Cat 3406 B RPMS / shifting

I've never driven a 3406 CAT, but if it's an Eaton Fuller 13, you should be more than capable of getting the gears to shift between 1500 and 1000, both up and down. I drive C-15's with 13's and 18's and they all shift around 1500, whether split or direct.

The RPM drop, assuming US weights (no more than 80000), shouldn't fall below 1000 if you are quick enough. And knowing the truck with an MBN CAT motor, it'll pull without lugging as low as 800.

 

Bad advice it's a mechanical keep it above 1200 unless light on throttle even 1200 is low

 

My 3406 b 425 HP pulls good all the way to 900 rpm and when always keeping low rpm truck gets great fuel mileage. If revving over 1500 rpm she becomes a fuel pig

 

Driving a 3406B like a modern engine is going to cause problems. 1200 is more like it. My '89 T600 with a 425 3406B 15 speed runs 70mph at 1600rpms and gets 7 mpg. Plenty good for me.

 

I was told by Cat that you could pull them down to 1,000. I had a low horsepower B, and buzzing it it did better.
With a 13, if I shifted at 1,500, I'd pick it up at 1,200.

 

a cat will tell you when to shift

when she chatters she is ready

 

The issue with low rpm isn't the pulling power it's the fact fuel dilution goes way up pulling it too low all the time before you know you have to roll in new bearings

 

I guess we all have different opinions I dont pull my B's down below 1400. I shift where the rpm falls back to 15 then easy in the throttle as well as back out of the throttle. I run a 13 which puts my shift right at 17. Empty or bobtail I will up shift a little sooner. I will cruise at 14 to 15. I am not saying they won't do it or do well down low I was just taught diff. I also know when my 2 sound most relaxed and get the best mpg.