1997 Indy 500 gearbox specs question

[Mac Miller]

I have replaced my two bottom large gears from a complete used chain case assembly I bought on eBay. The inner bottom gear that I bought is a couple of mm smaller in width than the old one. After seeing this, I checked the other parts. Sure enough, the chain and the small single top gear were also a couple of mm smaller in width.

is it ok to run this “thinner” bottom gear under a wider chain? Or should I change out the whole thing and use the smaller chain and the smaller top gear?

Thanks in advance,
Mac Miller

 

[MrSled]

I have replaced my two bottom large gears from a complete used chain case assembly I bought on eBay. The inner bottom gear that I bought is a couple of mm smaller in width than the old one. After seeing this, I checked the other parts. Sure enough, the chain and the small single top gear were also a couple of mm smaller in width.

is it ok to run this “thinner” bottom gear under a wider chain? Or should I change out the whole thing and use the smaller chain and the smaller top gear?

Thanks in advance,
Mac Miller

I would run the smaller chain and top gear? Are does it look like the hubs are the same so the spacers will work?

 

[Mac Miller]

I would run the smaller chain and top gear? Are does it look like the hubs are the same so the spacers will work?

Sorry, I’m really new... are the hubs the two interlaced gears between the top and bottom gears? If so, then yes those are the same.

 

[Mac Miller]

Sorry, I’m really new... are the hubs the two interlaced gears between the top and bottom gears? If so, then yes those are the same.

Ok after a little research the hubs are located in the center of the sprockets. I’ll have to take them back out tomorrow and put both old and new side by side and measure. Thank you!

 

[MrSled]

Ok after a little research the hubs are located in the center of the sprockets. I’ll have to take them back out tomorrow and put both old and new side by side and measure. Thank you!

Your welcome!

 

[Mike-DRH]

The original chain you have is 13 wide which is the total number of plates on each pin at the widest point. The chain you bought is probably 11 wide, older version.

It would be a good idea to run every part out of the chaincase you bought unless you have the time to look up every piece by part number and make sure they are the same.

Chain alignment is very important you should check it before you put the cover on.