Crank to Flexplate bolts keep backing out

Throw a 6.7 balancer on there , and taking weight off the crank amplifies harmonics . There is a reason common rail cranks are heavier.
 
A couple of things... I would also use the angle method to tighten the bolts. The BD flex plate is a "rougher" surface then a stock flex plate. The stock torque value will end up with less clamp load. I also use the ARP bolts made for the application. They have a larger head for more surface area against the flex plate.

Make sure you use the pin kit if you use a Fluidampr. They have worked for me. I do not have any direct experience with the ATI in a Cummins application.

Paul
 
Does anyone have data on harmonic frequency change in an application with just weight removed? I would like to read through if anyone has anything.

I know that Finnish dude cut the hell out of his crank and I thought he had no trouble from it?

Not calling anyone into question, just like to read.
 
zfaylor said:
Crank to flexplate bolts not flexplate to converter bolts....

Unless I am missing something here why would you make yourself work through a 1.75" hole? Move the tranny out of your way!
Click to expand...

:doh: My bad, was thinking flex to converter
 
turboram said:
Throw a 6.7 balancer on there , and taking weight off the crank amplifies harmonics . There is a reason common rail cranks are heavier.
Click to expand...

CR cranks are heavier then what? Cause everyone one of them I have weighted have been the same as a 12v or 24v. When I was picking a crank for my last motor build I was weighting cranks to see if there was any difference in weight and my CR crank I used was within .20 to a 24v crank.
 
The torque spec on the arp bolts is also higher at 120 or 125 ftlbs. I don't remember which one exactly.. they also wanted arp lube and blue loctite on the bolts. Lube up top and loctite down near the end of the bolt. Just stating this being more surface area on the bolt heads and the higher torque there should he a considerable amount more of clamping force. I'm running arp bolts on one of those cheapie flex plates.
 
I plan on checking to see if the crank to damper faces look chattered. I suspect they are. Anyone have part numbers handy for ARP damper and crank flexplate bolts?
 
Flex plate bolts for 94-02 #147-2901
Flywheel bolt kit for 89-04 #147-2802
Balancer bolt kit #147-2503
 
What are anyone's thoughts on a chemical friction enhancer between the surfaces? I know we used to use "bearing mount" on races, but everything switched to loctite and I'm not sure the green compound is equivalent
 
The balancer bolt kit for the 5.9L is #147-2502, not sure what the difference is between those and the #147-2503 for the 6.7L.

I used the #147-2901 for the Flex plate to crank on my 05.
 
LOL I'm feeling under endowed. Stock bolts front and back. Has to be decent stuff.
 
Joesixpack said:
LOL I'm feeling under endowed. Stock bolts front and back. Has to be decent stuff.
Click to expand...

That's impressive.. I kind of figured in such a high hp truck everything would be a high quality "space age" fasteners.... the only reason I have arp flexplate bolts and not stock is because I swapped from a manual, and had no stock bolts.
 
okie18 said:
:doh: My bad, was thinking flex to converter
Click to expand...

All good LOL I figured you were. Honestly I had to go back and re-read the thread after you said that to make sure I wasn't losing it.
 
biggy238 said:
Does anyone have data on harmonic frequency change in an application with just weight removed? I would like to read through if anyone has anything.

I know that Finnish dude cut the hell out of his crank and I thought he had no trouble from it?

Not calling anyone into question, just like to read.
Click to expand...

What was that thing laying down sub 400hp? Don't think it was even seeing high rotational speed.

dixon700 said:
That's impressive.. I kind of figured in such a high hp truck everything would be a high quality "space age" fasteners.... the only reason I have arp flexplate bolts and not stock is because I swapped from a manual, and had no stock bolts.
Click to expand...

That fluid damper even dowel pinned in three different places and torqued properly shows signs of fretting between the mating surfaces. It's just a lot to ask of such a small bolt circle.
Not suggesting that a guy should be using the stock fasteners just a bit surprised I've been getting away with it. The Damper fretting has been an ongoing concern maybe the arp solution will cure that.
 
Last edited:
Id imagine that the issue is what a previous poster mentioned, that trimming the weights resulted in more abrupt torsion loading on the crank. You can balance the rotating assembly, but the weight is probably designed into it with certain torque loads in mind.
Its banging those bolts out like an impact wrench. No idea how youd keep them in there. Dowels are for side loads, bolts for clamping.
 
Last edited:
ATI suggested a different durometer o-ring would help. I may try that direction as well.
 
You must log in or register to reply here.
Top