I just got a refund check from Jasper Transmissions.
They too don't know why overdrive keeps failing in my truck. 4 in two years!
I talked to a Gentleman in Knoxville, Tenn. who offered to install an Allison behind the Cummins. Has anyone had any success ?
I have compounds,larger injectors,and a Smarty on the 7th position.
I pull a 15000 pound Sprintcar trailer.
Any input would be welcome,
Dave

 

what kinda input are you looking for?

ive not seen an problem with the nv5600 in over drive. is it striping it, or is it the synchros going out?

 

Thanks Big Ed,
It strips and sends debris through the rest of the tranny. In this instance, I was just reaching for the turn signal ,getting ready to exit the interstate,and the awful noise happened. No warning.
I'm through with the 5600. I just wanna feel warm and fuzzy about putting an Allison behind the Cummins.

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The design of the 5600 is crazy,no solid shaft, but Timken bearings opposed let things flex and its all over. 3 and 4 are usually toothless by the time I come to a stop. Very strange.

 

Sorry it has ruined you on the nv5600. What was the original reason for going to a new one? Same thing?

The last four that have went bad sounds like probably a bearing problem. Bearings not as good as factory pnes


Back from the forum grave

 

Sorry to hear about your bad luck with it. The 5600 generally considered a fairly strong trans. I would point the blame more towards the components in the rebuild than the trans itself. I would look for a used factory trans instead of an allison swap, but thats just my .02.

 

Yes it was. I went through this original myself. I've got a lot of experience with manuals. Mostly big trucks, I could not understand why this one was so poorly designed. I set it up on the tight side and it lived for 20000 miles. After that, I turned it back down to almost stock settings . It broke. Then I turned to remans. Jasper assured me this was the last trans that I would buy. Every time you build 50 pounds of boost, crunch!
I hope the Allison is the answer.
The truck will do around 650hp on a chassis dyno, when its turned up. Now it's back to near stock settings and still no joy. I won't throw good money after bad.

 

have you gone ahead with this plan? i have wondered about saying goodbye to my 48re in place of an allison would love to see pictures / know more about this process if possible

 

LOL, and you expect a transmisson rated at 550 input TQ to last at those levels WHY?????

In the OD gear. the weakest geat in the trans, to boot.

Sorry, but this well deserving of a C'mon Man!!

 

Alison will not survive 48re is way better! Put the truck to stock sell it and buy an auto put all your goodies on it and drive with a warm fuzzy feeling! Of course you will have to build the 48re right but at least it can handle a lot more than the manual and Alison

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Check this out: Allison 1000 cummins conversion kit - Competition Diesel.Com - Bringing The BEST Together

 

They make conversion kits and im sure you could find a shop who would do it. Ive heard a lot of good about the allisons but don't know cause ive never owned a chevy