dbrad's GP mods

[dbrad]

Hello all. I've made a few changes to my GP. Here are some of them.

There's a lot of rock around Victoria and I don't know of too many places to do high speed runs. The majority of my mods will favour crawling but I still want it to be capable of moving faster than I can walk and take jumps (because I already have a 2.2 comp crawler but wanted something capable of moving faster). I've got some longer shocks on order and some servo savers. I plan on making the wheelbase longer (and more stable, this things loves to roll over).

I have done a few other things so far but don't have pictures yet because my GP is still in pieces. I've added 14mm E/T-maxx hexes, Proline wheels and some larger crawler tires (Imex I think).


I moved both steering links above the steering knuckle to get better clearance.

And as you can see, I've made an axle brace out of aluminum. That's right, I broke an axle too.

I'll need to add some spacers in between the brace and the axle, due to the axle not being flat on top. I'll also have to shave 4mm of the bottom of the servo mount to get it back down to it's original height (relative to the axle).

Top view. You can also see the battery tray extension in this pic, which is my next subject for today.

I've lowered the battery/electronics tray by 20mm to help lower the COG. I've read that many of you have reversed the battery tray but I didn't quite understand the benefit (or rather what exactly was being done). I wanted to keep the motor at the front but I also wanted to move the battery up front too. So I extended the battery tray to go far enough forward without having the servo hit (upon full shock compression). The on/off switch still fits in the same spot. It goes through an existing hole in the battery tray.

Here's a shot from underneath to get an idea of how I mounted the battery tray extension.

Thanks for taking a look. That's all for today. More to come in the future.

 

[Grave Digger1]

Looks great!! I love the mods!!

Your extending the battery tray so it is in the front is pretty much the same idea as reversing the battery tray. The idea is too get more weight in the front nose to make it more stable on jumps and to help keep the nose down in flight.
Your job was less head ache then the tray reversal. I should have done that myself and thought so well after I had mine already done.
Looking forward to seeing more updates.

Lynn

 

[HawnMT]

Great to see new ideas, great work.:tmb

I've lowered the battery/electronics tray by 20mm to help lower the COG. I've read that many of you have reversed the battery tray but I didn't quite understand the benefit (or rather what exactly was being done). I wanted to keep the motor at the front but I also wanted to move the battery up front too. So I extended the battery tray to go far enough forward without having the servo hit (upon full shock compression). The on/off switch still fits in the same spot. It goes through an existing hole in the battery tray.

I've thought about dropping the tray but the links and driveshaft were already touching the motor on full compression the way it was(this was before the low profile motor mount though).

I see you have the shocks mounted to their lowest position on the chassis so while you've lowered the tray you've raised the chassis higher so COG may be the same or even higher.

 

[william g]

love that axle brace :tonguedrop

 

[dbrad]

Great to see new ideas, great work.:tmb



I've thought about dropping the tray but the links and driveshaft were already touching the motor on full compression the way it was(this was before the low profile motor mount though).

I see you have the shocks mounted to their lowest position on the chassis so while you've lowered the tray you've raised the chassis higher so COG may be the same or even higher.

I already had the shocks mounted at the lowest spot because ground clearance was important to me. The battery tray is as low as it can be with the upper links and the shocks set at their lowest mounting points. The motor is more in the center of the chassis with a smaller pinion. Everything's a bit tight under there now.

I should have done some kind of side-roll test to compare the COG before and after. I guess I still can...

Thanks for the comments guys.

 

[dbrad]

Fun story. I had some barely used chrome rims and crawler tires laying around. I'm not a big fan of chrome and I had learned that you can remove the chrome and then dye plastic rims. So I had to experiment.

I figured I'd dye them black because I like black wheels. At the store I noticed they had both black dye and navy blue. I made sure to get the black. That would be funny if I had blue rims. So after several hours of boiling my rims in black dye, they looked very blue.

I swear I grabbed the black dye. At least the GP theme is blue.

Anyways, here are my new navy blue wheels with some crawler tires.

And some comparison shots between stock and new.

 

[dbrad]

Here's my axle brace all finished up (well the front one at least).

The servo sits at pretty much the same height as stock.

I'm thinking some type of bumper/skip plate might be necessary, like the one GraveDigger1's got.

 

[william g]

whoa, those are tall, taller then I thought.

Still, they look good, more of a monster truck looking tread than the stockers IMHO. you could probably get some of that krylon spraypaint for plastic and paint them black. It should stick well, and even if it did chip be barely noticeable.

 

[dbrad]

Those last pics may have given a preview of what I was busy with over the weekend.

My Savage shocks came in. So on to the process of lengthening this beast.

Longer links.

I got the front end done. Here are some front vs. rear comparisons.

Poser articulation shot.

Drive shaft extension. This was the most free way of doing this. I think it'll hold (steel is pretty strong.) A chrome drive shaft is almost too :bling for me.

 

[dbrad]

I came across this at a thrift store on the weekend.

A Dodge Rammunition!! I think it's a Radio Shack truck. The body is all I am really interested in. The truck had a 2000mah battery in it as a bonus.


It has working lights in the front and spot int the rear where lights could be added.

It's a bit longer and much wider.

Interior!

This kind of throws the blue theme off. If I use this body, my blue rims will look a bit ridiculous. I can always paint the rims.

 

[HawnMT]

To get the blue rims black just dye them again. It takes a couple of times to get white parts, or worse delrin parts, black.

Yeah if you can get that body to woork that would look badazz. The extra width would actually be good since the GPs axles are so wide. Oh yeah it's a New Bright Body.

 

[Grave Digger1]

I love the mods!!
You could always paint the body. But like HawnMT said, redye the wheels a few times or keep them in longer. I'm surprised they didn't come out a purple tint to be honest, most blacks have a purple base from past experience.
Lynn

 

[Brian34]

I put a Pro Line 2008 Ford Superduty body, on my GP. It too is considerably wider then the stock body. I was able to press the body on to the posts with no problem. Albeit I see you have an ABS body there. You could try retrofitting some vertical body mounts on perhaps..

 

[PestControl]

Tell us, what grade aluminum did you use for your axle brace? was it hard to bend?

Thanks

 

[Brian34]

How did you make that driveshaft extension ?

 

[dbrad]

The aluminum I used is approx 2mm thick. I don't know what grade it is as it is some scrap I found laying around. If I was buying some new, I would have gone to the next thickness.

I used a bench mounted vise and some pieces of wood to bend it. It took some effort but was not too hard to bend by hand. I also used a torch to heat up some of the pieces, that really helps.

To make the drive shaft extension, I had a piece of chrome steel tubing in my garage. The inner diameter was really close to the outer diameter of the female half of the drive shaft. Again, If I was buying some new material, I would have bought it so that the drive shaft had a bit of extra room inside. And I would have chosen rust-free aluminum.

I cut the female section of the drive shaft in half. Stuck each half in either end of the chrome extension. I used a Dremmel to ad texture to the inside of the chrome tube and the outside of the drive shaft and then used some hot glue.

This is essentially the same process I used to extend the links. With the hot glue, I can always heat up the tube with a heat gun if I need to separate the pieces and make changes.

My first thought was to buy two extra sets of drive shafts but this would have meant finding something to fit at the LHS or waiting a few weeks for them to arrive in the mail. Both would have cost money but would have been lighter weight. This is what I would have done...

 

[dbrad]

I got the rear end extension finished. No rear axle brace yet. but it's back together.

A few things were discovered.

The stock motor will smoke if worked too hard. Apparently locking the diffs and adding bigger wheels was too much, even with a 15T pinion. It can cruise around fine but the moment I try to crawl up some stairs or a wall (anything that requires more than the available torque) it strains the motor. No surprise. It's not a crawler motor and this is a big crawler. For bashing around, it hauls quite nicely. I actually "squealed" the tires in my driveway. Like all of you, I have dreams of a brushless system.

Without planning, the servo cords are just long enough.

With the longer wheel base, it is so much more stable going up or down any kind of incline or off a jump. The way I mounted the link extensions, added bigger shocks and wheels, the chassis has gone back up. The lowering of the battery tray has helped but essentially been canceled out. I'm already thinking of a new chassis design (I can't help it).

The Savage shocks are awesome. There is a tiny bit of sag in them at rest. The front wheel will only kick up a bit when I gun it from a stand still (it is still the stock motor though). Off a jump it is so much more controlled (less bouncy). Under the weight of the truck, the shocks will not fully articulate (close but not fully). This leads me to believe that they can handle some big jumps.:wnk

The underside of the axle has too many things that catch on rocks or anything that isn't smooth ground. I have plans to relocate the shock/link mount to the inner-facing side of the axles.

At least for now it's in one piece and I can play with it. But that won't last for long. So many more ideas...

Thanks for feedback guys (and gals maybe?)

 

[TXT-2.0]

:shk that thing is big but very cool .... may be the angle of the pic but looks like your left front tire is hitting your shock

 

[Brian34]

I got the rear end extension finished. No rear axle brace yet. but it's back together.

A few things were discovered.

The stock motor will smoke if worked too hard. Apparently locking the diffs and adding bigger wheels was too much, even with a 15T pinion. It can cruise around fine but the moment I try to crawl up some stairs or a wall (anything that requires more than the available torque) it strains the motor. No surprise. It's not a crawler motor and this is a big crawler. For bashing around, it hauls quite nicely. I actually "squealed" the tires in my driveway. Like all of you, I have dreams of a brushless system.

Without planning, the servo cords are just long enough.

With the longer wheel base, it is so much more stable going up or down any kind of incline or off a jump. The way I mounted the link extensions, added bigger shocks and wheels, the chassis has gone back up. The lowering of the battery tray has helped but essentially been canceled out. I'm already thinking of a new chassis design (I can't help it).

The Savage shocks are awesome. There is a tiny bit of sag in them at rest. The front wheel will only kick up a bit when I gun it from a stand still (it is still the stock motor though). Off a jump it is so much more controlled (less bouncy). Under the weight of the truck, the shocks will not fully articulate (close but not fully). This leads me to believe that they can handle some big jumps.:wnk

The underside of the axle has too many things that catch on rocks or anything that isn't smooth ground. I have plans to relocate the shock/link mount to the inner-facing side of the axles.

At least for now it's in one piece and I can play with it. But that won't last for long. So many more ideas...

Thanks for feedback guys (and gals maybe?)

Nice to see I'm not the only one who tried Savage shocks on this truck. I tried the black & grey version(s) though. I took them off; I still have them, just not using them. Are you using this truck for a crawler or basher ?

If you are using it for bashing, I recommend the Traxxas Velineon VXL3s brushless system, with the 3500kv brushless motor. I'm running it in my GP with Clodbuster tires and it still picks the front end up off the ground quite easily. I hope to make axle braces similar to what you did, some day soon.
I want to be able to do significant jumps with my truck, and have the axle housings survive in one piece.

 

[dbrad]

I put a Traxxas Titan 550 14V motor in my GP. I'm very happy with it. With a 14T pinion, I've got enough torque to pull my truck up a steep slope with the larger tires.

I made a little video of it crawling and messing around on my first real outing with it.

http://www.youtube.com/watch?v=UlLbB8m7jS8

At the end there, you can almost see why I now need to get some new shock/lower link mounts. My axle brace held up though.