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

[nitrohobbiest]

So I have been bitten by nearly every major problem that I've recently read many others are having. Gearplate, square hexes, bad foams, garbage steering servo, and now, a busted diff housing. I have taken care of all of the other issues but this one will take some work. I've read about many of the fixes other's have done so I plan to take all of them into consideration and do them all at the same time.


What I plan to do, which I haven't fully figured out yet simply because my new case isn't here yet, is to beef up the chassis and beef up the new case. In this thread, I will document my progress and my end results so if this can be of any help to anyone else I'll be equally as glad. I also welcome any suggestions as I undergo this little project.

 

[big JC]

Hi, first time poster here. I am thinking about getting an XT, but am still on the fence between the XT & MT as the problems people are having with the XT. I am wondering if anybody has a definitive cause on the dif housing failures? Is it the bearing, chassis flex, or just under built in that area? Especially curious to know if just replacing the bearing with a higher quality one would help prevent a failure? Anyway, looking forward to any info posted and the future progress with your rebuild nitrohobbiest!

 

[Guest]

I believe its a little of every thing you mentioned. I am hoping that 7075 builds a aluminum dif case before I have a issue. Some don't drive as hard as others and never have a issue. If you like to beat the crap out of your truck, I would recommend the MT.

 

[nitrohobbiest]

Well, at this point, I have to recommend the MT as well. Although I can't speak from experience, I have heard good things about it. But its priced like a more quality truck should be.

I have stripped down the rear half of my truck and took hold of the chassis plate and I'll be darned if I wasn't able to get that thing to flex with little effort. I am quite pissed that not only is the chassis not very rigid, but they also machined areas out of the plate making it lighter but also weaker. Its a 35 pound truck. Who cares about an extra ounce of material! Now I am convinced that my truck must have taken a rear end hit, forcing the dog bone into the cup and pushing it upward to the point of destruction. I am willing to bet that if I merely re-support the rear area, the stock plastic case will hold up just fine, assuming that I replace the bearings with some better ones which I have.

 

[nitrohobbiest]

Here is the start:

My truck with the diff removed:



The diff busted open:



The diff gears with damage from being driven while the case was broken:



Here is the area under the tank in which I plan to brace:



Looking at the last pic you can see how Redcat machined away some of the chassis plate to save weight (I guess). This area will have to be backed up from underneath with more aluminum. My initial plan is to cut the aluminum bar to fit from the engine back and then drill and tap it to attach it all together. I may use a threadlocker or similar metal adhesive between the two pieces to help the screws do their job. I will most likely re drill all the existing chassis holes into the new piece and then add a bunch more hidden ones.

Anyone recommend any thin adhesives that will bond aluminum together well?

 

[DemonRC]

I also think the dogbone is getting wedge between the cups due to flex and forcing the diff pinion cup upward. I baby my XB more than I have my XBE which I pound on and the XBE diff is rock solid still. The difference is the XBE has two huge supports from the diff to the center of the car plus an alloy upper plate. It's rock solid back there.

 

[Obeast44]

I also think the dogbone is getting wedge between the cups due to flex and forcing the diff pinion cup upward. I baby my XB more than I have my XBE which I pound on and the XBE diff is rock solid still. The difference is the XBE has two huge supports from the diff to the center of the car plus an alloy upper plate. It's rock solid back there.

This^^^^^

IMO Its rear chassis flex and not the cases. Anyone busted a front diff case like this?

 

[nitrohobbiest]

I also think the dogbone is getting wedge between the cups due to flex and forcing the diff pinion cup upward. I baby my XB more than I have my XBE which I pound on and the XBE diff is rock solid still. The difference is the XBE has two huge supports from the diff to the center of the car plus an alloy upper plate. It's rock solid back there.

Of course its beefed up more because it has the extra room that the gas engine would have taken up. But in that respect, Redcat saw the need to add all of this bracing to the XBE, why not figure out a way to add REAL bracing to the gassers instead of soft plastic rods that flex and aim in weird directions that actually use the tank as a pressure point. Who came up with that idea?

I've half thought to brace right to the engine except I'm afraid of creating distortions in the case when I hit hard. This could ultimately cost me an early engine rebuild and I have a nice 4 bolter in there now from DogPile Racing.

 

[rcgasser]

Hi, first time poster here. I am thinking about getting an XT, but am still on the fence between the XT & MT as the problems people are having with the XT. I am wondering if anybody has a definitive cause on the dif housing failures? Is it the bearing, chassis flex, or just under built in that area? Especially curious to know if just replacing the bearing with a higher quality one would help prevent a failure? Anyway, looking forward to any info posted and the future progress with your rebuild nitrohobbiest!

You will diffently want to get a MT over the XT way better truck I have had to buy alot least parts on the MT then the XT.

 

[nitrohobbiest]

I appreciate all the posts but if we could stay focused on the rebuild and not a truck comparison, that would be great. This is going to grow way off topic quickly.

 

[rob64n]

This^^^^^IMO Its rear chassis flex and not the cases. Anyone busted a front diff case like this?

oh and yeah my front is going as well,lol

 

[rob64n]

wish I could agree with the flex thing, but it's not. my XB has no issue yet but the xt has went through two rear diff cases and I can hear my front skippin teeth when it hits second gear.

 

[nitrohobbiest]

wish I could agree with the flex thing, but it's not. my XB has no issue yet but the xt has went through two rear diff cases and I can hear my front skippin teeth when it hits second gear.

You haven't posed any info that says its not the flex. You've had the problem twice on one truck and not the other. Does that prove that the identical part used on two different trucks makes it the parts fault? Sounds like no. If the trucks were the same and the parts were different, then I would say one diff is inferior to the other. But in this case, the variable is the truck so I'm figuring something is up with the truck.

On the other hand, I'm planning to attack this problem at both ends. The chassis will be supported and the new case will be bulked up. At this point, I don't care what the problem is unless there is proof positive its one or the other. Bottom line is, I don't want to do this much work again, at least in the near future. So I'm doing it all now and getting done with it.

 

[cordy]

Check out neutech`s diff case,thier part number 057508,looks to be the same as the xb ,but notice it has gussets molded all the way around the case. They also have aluminum diff. cases. Perhaps it would be worth the $12 to see if it would work. When you get on the site look at parts for the thunderbolt tb2. Here is the link,www.neutechracingforum.com,then click on neutech usa on the left hand column.

 

[k.jensen]

Check out neutech`s diff case,thier part number 057508,looks to be the same as the xb ,but notice it has gussets molded all the way around the case. They also have aluminum diff. cases. Perhaps it would be worth the $12 to see if it would work. When you get on the site look at parts for the thunderbolt tb2. Here is the link,www.neutechracing.com. Thier located in plover wis,Scott is the owner,a very nice fella.

if it's this one you are talking about http://www.nutechracingusa.com/alloydifferentialbox.aspx then I have been told by a supplyer in germany that it dosent fit the redcat XB (they sell the gearbox but not redcat products). but try it, I would loove to know that it does

 

[Keith81]

Look into a mt roller and put your dog pile racing engine on it, you'll truly be alot happier as the mt is built better in my opinion.... Sorry to be off topic...

 

[DemonRC]

I would have to disagree with it not being rear end flex. I have proof in a bent rear center dogbone that happened on a ass landing. I know it was the rear end landing for a fact because after I went to turn my car back over. I revved it and the dogbone started clanking against the bottom of my engine case. The only way to bend a dogbone like that is to bend the rear end enough that it gets locked between the diffcups.

 

[nitrohobbiest]

Yea, I'm not sure why this is a hard concept to grasp. If anyone has ever owned a T-Maxx, one of the first things you should do is swap out the chassis braces with quality aluminum ones for what reason? Because the chassis flexes and cause gear mesh to change and wipe out teeth! Its just one of those things that can't be overlooked and its common among many different RC's. And the fact that these trucks weigh a bunch more is all the more reason they need to be rigid.

I decided I am going to seek out a piece of 1/4" thick 7075 aluminum plate to bolt to the rear half of the chassis. Then to figure out my method of firming up the new diff housing for added bearing support. Anyone have a cheap place to order aluminum stock?

 

[Guest]

I decided I am going to seek out a piece of 1/4" thick 7075 aluminum plate to bolt to the rear half of the chassis. Then to figure out my method of firming up the new diff housing for added bearing support. Anyone have a cheap place to order aluminum stock?

I was actually thinking if 7075 machines a billet dif case it could incorporate a thick plate extending under the fuel tank. That would add a lot of strength to the rear of the chassis.

 

[nitrohobbiest]

Check out neutech`s diff case,thier part number 057508,looks to be the same as the xb ,but notice it has gussets molded all the way around the case. They also have aluminum diff. cases. Perhaps it would be worth the $12 to see if it would work. When you get on the site look at parts for the thunderbolt tb2. Here is the link,www.neutechracingforum.com,then click on neutech usa on the left hand column.

I'm still new to the Redcat scene so I need to ask why you would think this might fit? It the Thunderbolt a side brand of the Rampage? I does look like a better made case for sure. If I knew my innards would fit I am sure I can get it to bolt onto the chassis.