output extension to run larger spur option

[mulepic]

I came up with this when I realized that you can't run a 96T spur w/ the stock output shaft. The drive shaft interferes with the spur when it gets over 92T. So I extended the output shaft of the transmission. I tried several options and I wanted to do it with little expense. This meant finding typical hardware store items. I have two iterations I came up with. One uses a dowel pin and the other uses a threaded coupling. In both case I used 3/16 rod not 5mm. It's readily available and tolerance is close enough. I do have a piece of 5mm I ordered but I don't have the details worked out yet. The 3/16 rod is pressed (hammered if you like) into the coupling and a set screw is used to attach to the transmission output shaft. I used a #13 drill bit for the 3/16 rod and a #8 for the transmission side. The dowel pin comes w/ a 1/4-20 hole for the set screw so you need to purchase a 3/16x1/4-20 set screw. For the threaded coupling I tapped a 8-32 hole. It works great and you can make this for under $10 if you don't have the drill bits. If you do then under $5. I'll update this when I use a 5mm rod, I mainly have to work out which size drill bit. #9 was a bit too big, so I'll try #10 or #11.

Here are some pictures:





In use. You can see there is plenty of clearance. I wish I had a 98T to try.

[yotachump]

I dont think that output will last long now.

[mulepic]

I'm sure you do have knowledge of this. So which will fail, the oem shaft, the coupling, and/or the 3/16 rod? I should note that my build's goal is to keep it as light as possible. I don't run any weights and I use a small 2 cell lipo. I'd be interested in a heavier rig trying this.

[maro69camaro]

why. i dont get why you would do this and making it weaker. when there are so many motor, spur, pinon that this would be a very bad idea. but thqats just my 2 cents

[mulepic]

I'm not claiming I have months of experience with this setup but I have no reason to believe why this would be weaker. Can someone explain to me why this would be weaker? I will update this thread with my long term experience.

[cembom]

Probably just like taking a 1.5" rod and trying to bend it, versus taking one thats 5". The longer is much easier. It doesnt look weak at all though. I think it will last a while like that. I think the worst problems would come from bending or hard startups or binding. Im not sure if I under stand but if the one is drilled through both the coupling and the extension the pin will probably fail due too prolonged twisting.

[mulepic]

I'll explain the drilling steps to hopefully answer your question.

note: 3/16 = .1875", #13 drill bit = .185", #8 drill bit = .199", 5mm = .1969"

1. I first drill all the way through the coupling w/ a #13 drill bit. This is .0025" smaller than the 3/16th rod so it's a tight press fit.

2. Press the 3/16 rod into the coupling half way. Actually using a hammer can deform the rod so if you have a press I would use it.

3. Drill from the other end w/ the #8 bit till you hit the 3/16 rod.

4. tap the 8-32 hole if you are using the coupling

5. I trimmed the coupling to 5/8". The dowel pin is 16mm which is a usable length.

[Nabil]

mail me one, i will put it in my axial, and i will break it in 2 minutes.

i will post video

[mulepic]

I'll send you a pm to get your address. I appreciate you testing it out; I enjoy coming up w/ solutions to these sorts of things and making them better. I hope it last longer than 2 mins. I hope to get it out to you by next week.

[CRAWLER_H19]

Putting a 96T spur on my AX-10 tranny was the first mod I made. RC4WD makes a stainless steel 6MM to 5MM adapter. See the AXW3 build on WARCRC. I run a brushless and have had no problems with it...

[mulepic]

is this what you are referring to: http://rc4wdstore.com/product_info.php?products_id=557

I wish it was 5mm to 5mm, but I could have worked w/ the 5mm to 6mm one. Thanks for the info, I might have gone this route had I known about it. But I enjoy the opportunities I get to work w/ my tools when I can.

[CRAWLER_H19]

Originally Posted by mulepic

is this what you are referring to: http://rc4wdstore.com/product_info.php?products_id=557

I wish it was 5mm to 5mm, but I could have worked w/ the 5mm to 6mm one. Thanks for the info, I might have gone this route had I known about it. But I enjoy the opportunities I get to work w/ my tools when I can.

Yes, that's the part. Mine came in raw stainless not black. I think I even put the exact drill bit size I used and all in the build? It's been a while... Note - I drilled by hand, so i gained like .015" slop over the drill bits true dia. If your going to use a drill press, I would use the correct size to match the RC4WD output dia.

[mulepic]

Speaking of drill presses, I have one. But the biggest issue I had w/ this mod was getting the hole straight. Even w/ the threaded coupling, my hole wasn't perfect. The closest I got was to chuck the threaded coupling or cross dowl in the drill and mount the drill bit in a vice.

Another option for making one of these would be to order a spacer and dowell pin from mcmastercarr. The pins come slightly oversided to give you a pressed fit, but if it's not tight enough you could put some small grooves in the pin and apply your favorite epoxy, maybe jb weld.

Here are two part numbers on mcmastercarr I was considering: spacer 92510A626 and dowel pin 93600A151 this spacer would have to be drilled but there are others out there.

btw, I run a 12t pinion and 96t spur w/ the novak brushless goat and I love the low wheel speed. When my wheels spin I feel out of control, but I think everyone has their own opinion on this.

[CRAWLER_H19]

Originally Posted by mulepic

Speaking of drill presses, I have one. But the biggest issue I had w/ this mod was getting the hole straight. Even w/ the threaded coupling, my hole wasn't perfect. The closest I got was to chuck the threaded coupling or cross dowl in the drill and mount the drill bit in a vice.

Another option for making one of these would be to order a spacer and dowell pin from mcmastercarr. The pins come slightly oversided to give you a pressed fit, but if it's not tight enough you could put some small grooves in the pin and apply your favorite epoxy, maybe jb weld.

Here are two part numbers on mcmastercarr I was considering: spacer 92510A626 and dowel pin 93600A151 this spacer would have to be drilled but there are others out there.

btw, I run a 12t pinion and 96t spur w/ the novak brushless goat and I love the low wheel speed. When my wheels spin I feel out of control, but I think everyone has their own opinion on this.

I know what you mean about keeping the hole centered, and that is why I chose to chuck the yoke in the vise, and drill by hand. I even turned the O.D. of the yoke down by sticking the yoke in the chuck of the drill and pressed the thin side of a file on it. It takes a little while, but the finished product performs, and to me that's all that really matters. I don't know if I mentioned in the build, but if you turn your yoke, like I did, put a set screw deep in the threads, so that when your done turning the O.D. down, you can back the set screw out, and have a clean thread.

[mulepic]

I just used the same design as above but I used a 5mm rod instead of the 3/16. A #10 drill bit is the correct size but I had to use a press to get it in coupling. I also discovered that a #9 bit works great for the transmission output shaft. So everywhere I said to use #8, a #9 works even better.

Also, to test the strength I put the piece in a vice and attached a torque wrench to it. I couldn't get beyond 25ft/lbs w/o the piece slipping in the vice. I may try welding it to a piece of plate and then repeat the test.

[Reflection]

Originally Posted by mulepic

I just used the same design as above but I used a 5mm rod instead of the 3/16. A #10 drill bit is the correct size but I had to use a press to get it in coupling. I also discovered that a #9 bit works great for the transmission output shaft. So everywhere I said to use #8, a #9 works even better.

Also, to test the strength I put the piece in a vice and attached a torque wrench to it. I couldn't get beyond 25ft/lbs w/o the piece slipping in the vice. I may try welding it to a piece of plate and then repeat the test.

No no no,your testing the wrong part. The parts you made are steel and stronger than the factory aluminum outputs. Your parts though,like you said,are drilled crooked. THATS the problem.

When in the tranny is spinning,being crooked,they will not spin true with the rest of the drive train. That will just add more stress to the already super weak aluminum outputs.

Props to ya for trying.

I really don't see the need in running a spur gear that big anyway. Stock is almost to low already. If a guy needs that gear though,the best,easiest way is to run the CDW outputs that will push the yoke away from the spur.

[Trugg]

Get some CDW outputs....you'll be glad you did

[mulepic]

One of the reasons I enjoy this hobby is the creativity everyone brings to the table, it's contagious. Many times ideas like this come up b/c there isn't a product you can 'buy it now'. I've heard of the cdw outputs and searched the vender site and I didn't see any w/ the extension and 5mm output shaft. Even if there was a product I could just purchase, I haven't broken the current output shaft so before spending money to replace it I thought I could spend a lot less and make it fit my needs. So I posted this idea for others in a similiar situation that want a 10 minute solution for under $10. Outside of extending the output shaft, the info provided may spark a new idea for someone else. Who knows, I may start breaking things in which I might have to buy cdw outputs, but the exerpience of learning new things is invaluable.

Thanks for the tip, I'll keep this thread updated w/ the long term results.

[Nachies]

Crawler H19, After 6 months your going to let the cat out of the bag?

How dare you!!
Warning!!!
While doing this mod don't follow in my foot steps.

Take the drive shaft off the yoke before you start to dill. It's pretty rought on the fingers.

[CRAWLER_H19]

Originally Posted by Nachies

Crawler H19, After 6 months your going to let the cat out of the bag?

How dare you!!
Warning!!!
While doing this mod don't follow in my foot steps.

Take the drive shaft off the yoke before you start to dill. It's pretty rought on the fingers.

It's all good dude... It's not like someone couldn't see it at a comp and then go home and do the same thing... Besides, the AXW3 build on WARCRC has been up for days... I'm sure someone has either done it the same way, or saw it and made something better

Can you see me? I'm right outside your window.... In the bushes... Shhhh