Help with Input shaft pin
 

Hi guys I was practising today and the pin on my input shaft got broke any suggestions to make it stronger? thanks

i've heard of guys snugging a 2mm allen wrench (cut to fit) in it's place.

There was another thread recently that mentioned that. IIRC, they mentioned something about using the shaft from an appropriately sized drill bit...

Assuming you completely sheared the pin the secures the input gear to the input shaft follow these steps:

1 drill out the old retaining pin from all parts.

2 find the next size allen key/wrench that is just barely too big to fit in the holes you just cleaned out.

3 take a dremel with a cutting wheel and ever so slightly grind some of the edges off of the allen key/wrench...keep doing this until you can eventually force the allen key/wrench into the holes. It stands to reason that when grinding the key/wrench, make sure you grind more from the front (point of insertion) and less from the rear....kinda like a tent peg.

4 cut the key off at the gear collar and grind & file to perfection.

5 for added retention, carefully apply a dab of JB Weld on both sides where the new pin (allen ke/wrench) is visible. let it dry/cure per instructions.

6 clean and file to perfection using fine jewelers file.

Information on JB Weld:

http://jbweld.net/products/jbweld.php

By the way...I have bullet proofed two input shafts to date and wanted to let you know that it is a pain in the butt:028: . But it is worth the effort once it is done.

LuvsRC, once I get my parts for my truck early this week, I will do the pin mod right away and I'll post the results for you... if you can wait that long.

BTW, you don't need to drill out the pin.... just take the gear off, and get somethign smaller than the hole to hammer the pin out. I agree though, using an allen wrench is the best bet, I think that's what I'll use, because you can easily take away material from those edges.

I recommend drilling out the hole...this serves two purposes:

1 makes the hole just a tad bigger for a larger/stronger hex key.

2 cleans the metal so the JB Weld will stick better.

That's true that it will make it stronger, but how strong does it have to be?

What size allen key did you use? And drill bit size?

Actually I shouldn't say that.... :005:

Have you checked out my Quark heatsink thread? To big?! :005:

I started out by using a small nail....actually drove it down inside the existing hollow pin. It eventually failed. Then I spent the next couple of days disassembling my maxx tranny and doing it the right way. You ask how big does it (the pin) need to be....well there is definitely a balance-afterall you don't want to weaken the shaft.

I ended up using a 2mm hex key...but bear in mind that it did take a little bit of gentle grinding to get it to fit in the hole. I think I used a 5/64 drill bit.

thank you guys:027:

yah, thanks sssp.

2mm would be more than enough yes, what are the pins in the cvd shaft's? around there, and alot more torque(plus it's loose fit), so this should last for sure.

I did the hex key trick a while back, but just sheared it clean off last week.
This time I drilled out the holes a bit bigger and put a drill bit shaft thru instead.

I was going to use green locktite (max str bearing retainer formula) on the gear and shaft as well, but I got impatient and just went with the drill bit.

If it breaks again I will use the locktite, and possibly drill bigger and tap w/ 3mm to use a driveshaft thru pin. Don't want to go too big and weaken the shaft, but I think it would take it.

Finnster, was your hex that you used very tight in there? If it's not in there very tight, the strength of it will be severely compromised. I think it should only be able to be put in with a hammer, or a vice (tighten it up). How was yours?

Wow...what are you running that you sheared the 2mm hex key?

I don't really think having a more powerful motor than a XL motor is going to put anymore stress on the pin. Only so much torque can be put through the transmission anyways, simply because too much will just flip the truck.

Weight, length, and front/rear mass ratio, and CG impact how much torque can be put through the system.

like ssspconcepts i also did this mod but i have yet to try it. but it seemed to work good and it is strong.

You are right...sorta...but weight of the truck and your slipper will significantly influence how much torque is transferred to/from the input shaft and eventually passes on to the rest of the drive-train. There are a lot of factors that influence how much torque is able to make it from the motor to the tires.

Yes, i agree more factors like terrain... grass, gravel, tarmac...

But generally, as far as the truck is concerned, that is what affects it.

I suppose shocks too, like for shock load, having loose setup will reduce the shock load, but that will also lower the CG when that happens... :019: :005:

ooooh, so many variables

I can't recall for sure what size now (2mm think tho), but yes, it was very tight and had to be forced thru w/a hammer. It was a real bastard to get thru :)

I have a 8XL running on 4S and 5S. Lots of TQ. Slipper is kept pretty tight so it doesn't slip and heat up too much. Overall I'm not that hard on the truck tho.

i used 5/64 and sanded a tad off and pressed it in using channel locks.

Thanks...its good info to have...now we have a bench mark for the 2mm key:027:

Now wouldn't it be nice if they came with the mod....

Well, you know... we COULD just weld it. It would have to be a good weld, to maintain shaft balance. Maybe just two tacks on each side?

I finally put the hex over to the input shaft .
Boy it was hard to put into with a hammer there is no way it will get slip and out of that hole,for a while I thought it will not go inside,I file it first just like SSS did suggest and it finally went all the way in to the other side with a hammer. here is a pic

Here is mine that I did. Guess what happens when your pin is to large? :026:

I had to use my old gear after I broke the new one! :035:
But it turned out very well, it was a very, very tight fit. I had to stop hammering it, and use a large vice to force it in. It worked!

Glad it worked out for you....looks good.

Oh, i forgot to mention, i used a drill bit end. I can't remember what size but i had to grind it down alot, the first one showed it wasn't ground down enough.:024:

So hopefully this stands up to my 7XL. The gear is actually to original gear from my first emaxx.... 6 years old! :005: Still looks as good as the new, only a little grime inside the gears.

I did some test runs with it and so far it is holding up really good thanks for the tip guys:027: