BJ4WE Slipper

[Richard Lowe]

My guess is it will just light up the front tires and go nowhere, unless you have a proper torque split I can't see it working. Should have massive on-power understeer too.

[Lee]

So what advantage are you hoping to gain with a centre diff

[jordix]

hi, I have tested it but only near home, not at track, it seems to work fine and the car turns very well and keeps on the turn under throttle much better (this is I was thinking to gain) with no loosening of the parts and no slipping of the diff.
And yes, I know I will lose power if front or rear train light up but I think this should be compensated adjusting the differential.
By other side I think that I lose the slipper function only if the car land with four wheel at same time, if not (the usual) the excess of rpm´s will "go out" through the train that its still in the air.

This its only an experiment, as I said Im bored and Im not really very very interested in offroad racing but if somebody wants to know what parts I used for it and how I will tell gladly.

sorry if you dont understand too well my poor english!
greetings!

[fastr]

No matter if it works or not, I still would like to know which parts you used !

[albertobdq]

Think about it a little more! 1/8 bugys use central diff and don't suffer from unloading on front wheels.

While turning every train keeps much planted and it's more neutral without the rear breaking out. It seems that can always turn as much as you want.

That's what you mean, isn't it Jordix? In other words: va de cojones.

[RogerM]

Breaking through a one-way might be an issue though, you might loose a load of breaking effort on rough surfaces as the loading changes front to rear.

[Richard Lowe]

Originally Posted by albertobdq

Think about it a little more! 1/8 bugys use central diff and don't suffer from unloading on front wheels.

Don't they use oil filled or torsion diffs though? A normal ball diff has no limited slip effect at all.

[jordix]

Originally Posted by fastr

No matter if it works or not, I still would like to know which parts you used !

here you got it:

associated parts

1766-B4/T4/GT ligthweight outdrives
6589-5/32" x 5/16" bearings
7677-differential rebuild kit for RC10GT

or you can order 7677 items separately
7666-diff rings
6575-thrust bolt and t-nut
6574-thrust balls
6582-thrust spring
6573-thrust washers

-I used duratrax spur gear (78T or 81T) but I think are the same that kimbrough spurs.
-For last yor will need eight 1/8" differential balls, associated or any other (these are 1/12 cars ball differential)

you must make some dremel work because the differential bearing dont fit the spur center hole (outer diameter of the bearing its smaller), I saw that standar 540 motor bearing do it but internal diameter its worst...

I made a plastic part (like a bushing) to fit the gap between bearing and spur internal hole, you must put special attention to make it well rounded because if not the spur will be eccentrix, (I have to test the resistance of this piece, I think will be better in metal material but its more difficult for me making it).

Now you can mount the diff. and tighten till the spring full compression, then loose 1/4 turn.

When you mount the diff. you have to do it with T-nut towards front center shaft and insert first rear shaft (I "touch" with dremel the rear upper deck inner edges a bit for easily outdrive insert through).

Now you will see that front outdrive bearings need a spacer to stay in its correct site of the bulkhead, its very easy to make a spacer for this, you need a 4.5mm spacer (from a brass ballpen jeje).

In the rear outdrive bearing I used 2 or 3 shim spacers (ASC2293)

It can be that spur touches the center bulkhead cap so you know: dremel work in the center bulkhead, only a bit...

Some pics (for sucolega AJAJAJA):





The problem of the spur centering comes fron T-nut/front center shaft, with a shortest t-nut or shaft the spur wold be perfect in its place but...

[albertobdq]

Originally Posted by Richard Lowe

Don't they use oil filled or torsion diffs though? A normal ball diff has no limited slip effect at all.

A ball diff is a limited slip diff by definition. Oil used inside gear diff slow its operation making them to work tighter than they would without grease. In other words, ticker oil means more torque diference needed to make wheels turn at diferent speeds.

When you tigh a ball diff you are adjusting the diference in torque terms that is needed to make one wheel to turn faster than the other.

Ball diffs are better because their ability to change set up very easily and their much lower weight. However they can't take so much abuse as gear diffs do, and need more skills buiding and maintenance them.

"Sucolega" thanks the pics.

PS: Sioux speak better than us!

[jordix]

Originally Posted by Richard Lowe

Don't they use oil filled or torsion diffs though? A normal ball diff has no limited slip effect at all.

you can adjust the diff. action in a ball diff. like in a oil filled diff but more easily and quickly, its the same, but both have no slipping effect at all (I refer to a standar slipper clutch), diffs. slipps one wheel respect from the other not from the pulley or spur.

"hau" alberto

[fastr]

Nice work man!!
I wonder what it does on a off-road track.

BTW ever thought about a slipper on which you can adjust the amount of slip to the front and rear seperately. Solution to problems??

[albertobdq]

In fact something of that already exist. On XX4 you can find different slipper pads for front and rear.That makes them slip at different points, so there you have your idea. You can always play with that using different slipper pads or just wswapping between new and old pad to achieve the setting you want.

[fastr]

!!!!?

[albertobdq]

What's the point of that?

I mean... both springs load on the same piece so... they share tension so it's the same than a single spring with different tension. Always the softer one will "unload" and the tension on the pads will be just the same. The only thing that will vary the friction will be the mu coeficient between disc and pad.

You need something a litte bit more complex to achieve an adjustable "bi-slipper" so both end can use its own tension.

[fastr]

Oh, sorry I should have mentioned that the middle-ring is attached to the spur.......

[albertobdq]

Middle ring = piece wich the screws are attached? In that case I don't understand its design. Why is it asymetric? 2nd Newton law says that in spite middle ring is attached to the spur the tension on both sides will be the same.

[Northy]

Because if it wasn't how would you get it both sides of the spur and still one piece?

G

[fastr]

An exploded view.
Maybe this will clear things up?

[albertobdq]

Good design But... I don't have things clear enough. My brain is out of order for today, we'll see tomorrow

[jordix]

arrgh, Im going crazy but I think its the same thing as in the first drawing....