XR mod ??

[Johnnysplits]

It was suggested that I do the XR mod to my front axle to gain the maximum amount of steering. In order to maintain stock width, the XR axles have to be cut down. I've read to simply cut the axles down and grind new flats on the ends. I just tried this on a spare axle. Doesn't work. Soon as you start torquing it up, it spins in the locker. So then the only way to make it work is to cut the axles in half, then measure and cut the extra length that needs to be removed, then weld the axle together. Problem...I have no welder. Is there any other way to get this done?

[boohoo]

you cant weld plastic axles together unless you plastic weld them with resin of some sort

[Solitaire]

I think he was referring to the universals and not the axles (cases).
I've done it on a SCX10 build...cut the shafts and ground a new flat. You have to be very careful not to take too much off (as you've found out). Make sure the length is bang on and grind until it just fits. I've had no issues with mine yet.

I also have to mention I used HR lockers which may be a bit tighter than stock. Locked-Up RC also has F1 spools that I've heard have tighter tolerances.

[Johnnysplits]

Yes the axles, not the housings. Thanks for the info Solitaire. Maybe i'll order a set of the Locked up spools. You must have barely ground those flats on there.

[Johnnysplits]

Locked up FI spool ordered

[meatmonkey]

When I did mine I measured the width of the flat spots on the "tang" that goes into the lockers. I then used my vernier calipers to ensure that my hand-filed flat spots were dimensionally identical and parallel.

Sounds like you possibly ground a little too far?

I'm also using a Felsenfest zero-slop set-screw style locker. My flat spots are barely wide enough for the grub screws to evenly contact the axle.

If your still using the stock "sintered" locker then you should remove it to inspect where the shaft's flat spots rest. It is very common for the locker to get egged out from abuse over time, this will accentuate your looseness issue.

Just so you know, even without widening the housing to use un-cut shafts, you gain about 1/4 in width just from the c-hubs and knuckles.

Over the years I've seen lots of pictures on here of broken welded shafts. Makes me think that the welded portion is more brittle/less ductile than the rest of the shaft. So I do not reccomend you do any welding on the shafts.

[Postclanker]

It's going to be really hard to maintain the original width unless you can find a set of the original splined beef tubes. The new styles have the sleeves to keep the axle halves together and keep them from splitting. That's a better design actually, but adds about 3/4" to your track width.

You can take the sleeves off, I've done that, and the increase is much less....but there's some fabbing to be done to the delrin tube....the aluminum tube isn't possible IMO.

I've done several of these, it was a bit intimidating cutting and grinding on perfectly good parts the first time, but it works remarkably well once you get the hang of it. Best of luck Mr. Splits...I'd be glad to help if I can.

[Johnnysplits]

Originally Posted by meatmonkey

hand-filed flat spots

Sounds like you possibly ground a little too far?

Well that answers that question. After I cut down my experimental axle, I ground the flats with a benchtop disc sander with 150 grit paper. Yeah, guess I went too far. Need to get a hand file.

[Johnnysplits]

Originally Posted by Postclanker

it was a bit intimidating cutting and grinding on perfectly good parts the first time

Tell me about it. I want to get my "practice" axles perfect before I start cutting up and grinding on the set of Dlux Fab 70* XR axles @ $48.

[Solitaire]

Don't worry about 70 degree unis. You can't go that far without over-extending your servo in a bind. I had to add stops to the steering for that reason, otherwise a bind would snap my servo arm to 90 degrees or even over-center and I'd have to pick the truck up and physically straighten my wheels and servo. Just a little rounding of the tangs on the unis will be all you need.

[Johnnysplits]

Oh yeah not gonna use all 70*, more like 55-60* but at least it will spin freely and not start to bind at that angle like they do now at 40*.

[FATBOYrs10]

Originally Posted by Johnnysplits

Well that answers that question. After I cut down my experimental axle, I ground the flats with a benchtop disc sander with 150 grit paper. Yeah, guess I went too far. Need to get a hand file.

I regrind my new flats on a bench grinder

[Johnnysplits]

Don't have one

[Postclanker]

I have a bench grinder, but I use a file....I'm a bit too aggressive with the grinder

[Erin]

I like to file flats before cutting, use exsisting flats as a guage, then make small passes checking with calipers so you dont cut to far. This also helps with keeping flats even and centered.

[Postclanker]

Originally Posted by Erin

I like to file flats before cutting, use exsisting flats as a guage, then make small passes checking with calipers so you dont cut to far. This also helps with keeping flats even and centered.

Absolutely the way to do it....
I use a grip fab spool, the fit is so tight I've had to take the anodizing off the flat to get it to fit. And "Zero" slop .....is always nice

[ZippoMan]

Can you guys post pics of the mod? I am curious to see it.

[Johnnysplits]

Gentlemen, I have achieved success in grinding flats on my experimental axle!! I was waaaay too aggressive on my first attempt. This time I very gingerly touched the axle to the sander on both sides, test fitting as I went. It took 4 passes to get the flats to fit absolutely perfect into the stock locker. Now I can't wait for the new xr axles and FI spool to show up along with the axial plastic wraith C's and K's.

[Johnnysplits]

Originally Posted by ZippoMan

Can you guys post pics of the mod? I am curious to see it.

I'm kinda following this...XR10 Knuckles&C-HUBS on AX10/SCX10 axles... - WARCRC

[ZippoMan]

Ok cool I will check it!! Thanks