Transfer case sprocket and chain

[pontiac428]

Automotive engine timing chains run up to 7000 rpm, wuth sustained duty at half that. They were good for 60k miles before better belts came along.

 

[strantor]

Automotive engine timing chains run up to 7000 rpm, wuth sustained duty at half that. They were good for 60k miles before better belts came along.

I hadn't considered timing chains.. I Googled it just now and there seems to be a mix of different chain technologies used. Interestingly, some of them seem to be the same type as t-case chains. In this picture you can see both used inside the same engine.



The fact that that they used the t-case-type chain from crank to intermediate shafts implies (to me) that it's good for ~2x the torque of regular (whatever regular means) timing chain. Maybe not 2x more, but "some amount" more. Then again, it's driving step-down gearing, so... I'm kinda puzzled as to why they used two different chains, and which one is better.

How much torque does it take to spin a camshaft? Timing chains are obviously good for high speed, but what about torque? I have no idea.

 

[RandyWilson]

Look into chains from the 80s/90s/00 Ford and GM front wheel drive units. AX4S/N, AXOD, 4T60/65. Or the monster Cadillac 4T80. They handle full engine torque at engine rpm. GMs ran three chain ratios, 33/37, 35/35, and 37/33. and three diff ratios. Ford used a whole bunch of chain ratios with two diffs.

 

[epanzella]

New Process Gear was owned by Chrysler. They sold transfer cases to GM until GM acquired/started up New Venture Gear. Borg Warner is a conglomerate corporation that buys other companies. It's hard to tell who owns what, but one thing is for sure, those chains are strong. Take that 400 lb-ft and multiply by the 1st gear ratio and the low range ratio- that's tons of torque.

And THEN pop the clutch!

 

[RandyWilson]

As an example, what is currently residing on my bench, a 35/35 from an '06 Impala 3.5L. Though the 5.3L police cruisers use the same parts.