Older MaxIV - Maintenance & setting expectations

[tyson72]

I picked up an old MaxIV about a year ago. I don't know how old it is really...but it looks pretty old. It has the splined axles with set screws for the drive sprockets if that helps...the metal plates are all painted over.

Bought it on a whim...I really don't know much about the history/versions-iterations/etc. It ran great and then started to have clunking noises/chain would skip off of the rear left drive sprockets (between transmission and rear axel on engine side), bearings blew up and disintegrated on a couple of the idler/tensioning sprockets.

I could always take bits of it apart, get things lined up again and have it running for a bit longer...but it was getting to the point that I'd get in a bit of time driving around and then it'd be out of commission again with the chain off of the sprocket (same one).

Eventually got enough of it apart (vs. just finagling the chain back onto the sprocket) to find that the set screw that fixed the rear sprocket (on engine side) had sheared, which let the rear sprocket set slide left/right on the splined axel. As it did that over and over the teeth of the large sprocket got really chewed up. Thankfully the transmission sprocket is ok.

To get the rear chains that connect the transmission to the large rear drive sprockets "tensioned" (in quotes because it's still pretty sloppy on the left engine side) enough, the two tension/idler sprockets are maxed out pulling the chain in as much as possible.

I drilled and tapped a new set screw through the rear sprocket, shattering two taps like an idiot as I was doing this out in the middle of a field balancing everything on a lunch box, and divot in the axel. Got it lined up enough so that what's left of the teeth on the large sprocket are centered/lined up with the transmission gear. Runs decently smooth now...hopefully for a while until some new parts come in.

I had to scavenge an idler sprocket from the front chain to get the rear two axels driving (took out both front chains) as they ate their bearings, so it doesn't steer all that well over bumps/uneven ground at the moment.

So...I think what happened was that the bolt that holds the end of the axel to the frame backed out (found it in the floor pan rolling around)...the axel backed out enough to strain the idler sprocket laterally (then it eventually blew it's bearings) and it strained the set screw of the drive sprocket enough to shear it (allowing the sprocket to move around on the axel). Then the drive sprocket was misaligned...allowing the chain to chew up the sprocket teeth and stretch out the drive/transmission chain.

Ordered a couple of sets of idler sprockets, new rear drive sprocket sets, new rear drive chains, new transmission chains and "splined axel screw collars". My rear axels don't have the spring/c-clip retainers and washers/spacers to keep the rear drive sprocket lined up...so the collars should clamp onto the axel on either side of the sprocket and keep it in place.

Being in Canada and ordering from https://6x6parts.com/...I hope things clear quickly through customs. I'm anxious to get these new parts in and hopefully I won't be wrenching on this thing every couple of hours to keep it going.

General questions for others:
How often do you go over your 6x6's to check that things are tight/inline/tensioned/etc...? After a given number of hours? Every so many outings?

Although probably best, I can't see doing that before/after every use (it'd be a pain to take out the seats/floor boards each time), but I don't want to end up stuck again.

[john swenson]

hey tyson ... max 4 are great machines . when they have sat for a good while ( any 6x6 ) it's usually chains . sprockets , axles and and bearings and idlers that need attention . once you have repaired and replaced whats needed , just general maintenance can keep them running well . chains oiled and correct tension on chains and bearings lubed good from time to time . i don't think it's always needed to check everything after each ride . maybe after a couple of days of heavy mud bogging or such. maybe check the set screws on the sprockets every so often . you can usually hear or feel when something amiss when riding . anyway have fun and keep us posted . you will have alot of fun with it . johnboy va.

[tyson72]

Thanks for that, much appreciated. The MaxIV that I got only had the factory plastic foot/floor panel for the driver's feet....the rest of the benches/floor was missing. I bolted together a bunch of L channel and plywood to make up some benches and a floor board for the rear passengers. They're tightened down to the studs that were already in the frame. They're removable, but a pain. They're a decent fit...but there's gaps on the sides (not much...1/2" or so) of the seats/floor boards...so when I go bush wacking it it I end up with a lot of pine needles/leaves/twigs/branches/etc...in the bottom of the tub.

I'm wondering if it's worth it to fix in a bunch of that under the door weather stripping strips to try and reduce the amount of stuff that gets in there...or maybe it's futile and just how things are.

Do the original floor panels and seat design stop stuff from getting into the bottom? If so how? Is it molded/wrapped up the side of the tub to make a seal...is it just a really tight/close fit....etc.?

Or is it "normal" to collect a bunch of stuff as you ride and you just take out the seats and floor boards every so often to use a stick and a vacuum to get all the junk out? I've got a small ecosystem accumulating in the back area by where the drain hole plugs are.

[john swenson]

most all machines get debri in the tub when running thru woods , high brush , etc. if you are not planing on having passengers there's no point in a back seat or floorboards . just the front seat and a small floorboard for your feet is sufficient . the advantage to that is it makes easyier access to chains and bearings and tensioners to keep a eye on them . the floorboards don't really need to be fastened down .they may rattle a bit but are quick to remove for cleaning . your choice. some max 4 guys who don't carry people install just a single drivers seat . original seats and floor pans still won't keep out all the stuff. i use a shop vac to get out most stuff , then park my machine on a small slope , pull the drain plugs and use a hose and nozzle to wash the rest out . you may need to '' unplug the drain holes '' cause sticks and stuff will plug them up while washing. j boy

[tyson72]

Ok, I'll just keep at it with vacuuming it out occasionally. Since it's been broken down a lot I've been leaving the rear bench and rear floor board out.

90% of the reason I bought this thing was so my buddies and their kids could goof around in it and so to that end it's been money well spent (lots of giggles and laughs every time) and I think I'll keep the rear bench in there for that purpose. For the size of the MaxIV (~5'x8') there's surprisingly little room in the back bench...especially if the guys are wearing rubber hunting boots. I guess I could have put the front bench up a bit further but I didn't want to have to contort myself getting in and out.

That's why when I got it the old guy didn't have the original benches/interior. He had taken it all out (and it was all junked/stolen from his property) to put in a flat platform and a single boat chair. He used it for fishing around his pond with his dog.

[john swenson]

sounds good . they are alot of fun and will last lots of years with a little tlc . jb

[tyson72]

Definitely! It's been great fun so far and I think I'm just a bit disheartened that it's been beat up enough to be not-so-reliable. Of course wherever it breaks down it's in either in boggy mud or else chest high grass and it's a pain to drag all the tools/jacks over to work on it. I'm getting pretty good at it though now...LOL

Parts are on order and I'll go from there.

[john swenson]

new parts equal peace of mind ! jboy

[tyson72]

Just a little follow up...

From 6x6 Parts...I bought
2x rear sprockets
2x rear drive chains
6x idler sprockets

The right side rear drive sprocket and chain were in really good shape still, but the left drive side was all chewed up. Replaced that side's drive sprocket (transmission sprocket was fine) and both middle chains, put back in the front chains (makes a huge difference when trying to turn). Finally the drive line was reliable again...hasn't broken down/slipped its chains since on several outings. Checked and adjusted tightness in the chains after the first couple of outings.

...then the throttle cable snapped...LOL. It was rusted and frayed...and eventually let go. Ordered a replacement heated throttle cable and throttle lever and got that installed.

So I have an extra drive sprocket, extra chains and a few extra idler sprockets on hand now for emergencies. In the spring I'll see about fixing up that throttle cable to have a spare one too.


The last post of "new parts equal peace of mind" = so true!

Now it's running like a champ again. Thanks to all for the advice.

Tys