Need new motors? break a chain? brakes not work? swapping out pinions or sprockets?

Moderators: robnewyork, bassiclyLouDog, gameboy

#25752
I am trying to get this project on the road for the little one, and I created an issue by switching from a 47t rear sprocket, to a 54t sprocket. I had a new chain (TF8) with a master link, and I resized it by testing the open chain on the motor and sprocket, but when I tried that out on the Razor Quad with the tensioner spring engaged, it seemed very tight, almost making it difficult to spin the rear axle with my hands. I added 1 link (which is basically 2 links), and chain was way to loose, with the spring tensioner hardly creating any pressure. I then attempted to remove 1 link (half link), but cannot close the chain as I do not actually have a 1/2 link, and the chain appeared to be the correct tightness as to what the OEM on the original sprocket was.

When checking another forum member's build, his chain tightness in the photo appears to be similar to my chain tightness with only 1 link missing.

I have attached 3 photos below, that demonstrate my position. I think changing to an even number sprocket 54t from an odd number of teeth 47t, may have put me in this position. I do not have any half links, and do not think any local bike shops will have half links in 8mm chain either (MA/NH border).

Any suggestions? Should I just use the chain tightness from the middle photo? It is not too tight without the spring tensioners engaged, but with it engaged, it just feels like a piano string with the tensioner engaged.

Thanks a million for any suggestions.

Chainview.jpg
#25762
bassiclyLouDog wrote:Pic 3 is what you want...but getting there?! Chain should always have a little play. Maybe pop the link in and find a stronger roller spring??


Popping the pin in, is the problem I have, as in, if you view the close up of the link separation, one end is the smaller (inner link), and the other end is the larger (outer link). I think I would need a half link, but I can't find one for T8F chain.

Also, the modder from the first photo seems to have the correct setup, using same sprocket and chain combo, but I can't see any half links in his photo, so how did he achieve this?
#25763
AVInstaller wrote:I think I would need a half link, but I can't find one for T8F chain.

does the other modder have the same version DQ as yours? wouldn't be surprised if the frame measurements were off by a hair. razor tolerances are on the low side imo...

PFS has the half link for your chain:

http://www.partsforscooters.com/115-37? ... ory=132536
#25779
Was I the other modder? I did the mod and the chain was tight. Part of the problem is that the axle sprocket is a larger diameter. This make the angle of the chain to the front sprocket larger. It worked fine really tight. If it really bothers you the pull the motor and enlarge or elongate the mounting holes to allow it to be slid back or forward a little bit. It will buy you a little but letting the motor slide towards the rear sprocket will make the angle even larger.
#25783
zen_racer wrote:
AVInstaller wrote:I think I would need a half link, but I can't find one for T8F chain.

does the other modder have the same version DQ as yours? wouldn't be surprised if the frame measurements were off by a hair. razor tolerances are on the low side imo...

PFS has the half link for your chain:

http://www.partsforscooters.com/115-37? ... ory=132536


Thank you ZR, order placed for half link...hopefully that does not become the weak link and blow the chain out. The other modder XCNTRK, had an older model DQ....very good point, as that may be all the difference.


codeman wrote:Was I the other modder? I did the mod and the chain was tight. Part of the problem is that the axle sprocket is a larger diameter. This make the angle of the chain to the front sprocket larger. It worked fine really tight. If it really bothers you the pull the motor and enlarge or elongate the mounting holes to allow it to be slid back or forward a little bit. It will buy you a little but letting the motor slide towards the rear sprocket will make the angle even larger.


Thanks Codeman, other modder was XCNTRK, but I remember you did the same mod too. I wasn't sure if you used the same T8F chain as other modder did. I was not sure what the (ideal chain tightness) was supposed to be when a chain tensioner is involved, but I remembered the stock setup being looser, but not loose enough to remove the chain (with spring tensioner disengaged). When I tried the first number of links on the motor/sprocket, the chain easily fell off without spring tensioner engaged. When I removed 1 full link, the tightness felt reasonable with some play, until I connected the spring tensioner, the spring was adding a lot of pressure, making the chain feel unreasonable, and a little difficult to spin the axle freely. I think you hit the nail on the head with the wider stance the new sprocket takes, as it also causes the spring from the tensioner to be stretched further. I was just surprised at the huge swing in either direction with the difference only being 1 full link. I will try the half link scenario, and if that doesn't work, just try the tighter full link, and possibly find a weaker spring for tensioner.

Thank you for your help...
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