TheMachine

Anyone got a milling machine with a rotary table and cutters small enough to cut a 4mm wide bearing retaining grove in plastic ?

I`ve just more or less worked out that is is possible to fit a 15x21x4mm bearing in the side of the savage diff casing, this would greatly support the outdrive cup and greatly reduce wear and failures of the diff cup, bearings, outdrives and spider gears etc.

I have just stuck a HD hardened outdrive cup from a flux HP in my lathe to see if it could be easially turned down to have a 15mm id bearing(4mm wide) slipped over it close up to the diff side bearings(and still not interefer with the dogbone sliders etc...just enough room not to foul I believe!)

The cup turned like butter with plain tool steel...so thats no issue, but I don`t have a milling machine or access to one with a rotary table to cut the 21mm(4mm wide) groove in the casing to hold the bearing.

Anyone have the equipment and willing to give it a go ??? ...I`lll send you money to buy a brand new case the ship it to me once machine so I can assemble and test.

This is in an efffort to get the savage to survive 6s for long periods with-out destroying the rear diff to the point of binning it and buying another complete assembly(most cost effective way at present).

Let me know if you can help

MadManAndrew

I'd love to help you but australia is too far away! Lol I think you'd be much better off finding someone on your continent.

TheMachine

Do you have a mill with rotary table ? and cutters to do the job ?

I may be able to make a tool to do the bearing groove my self for plastic.... but if I go with an alloy case I would definately need it does with the right equipment.

Finding a machine shop to do somthing so small and fiddly may be tricky....you really need to be an R/C enthusiest to do these sorts of things !

Postage may not be too bad from you to australia ! got any spare/old diff casings lying around ?? I`m sure you could get a new casing off ebay pretty quickly in the US

cummins driver

My Feedback: (31)

Would this weaken the drive cups though? Sounds like it could move the failure to the drive cup if you are taking material off of it; which would be aggrovating to fix if you had to machine a cup each time.

TheMachine

I would be taking about .5mm of a 3.5-4mm wide strip on the back end of the drive cup(drive cup is 16mm od, bearing is 15mm id)...and then replacing it with a intereference fit bearing, most likely using a retaining compund also.

The slot in the bearing cup extends into this area so your not really removing enough material to weaken it much more than it already is by design !, I`m actually covering a bit of the slot and adding strength i hazard to guess [:-]

Only after extensive testing would I say it doesn`t affect it at all....so I am going to see what happens !

From what I have experieced the latest HD cups and dogbones no longer have a issue with spreading etc like previous models....I am still however able to twist the dogbones and bend them often.

The way I see it i`m up for a new diff assembly from ebay every 100-120mins of run time on 6s. That whole assembly comes with drive cups(most defnately cheapest way to rebuild the diff)...and when you flog out the cup/bearings and or smash the spiders etc the out drives and there cup are fubar as well.

Nothing to loose trying this out, maybe double the service life to gain....then I`ll move onto fixing the trans issues