Rebuilt driveline super tight.....any ideas??

2QIK4U

Member
Messages
7
Gday all

Just got my beast back together.
Rebuilt front and rear diffs with heavy duty internals 10k weight oil. New bearings all round. All done up properly and seems to be aligned.

Does run but sounds like metal on metal...

....do I run it hoping its just tight and will run in? Or do I strip newly rebuilt diffs and start again?
 

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InTheZone

Active Member
Messages
70
The diffs are perfectly seated in the grooves in the bulkhead?

How many shims did you throw on each side of the diff?

How many shims on the pinion gear?

You don't want the diff to bind, you want minimal side to side play. I have one shim on each pinion and I believe 2 on each side of the diff.

You're going to have some notchiness to the gears, but too tight and you'll have an extreme amount of notchiness and when you roll it there'll be resistance
 

2QIK4U

Member
Messages
7
Tks for reply mate

New to Flux....but built 2 x custom 2 stroke race boats so lots rc experience...

Not sure if diffs are seated properly...I think so.

Diffs were tight but moved ok by hand. When in casing it moves but it needs a screwdriver in the driveshaft to turn....smooth but super tight.

I put 2 spacers and the bearings on either end of both diffs. The diffs were beautiful until I put the top bevel and drive gear on top it started binding up. The new gears are spiral...I put one copper spacer on the bevel gear.....2 looked better but I couldnt get the drive shaft pin through so had to go back to just 1.

Centre gearbox/driveshaft seems ok

The diff cups were nice smooth fit on the bottom of the cup but on the top (gear end) the shaft was tight in the gear. Should it slip nice or be tight?

I ran it with no wheels and sounds like a cnc machine so didnt want to damage ...

Any ideas much appreciated
 

InTheZone

Active Member
Messages
70
Diffs were tight but moved ok by hand. When in casing it moves but it needs a screwdriver in the driveshaft to turn....smooth but super tight.

I put 2 spacers and the bearings on either end of both diffs. The diffs were beautiful until I put the top bevel and drive gear on top it started binding up. The new gears are spiral...


The diff cups were nice smooth fit on the bottom of the cup but on the top (gear end) the shaft was tight in the gear. Should it slip nice or be tight?

Any ideas much appreciated
With the driveshaft disconnected and the diff installed can you spin the bevel by hand? You should be able to with ease

The diff has two halves, you're saying when you put the gear side on it becomes tight and hard to spin the cups by hand? It should be easy. You'll feel some resistance due to oil/grease Inside.

When installing diff outdrives/cups make sure you use one o-ring slightly oiled and seated fully prior to the washer installed, one large flat washer and then the pin. All should feel the same when spinning by hand, but should feel somewhat easy to spin. They won't spin freely, but they won't be hard to spin.

With the gear off the internals should sit flush with the case and fluid should be filled to the point where it covers most of the spider gears, but not topped to the top of the case. I weigh dry and after I fill for a baseline difference and use that to top the other off.
 
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olds97_lss

Well-Known Member
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Dekalb, IL 60115
Without the motor in it, it should roll forward and back with no resistance. If your talking about spinning a right tire against a left tire, then there you will feel resistance due to the diff oil. WIth 10k oil... you won't feel much resistance at all. I run 50K in my flux HP diffs and I can pretty easily spin one tire while holding the other. I run 100K in my outcast front/rear diffs. lol!
 

2QIK4U

Member
Messages
7
Tks olds....I thought 10k was pretty heavy but seems not the case....hmmmm lol
 

2QIK4U

Member
Messages
7
I decided to strip it down.

Seems a bunch of things all working against each other.

This one diff shim was the major culprit.
Also found front centre driveshaft was out of whack and bevel gear end was rubbing on diff cup!! That wouldnt have lasted long.

Lesson I guess is detail, detail, detail... ;)
 

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