How-to/MOD: Stronger rear axles for under $35!

[qwig]

Hey guys. I have been working on an inexpensive rear axle solution for awhile now. While going through my part box trying to come up with some ideas, I found some parts that looked like they would work! Although it's not all steel like I had wanted, it should still be a nice improvement.

This mod will increase strength at all the common breaking points. It will also increase the stub axle diameter to 6mm like the tekno kit.



Top one is the new shaft, bottom is stock. Every part of the new shaft is bigger than the stock one. The new shaft is a t-maxx 2.5 half shaft. You will need to cut the male and female splined parts down to around 1.35" inches each.



Much better!



I had some 6x12x4 bearing out of some extra revo diffs. You can buy 6x11x4mm bearings from boca bearings for about $14 for a set of 4. That would save you the trouble of boring the bearing holes to 12mm.
Side thought: I am running an RPM e-rustler rear carrier on one side and the 6x12x4 bearing popped in quite nice. Stock slash carrier, not so much.



You will need to drill out your stock 12mm hex to 6mm ID to fit the new axle.



Ready for the hex! On the stock carrier, it doesn't need shimmed. On the RPM e-rustler carrier, it would need a couple shims. This could change depending on how your bearings fit in the carrier after drilling it out. For this reason, I would get some shims/washer just incase!



Ready to roll!

This looks like it should really hold up much better than stock. I will do some 6s runs with my 2200kv to really abuse them and see how well they do!

Parts list:

4951x - (2) tmaxx half shafts - $7.69
4928x - (2) diff output yokes- $4.79
4953x - (2) stub axles - $7.69
DTXC9767 - 6mm shims (10 pack) - $1.79 x 2
5147x - 5mm flanged lock nuts - $3,39
5117 - 6x12x4mm ball bearings - $3.89 x 2 (These require drilling/sanding of carriers. Buy 6x11x4mm for direct fit)

These are the prices at Tower. You can probably find them cheaper. For example, I just bought a full set of 4 half shafts (the first 3 items on the list) for $16 shipped.

I think these should work for the front with a few more mods. I will try to get them to work shortly.

Thanks for looking!

[Mud Puppy]

don't you need 6mm lock nuts, not 5mm?

[qwig]

don't you need 6mm lock nuts, not 5mm?

Nope. The threads on the 6mm axle are 5mm. Just like the slash 5mm axle has 4mm threads.

[Mud Puppy]

Nope. The threads on the 6mm axle are 5mm. Just like the slash 5mm axle has 4mm threads.

ah, that makes sense.

[phil1234]

looks good ,,,,I thought about my t-maxx 2.5 which is 6 years old with out any drive shaft problems,,never rebuilt them too. Definatly a good idea!

[ScottStaypuff]

Nice modding! I like it a lot.

[qwig]

I was able to get the fronts working also. I will take some pictures tomorrow. You can also buy the above parts from myatomic.com for about $10 bucks cheaper, plus free shipping!

[rawpwr]

Nice work!!! I have also been looking at my old t-maxx drive shafts but i don't want to cut up my aluminum rear bearing carriers

[shadowwalker702]

Nice work!!! I have also been looking at my old t-maxx drive shafts but i don't want to cut up my aluminum rear bearing carriers

You don't have to if you get the 6x11x4 bearings.

[ScottKelly911]

Props for thinking outside the box. Quick question, does this allow full travel?

[madkawi650]

My only thought is that it might bind on an RPM A-Arm at the outer end.. the Stub Axle U-Joint pins on my FLM Stubs will slightly rub my front A-arms when the suspension is at full drop and the wheels are turned..

Sorry,,, Actually my first thought is AWESOME WORK !, my second would be the rubbing.

Thumbs up,,,
I'm going to try this very soon.

[markturbo]

Thats a great idea!

I'd like to try that for the front.

[asheck]

This was done on RC-tech months ago. I'd look there for info, as it seems there are some better variables for it.

[jrmbtr]

So if you used TRA5451X, the only change to the driveshafts themselves would be shortening them?

[qwig]

Props for thinking outside the box. Quick question, does this allow full travel?

Using the middle top mount and the most inner bottom mount, there is binding at full droop. Using the 2nd most inner on the bottom, there seems to be slight rubbing. Shaving a bit off the a-arms would give you full travel. I haven't tried moving the top mount position. Any particular positions you need verified? I will check with RPM arms also. My honey-do list is growing so I need to stop playing with the truck! lol

This was done on RC-tech months ago. I'd look there for info, as it seems there are some better variables for it.

That's cool. Care to link us? I hadn't seen anything on here about it, and I needed stronger shafts, so that leads here.

So if you used TRA5451X, the only change to the driveshafts themselves would be shortening them?

5451x shafts are too wide (they are huge!). The shafts I used barely have enough clearance for the a-arm.

[qwig]

Well I have the shafts working for the front too. I replaced the 10x15x4 bearing with a 6x15x5mm bearing I had in a e-maxx rpm axle carrier. I then put the stub axle in my drill press as a make-shift lathe. I used my dremel cut off wheel to sand the outer diameter of the axle down to under 15mm. A file would have made a quicker and cleaner job though. Now that the axle is under 15 mm, it will fit in to the front carrier just fine.

I drilled out the outer bearing of the carrier to fit a 6x12x4mm bearing.


Fits nice!


Left side modded, right side stock.

6x15x5mm bearings can be found at www.bocabearings.com. They start at $4.50/bearing. You will need 2.

[jrmbtr]

5451x shafts are too wide (they are huge!). The shafts I used barely have enough clearance for the a-arm.

Isn't 5451x the assembled 4951x, 4928x, and 4953x?

[FangsCPO]

Impressive!!!

[SirSlash4x4]

Very interesting

[qwig]

Just got back in from running. Half shafts held up great, but a few minutes into the run 6888 broke off! Arrrrg! Here's a short video.

http://www.youtube.com/watch?v=3Ib8uQWKHQw

[SirSlash4x4]

Sorry about your 6888, mine did the same recently.

The last part of the vid is wicked though!

[fisheydude]

Love the grass being eat up by the badlands!

[ScottKelly911]

when you replace 6888 go with 6888x that's the hardened steel one whereas 6888 is the plastic one. I heard the Ultimate comes with the 6888x stock, but haven't verified this. I have the aluminum STRC one, it's held up fine so far, but I wouldn't be surprised if it eventually fails also, but at least it'll last a lot longer than the stock plastic piece.

[qwig]

when you replace 6888 go with 6888x that's the hardened steel one whereas 6888 is the plastic one. I heard the Ultimate comes with the 6888x stock, but haven't verified this. I have the aluminum STRC one, it's held up fine so far, but I wouldn't be surprised if it eventually fails also, but at least it'll last a lot longer than the stock plastic piece.

I originally thought I had the 6888x, but after a 2nd look it appears to be plastic. Once I get a new one, I will do some more bashing to see how the axles hold up.

[shadowwalker702]

My ultimate came with the 6888x stock.

[madkawi650]

This was done on RC-tech months ago. I'd look there for info, as it seems there are some better variables for it.

I searched RC TECH and can find nothing. Could you post a linky...

[qwig]

I searched RC TECH and can find nothing. Could you post a linky...

I found it. It's in the "Slash 4x4" thread in the electric off road forum. Do a search by user "Nighthawk". From what I had read, he was going to do a write up about the mod and never did.

Anyways, for people wondering about suspension travel; in the rear with RPM a-arms, there is no rubbing using any of the outer 3 bottom mounts with any of the top mounts. Using the inner 2 bottom mounts results in suspension droop being limited by the axle rubbing the a-arm. It would be rather simple to grind the area down to get the clearance. Even with it rubbing, you can't tell it is. There is no binding; it just rolls smoothly on the a-arm.

I haven't tested the front yet, but I will get around to it. I am still working on an all steel solution. I do think I am on to something, and if it works they would cost around $35/set.

Thanks guys!

[NITROTUEL]

This is really cool.All steel ones though? These look pretty darn burly enough without the weight and wear of steel.I just broke my last rear stub so I went to gather all the parts...got everything except the 6x11x4 bearing.I had to order it,but they're only 3.75 a piece right now at boca.I tried your milling out method with an old carrier but me not so good miller.So, I wait.

[qwig]

This is really cool.All steel ones though? These look pretty darn burly enough without the weight and wear of steel.I just broke my last rear stub so I went to gather all the parts...got everything except the 6x11x4 bearing.I had to order it,but they're only 3.75 a piece right now at boca.I tried your milling out method with an old carrier but me not so good miller.So, I wait.

Glad you're going to try it! I luckily have a 12mm drill bit, but even then one of my carriers came out a little off center. Now that I know it works, I will buy some 6x11x4 bearings when I decide to replace the carriers. I noticed earlier that the lower part of the front shock tower is rubbing slightly on the shafts up front. A little bit of dremeling should clean it right up.

The reason for the all steel shafts is that I want a fix that is even stronger and doesn't require modification. I think these plastics shafts will hold up great as well, but we know some people would rather have a part that slips right in.

jrmbtr - 5451x is the shafts used on the newest e/t-maxx and e/revo. They are probably twice the diameter of the parts used in this mod.

Edit: I have read that the stock wheels will need to be drilled to 6mm to except the new axle. Also the flanged style 5mm lock nut may not work. They do offer a non-flanged version though.

[iRoll]

What about the diff side? I tried something like this with my TMaxx Classic axles when I broke my first set of stockers, and the diff outputs were too small. It would work, but it wouldn't last very long.

[qwig]

What about the diff side? I tried something like this with my TMaxx Classic axles when I broke my first set of stockers, and the diff outputs were too small. It would work, but it wouldn't last very long.

There is no play at the diff end. I had originally planned on trying to put the revo diff outputs in, but it isn't needed as far as I can tell.

[iRoll]

Sweet. Thanks for the heads up on this swap.

[ScottStaypuff]

What about these big axles in conjuncton with these wide suspension arms:

http://shop.rc-solutions.com/Slash-4...rm-Set-211.htm

I'm thinking sweet combo!

(I'd prefer plastic arms but might give these a shot)

[madkawi650]

Just came come from the LHS with my supplies. It cost me $55 for evrything. That includes the 6/12 bearings that would require me to mod the carrier. Seems to pricey but I thought I would give it a try while I waited for MIPs.

First thing i did was try to install the output yoke because I had no idea how it would fit in that little space,,, but it fits I there... HOWEVER, it does not fit the output shaft . The shaft is 5mm with the sides shaved off to make the flats. The distance across the flats is about 4mm + or - .... The TMaxx yoke is 6mm... It does have approx 4.5mm across the flats, so it seems to fit ok. But, the 6mm coupled with the wider flats gives a very wobbly setup. Even with the screw pin tight, it sat crooked. Now I could have tried to straighten and re tighten. But I thought for $55 I could have a set of flm cvd's and still not get full suspension travel.

Don't read this the wrong way.. I love when people mod things and try new stuff to save time and hasstles and $$$. Just for ME, this one costs to much not to be near perfect... If you have some old stuff around or your prices at you lhs are cheaper than mine, than by all means give er a roll.. The slop o the yoke might be the only issue, and might prove not to be a problem after all.. Good luck to all who give it a try.

[qwig]

Just came come from the LHS with my supplies. It cost me $55 for evrything. That includes the 6/12 bearings that would require me to mod the carrier. Seems to pricey but I thought I would give it a try while I waited for MIPs.

First thing i did was try to install the output yoke because I had no idea how it would fit in that little space,,, but it fits I there... HOWEVER, it does not fit the output shaft . The shaft is 5mm with the sides shaved off to make the flats. The distance across the flats is about 4mm + or - .... The TMaxx yoke is 6mm... It does have approx 4.5mm across the flats, so it seems to fit ok. But, the 6mm coupled with the wider flats gives a very wobbly setup. Even with the screw pin tight, it sat crooked. Now I could have tried to straighten and re tighten. But I thought for $55 I could have a set of flm cvd's and still not get full suspension travel.

Don't read this the wrong way.. I love when people mod things and try new stuff to save time and hasstles and $$$. Just for ME, this one costs to much not to be near perfect... If you have some old stuff around or your prices at you lhs are cheaper than mine, than by all means give er a roll.. The slop o the yoke might be the only issue, and might prove not to be a problem after all.. Good luck to all who give it a try.

Sorry to hear about your experience. Could you take pictures of the new shaft next to the stock one? All my parts were pulled off old trucks so I may have got a part number wrong. My output yokes seem to be tight and square. An idea for you would be to use some 5x8 shims between the cup and the diff bearing. That should help keep it square.

[madkawi650]

No need to apologize for anything. I was just sharing my experience. I didn't take the other parts out of the packages so I will be able to return them. I was thinking about an idea like you'd from the first time I bent a stub axles.. When I saw the idea here I wAs excited and rushed right out to buy the parts. I think at my Canadian lhs prices I would be better off buying the FLM cvd's. His brand new ones just came in from heat treatment today and he says they are better than ever.

Typing is bad on my iPhone you'll have to excuse the typo's

[qwig]

I'm glad you will be able to return them! I'm not sure how much play you had, but I just checked again and mine is very minimal. If anyone is iffy about trying it, you could always buy just the output yokes and see if the play is acceptable to you.

In other news, I decided to play around with some more modding. This time I busted out the 5451x shafts from the new revo and maxx. After trimming a bit and inserting the steel stub axle from the 2.5 maxx shafts, I have a new beast of a shaft.


Oh my! LOL


Mounted up!

[madkawi650]

Is that a revo output yoke ?

I have one complete revo axle shaft, dust boot and all. Plus I have a set of the revo center drive shafts left over from my revo days. They are H U G E,, but I might have to play with them tomorrow..

[qwig]

Is that a revo output yoke ?

I have one complete revo axle shaft, dust boot and all. Plus I have a set of the revo center drive shafts left over from my revo days. They are H U G E,, but I might have to play with them tomorrow..

Yep, it's the complete revo shaft minus the steel axle. I cut up one of the 4953 stub axles (4953x should be the same) and used a vise to press out the pin. Then I had to take my 6mm drill bit and drill out a bit of the revo cup where the axle shaft slides in. Re-insert pin with vise. Put the new shaft through the modified carrier and see how much plastic you need to trim off the axle where it meets the carrier bearing. The revo shaft will NOT work on the front.

[SirSlash4x4]

HAHA the second one is beast
Great work, I can't wait to see what you come up with for steel ones!