Axle gears stripped, need some help

[thirdeye]

What's up everyone? I stripped the front axle pinion gear, and am looking to upgrade both front and rear now. Of course using Harley's guide. He posts different gears for front and rear; 38/13 for the front and 43/13 for the rear. My experience with real jeeps is that the gears front and rear need to match. Not true for rc? Any info is appreciated.

-thirdeye

[DUWraith]

true, I use the underdrive HD only in the rear, standard HD front, helps it turn better and climb better. Do search, there's lots on here about it.

[Revoasian]

You are absolutely correct in the 1:1 world, that would be bad news. But fortunately in the RC scale world we can get away with such mods as the OD/UD diff gears. If you are using your rig more for trails and speed runs, this set up would not be advised. However, if your rig is set up for rock crawling only like mine is, then it would be beneficial. I use this set up with weighted wheels front and back to help me with verticle climbs. The front wheel will spin faster than the rears which help pull the rig up steep climbs and ledges and prevent it from tipping backwards. Also too it helps with tighter turns which is a plus. Some on here will use the UD gears in the rears only which is also beneficial, but again it's for their application. If you don't feel comfortable with any of these set ups, I would just purchase the stock gearing but in the HD bevel set and be done with it. Now would be a good time to beef up your pinion bearing with thicker ones or use bushings like the Traxxas oil lites. Hope this helps.

[SCREAMER]

Originally Posted by Revoasian

You are absolutely correct in the 1:1 world, that would be bad news. But fortunately in the RC scale world we can get away with such mods as the OD/UD diff gears. If you are using your rig more for trails and speed runs, this set up would not be advised. However, if your rig is set up for rock crawling only like mine is, then it would be beneficial. I use this set up with weighted wheels front and back to help me with verticle climbs. The front wheel will spin faster than the rears which help pull the rig up steep climbs and ledges and prevent it from tipping backwards. Also too it helps with tighter turns which is a plus. Some on here will use the UD gears in the rears only which is also beneficial, but again it's for their application. If you don't feel comfortable with any of these set ups, I would just purchase the stock gearing but in the HD bevel set and be done with it. Now would be a good time to beef up your pinion bearing with thicker ones or use bushings like the Traxxas oil lites. Hope this helps.

Can you elaborate on these thicker bearings? Are you talking about the ones that require modification of the housing to fit?

[MountainStorm]

Originally Posted by SCREAMER

Can you elaborate on these thicker bearings? Are you talking about the ones that require modification of the housing to fit?

The pinion gets forced away from the bevel gear in two directions and this rapidly degrades the tiny bearings in the housing. Once the bearings degrade they often spin in their bearing pocket. The housing is soft plastic so it rapidly deforms and in short order the pinion and bevel gears are no longer held in proper alignment.

There is no real solution to this. Dlux (vendor here) mods the housing to accept a larger bearing. I have blown through 3 of these in less than a month. They might be better than small bearings but they are not a solution. Oilite bushings wear very fast as they are porous by nature and crumble away under the thrust load so I don't even go there.

Aluminum housings by SSD and more recently VP use a larger bearing like the Dlux housing but once again this is not a magic bullet.

The bottom line is the diff will always be a "problem" and will always require proactive maintenance.

Bearings are much cheaper than gears so having serveral spares on hand and changing them out on a regular basis is your best bet.

Also you should inspect the plastic housing and see if the bearings fit tightly in the pockets. if not throw that case away and get another. No sense in putting new gears or renewing bearings in a beat case.

Hope that helps.

[SCREAMER]

Great info MountainStorm! I've got a complete set of fast eddy's on standby. Do you think the fast eddy's ceramic would make any difference? Does this problem apply to the front and rear housings equally? I hope this doesn't happen too often. Complete axle rebuilds is going to get old fast. Who am I kidding, I love wrenching on my Spawn. Lol

[thirdeye]

Good info on the bearings, I will definitely pick up those bushings to replace. So being mostly a crawler, 38/13 front and 43/13 rear should work well then yea?

[MountainStorm]

Originally Posted by thirdeye

Good info on the bearings, I will definitely pick up those bushings to replace. So being mostly a crawler, 38/13 front and 43/13 rear should work well then yea?

Lots of guys here do that so I guess so. I run 38/13 front and rear because I am not just crawling.

I think most of the diff wear issues come about from putting more wheel speed and more power through the axle than it was designed to handle. I know that's why I go through them like tampons on a full moon. Driving style will also dictate how long an axle lasts. Bashing crawlers is hard on parts.

[thirdeye]

Yep, wheel speed is what did it for me. I put a fast motor in it just for fun to do some donuts. I figure if I was going to use it for high speed and no crawling like that, i could just take out the front driveshaft. Gonna go with the 38/13 & 43/13 combo, as I am usually running a 45T motor.

[Revoasian]

Originally Posted by SCREAMER

Can you elaborate on these thicker bearings? Are you talking about the ones that require modification of the housing to fit?

Ok, I guess I should have been a bit more descriptive. I went the easiest route that I thought would work for me. The stock pinion bearings I believe are 5x11x4? I went 1mm wider 5x11x5 on the bearing and use them on the front of the outer housing only where the pinion shaft exits the housing. I have VP housings but this will work for plastic as well. There are zero mods for this bearing application, being that it is 1mm wider ( thicker ) this will put the driveshaft coupler closer to the bearing so there is very little if any movement allowed for the pinion gear to push into the ring gear to bind. Keep in mind that there are many ways to address this issue eg: you can use bronze bushings from HPI, Traxxas oil lites, even the proper thrust bearings to help solve the binding and achieve proper back lash for your gears. If you're running a stock set up you shouldn't have these problems, it's mainly wraith owners with high powered rigs that will benefit from these mods.

[MountainStorm]

That's a new one for me. I usually shim the outside with a 1mm washer so using a 1mm thicker bearing would be perfect. Thanks! There is no real cure for the inside bearing though...thrust bearings don't like radial loads and radial bearings don't like thrust loads and I have yet to find a tapered roller bearing that small...

[SCREAMER]

Oh yeah, tapered roller bearings with a pressed in race would be perfect. Like the setup on a dirtbike steering stem. Ok, someone needs to make this now. Thanks for the info on the thicker bearing Revo. I will definitely try those on the next refresh.

[Erik D_lux]

Originally Posted by MountainStorm

Dlux (vendor here) mods the housing to accept a larger bearing. I have blown through 3 of these in less than a month.

Wow! Thats crazy!

I have only heard of one other guy EVER blowing the bigger bearing in my housings and he said it happened in less that 2 packs so I figured it was his setup.

My tester is going on 2yrs of HARD driving and he puts a serious amount of packs through his car. Again, thats 2 YEARS ON THE SAME BEARING!! Unless people are not saying anything, I think this is more common. I have sold tons and tons of these housings with nothing but good feedback.

I wonder what the difference is between you and everybody else? Got any pictures of the bearings?

[84yoda]

Mountainstorm, what is your setup?

[MountainStorm]

Originally Posted by Erik D_lux

Wow! Thats crazy!

I have only heard of one other guy EVER blowing the bigger bearing in my housings and he said it happened in less that 2 packs so I figured it was his setup.

My tester is going on 2yrs of HARD driving and he puts a serious amount of packs through his car. Again, thats 2 YEARS ON THE SAME BEARING!! Unless people are not saying anything, I think this is more common. I have sold tons and tons of these housings with nothing but good feedback.

I wonder what the difference is between you and everybody else? Got any pictures of the bearings?

First off much respect for you and your mods and designs.

First housing I split at the output when I was pushing a 5 pound rig with a CC SCT3800 set up and going hell for leather FOFF-style launching up a near vert 8'+ dirt bank here at the house. The plastic tore right where the pinion output protrudes from the housing. I don't fault your housing...the link mount I chose screws to the top (poor design IMO) and when it tore loose the axle over rotated which put a lot of stress on the MIP shaft/pinion connection. Second housing got torn up at the link mount and when I repaired it by glomming on another link mount with CA glue I checked the bearings and the big one was crusty and gritty feeling. Considering that it was inside and no water intrusion I assume it was just worn out...you know how a worn bearing feels...gritty and tight. I put in the bearing from the first housing and ran that until I tore up the plastic to the point I could no longer repair it. Third housing I ran for a good while until the gears no longer made contact and when I opened it up the pinion had ground away one side of the plastic inside and when I inspected it further the bearing was loose in the pocket...loose enough to come out with the pinion. That was running a Puller Pro BL XL and BLE Pro with an 11 pound tuber. The bearing felt fine though...so I have to think it was just from side load not spinning in the pocket but I can't really know.

2 out of 3 bearings survived...one failed. All 3 housings were torn up from hard running.

I run HD 13/38 gears with FI spool and OT shafts and heavy Pitbull Wheels and Rockbeast II tires on the axles. Weight has varied from 5 to 11 pounds and my current rig is about 7.5 pounds. I run hard...not crawling...more like trail blazing with plenty of throttle. I use Beef Tubes in the rear and Burly Splined Tubes in the front.

When I scrape together some coin I will be getting another pair of your modded axle housings because they are the best bang for the buck IMO. And I have already invested in the tubes...so I will keep using plastic housings for now.

I run about 2 times a day for about an hour per session. I drive it hard. That's a lot of wheel time IMO. So no complaints. The modded housings have made my gears and bearings last much longer than stock housings.

Originally Posted by 84yoda

Mountainstorm, what is your setup?

Currently running a CF custom chassis with CMS and built axles XR modded front VP ends all around, Locked Up/HD Internals, Beef and Burly Tubes, Heavy 2.2 Scale Bead locks with 5.75" OD Pits and CI Deuces Wild Foams. These Pits hook really hard...I have no problem lifting the front when I goose it. HH power 540 Puller Pro BL XL (10 ounces!) and Trailmaster BLE Pro ESC on 3s.

[MountainStorm]

When I look at the post I made on blowing through 3 housings I realize that it could also be read as me blowing through 3 bearings...which I can see would be confusing. Breaking plastic housings is going to happen. Burning up such a large bearing is harder...but I can do it. If you ever want to torture test a product send it to me. I have a loooooong history of beating the snot out of stuff...tools, motorcycles, 1:1 trucks and cars. If it can be broken I will eventually find a way to do it. In my defense I would like to add that I have a GREAT time doing it and have learned how to build some nearly indestructible rigs in the process

[ussprinceton2004]

Originally Posted by Erik D_lux

Wow! Thats crazy!

I have only heard of one other guy EVER blowing the bigger bearing in my housings and he said it happened in less that 2 packs so I figured it was his setup.

My tester is going on 2yrs of HARD driving and he puts a serious amount of packs through his car. Again, thats 2 YEARS ON THE SAME BEARING!! Unless people are not saying anything, I think this is more common. I have sold tons and tons of these housings with nothing but good feedback.

I wonder what the difference is between you and everybody else? Got any pictures of the bearings?

do you sell those larger replacement bearings only? I don't see them at your website