Losi XXT CR Graphite Plus - Runner build

[LosiXXkid]

Glad to hear I am not the only one, lol.

Got it running, but I am unhappy with the electronics. I will be replacing the esc, battery, and maybe motor.

I am having a real issue with differential. I can't get it to tighten enough not to slip. I keep tightening it, but it continues to slip. I have taken it apart several times to make sure everything is setup right. Does anyone have much experience with these, who can maybe shed some light on what I may be doing wrong? I would appreciate any help. Thanks.

Hmmmm? Assuming that you've built the diff correctly as per the manual, then it really shouldn't slip. Did you rebuild it with new diff rings and diff balls?

Maybe some photo's of the disassembled diff will help with the diagnosis....

[matt1ptkn]

Whats wrong with the electronic setup? And this may be a dumb question, but are you sure its the diff slipping and not the slipper? I often overlook the simple solutions, so I try to help ensure that others avoid my mistakes, whenever possible.

[Lavigna]

Whats wrong with the electronic setup? And this may be a dumb question, but are you sure its the diff slipping and not the slipper? I often overlook the simple solutions, so I try to help ensure that others avoid my mistakes, whenever possible.

Yes, I made sure it is not the slipper. I was thinking that myself, so I tightened it down all the way just to rule it out.

I am 99% sure everything is built and assembled correctly. I have rebuilt it several times just to make sure. The diff balls are not brand new, but are in very good condition. The diff rings are new. I began tightening the diff further while on the truck, then running it to see how it felt. It was getting better, but the diff was very tight. Finally, I tightened it too much, and it let loose. I took it all apart again, and re-tightened it, nothing broken. It still doesn't seem right. It is very strange. I will continue to work on it.

[Lavigna]

I changed out some of the electronics, and am much happier. After much messing about with the diff, I think it is working well now. I still have not driven it outside, but my few indoor tests felt good.

Just a few minor details to finish, and I need to order and paint a TBG body for it. I don't want to use any of my originals on it. I will post some better pictures soon.

[Lavigna]

I finally ran the truck in my driveway, and was very impressed. It seems to handle great. I think it would easily be competitive in a modern stadium truck race. Very impressed.

[LosiXXkid]

I finally ran the truck in my driveway, and was very impressed. It seems to handle great. I think it would easily be competitive in a modern stadium truck race. Very impressed.

Looks great! And practically like a new build.....

[matt1ptkn]

So what did you end up doing with the diff? I'm rebuilding a XXT right now and I'm having the same issue you described. I have to really crank it down tight to prevent it from slipping. I had wondered if it is related to the mountain of bevelled washers and if there is a benefit in replacing them with a spring like the XXXT? Or maybe new bevelled washers? Thanks for any info!

[Delorean]

Just a general question for people running XX buggies or trucks with stick lipos.

How are you getting around the "step" part inside the battery tunnel that narrows the width down to around 42-43 mm which is narrower than standard stick packs. i want the pack to sit as low in the chassis as possible, i'd rather not put a plate in the bottom and have the battery sit higher

cheers

[Lonestar]

Nice XXT! I miss mine from bitd

Couple of things that explain a poorly performing diff (assuming all parts are in good shape)

- a wrong (too thick) part inside that takes pressure off the main balls and takes that burden itself instead
- wrong fluids (you want graphite on the thrust bearing and a diff-specific one on the main balls, use RC brand names only...)
- fluids that have mixed (typically graphite reaching to the main balls)

This is too nice a car to run - shelf it!

[snowfox]

Just a general question for people running XX buggies or trucks with stick lipos.

How are you getting around the "step" part inside the battery tunnel that narrows the width down to around 42-43 mm which is narrower than standard stick packs. i want the pack to sit as low in the chassis as possible, i'd rather not put a plate in the bottom and have the battery sit higher

cheers

Dremel it out

[LosiXXkid]

Just a general question for people running XX buggies or trucks with stick lipos.

How are you getting around the "step" part inside the battery tunnel that narrows the width down to around 42-43 mm which is narrower than standard stick packs. i want the pack to sit as low in the chassis as possible, i'd rather not put a plate in the bottom and have the battery sit higher

cheers

Dremel it out

Stop! Don't do that just yet,......well at least not before you check out this thread:

http://www.rc10talk.com/viewtopic.php?f=27&t=27241

[matt1ptkn]

Nice XXT! I miss mine from bitd

Couple of things that explain a poorly performing diff (assuming all parts are in good shape)

- a wrong (too thick) part inside that takes pressure off the main balls and takes that burden itself instead
- wrong fluids (you want graphite on the thrust bearing and a diff-specific one on the main balls, use RC brand names only...)
- fluids that have mixed (typically graphite reaching to the main balls)

This is too nice a car to run - shelf it!

Item #1 was my culprit. Being that mine is a XXT Sport, I assume that it did not originally have ball bearings in the diff. Someone before me had put bearings in there and the one in the center of the diff gear was too thick. I fabbed a bushing for mine that matched the thickness of the diff gear and it now works flawlessly.

As for battery fitment issues, just search for different batteries. There are almost infinite battery possibilities out there and several that fit perfectly in a XX chassis. Here is what I use that fits just like the NiMhs.

[Delorean]

Dremel it out

Cheers mate, i had thought of that, i was worried that it might go through the chassis. have you seen it done? is there enough meat on the bottom of the chassis so it wont create holes underneath?

Losi xx kid, i had a look at that thread you linked but i couldnt see much in the way of an answer other than them putting balsa under the battery to space it up

i had a look at hobbyking and they have narrower packs in the zippy compact range that are 43mm wide, i can get up to a 4000mah pack which is plenty and it should slot in without any modification

i picked up a short graphite chassis for the car and didnt necessarily want to take a dremel to it as soon as it comes out of the packet lol

[LosiXXkid]

Dremel it out

Losi xx kid, i had a look at that thread you linked but i couldnt see much in the way of an answer other than them putting balsa under the battery to space it up

That's the bit that I was trying to highlight. Dan seems to have had good results with a thin piece of balsa wood to provide a flat base for the Lipo to sit on but in the end I guess it depends on how determined you are to get the CoG as low as possible!

[Lavigna]

Couple of updated pictures. I am hoping to make it to Vonats this year.