Sprocket spacing question

Doug Johansson · Post by **Doug Johansson** » Sun Mar 20, 2011 10:03 am

Apologies for the newbe question

but the manual states that the drive shaft must be flush with the outer edge of the taper lock but mine is approx 3mm too shallow. Even if I mount so that the sprocket is rubbing against the drive housing it is still not flush so my question is just how important is this?

From my experience with 1/8 tanks unless everything is aligned 100% with the track guide horns then the track will have a tendency to ride up off the sprocket (or idler)

Heres a pick of the gap between the shaft and taper bush.

And heres the gap between the sprocket and drive housing. How does this compare to other Shermans out there?

Robert E Morey · Post by **Robert E Morey** » Sun Mar 20, 2011 8:01 pm

Doug, the spacing of the sprocket to the drive housing is way more critical, and the spacing on yours looks about right. Mine looks the same as yours, just enough to clear the screw heads plus a little extra. The spacing of the drive shaft to the end of the taper bushing is a rule of thumb only, and not critical.

It is most important that when the sprocket is mounted that the track is not twisted, and moves straight over the sprocket and down to the bogeys. This will reduce the track tendancy to ride up over the sprocket. Finally make sure it never hits the drive case. It will do some serious damage to the drive case housing if contact is made. I machined a brass spacer (fits on drive shaft, between gear case and taper lock bushing) to insure the sprocket never hits the case on my tank. Below is a photo of the bushing I made for the Panther, same idea applies.

Keep the sprocket spacing as you have it away from the gear case. It doesn't really matter that much where the end of the drive shaft is in relation to the taper bushing.

Hope that helps.
Bob

Adrian Harris · Post by **Adrian Harris** » Sun Mar 20, 2011 8:06 pm

Hi Doug.

As you have the drive gear casing off, are there any witness marks on the outside face of the main front housing, from the drive gear rubbing on it ?

If there are, it would indicate that the drive gear isn't being held in the bearings, which might explain the gap at the end of the taper lock bush.

Adrian.

Doug Johansson · Post by **Doug Johansson** » Sun Mar 20, 2011 8:37 pm

Thanks gents, I believe the previous owner (Dale) has already made up a alloy spacer (see pics below) for the sprocket as a spacer is not illustrated in the owners manual.

As Robert states I suppose the critical thing is the gap between the transmission housing and sprocket and to also ensure there is no lateral movement in the shaft

I was originally thinking that perhaps I needed to file the spacer down so that the taper bush and drive shaft were flush (as stated in the manual) but then realized if I were to remove any more material from the spacer then the sprocket would rub on the transmission housing.

Heres some pics to explain what I mean. BTW those minor rub marks you see on the transmission housing were from me seeing what happens when I remove the spacer I.E. the sprocket rubs on the housing. Currently I have no motion pack to test the running gear.

Post by **Armortek** » Mon Mar 21, 2011 8:46 am

Hi all

This is one that come up quite frequently. There is golden rule in the use of taper lock bushes. Never fit a spacer behind a taper lock bush. The reason is, it prevents the taper lock bush from being properly fitted. This rule is repeated by all the major taper lock bush manufacturers. The installation instructions for the bushes are printed in all the recent manuals and there is a link in the tech section of this forum.

http://www.armortek.co.uk/TaperlockLR.jpg

The spacing of the sprocket should be judged from the hull side so as to line up with the wheels etc. The alignment of the end of the drive shaft is not critical and will vary considerably from model to model.

Mark

Robert E Morey · Post by **Robert E Morey** » Mon Mar 21, 2011 4:11 pm

Doug,
Interesting to see the mud? smeared on the sprocket and gear case since the tank is not fitted with RC motors. Someone weathered the tank natuarally with mud? Thats some serious dedication.

Do you intend to make it RC? The sherman is a nice driving tank.
Bob

Phil Woollard · Post by **Phil Woollard** » Mon Mar 21, 2011 4:32 pm

Hi Doug, if you have no motion pack as yet and want to check the running gear a quick and slightly mad way ( it must seem mad to the people living next door) is to pull the model around the garden I use a ride on mower, you can then check those witness marks on all the relavant surfaces and then maybe make some adjustments, this also breaks it all in so the motor/gearbox has less work to do when you finally fit the motion packs, cheers Phil.

Doug Johansson · Post by **Doug Johansson** » Mon Mar 21, 2011 7:39 pm

Re: Armorteks reply in not recommending the use of spacers if I was to remove mine then the sprocket would definitely rub on the transmission housing however im not 100% sure just how far the taper lock presses into the alloy drive hub.

If you look at my first pic in this thread you will see the taper lock protrudes from the hub by 1-2mm even with the 2 grub screws locked down as tight as they can go. In this scenario even without the using the key way on the shaft the hub is locked down onto the drive shaft pretty darn good. (unable to remove by hand) so I would say the taper lock is doing its job pretty well.

But the question remains, does the taper lock also need to sit flush in the hub as if it did perhaps I could get away with not using the spacer and maybe the sprocket would not rub on the transmission housing. will need to investigate further.

Bob, yes this Sherman looks like it has already seen some major action even though it has never moved an inch under its own power! Very nice paint job on this one

Phil, maybe I could sit my 2yo inside and push him around to bead in the tracks at least this way I wouldn't look like a complete idiot

Post by **Armortek** » Tue Mar 22, 2011 9:26 am

Doug.

Please read the instructions for fitting the taper lock bushes again. The bush does not need to be flush with the shaft. The bush does not need to be flush with the face of the sprocket centre. DO NOT USE SPACERS. Fit your bushes as the instruction state, including the part where the bush is tapped up the taper. The bush will grip the shaft axially and radially and the sprocket will not hit the drive case if you set the bush to suit the rest of the running gear. Once again DO NOT USE SPACERS.

If you use spacers you will not be able to tap the bush up and it will fail in service. DO NOT USE SPACERS. Hopefully this clear.

Mark

Doug Johansson · Post by **Doug Johansson** » Tue Mar 22, 2011 10:22 am

Ok thanks Mark. Got the message loud and clear

I will remove the spacers and give it another try. Glad I asked the question now before actually installing the running gear. Hopefully this helps out other owners besides myself as based on reading through all the various posts within the forum there seems to be quite a number of other tanks using spacers on the drive shaft.

Its great to have such great aftermarket support from the manufacturer as well as other experienced owners who lurk around here.....cheers