Balancing the clutch -TRex 700

[J-S-Q]

Just checked my clutch/hub assembly on a Dubro balancer and it's off balance. Are many people bothering to balance the clutch on a TRex 700 and if so where are you removing material from? I would assume on the clutch itself rather than the hub but if anyone has a photo of how they've done it I'd like to see it.

[J-S-Q]

Just read this on another forum:

"There is no point in trying to balance the clutch as the shoes will not be in the same position when it's engaged. Just balance the fan and hub without the clutch installed."

That does have a certain logic to it. Any thoughts? Is it a waste of time balancing the clutch or even the just the hub (which is also slightly off balance but I don't know if I want to start grinding material off it)?

[glen_j]

its a good question, i just stuck mine on the engine and didn't worry about it, always nice to get rid of any vibes that you can though

[J-S-Q]

I've never bothered balancing it before but I have noticed some mild foaming of the fuel in my 700 and seeing as I had the engine out I thought I'd check it.

[Bruinbear]

I've balanced the clutch/fan/hub on my Raptor 50 and Synergy. Even done a few for the guys at the club and it does make a difference.
You're quite correct about the clutch though. Due to the arm movement during use balancing has it's limitation here.
Depending where an item is off balance, depends on how to deal with it. Sometimes a different head size bolt or a washer can give you what you need. Sometimes drilling a number of countersinks is required or sometimes adding weight with epoxy or CA.
As long as you're improving things I think it's worth the little extra time. Less vibration is always good for radio gear and bearing wear.

Mike.

[J-S-Q]

Sometimes a different head size bolt or a washer can give you what you need.

Funnily enough I found that if I used a longer bolt on one side of the fan hub (where it clamps onto the crank shaft) it improved the balance -so you think that is a valid way of doing it?

[Bruinbear]

Yeah, a longer bolt works. Just some way to get the required weight to get the balance right.
Do be aware on the clutch that the the bolt heads are below the surface it may catch/rub on the inside of the clutch bell. I had this issue when I tried adding a washer to one bolt.
Mike.

[Rctintin]

This is my findings: http://www.rcheliaddict.co.uk/align-...le-clutch.html

[J-S-Q]

This is my findings: http://www.rcheliaddict.co.uk/align-...le-clutch.html

I don't have a dial indicator so I can't check the runout on the clutch but using one short bolt and one long bolt on the fan hub has made it balance perfectly on the Dubro balancer so I'll try it like this and see how it goes.

[chugga-bug]

Well, my tank was foaming like a b'stard yesterday. To the point that the header was emptying cos it was being filled with air instead of fuel.
I just dialed the clutch and it was only 0.06mm (0.002") out, rotated the clutch 180degs on the hub and it's now within .01mm (0.0004"), so should be a bit better.
Thing is I can't believe 2 thou is enough to cause the amount of foaming I had going on!
I need to make a puller to get the damn hub off, and have a go at balancing it now!

[J-S-Q]

I need to make a puller to get the damn hub off, and have a go at balancing it now!

I used one of these to get the hub off. Not bad at 6 quid including postage. You have to take the plastic fan off first though and pull the hub itself.

3" 75mm 3 JAWS GEAR/HUB/BEARING PULLER on eBay (end time 23-May-10 14:10:09 BST)

[chugga-bug]

I knocked this one up in 2 mins last night.. Cost £0.00
Worked a treat!

[J-S-Q]

I knocked this one up in 2 mins last night.. Cost £0.00
Worked a treat!

Bargain!

[draeroheli]

I knocked this one up in 2 mins last night.. Cost £0.00
Worked a treat!

Can you show me with your home made instrument , what is the hub you are trying to take it out?

I am completely lost. Is it the bearing inside the clutch or the bearing at the clutch bell or the plastic fan attached to the aluminum hub you are trying to take it out? Please educate me. Cheers. Htin

[Steve]

It's a fan puller. I have one too. Once you take the nut of the end of the engine crankshaft, you often need the puller to get the fan and hub off the shaft where it has become friction-stuck on the taper collets.

Balancing the fan is pretty easy if you have a decent balancer. The fan has the largest diameter, so a small inconsistency will have a larger vibration affect than any minor discrepancy on the clutch, which is more dense and smaller diameter.

Remove some material from the heavy side of the fan - easy way to do it is to drill part holes in the flat side, not all the way through, just tease a 5-8mm drill into the material so that only the pointed tip of the drill goes in, taking care not make a hole right through. Keep doing it in different places and re-testing on the balancer until it is spot-on.

I've seen it done on other fans where people have cut a straight edge off the heavy side of the fan, and then had to cut some off the opposite side because they took too much off in one go, so you end up with two parallel flat edges. The end result is the same, but the edge trimming is a bit on the severe side for me with less control.

Gently does it.