My rebuild of the problem areas... with pics!

[big JC]

Yeah, I would like to hear from someone that has used it. The logical part in me believes the parts hammered on in the video were infact welded (or extremely soft aluminum) as there is no way to bond one metal to another on a molecular level without melting(welding) the metal. Awesome if it works though! Cordy have you tried to duplicate the results on the video?

edit--- oops saw your post just has I posted this. Let us know how it works Cordy!

 

[cordy]

Go to harbor freight ,put aluminum brazeing rods in the search bar then read the reviews by people who have used it,all 5`s. Thats why I bought them ,only $15 worth a try.I`m going to give a couple of rods to one of the guy`s at the track for x mas and let him expiremnt if he wants. Besides he can see straight.You must use a ss wire brush,when I was at h freight I talked with the old goat in the store and he told me they work but the key is the ss wire brush to keep the oxidation off.

 

[Bill_G]

I wouldn't recommend brazing. I played around with a few different brazing rods and whatnot for aluminum. It can be tricky. I also used the Alumaweld a lot trying to perfect the process on different thicknesses. Alumaweld same as Durafix, and also looks the same as a product Berzomatic sells, is a fluxless low temp brazing rod. It melts at ~700F which is good if you can keep the heat at that level. I think it works great on thinner material, anybody seen the pop can demo, but thicker just dissipates the heat too much. Most cases the Alumaweld just sits on the surface and doesn't handle any kind of stress.

The problem with brazing parts like this is most brazing rods melt in the 1000f range which is getting close to the melting point of the base metal. About 900f anneals most grades of aluminum, so there goes your temper and strength before the brazing rod even melts.

There is one aluminum braze I would like to try called Super Alloy 5. Its more like a hi temp solder. A little pricey tho.

Brazing has it's place, but if you're gonna generate all that heat TIG welding would be best if the parts can't be bolted together. You need to know what grade the aluminum is before welding cause some don't like it.

Use short spot-like welds and heat blocking putties and let it cool between welds so the heat doesn't spread or build up too much.

Find someone that knows how to weld aluminum and it may not sacrifice the overall strength on something like a chassis plate.

 

[GTS 666]

Enjoyed reading this build an awesome effort very helpful info too. Will be re reading if I ever get a XB still holding off for the moment. I just thought I would add that most body shops when replacing a roof on a vehicle now use a glue to bond it on instead of spot welds. This glue is apparently stronger than the factory welds I can find out some more info tomorrow as to it's other uses and name of the product. Just for curiosity anyway.

 

[nitrohobbiest]

I believe you are referring to a process many shops have started doing where they rivet the panels where they can and use seam sealer everywhere else. Many body panels are attached in areas covered by a molding or other part so this method not only works well, but it remains much more rust proof and no one can see it. If you weld the panel on, you risk burning off any corrosion protection in areas that you can't get to for reapplication. You also risk warping the panel. Seam sealers and urethane glues are very strong. Now I'm thinking outside the box here and wondering if it would work to repair cracks in my lexan bodies. Hmmmm.

As for brazing the chassis, the one positive thing I can say about having used bolts is I didn't have to strip the entire truck down. I removed everything from the engine back but that was it. If I brazed it, I would have had more parts to install. And then there is that risk of it not working out as planned. The other thing to remember is once you braze the plate on, you still have to re-drill every hole that mounts something to the chassis. When you do that, your basically bolting the plate on with the parts above, nearly cancelling out the need to braze in the first place.

I've decided that I made the right decision. I was able to do it in my basement with no worries of screwing anything up. And the 1/4 inch plate adds no real clearance issues. I mean I don't go climbing over limbs or anything like that so it does the job well without interfering. And between the hardened screws combined with red Locktite, its not going anywhere.

 

[cordy]

Thanks for the info on super alloy.The simple solution is for the manufacture not to cut pieces out of the chassis to save weight,or supply an aluminum differential housing.Yes thier all pricy,and no matter what brand video you watch each one implys thiers is the best. Guess the aluminum brazeing bussiness is like politicians.This was only a thought to put back in the gussets that the manufacture took out.There is no point in raceing the platform if you constainly have to put in a differential housing because of chassis flex.

 

[nitrohobbiest]

Cordy, I don't think replacing the gussets is enough all though it would help. The flex is directly between the diff area and the wider part of the chassis. there is no material removed from that particular area. It just needs a thicker chassis all together. I would say 4mm would be the bare minimum if they plan to not add good chassis braces like they did. A solution would be to make the braces off of the rear tower and over the tank out of aluminum. The plastic ones are just not doing anything.

But i have to say also that making the diff housing aluminum is fine but it can't be designed to do all of the work. If the shaft gets forced into the housing, and the housing doesn't budge, then that impact gets directed to the shaft and the center diff carrier. My carrier was also broken which is why I made mine out of aluminum. So anyhow, if both carriers are aluminum, then that means the shaft takes all of the impact and could lead to a bent shaft or a damaged rear diff carrier. The carrier in the rear housing is also plastic. The crown gear could possibly strip right off in the worst of landings. You have to be focused on the cause and the solution to ending the cause. Obviously you did, Cordy, as you added the lower plate. But I'm afraid that if "7075" finally makes this aluminum housing for $80 or so, it will just direct problems to other areas. It will help in many cases but not all of them.

"Ol Fart", I'm suggesting aluminum tank/tower supports to go with your soon to be rear diff housing. This is the only direct bolt on fix I can come up with that wouldn't involve making new holes for an inexperienced R/C enthusiast. That and possibly a front to rear roll cage.

 

[Guest]

A nice cage connecting the two shock towers and a couple points on the chassis in-between will also stop that flex. I know this is a different platform but there is no flex.

I plan to make one for my XB as soon as Grafils bodies are done. I want to make sure it will all fit nicely.

---

 

[big JC]

A nice cage connecting the two shock towers and a couple points on the chassis in-between will also stop that flex. I know this is a different platform but there is no flex.I plan to make one for my XB as soon as Grafils bodies are done. I want to make sure it will all fit nicely.

This approach makes more sense to me than trying to support it from underneath. When I finally get my rampage I plan to do something similar. That looks absolutely awesome by the way nice work! Be sure to post up pictures or better yet step by step details and pics when your done with the xb

 

[brio]

Once again, Another sweet ride RCDad!

And.. how many RCs do u own?

 

[Guest]

Once again, Another sweet ride RCDad!And.. how many RCs do u own?

Over a dozen, and still want more. LOL. the last four purchased are Redcats

 

[nitrohobbiest]

Is that roll cage your handiwork RCDAD? Truly impressive.

 

[Guest]

Is that roll cage your handiwork RCDAD? Truly impressive.

Yes. Thanks for the compliment.

 

[Obeast44]

It doesn't take much to get them stiffened up quite nicely.

My old MT pro had a small chromoly cage, and gussets. It was light, fit in the stock locations and stiffened the chassis up like nobodys business. Im a big guy and I could literally jump up and down on the car without worry. Thanks to DemonRC for the cage

 

[nitrohobbiest]

Well, I'm convinced. A roll cage will be my next adventure but probably over the winter. Right now it pretty runable once I repair the shock and vent my tank better. Another run day is coming this Sunday with all the Losi 5ives so I need to put them in their place.

 

[nitrohobbiest]

So here is an update and not a happy one. All of my mods are doing great. But new problems quickly arose. First off my gas cap is just bad. I reemed out the vent holes but nothing I did worked. Secondly, the shock is back together and fine so that is a plus, however the pulling that I was having wasn't because of a leaked shock, it was from a bad front diff. I seems as though a pin broke behind the drive cup. It pulls the one wheel but not the other mimicking 3 wheel drive. This makes the truck really hard to drive straight. But I managed to continue running laps like this last weekend. So as I frustratingly forged along, I ended up snapping a rear wheel drive cup along with twisting the dogbone. Somewhere during this incidence, I also broke a front steering knuckle. Of course the brand new Losi's were running circles around me. There was 4 of them and every one of them went home with no broken parts except one with a blown steering servo. That particular truck cranked out 190 laps that day with a best lap time of 17.6 seconds versus a best lap time of a nicely modded Baja of 19.9. Those trucks are just damn nice.

So I'm gonna fix this truck like I always do, run it again and see what happens. But I don't see me keeping this thing much longer. So if you want a heavily beefed up XT, keep an eye out for it when it hits the market. I will certainly sell it in working condition but I won't be happy about it, lol.

 

[big JC]

That's bogus nitrohobbiest, sorry to hear it. However, I do find your thread very helpfull as you are obviously putting this truck through it's paces and post clear, concise, unbiased, feedback. So on that note I thank you for taking the time to do your best with the truck and post about it.

 

[Deluge]

That sucks, dude. Hope you get it figured out.

 

[nitrohobbiest]

Finally taking the time to fix this thing. The rear is all buttoned up. I replaced the snapped rear wheel axle cup along with the horribly grindy bearings. Of course I already had axles for the MT, not the XT (another poorly described Redcat part that I picked up from DDM before I knew any better) so I had to do yet more modding of the hub carrier to accept a longer axle. I also spent some time building a shim thick enough to take up the slop that my Baja to XT adapters leave when installed. They don't fit at all like the stock square hubs do. I also created a mod that takes the slop out of the area that supports the bearing. I happened to have a CV joint boot clamp for a real car that, when clamped around the hub carrier over the outer bearing using a special tool, tightens that sloppy plastic right up tight around the bearing. My rear wheels have very minimal movement now. I only had one of these clamps and finding the right one at a parts store is hard or impossible without buying the boot, too, so I used a small hose clamp on the other side. I did this before and it backed off so I CA glued it to the plastic and added red locktite to the screw.

Now the front. My 3 wheel drive issue was due to a snapped diff cup, not just a pin like I was hoping. Not only had it snapped inside the case on the previous run day, but it snapped again on the outside of the case during my final run. I don't know the sequence of events but what I found was a loosened grub screw holding my cvd pin in. This in turn wiped out the hub carrier pivot nut, bent the axle, possibly broke the cup the second time, and may have also led to my newly discovered broken A-arm. I can't get a freakin' break! I now have to hope my local shopn has these parts or else I will be ordering stuff again. He has Rampage parts but its a mixed bag between the MT and the XT. I'm pretty sure I remember seeing the cups but iffy on the lower arms.

I have dumped so much time and money into this thing. I know if I just turn it into a backyard basher, it may never die. But the fact remains that I have a really fun track to drive it on and it has jumps that I refuse to roll gently over. This truck will be fixed, gently played with, and sold in the upcoming season. I have my mind set on the Losi 5ive. Its a great truck and handles the abuse with flying colors. But I'm gonna dump the 26 from the new Losi into the Rampage and keep my DogPile 29.5. So hey, it'll have a brand new engine in it for resale.

 

[cordy]

Sounds like a plan. I`m shure the losi will fill the bill for you.Good luck to you on the new race season.