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Long drive cup

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That's what I'm working with but the bone barely catches each cup when shimmed properly,

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In situations where I need a longer input pinion for the stock E/Tmaxx diff I use the revo center diff long pinions (part# 5416) and cut them to the length I need. Although the bevel looks different it is the same as well as the tooth count. The gear face is a little narrower and you must shim it well and it’s a little more tedious, but I have put many gallons through the diffs with that’s setup and had no issues. You just shim as usual but you must make a spacer/bushing to go over the pinion shaft that fits between the drive cup and the outer diff input bearing.
You can make almost any shaft that’s a little short fit with this method.

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Okay snook I will use the revo pinion that I have#5416 and shim it well,I have always trusted your oppinion and if you say it works then it works! Thanx everyone.ill post pics of before and after


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---------- Post added at 1:25 PM ---------- Previous post was at 1:13 PM ----------

Here is the before pic,as you can see I was experimenting with different ways to shim the bone,I like the springs but they push on the rear diff too much,but since I am going to make a shim/spacer for the other pinion I think that this won't be an issue anymore,the o rings are nice as well they cradle the round end of the bone nicely unlike fuel tubing and they stay in place
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...........I'm afraid to run it like this,would any of you?
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Moch up is complete,the ti bone fits nicely now,Still gotta put the finnishing touches on"not really needed but I like my custom mods done as good as I can" anyway here's a few pics.
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The first 3 pics show the stock ring gear and the extended gear,I cut the extended gear just below the mounting hole then instead of trying to drill a new hole and worrying about having it "dead center" I took snook man's advice and just ground it flat and used a grub screw," which I made from the existing traxxas axel screw,..the next pic is the shim/spacer that I made,the spacer is the most important piece and without it being just right the pinion will push on the ring and"you know what happens" ...next pic compares a stock length pinion to the extended one installed in the diff,and last but not least the finished product,this pic shows the maximum amount that the bone will slide backwards in the cup"a far cry from the original setup seen in my first pic! Now that I've done one I can already see a few things that I wanna change.
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Thanx man,I'm gunna use a different apacer and maybe a double set screw cup,

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A double set screw cup will probably be a good idea. Along with some blue loctite.
 
Put a glow plug gasket or any small 6mm washer between the spacer and the pinion bearing so the spacer only comes into contact with the inner race of the bearing. The way it is now will work fine, but it's creating more friction.
 
Yeah that's why I am gunna use another spacer that I have,much thinner and like you said it will only contact the inner race,I am fresh out of washers,probly the only parts that I don't have any more of,and grubscrews,lol,Still waiting on some diff shims in the mail

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Lol,ya me too ,but I can only take credit for the work, it was......... snook man's creation

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i just love the spring in the cup idea. even if you didn't run with it its just awesome. i've been using chopped fuel tubing for spacers and dampers in the c-cups to remove lateral play but thinking ill give the springs a shot.
 
The spring I came up with,it is awesome but if you don't have the rear diff shimmed just right you will blow ring/pinion constantly,as an alternative o rings work perfect because you don't have to cut them and there perfectly shaped and the right size ones won't fall out of the cup,

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Springs in the cup will work, but if your using a diff with a floating pinion any pressure from the spring against the cup will cause the ring and pinion mesh to be too tight and cause excessive wear.
 

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