free wheeling front hubs

[jakub]

The subject was mentioned sometime ago, however idea of machining down spare set of front axle covers didn’t really convinced me since firstly it destroys otherwise perfectly good parts and secondly and more importantly leaves end stub of driveshaft without any support. When stationary driveshaft end sits in the middle of hub, however what would happen during driving, especially on bumpy road, will the driveshaft end bounce around ???

Below my answer to the matter, please bear in mind that I was getting parts in the hurry before long trip so they not finished to the look best specification, also I am including pictures first time in my post so don’t know how this will work out.

drive shaft as it is
http://imageshack.us/photo/my-images/856/img9367p.jpg/

So to go around the problem I’ve made sort of set of four parts (sleeve, magnet, rubber seal, cover), pictures below:

plastic teflon sleeve for protecting the driveshaft stub
http://imageshack.us/photo/my-images/204/img9372f.jpg/


on blind side of sleeve there is little sleeve
http://imageshack.us/photo/my-images/196/img9371e.jpg/

to hold in place strong magnet, which prevents sleeve from sliding out (when driving, driveshaft and inner part of hub remains stationary while outer hub rotates)

http://imageshack.us/photo/my-images/33/img9375s.jpg/

On top there is plastic PVC cover

http://imageshack.us/photo/my-images/838/img9376n.jpg/
http://imageshack.us/photo/my-images/259/img9377n.jpg/

for untrained eye everything looks as it should,
http://imageshack.us/photo/my-images/38/img9379q.jpg/

Of course this set-up is pain in the bottom compare to AVM free wheeling hubs.

Changing from one mode to another takes about 15-20 minutes and requires jacking one wheel in order for splines and bolts to line up.

So far I did 900 kilometres with that set up and so far results are, considerably less noise, slightly easier steering and possibly better fuel consumption.

[mudflap]

Hi Jakub,

Very nice work. I especially like your idea for holding the support in place with a magnet.

BTW, what did you use to index the eight holes for the mounting bolts? Did you just use the old hub as a jig and transfer them? Or did you use some other method?

Best Regards

[jakub]

autoCAD drawing printed and used as a guide to mark drilling points, for replaceing one with another I use cordless drill with 3/4 socket, it takes few minutes to replace one with another,

[R Cubed]

Looks much better than leaving the stub shaft to just float around. Has any thought been made to the fact that the front prop is now stationary and so is the output drive shaft of the transfer box but all of the rest of the internal parts of the transfer box are whizzing round at high speed !!!

[dr deuce]

I have had dummy hubs on my Chevys and CCKW for probably a total of 10,000 miles without any problems with the (banjo) transfer case. I keep the real hubs in a trash bag under the seat in case of ....

[mudflap]

Has any thought been made to the fact that the front prop is now stationary and so is the output drive shaft of the transfer box but all of the rest of the internal parts of the transfer box are whizzing round at high speed !!!

R Cubed,

Your point is well taken. I have been thinking about such a conversion and did not even consider this. That's one of the things I like about this forum, lot's of people looking this stuff over.

Chapter 3 of TM 9-1801 has a number of diagrams showing the power flow through the transfer case.

For the banjo design, the front driveshaft is engaged when the output shaft (A) is connected by the sliding gear (B) to the constant mesh gear (C). When the front driveshaft is not engaged, no power is transmitted, but since the output shaft (A) is being turned by the front wheels, it is spinning at approximately the same speed as the constant mesh gear (C).



If the vehicle is in motion while the front output shaft is stationary, such as when the hubs are disconnected, the constant mesh gear (C) will be spinning freely on a stationary front output shaft. Fortunately, the constant mesh gear rides a set of rollers (D). I'm wondering if the designers included this feature in anticipation of applications that would not always result in a spinning front driveshaft? Otherwise, they might have just used a bushing in this location.

As for the split design, Timken chose a very different layout. To engage the front axle, the front output shaft (A) is powered by the driven shaft (C) via the sliding clutch (B). In the above scenario, where the front output shaft is stationary and the vehicle is in motion, the only issue that I can see is if the two shafts (A & C) rub together. I'm not sure, but I'm betting that there is probably clearance between those two shafts. Perhaps someone who has been inside a split transfer case would know the answer.



In any case, I think the likelihood of any transfer case issues being caused by disconnecting the front hubs is very unlikely. Dr. Deuce's experience would seem to support this assertion.

On a related note, one thing I just realized while looking at these diagrams is that on the banjo design, the front driveshaft spins in the opposite direction of the rear driveshafts. After thinking about it, this makes sense (duhh..), since the front differential is flipped around as well. I just never noticed until now. I had always heard about the incompatibility between the two applications - now I see why this is the case.

Best Regards...

[R Cubed]

Yes it looks like the experience of Dr Deuce would prove the point just the thought of a stationary prop in the transfer box and the rest spinning round seemed a bad thing but without me investigating the boxes I though I would mention it. I have a GMC 352 split but never considered it as many shows we attend some times lead to using the front axle, as this provides some good traction.

Interesting about the banjo's having flipped the front diff so the rotation can turn in the other direction because on the splits the front axle output from the transfer box is the end of the bottom main shaft which is the output to the front rear axle and so has to rotate the same way...... Would be interesting if someone was to fit banjo axles to a split axle chassis..

[dr deuce]

Both of the xfers have the bottom gear always turning and throwing GO up onto the other parts.