze
washers in the diff housing which will tend to seal them, but I don't usually build things on "tendencies"......I prefer
certainties!
How is the oil prevented from leaking out down the outside of the output shafts??
I am not sure, but if you cant get an answer i can have a look and see how we do it.
Last years cars diff looked like this:
Mind you, having said that it leaked a bit around where the sprocket was bolted on, but thats a simple fix.
David
How many teeth on that sprocket? 
oh to have a vertical mill........really must get myself one sorted out!!!
Some information here, but probably not detailed enough.
http://www.westhouse.plus.com/chaindrive1.htm
no, just been looking there! He mentions rtv sealant to seal the can to the carrier, but nothing of sealing the can/carrier to the outputs!!
Probably about same as mine - 52ish
Gives a 4:1 with a 13tooth sprocket
as regards sealing, yeah interesting to know, it wouldn't flood out through the holes here but certainly must leak slowly. maybe a very thin o
ring between the faces would be enough to do it and still allow the circlips to be installed to hold driveshafts in?
Something I have to figure out for my own diff too
James
[Edited on 10/11/06 by cloudy]
[Edited on 10/11/06 by cloudy]
They certainly weap a bit, that's the main reason they probably recomend either heavy oil or grease. If you put the proper oil in, it would be
everywhere.
Some people have put the original oil seal on the outside of the bearing carrier, which would mean a machined carrier, still would weap a bit from the
other side of the bearing but would help.
I think someone said that VW diffs have an internal oil seals in the outputs
Cheers
David
[Edited on 10/11/06 by Minicooper]
cheers folks!
Sounds like I wasn't missing something obvious then!
I know I have seen diffs on grassers, where they have used and English or atlas lsd casing, with circular bits welded into the casing holes, with one
drilled and tapped for a grease nipple and another with a drain bung in it of some sort, but I never got an answer to the oil sealing!.
thanks again
Nat
If you are building a grasser
you don't use a diff do you?
When I built my Mini at z cars the grasser with twin engines had no diff
No, no diff on this project, but I am always thinking!!!
The idea at the mo for the grasser is either use a sierra diff, welded up, mounted in bearings with a sprocket on the crownwheel mounting face, or, if
I can sort a drawing, spark erode (we have a cnc eroder at work) some internally splined bosses to take sierra output stubs and do it that way.
The latter would avoid the weight of the sierra diff, but mean more work!
I think it will end up being the sierra diff with welded up side gears............agricultural but functional............
and my degree was in agricultural engineering after all!!
why not take the gubbings from a sierra diff (ie internally splined bits) throw the rest away and weld them together.
You don't need input or crownwheel, casing etc so why carry them?
I need something to mount the sprocket to though and the gears are not really weldable steel. When the weld is more just "locking" than under full force this method works ok, but I couldn;t just weld the side gears to a home fabbed carrier and expect the welds to hold
I bought this sierra 4 X 4 "lsd" diff from a member on here who bought it from Z Cars.
Shouldn't be too difficult to make yourself.
I just need a 52 tooth cog.....If anyone has one 
diff1
[img][/img]
quote:
Originally posted by nitram38
I bought this sierra 4 X 4 "lsd" diff from a member on here who bought it from Z Cars.
Shouldn't be too difficult to make yourself.
I just need a 52 tooth cog.....If anyone has one
diff1
diff2
There were no markings at all, I had a really good look.
I don't know wether they had been ground off
David
Z cars are bastids and will only reply to your emails if they sniff some possible cash. So instead I worked out what they'd used myself...
The bearings I have used are UCPA-50 (50mm)
with the SA210 insert (to make it thin enough not to foul on the flanges) with the ecentric ring removed.
£12.79 ex vat each from Midland Bearings
You'll then need to turn up a spacer to match the sierra diff as it's a really odd size - I couldn't find a bearing to exactly match
something like this:
http://www.digital-car.co.uk/wr4/87.jpg
(ignore bearing in background that one was too wide!!)
Will get some photos of the completed setup too.
Btw B&C Express made up my 52tooth sprocket to match the sierra diff
James
[Edited on 10/11/06 by cloudy]
[Edited on 10/11/06 by cloudy]
Oh that is superb Cloudy!!! Just the info I needed, saved me loads of work!!
How much did you pay for the sprocket, out of interest?
I'll have to check for exact price but I believe it was about £40 shipped
James
forgot to mention - bearing specs are here:
http://www.fk-bearing.com/eBusiness/en/index.asp
they reference it as a UCPA210 instead of ucpa-50, same unit. midland can supply the alternate insert though - the standard bearing is way too wide
Midland seem to have most in stock...
[Edited on 10/11/06 by cloudy]
Was at the kart track today, so took a photo of a 50 mm kart axle bearing carrier.
Note this kart is partially assembled, the bearing carrier is missing the bolts that secure it to the chassis
Cheers
Fred W B
50mm
[Edited on 11/11/06 by Fred W B]
quote:
Originally posted by cloudy
forgot to mention - bearing specs are here:
http://www.fk-bearing.com/eBusiness/en/index.asp
they reference it as a UCPA210 instead of ucpa-50, same unit. midland can supply the alternate insert though - the standard bearing is way too wide
Midland seem to have most in stock...
[Edited on 10/11/06 by cloudy]
