Big Jerp is back

[BigSki]

This thing has been sitting dormant for over a year. I'm going over it in preparations for a trail ride on New Years Morning. I powered it up and it came back to life relatively well. I ran it on the jack stands and cycled the steering. It had jitters and the motor smelled like the comm was oxidized. I guess I'll teat it apart and have a look at it and clean up what I can. I have no spare parts anymore except for one other HH TM35T motor that has seen more abuse than the one in the Jerp. The tires are absolutely flat spotted from sitting on a shelf in the bag for so long.

I've wanted to do a full rebuild on this Jerp for at least a few years. The roll cage is tweaked in every direction from being rolled over so many times, the wiring is a complete mess. I can't remember the last time that the R&P or any drivetrain component had been opened up and cleaned/greased. I've basically not given much attention to this because of how infrequent it gets used.

I'll try to make this the motivation factor to get my butt into gear and go over this rig and start using it again. Cheers !

[KMS]

I had to pull the Tekin brushless system out of mine , I used the newer 3piece axial drive lines and it was breakin them , my hood hinge failed so going to try magnets to hold the hood on, Will be watching for updates ,,

[BigSki]

The biggest thing that I wanted to do was to fab a new roll cage with a different rear shape. I had to get rid of my oxy/acetylene brazing setup 2 years ago, so I can't braze anything right now. The maker space I go to doesn't officially have oxy/acetylene. The blacksmith has a torch set and the 'inner circle' people get to use it but I'm not one of the cool kids so I have to pretend that it doesn't exist.

I've been practicing my TIG welding, it's making slow progress and I haven't attempted welding small diameter thin wall tubing yet, I'm still struggling with keeping the tip out of the puddle during a lap joint.

I've had great luck with some Traxxas driveshafts that I think are from the E-maxx, but then I'm not making crazy brushless power. There were definitely times when I wish I had that kind of power on hand !

[THUNDER PRO]

Think you will have it ready for the hangover crawl.

[BigSki]

Originally Posted by THUNDER PRO

Think you will have it ready for the hangover crawl.

It will be there, just as it sits. It still moves and functions, it's just way over due for some love.

[mud bogger]

Thats a good lookin pile of jeep haha.

[wingnutcrawler]

Is the grill a 3d print?

[Nova's Ark]

Sweet rig. I am returning to several of my older builds and updating them too. I look forward to your updates.

[BigSki]

Originally Posted by wingnutcrawler

Is the grill a 3d print?

Yes, I've designed 2 different styles, a CJ2A/3A and the MB military style shown in the pic.

[BigSki]

I got a few hours in today, one of the biggest headaches has been the old DX6i Tx. A few years ago I fell into a deep stream during a winter run taking the radio with me. I revived it by taking it apart and literally filling a plastic bag with dry rice with the radio inside of the bag. After a few days I took the radio out of the bag, blew off the rice dust then put it inside of a toaster over for a few hours at 150°. It came back to life but has been a bit sketchy ever since.

Anyway, any one familiar with this radio knows about the thumb scroll wheel for entering the "mode functions"- once you find your mode you push down on the thumb wheel to select a file. Well, the thumb wheel has seen better days and it didn't always select the file that you were trying to select. I opened up the Rx today and removed the whole thumb wheel module and had a look. The tiny momentary contact switch underneath of one end of the thumb scroll wheel was suspect, so I opened up the switch using the edge of an exacto blade and a back-lit magnifying glass. All I saw was burnt contacts and green corrosion. I knew that the switch was toast and causing some of the glitching with the Tx.

Since this is a flight radio, there's a momentary switch called "throttle cut". I snipped the harness for this switch near the PC plug, de-soldered the tiny micro switch on the thumb wheel module PC board and hard wired the throttle cut button to replace the tiny micro switch. So now, I can use the thumb wheel to scroll through the menus and push the throttle cut switch to make a file selection. It ain't pretty but it works for now.

I also opened the hood under the Jerp and started pulling out the mess of wiring that I created. I found the servo plug was pulling out of the Rx extension cable, so I pushed it back in and secured the wiring harnesses a bit better. The glitching seems to be under control for now. I also just sprayed the motor comm with electrical contact cleaner while running the motor at warp factor 3. It seems to run smoother and a lot less sparks were flying out of the end housing. I'm sure that John Holmes will not be looking forward to getting this motor back for a rebuild.

My tires are permanently flat spotted, so I'll just run in the frozen dirt tomorrow morning and have a bit of fun. Hopefully I won't break anything. I'm not taking and spares other than a battery. It's going to be too darn cold to do any trail fixes.

[stevem50]

Glad to see the jerp getting resurrected.. I’ve got a template for a cage here for a hasbro willis and a mapp torch if you want to come by and put another together


Sent from my iPad using Tapatalk

[BigSki]

Thanks for the offer, I'll let you know. It was good to see everyone again this morning. The climb to the top was definitely challenging with the frozen rocks and snow covering everything. My LCD screen froze on the Tx, I couldn't see anything at all.

[THUNDER PRO]

Sorry I missed everyone this morning. I heard that willys was just awsome today.

[rockhugger]

Love these 6th scale jeep (re) builds.
any updates?

[BigSki]

Originally Posted by rockhugger

Love these 6th scale jeep (re) builds.
any updates?

Matter of fact...






I took it out on Saturday, got about 10 minutes into running and playing "follow the leader" with a SCX10 based rig, I managed to get the tires jammed pretty good into a crevice and tried to steer out of it, the rod end snapped. At first I was impressed that I snapped a Revo long rod end, then upon the autopsy I discovered that it was just a rc4wd rod end, and was impressed that it held together as long as it did.

Every other link is Revo rod end, I used a Hot Racing steering link kit for a Wraith and made the mods for it to work with the narrowed AR60 axles. I have it hobbled back together enough to run it some more, but after spending some time with it on the work bench I have accepted the fact that I really need to do something about the lower shock mount and it's mounting position. I'm going to need to cut into the body to allow a proper shock angle and to keep the tires out of the shocks when at full steering lock.

I'm also playing with the idea to do a bell crank steering system to get maximum drag link length and to get the servo horn out of the way of everything else. This whole front end was half-assed when I narrowed the AR60 axles 19mm, it's been working for a few years but it's never been "right" and now it's starting to bug me. I also used alloy Axial C's and knuckles, I've NEVER liked the shortness to the steering arm. It's time to tear it apart and address all of the issues and fix them. I love driving this rig, so I need to make it as good as possible.

I've been practicing my TIG metal melting, I'm finally getting over the hump and getting consistent welds, so I'd like to fab the needed parts instead of 3D printing.



Nothing to brag about, but they're finally being consistent and for some reason I have better luck with sheet metal thickness material.

[BigSki]

I got to doing some thinking yesterday about one of the big issues with the front tires hitting the rc4wd coil overs so badly that the rod end will eventually unscrew itself and spit the parts all over the place. I initially used the rc4wd shocks because of their small body diameter. The tires hit because of the narrowed track on the AR60 axles. I narrowed them 19 mm to keep the tires more realistically tucked inside of the body tub. I personally can't stand the look of tires sticking completely past the body, it's just not my taste or style preference, more power to the guys that like it. .

The other issue is the way that I mounted the shocks, I just tied into the stock AR60 lower link brackets and used spacers to move the shocks WAYYY outboard of the link mount. Hackery at it's finest...

Short of either using the hex drive conversion parts for the rc4wd steelies ( mine are the old style pin drive) or building a set of full width AR60's to gain clearance between the tire sidewalls and the shock bodies ( which both would push the tires outside of the body tub ) I was left with trying to remount the shocks of do some other type of suspension design. I had mocked up some coils and thought aboot doing a separate coil spring/shock design ( like on a 1:1 TJ ) but that is going to require a bit of fabricated bracketry, something I don't want to start right now. I started mocking up a shock in different places to see where I'd get the least amount of interference at full steering lock.

Turns out, there really is no place with these narrowed axles, the tire will hit no matter where I locate the shock, so then it became a question of finding the place with the least amount of interference. I had to get as close to the center line of the axle tube itself, which put the shock on top of the tube but it would still catch a tire at full stuff and turn. It was the best compromise I could come up with so I went for it.

I dumped out my bag of Tamiya suspension stays to see what I had to work with, just to keep it simple for now. If this design proves to work well, I will make some better brackets.

this is what I started with. After I made a 3mm tapped hole in the small miter box to hold the bracket, I just used a medium sized file to remove the material that I didn't need.



I mounted the bracket on top of the axle tube using one of the 'C' hub mounting bolts, then bent it around the face of the C hub then drilled and tapped right into the C hub.



The next issue was the length of the rc4wd shocks- they are the 100 mm long ones ( no longer made, there's a new-and-improved version that's back ordered) and those were going to be too long. I had some axial 90 mm shocks in my suspension parts bag, along with a ton of the colored main and tender springs for tuning the old Honcho spring rates. ( anyone remember doing that? LOL )

The Axial shocks were 90mm but have 30mm of travel which is the same amount of travel from the rc4wd shocks had in a 100mm long shock.

I found some green main springs and red tender springs which felt a bit firmer than the rc4wd shocks ( using my calibrated squish-o-meter between the first finger and thumb of my right hand ) so I gave that a try just to see where i'm at. I also have some yellow mains and tenders along with some blue tender springs.



My ride height is about where it was using the rc4wd shocks. The tires have the most amount of clearance that they've ever had although the sidewalls still rub the coils badly at full turn/suspension compression. I might buy a set of the newer style of the rc4wd shocks, although the 90mm length shocks have slightly less travel. I'm hoping to take the Jerp out one day this week and run it to see how well this setup might work.

The rear shocks also need some attention for a better way of mounting to the axle but believe it or not, it's even tighter for working space in the rear. I'm trying very hard to not cut into the body for shock clearance and I'm also trying hard to keep as much of the tire under the body. These 2 goals are working against each other.

[Big Mike]

Originally Posted by BigSki

Yea, old Tamiya brackets to the rescue again. Nice...

I'm wondering if you could rework the top mounts, and tip the shock into the fenderwell a couple/few more millimeters?

I agree, too wide just ruins the scale appearance...

[Mike Flea]

Just throwing this suggestion out there, I wonder if using Sawback shocks, with an internal spring, would give you the clearance you need

[Bitter End]

I had a very similar problem with the orange one. As you may remember that one is not a Hasbro but rather a Formative International. None of the measurements or geometry are even remotely similar.

This is how I got my shock as snuggled up as close as possible.

[BigSki]

Originally Posted by Big Mike

Yea, old Tamiya brackets to the rescue again. Nice...

I'm wondering if you could rework the top mounts, and tip the shock into the fenderwell a couple/few more millimeters?

I agree, too wide just ruins the scale appearance...

Originally Posted by Mike Flea

Just throwing this suggestion out there, I wonder if using Sawback shocks, with an internal spring, would give you the clearance you need

In one iteration of this vehicle, I was running the white "scale" shocks which worked ok, it just didn't look right with there only being a shock absorber and no coil spring, so I switched to the rc4wd coil overs. At least it looked believable.. The issue with trying to move the top of the shock inboard is that the upper mount is on the sloped portion of the fender, as the mount moves upward it also moves outward.

There is also the issue when the suspension fully cycles, the shock body will hit the chassis. I can fab a lower mount that would capture both of the C hub mounting screws and have tabs that would rotate the lower mount 90° from the way they are now so that the pivot on the shock wouldn't bind. If this quick setup proves to be function, the new mount idea will be the way I will go. I probably need to do something similar in the rear.

Ultimately, some coil buckets and an individual coil spring at each corner would be the most ideal design as far as placement/ tire clearance is concerned. I'm just not quiet ready for that much fab work right now.

Cutting into the body like Bitter End has shown is the only decent answer left for an easy way out, I'm just trying to avoid doing that right now.

If these Axial shocks work ok, the 90mm length rc4wd new version of the coil overs might be the easy way out right now. I just don't to spend $45 to try right now. I'll use what I have on hand and move forward from there.

Thanks for all of the comments and ideas, glad to see this section is still getting some attention.