Front crank dampener for a 8070

Yes, loads of good info on this forum. Thanks to everyone for their contributions. This dampener thing is hugely important. Seems like there should be a mfg’s schedule for replacement of their engine’s dampener?? Did AC dealerships receive company bulletins about it? Or,,, possibly it’s a difficult item to forecast? Maybe some wear out faster than others because of different customers’ usage?

Edited by AC7060IL - 04 Feb 2023 at 9:25pm

We always did ours at 3,000 hours.

I had been taught that a bad dampener could also result in a broken crankshaft.  There must also be some interesting industrial history here too (not that as Allis fans we are interested in industrial history).  Stahl dampeners were made by Carl Stahl who, according to his obit, worked for Cummins in IN and relocated to Memphis to start Cummins Recon.  Does not appear that Stahl became a major manufacturer or maybe he was bought out by someone else.  His obit states that he invented the Transdamper.  Wonder why he wasn't a major manufacturer with the widespread use of crank dampeners.  

Edited by jeickman01 - 05 Feb 2023 at 5:52pm

 https://www.vibratechtvd.com/detroit-diesel-replacement-dampers...

Agree Dale. That's why the BIG diesels have big dampers. when you take a given horsepower engine and crank it up,the OEM design balancer becomes inadequate for the new harmonics.

There was a crankshaft nose improvement on the last year or two (1985-86 ?) of 426 engines that not many people are aware of. A bad damper can cause lots of problems for sure, but there was an apparent weakness in the 426 crankshafts that was addressed in these last couple of years of production. The engineers removed the two half-moon keys from the cranks nose area (one for the crank gear and the other for the crank pulley) and replaced them with small round pins. This reduced stresses that were there with material removed when they used half-moon keys. The other change was they went to a smaller diameter bolt to retain the crank pulley that was much longer and was threaded deep into the front main bearing journal, putting the nose of the crank under compression, making it stronger. These two changes were an improvement to reduce crank nose breakage. Big Al cranks needed that done to them. A truck engine crank goes thru a lot of twisting under full acceleration and load. Then, you get completely off the throttle to shift gears and then back down to the floor again. This constant twist and release is very hard on crankshafts.

From the very first 7080 engine on up (7580-8070-N5-N6-R5-R6-4W220) always had a viscous damper. All these engines also had the counterbalanced crankshaft and produced the most HP at the highest rated RPM's.

Could be. Diameter of the pulleys the same??  Higher HP and higher RPM's is why they had to get away from rubber type.

Hopefully, the one from a 4-71 Detroit will fit.

Very good and informative conversations here for sure, In reference to Darrel's and Doc's post concerning crankshaft nose breakage. We had a neighbor that purchased a new Series 3 N5 in 1983. Really got along good with the machine until the fall of 1988 when the nose of the crank broke clean off. Didn't tear anything up and he didn't realize it had happened until the coolant temperature light came on. Catastrophic failure none the less, but at least it was only the crankshaft., Mike  

Edited by MikeKroupa - 07 Feb 2023 at 8:22pm

We have a 8050 that had cracked block. Bought a running 8070 motor from a junk yard. We might be swapping pumps out. Wondering after reading all this. Should we take fluid balancer off. 

I'm making a mental note of this for future reference as my 8070FWA is still my big horse.

IF you had a motor that was lucky to be closer in balance, would it make less of a difference then a motor that was farther out of balance? Or if the motor was being ran when the fluid in the balancer began to solidify verses a motor that sat for months without running and the balancer solidified and made it way out of balance?

Maybe someone can convince TCI to make their "Rattler" damper for our Allis applications. The cam gear on my C15 Cat has that design built in it.

That is a very informative article on fluid filled dampers. A very good read. Thank you for posting.