Chain Heat Testing

[yoshi]

Originally Posted by standfast

Yeah, I have the 6.3 gears in mine right now and want to go to the 4.7's but he doesn't have them in stock right now and the gear cutter is having some health issues or something like that so I am kind of stuck. Anyone here have 4.7 gears for a RPM box that they want to get rid of? I want to make this change asap but it looks like I am gonna be waiting. Next race is on the 25th of this month so I don't know if I will have them by then either.

If you leave your 16 tooth front sprocket, and drop the input sprocket of the RPM down to a 14 tooth, you will at least get down to a 5.5: 1 ratio, or stick a 13 on the rear and you can get a 5.1:1 ratio to hold you over till you get the gears.....

[Bennyhanna]

Maybe you could use some water based coolant from a cnc machine instead
Of oil in your drip system. It should serve the same purpose and be much
Easier to clean up.

[roostingrhino]

i am also having the same problem with my chain on my rpm gear box.... my ratio is 5.5:1 and my chain is 80 pins.. when i run hard for a long time = melt down... would making my chain longer like 120pins remody this problem?
so if i am understanding this right every ones car has chain troubles? i really get tired of messing with all the chain probs and want to find the fix!

[Bullnerd]

I think Standfast fixed his problem,read his thread on the snowflake race.

[standfast]

I seriously doubt a longer chain is going to prevent you from cooking the chain. It will likely just prolong it from happening a bit. Oil bath for the chain is the only real solution that I have found for the problem. I have 500-600 hard miles on this chain with the oil bath (including a couple hundred race miles) and it still looks great. I think the wear on the sprockets is going to be minimal now as well. You will still obviously have an initial stretch on the chain but after that it will stay the same. I have had the best results with RK 630 chain. I am using a spring loaded tensioner with a roller UHMW wheel (bearings inside). It is a piece typically use on a dirt bike near the swingarm pivto to keep the chain from hitting the frame/swingarm. It looks like the wheel should last a long time in the oil bath since there is no significant wear on it yet. There is very minimal friction on it with the bearings combined with the oil. The spring preload is adjustable although I haven't needed to adjust it since the initial setup with this chain. Chain noise has been substantially reduced and proper tension is constantly maintained with this tensioner. Even during chain break in when it is stretching out a bit, the tensioner stays on top of it so you don't have to keep chasing the chain tension. I have been running it with a lexan cover just so I can monitor the system. Eventually I may go to an aluminum cover. Maybe not though, it's nice to see that everything is kosher inside. You don't want to bury the chain in oil too much. I have read about negative side effects from that in a Tsubaki chain catalog. You want to only submerse about 1/2 to 3/4" of the chain in one spot. Based on the temperature that it gathers from the motor, and the temperature that the chain case reaches, that catalog suggests 140W oil so that is what I am using now and it works great. The thicker oil tends to fling less (stays on the chain) once it has reached operating temperature and does not spit out of the vent line like the thinner stuff. I suggest making the chain case with enough room on the outside of the chain so that if the chain comes apart it will not bind up in the box and snap that CS or input shaft. My chain came off inside this box multiple times (stupid clip style master link and CS sprocket nut coming loose) and it has enough room to just spit off to the side with no problems. My chain case is 3" thick. I suggest only using rivot style master links as well. Make sure you don't bind up that link when you rivot it together though. It should feel the same (pivot) at those two rivoted joints as the rest of the chain.

[Bullnerd]

Wow that was quick!

What did you make the housing out of BTW?

[standfast]

Originally Posted by Bullnerd

Wow that was quick!

What did you make the housing out of BTW?

1/8" steel. It was free so thats what I used. Plus I don't have to worry about killing the engine case anymore in a chain catastrophe. The case weighs about 12 pounds. .100 steel would probably be OK. I wanted it to be supplemental mounting for the FNR as well so the 1/8" really ties everything together in stout fashion.

[Bullnerd]

Nice job Standfast!This is very good news for Bike/FNR users!

[bajaBrothers]

Sweet now I can start my single seater. Good job Standfast looks like a straight forward simple fix for a very common problem.

[roostingrhino]

Originally Posted by standfast

I seriously doubt a longer chain is going to prevent you from cooking the chain. It will likely just prolong it from happening a bit. Oil bath for the chain is the only real solution that I have found for the problem. I have 500-600 hard miles on this chain with the oil bath (including a couple hundred race miles) and it still looks great. I think the wear on the sprockets is going to be minimal now as well. You will still obviously have an initial stretch on the chain but after that it will stay the same. I have had the best results with RK 630 chain. I am using a spring loaded tensioner with a roller UHMW wheel (bearings inside). It is a piece typically use on a dirt bike near the swingarm pivto to keep the chain from hitting the frame/swingarm. It looks like the wheel should last a long time in the oil bath since there is no significant wear on it yet. There is very minimal friction on it with the bearings combined with the oil. The spring preload is adjustable although I haven't needed to adjust it since the initial setup with this chain. Chain noise has been substantially reduced and proper tension is constantly maintained with this tensioner. Even during chain break in when it is stretching out a bit, the tensioner stays on top of it so you don't have to keep chasing the chain tension. I have been running it with a lexan cover just so I can monitor the system. Eventually I may go to an aluminum cover. Maybe not though, it's nice to see that everything is kosher inside. You don't want to bury the chain in oil too much. I have read about negative side effects from that in a Tsubaki chain catalog. You want to only submerse about 1/2 to 3/4" of the chain in one spot. Based on the temperature that it gathers from the motor, and the temperature that the chain case reaches, that catalog suggests 140W oil so that is what I am using now and it works great. The thicker oil tends to fling less (stays on the chain) once it has reached operating temperature and does not spit out of the vent line like the thinner stuff. I suggest making the chain case with enough room on the outside of the chain so that if the chain comes apart it will not bind up in the box and snap that CS or input shaft. My chain came off inside this box multiple times (stupid clip style master link and CS sprocket nut coming loose) and it has enough room to just spit off to the side with no problems. My chain case is 3" thick. I suggest only using rivot style master links as well. Make sure you don't bind up that link when you rivot it together though. It should feel the same (pivot) at those two rivoted joints as the rest of the chain.

thats exactly what i was thinking of doing... how did you seal the front and rear shafts? i really need to make a setup like this asap and advise on bearing and part numbers the you have use wouldbe great help to me. so you fill the case with oil till it reaches the bottom of the chain? looks sweet!