which MAC clutch is better?

izeman

1 GW
Joined
Jun 21, 2011
Messages
5,131
Location
Vienna, Austria
ordered a replacement clutch and gears from cell_man.
received in almost no time. super fast, perfect packaging. :)

i now compared the two clutches, and tried to find out which one is better. the new one (right) looks beefier, but who knows. please ignore the stripped gears, they will be replaced anyway.

what are the advantages of one over the other?

clutch.jpg
 
The right one is the new style shipping since last summer - I have one sitting here but haven't tried it yet. It looks very much like the BMC V4 clutch which is very tough - my preferred BMC clutch. The older MAC and BMC clutch design is on the left - not as strong - I have seized a few of those, but the new V4 style just keeps on truckin'.....

The gray gears are the strongest MAC gears at this time.
 
I believe the 'new gray gears' for the 'new MAC clutch' are a slightly different thickness than the gray gears for the old style clutch, so getting everything to build a complete new cluster seems the best plan...
 
How good are the MACs blue gears? Those are the ones that are in the new motor while the old one has the gray gears. And both of my gears are in the clutch of the 2nd pic and I have no way of taking the gears off the motor due to no tools like those on that clutch. I have to replace the bearing in that clutch of the old one just like I had to last year on the sprocket side cover of that same motor. Those bearing suck in that old motor but its a monster when it works properly which is why its my motor of choice.
 
i may not understand your question... afaik the blue ones are very rigid as well. you should be fine.
what to you mean by replacing the bearing? imho there are no replaceable bearings in the clutch. you just can replace the whole part. the only serviceable parts are the gears themselves. they can be easily removed with two blade screwdrivers prying between the old gear and the clutch.
 
This is what the old motor looks like and it appears that there is a race bearing of some type there otherwise why would there be ball bearings seen there? So what do I need to replace the whole clutch or just the bearings?
 

Attachments

  • IMG_20140203_213854_816.jpg
    IMG_20140203_213854_816.jpg
    116.2 KB · Views: 1,921
RLD70 said:
This is what the old motor looks like and it appears that there is a race bearing of some type there otherwise why would there be ball bearings seen there? So what do I need to replace the whole clutch or just the bearings?
i wouldn't waste time to replace this bearing (which i guess is the clutch itself) but just order a new clutch for $30 from cellman. it's the easiest way to solve that.
 
izeman said:
i wouldn't waste time to replace this bearing (which i guess is the clutch itself) but just order a new clutch for $30 from cellman. it's the easiest way to solve that.

Even Paul suggested buying additional parts when I bought the MAC but the budget wouldnt allow it and Ive already had to replace the race bearing in the sprocket side cover of this motor. Now what tools do I need to get the clutch off of this motor so that I can replace the clutch when money allows it? I might as well buy them since Ill more than likely be needing them to repair these motors when the parts wear out. And thanks for your help.
 
i'd really like to tell you how to do it. but i'm afraid you can't do what you what. these aren't serviceable parts afaik. it's no bearing. it's the clutch itself. there are little metal parts inside that allow movement in one direction and hold it in the other one.
even if you take it apart i think you won't be able to freely buy parts to replace anything inside.
 
is it possibly to modify these to be a direct drive?

Like i know its not ideal, but if someone has a broken gears and are not serviceable parts, like the clutch, can you just change it to be a DD hub ? Glue it up or make it a fixed unit ?


I had one of these geared motors in the past but never bothered opening it up
 
Hmmm - interesting picture above - I assume that is one of the new style clutches. If so, it is different than the BMC V4 clutches that have sprags instead of balls in that gap. The BMC V4 has an inner race that you can't really see between the inner and outer disc pieces - I assume the MAC is the same. Anyhow, it wasn't really meant to be serviced.

I have ridden many many hundreds of miles with seized clutches. There is noticeable drag with a 26" wheel when not under power but not terrible. If you want to salvage that assembly, I would remove the gears, de-grease it (wash with detergent then optional final clean with spray brake cleaner), pop out the little clutch balls and bits, and clamp the discs together with a couple of C-clamps. Take it to a welding shop or muffler shop and have them throw three or four tacks in the gap - it'll probably cost $10.

The only problem I foresee is wear on the clutch key. A sloppy key fit really hammers the key from bi-directional torque that it was not originally designed to sustain. I had an original key that got chewed up pretty badly in that situation. It would be worth making up a new key with a snug fit if you are going this route.

The BMC clutch uses a 5v5x11mm key and I assume the MAC is the same since the clutches are interchangeable. You can go to a large power equipment place (snow blower, lawn mower, ATV) and buy a 2" length of 5x5mm keystock for a buck or so. Just file one end to fit (rounded), measure and cut to length (a bit long), then file the cut end for a snug fit.
 
Thanks for the pictures. I'm in process of replacing the clutch and found my new & old clutch identical to the pictures. Not such much a question of "best", but does the new work in an identical manner. Which I'll soon discover.
izeman said:
.... it's the clutch itself. there are little metal parts inside that allow movement in one direction and hold it in the other one.
... and that, which explains what I'm puzzling about, of how the clutch works.... and why the one on the motor is not working.
 
Back
Top