New forum member, old 6x6, new problem needing help.

[cj7hawk]

Hi All,

I bought an old Max2. I'm not sure how old ( does anyone track serials? ) and I probably paid too much for it ( around US$2K ) but I figure to try and get it going. Forward works, steering works, plenty of rust and buckets of mud in the bottom that I'm having trouble getting out. Aside from that, no reverse.

So I'm pulling the transmission out, and I'm expecting that the outer drum is missing all of it's teeth.

Are there any easy ways to fix this that can be suggested? Do people make inserts to rebuild into the drum, or are these drums obtainable in good condition?

One other problem - I'm in Australia.

Any thoughts on the topic would help -

Thanks
David.

[dirtdobber]

Hey CJ,

Welcome to the world of 6x6'ing. Before you pull the transmission, adjust the bands. It is highly unlikely that all the teeth are missing from the drums. Make sure transmission linkage is working properly and properly adjusted. If it's not the band adjustment or shift linkage, they it could be the bands. I assume the diamond shifters are working correctly since you have forward, but you could pull them just in case. I guess you could have two bad pins and someone just set it to forward and put the shifters back in place.

Good luck.

[cj7hawk]

What I've checked.

I too thought that all of the teeth missing was a lot to ask, so I did the following;

1) Checked the pins. One was in place and in reasonable condition. The other was replaced with a center pin. Both seemed to operate the selector OK.

2) There is no feeling of resistance going into reverse.

3) With both band selectors pushed forward, the clutch wheel can't turn - which is what I'd expect if they were both working.

4) Operating the band selectors manually has no effect. Reverse still won't engage.

5) I've tried pushing the selector all the way out with a screwdriver - no improvement.

6) It's not that they don't move without enough power - they don't move at all. Manually pushing the chain around to give some slack so it can take it up, and then selecting reverse, accomplishes nothing.

So I'm thinking that the only thing I can think off is that all the teeth are missing, as strange as that seems.

I've been pulling this thing down for a couple of weeks in my spare hours, and need to remove the engine today. A couple of the bolts for the mount point are snapped off Not ideal Just rigging up a small crane to do the task now.

Also, the chains to the transmission are locked. I've removed the retaining pin, but it won't come apart. Any suggestions? The chain was a little stiff, but articulates OK now - except I can't get the locking pin out.

Thanks
David.

[dirtdobber]

Let's go back to your original post. You said forward and steering works. If you are able to steer, then I guess you mean when going forward you pull back on one lateral and the wheels lock on that side. If it will do that, the I don't believe bands and drums are the problem. When in forward, the reverse band and drum provide the braking action.

Let me ask a question but please don't be offended, because some people don't realize how these transmissions work. Are you aware the transmission has a forward, neutral and reverse gear setting? This is what the diamond shifters do. To get to reverse, you shift the transmission into reverse and then pull BACK on the laterals. To go forward, shift the transmission to forward and push FORWARD on the laterals.

You are finding NO resistance when shifting into reverse, then take a closer look at the diamond shifters and work you way back to linkage. Remove the diamond shifter and with a screwdriver slide the shift collar through all three positions - F, N, R. You should feel resistance as there is a detent for each position. With it in reverse, pull out on the top plungers (pull back on the laterals) and rotate the driven clutch. The sprockets should turn (very slowly) in reverse. If that doesn't work, you're going to have to tear it down and see what's happening.

[cj7hawk]

Thanks for the suggestion - I only figured out how the transmissions worked last week, and I can lock up one side while turning, so the bands seem OK. I never thought to explain it that way, as I can also turn with one side running and the other loose.

I didn't know about the detent and I though there might be something like that - I can feel it OK when I transition through neutral. Knowing what it's supposed to feel like during transition helps. What I meant was that I can feel resistance going into forward gear, which isn't present going into reverse.

I got the unit out last night - never realized how heavy it is!!!! Anyway, I selected reverse manually, and turned the clutch, and sometimes got sporadic movement without any chains attached, but even a slight pressure with my finger would stop them turning and they would make a quiet grinding sound. Also when I select reverse, I'd expect to feel the same resistance to turning a sprocket by hand that I feel when I select forward, and it simply wasn't there. There also wasn't the feeling of turning any mass within the unit.

I am dreading the tear down for what I might find inside. I'm in Australia and there's no support for these locally. I have a horrible feeling it might come down to machining replacement parts.

Are you able to tell me if entire transmissions come up for sale often? It would make sense to look around for one but they seem to have gotten thin on the ground.

[dirtdobber]

Only occasionally do I see an entire transmission come up for sale. What is more common is that a not-in good-shape machine becomes available. Of course you never know what you are getting. Tear yours down and see what you find.

[ARGOJIM]

I'd pull the diamond shifters, easy enough just 2 cotter pins and loosen 4 bolts. The problem you are describing sounds like wore pins, moreover pins wore one one side.
Quick easy and accessible.

[cj7hawk]

Thanks for that - the diamond shifters look good. I mean, not great, but compared to the ones I see photos for they look good. And one side looks like a relatively new rolled pin. I suspect someone already suspected the diamond shifters in the past and replaced the pin just generally.

I got the transmission out and just waiting to clean up my garage a bit before I strip it down. Hopefully in a week or so.

BTW, how likely is damaged material inside the transmission to cause further damage elsewhere? Or does it tend to collect in a safe place where it can't cause further damage.

Thanks
David

[cj7hawk]

Yep, ring gear spline all stripped out... No obvious damage to any other gears...

I reckon they must have made these things out of some really soft cast iron to strip like that.

IMG_20191204_190929_9 (Small).jpgIMG_20191204_191155_8 (Small).jpg

[cj7hawk]

A quick question - has anyone ever cut a gear from the forward plate and installed it into this drum? Also does anyone know what the thrust bearings are made from? Thanks.

[dirtdobber]

That's amazing. I wonder how many hours of operation it takes to accomplish that level of wear. Of course, there could have been a whole lot of grinding the gears when shifting.

I don't know if anyone has ever done a repair as you suggest. I think these drums are cast iron, so welding a new set of teeth to the old drum is not ideal, but probably doable. Unless you can do the work yourself you may come out ahead if you can find a new drum.

Are both drums damaged like this?

[cj7hawk]

I haven't pulled the second drum yet, but I'm expecting the same.

There was very little visible wear on the selector, so I'm assuming it's a hardness mismatch... How many hours? Well the hour-meter was disconnected but it stopped at 127 hours or thereabouts. I think it's only about 5 to 6 years old.

How did this happen? I have no idea. I can only guess someone really mistreated the reverse, or constantly held the sticks back when changing to reverse... Or perhaps the ring gear drum was just too soft and simple pressure and hard surfaces was enough over time. How they managed to do BOTH like that though.... I'm really scratching my head. Maybe someone tried to engage reverse with the engine speed too high, and it just machined away the teeth or something.

Another suggestion I got was an interference fit... Make the gear replacement larger than the hole and freeze it and then insert it, so that it jams in place.

It doesn't seem like 18 tooth replacement ring gear drums are available, so getting replacements doesn't seem like an option.