Sven
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| posted on 10/4/05 at 06:04 PM |
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Chain driven differential
I could have put this in middy or BEC sections. Anyway, this is the URL of a guy building a dry lakes speed record car with a tranverse mounted
motorcycle engine. He goes into some detail about how he converted a conventional car differential to chain drive and inboard brakes:
http://purplesagetradingpost.com/sumner/bvillecar/bvillecarindexpage.html
His methods for designing his frame is also very interesting.
-Steve
[Edited on 4/10/2005 by Sven]
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andylancaster3000
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| posted on 10/4/05 at 06:31 PM |
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I do like that rear drive system, very neat. For a while i've been thinking about making a chain drive diff from a normal car diff. What i am
confused about is the fact that the diff gears need to run in a bath of oil, which in that open system, it can't!. Would it be ok to mill the
edges of the open part flat the screw a plate onto either side with grease inside of it?
Alot cheaper then the only other alternative from quaife, but then that is an ATB diff.
Andy
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Aloupol
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| posted on 10/4/05 at 06:41 PM |
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It shouldn't be that difficult to build a cover with steel sheets or from a short wall thickness piece of tube.
I think it's the way used in all the grasstrack things or the R1ot or the first Radicals?
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dblissett
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| posted on 10/4/05 at 08:22 PM |
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roit
in the kit car mag i think the riot uses a fiesta diff moded to the same effect
i couldent see how it was done from the mag tho
that to uses a chain drive look a neat job
dave
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kb58
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| posted on 11/4/05 at 12:20 AM |
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I believe they just have a cup machined to slip over the diff, with a seal at the bottom for one axle exit. The top, open end, bolts to the ring gear
flange, again with a seal.
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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Rorty
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| posted on 11/4/05 at 04:24 AM |
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quote:
Originally posted by kb58
I believe they just have a cup machined to slip over the diff, with a seal at the bottom for one axle exit. The top, open end, bolts to the ring gear
flange, again with a seal.
Correct. I've done it to Mini and Golf diffs. I usually get the guys who spin my wheel rims to spin me a thing that looks like a desktop lamp
shade which slips over the diff and is sealed by an O ring close to the CW flange and at the opposite end by another (much smaller) O ring. The whole
lot is kept in place by the RH bearing/plummer block.
A simpler cover could be welded up from some suitably sized aluminium (or steel I suppose) tube with an end plate.
I usually weld a bung into the side of the cover for adding/draining the oil.
I read on another thread here recently that the Escort English diff has just a few holes in the casting which could be welded up thus doing away with
the need for a cover. Just don't forget to add an oil bung.
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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Spyderman
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| posted on 11/4/05 at 02:38 PM |
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A fascinating site and very useful for ideas!
I like the chain drive diff, but would question his planning! Alot of it is trial and error, not bad in itself, but why make a spacer for the sprocket
and then machine the diff down as well? Plus using different materials together does not sound good engineering practice to me.
Also for the purposes of the vehicle why even bother with a differential at all? He is hardly going to need to make sharp turns!
A locked diff would be far simpler and lighter.
I hope he is going to make a steel or alloy cage for the cockpit. I wooden  fancy driving inside a wooden body at anything above 100mph.
I know aircraft were made of wood, but they were not designed to survive a crash.
Got to be worth keeping an eye on now and then to see progress.
Terry
[Edited on 11/4/05 by Spyderman]
Spyderman
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Sven
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| posted on 11/4/05 at 02:59 PM |
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quote:
Originally posted by Spyderman
Also for the purposes of the vehicle why even bother with a differential at all? He is hardly going to need to make sharp turns!
A locked diff would be far simpler and lighter.
He says in his diary he has a welded up spider gear that he plans to use, which is, essentially, a locked diff/spool.
FWIW, I have a friend in Payson, AZ who built a +200mph salt racer and the last thing on his mind was saving weight. in fact the opposite, a light
weight lakes racer would be unstable. For example, rather than use a radiator my friend uses a 30gal total loss water tank placed in the car to help
traction and balance.
AFAIK, all the lakes racers use frames made from scraps of wood and fibre board ...  ...
-S
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Sven
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| posted on 11/4/05 at 03:02 PM |
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quote:
Originally posted by Rorty
Correct. I've done it to Mini and Golf diffs. I usually get the guys who spin my wheel rims to spin me a thing that looks like a desktop lamp
shade which slips over the diff and is sealed by an O ring close to the CW flange and at the opposite end by another (much smaller) O ring.
Hey Rorty,
I am discussing this elsewhere, privately, with a friend. Anyhow, he suggests that overfilling the differential may result in a bad beer story, as
the fluid expands it could cause hydraulic lock or even blow a hole in something.
Any hints for how much to fill a converted diff?
-S
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Rorty
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| posted on 11/4/05 at 09:18 PM |
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quote:
Originally posted by Sven
quote:
Originally posted by Rorty
Correct. I've done it to Mini and Golf diffs. I usually get the guys who spin my wheel rims to spin me a thing that looks like a desktop lamp
shade which slips over the diff and is sealed by an O ring close to the CW flange and at the opposite end by another (much smaller) O ring.
Hey Rorty,
I am discussing this elsewhere, privately, with a friend. Anyhow, he suggests that overfilling the differential may result in a bad beer story, as
the fluid expands it could cause hydraulic lock or even blow a hole in something.
Any hints for how much to fill a converted diff?
-S
I just put enough oil in the can to keep everything damp using the splash method. Definitely don't fill her up like a conventional rear end.
As with just about every home made car, I'm inclined to change oils etc on a more frequent basis than my factory built cars.
There's so much space in there that even with heat build up, the air does not pressurise enough to blow seals. If you were in any doubt at all,
you could fit a pressure valve to the can.
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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chrisf
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| posted on 11/4/05 at 11:27 PM |
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quote:
I just put enough oil in the can to keep everything damp using the splash method.
You have to be careful with that too, right? If you put too little fluid in, the oil gets whipped to the outside of the diff by centrifugal force.
Then, none of the bits get oiled. But like Sven says, it would seem that too much oil could blow the party to bits.
Rorty, how do you trap the oil in the LSD?? Do you make a casing over the LSD and cap it off at the top?
--Chris
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Rorty
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| posted on 11/4/05 at 11:38 PM |
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quote:
Originally posted by chrisf
Rorty, how do you trap the oil in the LSD?? Do you make a casing over the LSD and cap it off at the top?
--Chris
quote:
Originally posted by chrisf
Rorty, how do you trap the oil in the LSD?? Do you make a casing over the LSD and cap it off at the top?
--Chris
I have only encased open Mini and Golf diffs, but I can't see the problem with encasing a LSD in the same manner.
Encased Torsen diffs just run in a bit of aluminium tube like the one below.
 
Rescued attachment Torsen_02_sml.jpg
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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chrisf
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| posted on 12/4/05 at 12:07 AM |
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Thanks for the pic. How do you keep the oil from leaking out where the driveshaft 'ears' are inserting into the diff?
--Chris
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Rorty
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| posted on 12/4/05 at 12:27 AM |
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quote:
Originally posted by chrisf
Thanks for the pic. How do you keep the oil from leaking out where the driveshaft 'ears' are inserting into the diff?
--Chris
There's no direct route from the output shafts to the oil inside. Some output flanges require an O-ring, but some are actually stub shafts which
are sealed.
It depends from one application to another.
On BMWs (and some others), the only thing sealing the drive flange and holding the complete CV and axle to the diff is an O-ring!
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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chrisf
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| posted on 12/4/05 at 12:51 AM |
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I think I'm missing something then because I'm not following. In the picture, the fancy bit is the casing that encloses the diff/LSD. The
output shafts (thanks for the correct term) are splined sections that slide into the differential. Do they not have to pass through the custom casing
that is filled with oil?
Perhaps I need to buy an LSD and have a look at how these things work. Do you reckon a BMW is a good candidate for the application?
--Thanks for the help, Chris
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Rorty
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| posted on 12/4/05 at 01:40 AM |
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quote:
Originally posted by chrisf
I think I'm missing something then because I'm not following. In the picture, the fancy bit is the casing that encloses the diff/LSD. The
output shafts (thanks for the correct term) are splined sections that slide into the differential. Do they not have to pass through the custom casing
that is filled with oil?
Perhaps I need to buy an LSD and have a look at how these things work. Do you reckon a BMW is a good candidate for the application?
--Thanks for the help, Chris
The Torsen unit, in the post above, has male drive flanges which are about 160mm long and have splines on their inner ends. These do run into the
centre of the diff amongst the other components and the oil and they either require O-ring grooves machined into the shoulders to seal properly, or
sealed outer bearings.
As I said though, some male flanges are inserted into sockets and are isolated from the oil.
Some drive flanges are female and are circlipped onto the male splines of the stub shafts.
I only mentioned the BMW diffs as I'm quite familliar with them too; I've used them and their CVs and axles on many occasions. The larger
cars (7 series?...can't quite remember) use the same infamous "930" CVs as the Porsche 911 Turbo. They'll cope with big
amounts of horsepower and torque.
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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Sven
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| posted on 12/4/05 at 02:52 AM |
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FWIW, chrisf is the other party in the aforementioned private discussion. He and I have been discussing BEC engined middies for some time and
we've been researching converting a car diff to chain driven.
Looks reasonably straightforward now we've talked to just about everyone that knows and read everything we can find ... 
I'm intrigued about how to convert a FWD transaxle because my impression is that they are usually lighter weight than a typical RWD differential
and, probably, easier to source. I'll just have to obtain one and stare at it while holding a beer, that usually works for everything else.
-S
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Rorty
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| posted on 12/4/05 at 03:08 AM |
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quote:
Originally posted by Sven
I'm intrigued about how to convert a FWD transaxle because my impression is that they are usually lighter weight than a typical RWD differential
and, probably, easier to source. I'll just have to obtain one and stare at it while holding a beer, that usually works for everything else.
-S
I can highly recommend the Golf diff in that case. Once you have it fitted, you can swap it over to a Quaiffe, or even better, a Peloquin diff.
There are dozens of suitable axle lengths available too (different lengths on each side of a Golf plus various different models). You can also buy
racing CVs off the shelf for the Golf CV PCD.
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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sgraber
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| posted on 12/4/05 at 04:02 AM |
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Steve, Sven, whatever your name is... LOL
Since you are in Phoenix, we need to get together soon to discuss this chain diff issue.
My neighbor just gave me a Honda differential from a mid 90's Acura LS 5 speed and it's a small, lightweight unit. I can easily see that
it's only 6.5" from bearing to bearing. Once I remove the main gear I'd bet it's only a few pounds.
Graber
Steve Graber
http://www.grabercars.com/
"Quickness through lightness"
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kb58
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| posted on 12/4/05 at 04:19 AM |
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quote:
Originally posted by sgraber
Steve, Sven, whatever your name is... LOL
Since you are in Phoenix, we need to get together soon to discuss this chain diff issue.
My neighbor just gave me a Honda differential from a mid 90's Acura LS 5 speed and it's a small, lightweight unit. I can easily see that
it's only 6.5" from bearing to bearing. Once I remove the main gear I'd bet it's only a few pounds.
Graber
Alright Steve/Sven/Graber, are you writing this to yourself? I think it's time to give your other selves a rest...
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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Rorty
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| posted on 12/4/05 at 04:24 AM |
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quote:
Originally posted by sgraber
Steve, Sven, whatever your name is... LOL
Since you are in Phoenix, we need to get together soon to discuss this chain diff issue.
Graber
I expect a full dissertation from Phoenix by next Monday! 
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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sgraber
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| posted on 12/4/05 at 01:32 PM |
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damn ! You're onto us... Brothers from different mothers... 
j/k
Steve Graber
http://www.grabercars.com/
"Quickness through lightness"
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Sven
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| posted on 12/4/05 at 03:24 PM |
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quote:
Originally posted by sgraber
damn ! You're onto us... Brothers from different mothers...
j/k
Steve got the brains and I got the stunning good looks.
Hey Steve, doesn't the Honda motor/diff rotate in the opposite/unconventional direction, meaning it would be perfect for your new aquisition?
I'm excited about this whole thing and seeing your car ... let's make a date.
Rorty, sounds like the VW diff is perfect for me, as I'm planning to use a R1 motor.
-S
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Rorty
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| posted on 12/4/05 at 10:11 PM |
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quote:
Originally posted by Sven
... let's make a date.
-S
OK guys, don't forget the diff the the primary concern here.
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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Spyderman
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| posted on 12/4/05 at 10:33 PM |
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quote:
Originally posted by Sven
He says in his diary he has a welded up spider gear that he plans to use, which is, essentially, a locked diff/spool.
AFAIK, all the lakes racers use frames made from scraps of wood and fibre board ... ...
-S
Must admit I never read all the text, just skimmed over it!
Still seems like a lot of unnecessary work using a diff at all.
Can't understand why they would want to add weight when using such a small capacity engine. Seems counter-productive to me!
Why use the wood if it is not to keep weight down?
Not argueing, just don't understand the logic!
Terry
Spyderman
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