GMAC/ Freewheel body replacement

Jil

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Bordeaux, France
Hi,

I need to replace the free-wheel of my GMAC.
But I have never done it on a rear hub motor.
Does anybody know how to proceed, and what are the tools needed ?

Thanks !
 

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Is the freehub body (rachet) not working correctly? Or is it only the cassette (sprockets) you want to replace?
 
No it's the freehub, which is dead.
I understood that I have to use that kind of tool, but I don't find the one with good dimensions on the web.
 

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Many thanks :)
I have indeed seen this video yesterday after posting here, and it answers my question (one of the many plus of Grin : you generally find on their website plenty of explanations on how to install and service your motor).
But thanks for taking the time to answer, that's nice !

Now I have to find this tool, a new free hub, and also new bearings, which are damaged also on the freehub side --> I guess using my bike on the beach, even with thorough washing afterwards, was not a brillant idea :wink:
 
Jil said:
Now I have to find this tool, a new free hub, and also new bearings, which are damaged also on the freehub side --> I guess using my bike on the beach, even with thorough washing afterwards, was not a brillant idea :wink:
How about contacting Grin and tell them you saw Justine's video and if they sell the tool (or know where to get one) and the freehub.
 
I have found the tool : https://www.probikeshop.fr/cle-a-ergots-pour-roue-libre-park-tool-spa-2/103906.html
 
Jil said:
I have found the tool : https://www.probikeshop.fr/cle-a-ergots-pour-roue-libre-park-tool-spa-2/103906.html

I'm sorry to tell you that's not the right tool. That's a spanner for round pin holes, like in a traditional bottom bracket adjustable cup. You can't apply very much torque with it.

You should definitely contact Grin and see what tool they recommend.
 
Jil said:
No it's the freehub, which is dead.

When you say it is dead, do you mean it is locked up (bearings), or spins in both directions (pawls)?

It is possible a bearing is destroyed, or pawls or their springs are broken.

Before replacing it, I would try flushing it with WD-40 first. if it frees up, run light oil into all seams until you see it seeping out. I am cheap, and lazy. :)
 
Hi,

I reopen this subject as I'm going to have the time to fix my GMAC.
I have finally found the right tool (I hope ! At least the dimensions seem OK : https://www.la-becanerie.com/demonte-roue-libre-super-b-pour-shimano-a-2-crans.html)

To answer Warren...
Warren said:
When you say it is dead, do you mean it is locked up (bearings), or spins in both directions (pawls)?
...it spins in both direction, the bearings are damaged, and the freewhel is globally loose. Replacement is really needed.

And to answer Chalo...
Chalo said:
You should definitely contact Grin and see what tool they recommend.
I have -finally- contacted Grin yesterday and am waiting for the answer. Just in case I don't get an answer quickly (but generally they respond quickly) and in case someone has already ecountered the same issue with a MAC or GMAC... can somebody advise me on the right freewheel body to order (entire body, bearings included) ?

Thanks :)
IMG_6588.jpgIMG_6589.jpgIMG_6591.jpg
 
I have finally removed the freehub, but what a pain !
The tool I ordered was the right one (https://www.superbiketool.com/en/product/detail/Freewheel_tools/TB_1018), but it broke almost immediately. Indeed, the freehub was totally stuck :shock: I had to cut with a Dremel the rotating part in order to be able to grab the freehub with a pipe wrench. And with a lot of WD40 and 60cm extension pipe, it finally came !

But... I'm now looking for the replacement part, and I cannot find it ! Do you know what is the reference of this freehub ?
IMG_6741.jpg
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I let my feedback here, in case it would be useful for others.

The freewheel body is a special part from Grin Tech, currently not available for sale. You can only order it by contacting Grin.

Grin has considered it was a failure, and has proposed to send a replacement freehub body to me at no cost, very nice from them :thumb:
But I suggested them anyways to propose this part for sale on their website, because I think that’s normal wear and tear to replace it after a certain mileage.

And Grin confirms that the removal of the freehub is complicated. I will mount the new one with anti-seize to see if it helps for the next replacement.
 
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