Chain Idler

[RussMcB]

I'm considering introducing a chain idler on my car to make chain adjustments easier. While Googling I came across this:

http://www.terog.com/case/cihidle.htm

It's an idler without teeth. Supposedly easier on the chain and quieter.

Just wondering if there might be any reasons not to use it.

[Purple Frog]

Russ,

It appears to be spinning on it's axle (which would be the bolt that attaches it to the frame)with it's own body acting as a bushing, and not spinning on a ball, nor roller bearing, I'd call the manufacturer and find out the load and rpm it could withstand.

[RussMcB]

Good point. It says they have "High RPM Bearings". I assumed that meant high quality ball bearings but that may not be true.

[group7]

ATK motorcycles used an two idlers on there drive. They held up well even in off road conditions and used off the shelf, easily replaced bearings.

http://www.americandirtbike.com/atkparts.htm
Daryl E.

[RussMcB]

When I first started Googling, I found several sources of idler sprockets with ball bearings. They were the regular ones with teeth. Then I ran across the Terog Idle Master unit without teeth (referenced in post #1). It looked pretty interesting, but would need to confirm it's specs before using it.

As an aside, I use a 530 chain on my car and realized after a while that it is the same as SAE size 50 chain. That made searches easier.

[Teh_3vil]

You might want to look into these:

http://www.renold.com/Products/Trans.../Roll_Ring.asp

Not much fabrication required.

-Kyle

[Eric Cruz]

Just looking at the picture in the lower right of the webpage Russ linked to, it appears to me that they do include a bearing or two. You can clearly see a part of the snap ring that would probably retain the ball bearing.

Best regards,
Eric

[RussMcB]

You might want to look into these:

http://www.renold.com/Products/Trans.../Roll_Ring.asp

Not much fabrication required.

-Kyle

Kyle, That's cool! Makes me think it probably wouldn't work for us because it would be too easy. :-).

I'll see if I can learn more about it. Thanks for sharing this link.

[sidney]

This may be a great setup for you Russ, since you have sprocket sizes that are similar to one another IIRC. For those of us running a "traditional" driveline, I'd guess that there would be issues with generating less engagement of the drive sprocket using this device. Cool demo video.

[RussMcB]

I think the Maximum Chain Speed for the Roll-Ring may not be high enough for our use. It's rated between 1,000 and 2,000 feet per minute.

Anyone know what our chain speeds are? I think my setup (with the intermediate jack shaft) may have lower chain speeds than typical FB/SR set ups, but the math is starting making my head hurt.

This is probably flawed, but I've figured that:

At 150 MPH our rear tires are turning about 2,263 RPMs.

My rear sprocket has 40 teeth and the chain pitch is 5/8". That means that 2,263 revs of the rear sprocket equals 56,575 inches of chain travel, or 4,415 feet per minute, which is too high for the Roll-Ring.

Anyone want to check my math? I hope I'm wrong, because the Roll-Ring seems pretty cool.

[Eric Cruz]

Easiest thing is to know the diameter of the rear tire and the rear sprocket that's fixed to it via the axle.

Car Speed (mph) * Tire Dia / Sprocket Dia = Chain speed (mph)

[or you could convert everything to angular velocity, then back to tangential velocity, but only Richard would really WANT to do that....]

Multiply speed in mph by 88 to get feet per minute.

Best regards,
Eric

[RussMcB]

You might want to look into these:

http://www.renold.com/Products/Trans.../Roll_Ring.asp

Not much fabrication required.

-Kyle

I sent an email message to them asking their opinion about using it in a race car. Thier response:

"My engineer has reviewed this application, and is not in favor of using this product in this situation."

They didn't elaborate, but I'm not surprised. I think the chain speed would be too high. Also, I think we want as little slack as possible and this product requires slack.