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-   -   Jebster's 10x10 HEMTT rollback hauler (http://www.rccrawler.com/forum/multi-axle-rigs/594176-jebsters-10x10-hemtt-rollback-hauler.html)

jebster 03-13-2018 09:14 AM

Re: Jebster's 10x10 HEMTT rollback hauler
 
A short video showing my first test of the screw drive system I'll be using for the rollback feature.

https://youtu.be/PxkhIfYlN48

jebster 03-13-2018 01:40 PM

Re: Jebster's 10x10 HEMTT rollback hauler
 
3 Attachment(s)
Also got a set of shocks to try out. I really like the small diameter and the resevor adds a nice look but they are a pain to bleed. Still not sure I did it right. I bought two pairs but I'm not sure I'm going to buy 3 more.

Gula 03-15-2018 03:56 PM

Re: Jebster's 10x10 HEMTT rollback hauler
 
Looks great sofar. You wouldnst happen to have a link to the shocks?

jebster 03-15-2018 05:38 PM

Re: Jebster's 10x10 HEMTT rollback hauler
 
Quote:

Originally Posted by Gula (Post 5811462)
Looks great sofar. You wouldnst happen to have a link to the shocks?

Thanks.

I don't have a link but you'll find them on ebay if you search for xtra speed 70mm piggyback shock.

Just so you know I'm not happy with the shocks and will be getting something different. The reservoir diaphragm has no seals so it leaks. Plus getting the tube to stay connected on each end is tough. I ended up putting some heat shrink tubing on the small nozzles so the the tube had something to hold onto.

Gula 03-16-2018 02:36 PM

Re: Jebster's 10x10 HEMTT rollback hauler
 
I found some pretty neat 70mm shocks on feebay for like $22 for 4 and they work pretty well. Unsure of the name but they're blue

jebster 03-24-2018 11:32 AM

Re: Jebster's 10x10 HEMTT rollback hauler
 
2 Attachment(s)
More work on the rollback mechanics. Pretty much complete. You can see the white delrin blocks that the channels on the underside of the bed deck will slide on.

Also started thinking about the transmission options. I have a GRU I might try. Do people have any issues with these handling brushless power?

https://youtu.be/PxkhIfYlN48

https://youtu.be/fLwiAiLo8-o

tcanin00 03-24-2018 08:44 PM

Re: Jebster's 10x10 HEMTT rollback hauler
 
Quote:

Originally Posted by jebster (Post 5814193)
More work on the rollback mechanics. Pretty much complete. You can see the white delrin blocks that the channels on the underside of the bed deck will slide on.

Also started thinking about the transmission options. I have a GRU I might try. Do people have any issues with these handling brushless power?

https://youtu.be/PxkhIfYlN48

https://youtu.be/fLwiAiLo8-o

I personally wouldn't run a Novak brushless motor since they can only run 2S. That, and I don't think they're as smooth as a good brushed motor on 3S. Personal preference.

Sent from my HTC Desire 626 using Tapatalk

jebster 03-24-2018 09:07 PM

Re: Jebster's 10x10 HEMTT rollback hauler
 
Quote:

Originally Posted by tcanin00 (Post 5814353)
I personally wouldn't run a Novak brushless motor since they can only run 2S. That, and I don't think they're as smooth as a good brushed motor on 3S. Personal preference.

Sent from my HTC Desire 626 using Tapatalk

I believe the novak can run on 3s since it was paired with a goat 3s esc originally. As far as a brushed motor being smoother I have had a similar experience but a good sensored brushless does pretty well.

tcanin00 03-25-2018 12:37 PM

Re: Jebster's 10x10 HEMTT rollback hauler
 
Quote:

Originally Posted by jebster (Post 5814367)
I believe the novak can run on 3s since it was paired with a goat 3s esc originally. As far as a brushed motor being smoother I have had a similar experience but a good sensored brushless does pretty well.

I let the smoke out of a Goat 3S a couple of years ago. I had the system on, not moving or under a load, because I was setting end points for the steering and it went up in smoke. Since then I've been reluctant to put 3S on anything Novak even if it is rated for it.

Sent from my HTC Desire 626 using Tapatalk

jebster 03-25-2018 02:49 PM

Re: Jebster's 10x10 HEMTT rollback hauler
 
Quote:

Originally Posted by tcanin00 (Post 5814568)
I let the smoke out of a Goat 3S a couple of years ago. I had the system on, not moving or under a load, because I was setting end points for the steering and it went up in smoke. Since then I've been reluctant to put 3S on anything Novak even if it is rated for it.

Sent from my HTC Desire 626 using Tapatalk

I've had issues with their esc before (hence the motor) but the motors have always run strong. That being said I'll see if this motor is a good match for this rig.

jebster 04-14-2018 02:47 PM

Re: Jebster's 10x10 HEMTT rollback hauler
 
8 Attachment(s)
Continuing to make progress. I have all the suspension set up including the front two axles panhards and drag links. Got the rollback structure mounted to the frame and it tilts nicely. I also made some crossmembers to eliminate flex.
Cut out the bed to size it up. Width is good but I need to shorten it up to around 21-22".

The only issue I'm having is picking shocks. I need 10 so I'm trying to find shocks that won't break the bank. They need to be either 60mm (compressed) - 75mm (uncompressed) or 70mm - 85mm. Not finding much.


Getting close to needing the cab. I may need to make it myself!

tcanin00 04-14-2018 03:58 PM

Re: Jebster's 10x10 HEMTT rollback hauler
 
Quote:

Originally Posted by jebster (Post 5821803)
Continuing to make progress. I have all the suspension set up including the front two axles panhards and drag links. Got the rollback structure mounted to the frame and it tilts nicely. I also made some crossmembers to eliminate flex.
Cut out the bed to size it up. Width is good but I need to shorten it up to around 21-22".

The only issue I'm having is picking shocks. I need 10 so I'm trying to find shocks that won't break the bank. They need to be either 60mm (compressed) - 75mm (uncompressed) or 70mm - 85mm. Not finding much.


Getting close to needing the cab. I may need to make it myself!

Looking good. If you can handle building the mechanics of this, you should be able to scratch build the cab.
That being said, my builds take forever because I am too critical of my own work when scratch building with styrene. It has to be anatomically correct or not at all.

Sent from my HTC Desire 626 using Tapatalk

Mike Flea 04-14-2018 04:25 PM

Re: Jebster's 10x10 HEMTT rollback hauler
 
Shouldn't have any flex with those beefy crossmembers "thumbsup"

jebster 04-22-2018 04:27 PM

Re: Jebster's 10x10 HEMTT rollback hauler
 
4 Attachment(s)
More progress. Got the rollback mechanics all functioning. Instead of adding a mechanical tilt I'm going to see if gravity can do the job. I added some shocks filled with 5k diff oil to make the tilt more controlled and prevent it from slamming around. I also included limiting straps to prevent the shocks from being over-extended. At the back of the bed there are some rollers I made that allows the bed to roll out once it contacts the ground.
I also mounted the steering servo so that is all working.

Getting to the point I will have to start working the body.

https://youtu.be/I_BDScTOqNU

JoeConti 05-12-2018 04:50 PM

Re: Jebster's 10x10 HEMTT rollback hauler
 
Quote:

Originally Posted by jebster (Post 5804852)
I got some time to work on the suspension and steering. The cantilever are twin hammers parts. Ran out of rod ends before I could finish the front axles though. Everything moves smoothly, just need to find some inexpensive shocks. The steering uses some tamiya semi steering blocks connected together and then to the servo.

First off, GREAT build. Congrats.

You over simplified the ideal way for a 2 axle steering. Funny when one tries to do something one tends to over engineer it .. but you have managed to make it so simple :) May I ask if you have a link to those steering boxes ? I see you are running SCX10 axles with what I am assuming are 1.9 wheels. Wondering if the steering boxes will hold up to AR60 axles with 2.2s. Found some Hot Racing steering boxes. Not in the mood of spending $60 for a pair. Wondering what you paid for yours.

jebster 05-12-2018 07:08 PM

Re: Jebster's 10x10 HEMTT rollback hauler
 
Quote:

Originally Posted by JoeConti (Post 5831085)
First off, GREAT build. Congrats.

You over simplified the ideal way for a 2 axle steering. Funny when one tries to do something one tends to over engineer it .. but you have managed to make it so simple :) May I ask if you have a link to those steering boxes ? I see you are running SCX10 axles with what I am assuming are 1.9 wheels. Wondering if the steering boxes will hold up to AR60 axles with 2.2s. Found some Hot Racing steering boxes. Not in the mood of spending $60 for a pair. Wondering what you paid for yours.

Thanks. I am running scx10 axles and 1.9 wheels. The steering boxes are from xtra speed and are intended for Tamiya 1/14 semi. I havent put them through their paces yet but they seem pretty stout. I got mine off eBay for around $13 each.

JoeConti 05-13-2018 02:22 AM

Re: Jebster's 10x10 HEMTT rollback hauler
 
Quote:

Originally Posted by jebster (Post 5831120)
Thanks. I am running scx10 axles and 1.9 wheels. The steering boxes are from xtra speed and are intended for Tamiya 1/14 semi. I havent put them through their paces yet but they seem pretty stout. I got mine off eBay for around $13 each.

Thanks for the info :)

Job well done :)

jebster 11-02-2018 08:20 PM

Re: Jebster's 10x10 HEMTT rollback hauler
 
I have been makings progress and will post of pics and a videos soon. In the mean time I have a question for others. I didn't expect a tight turning radius on a rig this long but I wanted to know if running open diffs (vs lockers) in the front two steering axles would improve things noticeably.

jebster 11-03-2018 10:36 AM

Re: Jebster's 10x10 HEMTT rollback hauler
 
1 Attachment(s)
Here is a videos of the rollback bed in action. The twin hammers on the back is no lightweight and it does fine.

https://youtu.be/Y92G1fkgL9Q

As you can see in the video the rear axles need heavier duty springs. They are buggy shocks so the springs are soft.

I did have a causality. The output on my GRU snapped off. Trying to decide if I'll buy another unit or fabricate my own. I need a LOT of reduction since the transfer cases I'm running increase the output ratio.

vwdaveb 01-28-2019 03:59 PM

Re: Jebster's 10x10 HEMTT rollback hauler
 
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.
http://www.rccrawler.com/forum/membe...4548-66757.jpg



http://www.rccrawler.com/forum/membe...4548-66756.jpg





http://www.rccrawler.com/forum/membe...4548-66755.jpg


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