Jebster's 10x10 HEMTT rollback hauler

[jebster]

That is a nice looking body. I've given up finding one that will work that I can buy or 3d print myself so I order a big lot of styrene and plan on makings the cab myself. Haven't really done that much body work before so this will take awhile.

Originally Posted by vwdaveb

Been working on this body for some time now. Started with someone else design but didn't like allot of it, so doing my own. Think I'm going to make it a go anywhere camper. Like your ideas. Going to use that steering idea in the rear. Started out was going to be 1/16 with WPL axles. Now I've decided to do SCX10 axles, with one set coming from a scrapped AX10 Crawler. Hope you don't mind showing these in your post. The different colors are for me to help distinguish the differ parts.

[jebster]

It's been a long time since I worked on this rig. Took it out for a test run and snapped the remaining piece of the GRU output shaft off. I guess the GRU just isn't meant for this much power. So I decided to change up the drivetrain. I had an ax2 tranny hand so I swapped that in. Had to run it through another transfer case to help reduce the gear ratio down. Plus having the 2 speed might be needed to give it any speed.

I also started prepping for the lower skid, floor and fenders. As you can see my plan is to bend up a single sheet of ABS so it will be a smooth continuous surface. Given the front sticks out over the wheels that should help it slide over surfaces.

[jebster]

Got the ABS sheet cut and bent. Fits well. Need to drill a couple holes to connect this to the frame.

Once I get this mounted I can start the rest of the body.

[Evilsage]

Wow, what a great build so far!

[jebster]

Originally Posted by Evilsage

Wow, what a great build so far!

Thanks. Hard to believe i started this project over 1.5 years ago. Did a couple others during that time so this has been on the back burner off and on.

I have continued to male progress. Over the past week I did get started on the cab. I like working with styrene but I need to be patient. Plus I need to set my expectations appropriately. Seeing some of the masters on here and what they can do is a far cry from what I will probably accomplish.

A few pics of the cab as of today. As you can see i will have the windshield and roof swing forward to get access to the electronic including the battery. I'll also have a hatch to get to the motor.

[jebster]

Was thinking about different tires for this rig. Came across a crazy idea.

[jebster]

Got some more body work done. Cab front is held in place by magnets. Engine bay is hinged and will also be held shut with magnets.

Lots of finishing work, filling and sanding to go but it is taking shape.

[chino]

Very cool!

[Natedog]

Wow dude, coming along very nicely! Difficult for me waiting on parts, modifying, then figuring out the parts I fabbed are not up to my standards or thought of a better way to do it. Looking forward to your progress and updates!

[jebster]

It's getting there. Have all the mechanics up and running. Added a winch and lights to the bed, operated by the radio. Body is coming along too. Needs accessories and some filler, a little sanding then paint. I will be adding a simple interior to cover the electronics.

A video and some current pics.

https://youtu.be/wBGdNXKPCAU

[jebster]

Did a little more accessorizing. Exhaust, light bar and started a spare time rack.

[bbrigg]

How do you get the dual steering axles to work? 1:1 trucks have different length Ackerman linkage so that the forward wheels deflect a little less for tight turns. Is that needed on scale vehicles?

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[jebster]

Originally Posted by bbrigg

How do you get the dual steering axles to work? 1:1 trucks have different length Ackerman linkage so that the forward wheels deflect a little less for tight turns. Is that needed on scale vehicles?

Sent from my LG-H870DS using Tapatalk

If you look at post #19 there are pics that should help you see what I did. Both axles are 3-link with a panhard bar. I used a steering block for a tamiya semi on the chassis end, with both of those connected to a single servo. Works pretty well.

I know on full size rigs used different Ackerman for the axles but I always assumed the front axle would turn more. I'll have to do more research.

Right now mine runs both in parallel. They are turning to the limits of my knuckles so I can't increase the turning radius for either. But if dialing one back would actual make the rig turn better or cause less stress on steering linkages I could mess around with the lower arms on the chassis mounted steering blocks.

[bbrigg]

You did a great job putting this together and I would like to see some video of it in action.

I'm not sure how much better any slight change in steering angles would make your rig turn. I spent a year in Myanmar a couple of years ago and there are a lot of dual steer trucks there with either dual or triple axles at the rear. The reason for this is to reduce the front axle loading without having a long overhang at the rear. Only rarely do they run dually wheels so your rig reminded me of them.

On the steering linkage the rears do turn a little more. Since that axle will inscribe a slightly smaller circle than the front axle it makes sense. With the low actual loading on a scale vehicle I'm not sure just how worthwhile it would be from a turn radius/tire scrub/linkage stress standpoint but it would sure look cool.

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[jebster]

Originally Posted by bbrigg

You did a great job putting this together and I would like to see some video of it in action.

I'm not sure how much better any slight change in steering angles would make your rig turn. I spent a year in Myanmar a couple of years ago and there are a lot of dual steer trucks there with either dual or triple axles at the rear. The reason for this is to reduce the front axle loading without having a long overhang at the rear. Only rarely do they run dually wheels so your rig reminded me of them.

On the steering linkage the rears do turn a little more. Since that axle will inscribe a slightly smaller circle than the front axle it makes sense. With the low actual loading on a scale vehicle I'm not sure just how worthwhile it would be from a turn radius/tire scrub/linkage stress standpoint but it would sure look cool.

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Thanks. this is a fun project and i'm always having to tweak the design.

and you are probably right about the steering. while it is heavy I would expect it doesn't scale up to be comparable to the weight a 1:1 10x10 HEMTT is carrying so my turning radius is probably good.

I've only done a couple quick runs to check out drivetrain but once I get it to a reasonable level of completeness i'll get it out and have some action video.

[jebster]

It keep moving along. Made up a center skid and the spare tire rack.
I slapped the wheels on and took it out for a spin. I'm liking it! Did learn or confirm a few things:
- The shocks need firmer springs. I'm thinking slash front blue springs will be better.
- Definitely need much firmer foams in the tires. I'll check out CI but given I need 10 I'll see if there is a homebrew solution.
- Given the turning radius is not surprisingly less than I would like I'm thinking of adding steering to the last axle. I think I can tuck a low profile servo back there. I can set it up like the front two axles with 3-link and a panhard bar. It will require some creativity but I think I can make it work.

Now for a couple pics and videos.

https://youtu.be/n1HZwwHfijI

https://youtu.be/HwByNzdTzKE

[jebster]

After looking it over I think I can add steering to the last axle. I have the axle parts, would just need a low profile servo, a servo stretcher (so I can adjust center/end points separately since it will run on the same channel as the existing steering) and some beef tubes so I can clock the knuckles to where I need them.

[jebster]

Got a low profile servo mounted up at the back of the rig to steer the last axle. I need to work up a panhard so I can run a 3 link setup like my front two axles. I also got my servo stretcher (mounted next to the motor for access) which will allow me to adjust center and endpoints for this servo. I did notice the servo moves very choppy, almost like the resolution of the radio system is not very fine. The hobbyporter radio works well for the price but this is probably something I will have to live with.

Also got to work on the cab interior. It is going to be pretty simple but give the impression of a real cab. Primarily needs to have access to hide the battery behind a bench seat.

Started on some additional exterior accessories. Made the side mirror mounts.

[MeanTT]

This is really amazing. Nice job.

[jebster]

Originally Posted by MeanTT

This is really amazing. Nice job.

Thanks. It is 2 years in the making but the end is in sight.

I got the last axle steering setup complete. It was a tight fit but it cycles smoothly. Haven't given it a test run yet to see if it makes a difference. Even if it doesn't it looks cool.

Spent more time on the interior. Made up my bench seat and the back will swing forward to give battery access. The roof locks the seat back in place. A little more structural support and then I'll add some apolstered seat material.