Transmission and auxiliary transmission

I can not dispute your comment about your 4spd. lasting as I can not say the guys that dropped a 4spd. out in the road wasn't grossing high and in overdrive which would do some damage. I have never run an Aux. so I have to get my info from others with first hand experience. No matter what its hard to get the full truth of it and even if it were me first hand as sometimes lack of experience will not allow you to lay out all of the facts.

About lockers and 2spd. rears Eaton does have a back rear end that is called a 2spd. low lock. When you drop the rear end on the low side it automatically locks the axles as a locker. BUT they do not offer on the front rear end. Even so you at least have 6x8 drive on low side with power divider in. Now after that being said I have not found a Peterbilt dealer tell me that it is or isn't true. I found that info pages deep in a google search. I guess to really confirm it is to get a hold of an Eaton rep.

 

I am at 4.33 and then when I go into the first underdrive it like 1.27:1 so effective 5.57 or so - set up was spec’d for upto 212k

 

Yes Mr Ron you are correct . You can not get lockers in a 2spd rear end .
You might be able to get posi track rear ends , but trust me you really don't want them .
I know I am going to piss poeple off with this , but what the hell. You have to be able to control your diff locks . First reason is to be able to steer . Ask someone who runs quad lockS , what there like to turn , now add ice , the big steers and trow a downhill grade in the corner and that's a place you don't want to be .
Second reason . You'll blow up the diffs in the right spot . Dad blow up 2 or three if I remember right.
Uphill pull , kinda muddy , 32 wheeler and a hard 90 corner on pavement . What do you do ? You have no control .
That's just what I have seen of them . Don't get me wrong , in there time and place they were the answer . That was a long time ago , in my opinion

 

Yes that is the case but it is close enough that they will build it - but it will be in your spec notes.

There is not a 100% factory approved solution for the weights you are spec’ing for. I felt getting the right operating solution was important.

You can look at an Allison main box with and A 3spd fabco FAT30 - and if you get this setup please explain how to actually run it going down the road - but it will be a $250k US truck.

I was very close to the Allison with the 4 spd spicer solution but no one explain how to safely operate it in regards to the aux transmission integration with the auto.

 

Ok, good info. Didn't know about the trip-drive scenario. Lets rule out 2spd. rears then. You still have one option in my opinion and that is no Aux. trans. at all. If you happen to think about that then I would consider a lower ratio (higher numerical #), but that is also determined with tire size.

But the one thing I see that is confusing is that if each ratio changes the gross weight capacity then they need to tell you what tire size that is being factored at. For example a 4.10 ratio with 11R22.5" tires is the same as 4.30 with 11R/24.5" tires. It will be the same mph at the same rpms. If that doesn't change how come the gross weight does?

The other thing is that I have seen guys run a ton load of loaded miles grossing 200k+ with 3.90's and 4.10's. Even came across a guy one time on 8 axles grossing 150k with 3.36's which wouldn't make that chart. None had issues. But as long as that is a guideline and they won't use it as a tool to void your warranty I'd say just take that with a grain of salt.

 

I know the feeling. I had to short neck into a muddy/icy yard in Calgary with about 80k on the drives and it is virtually impossible to turn

 

The warranty is really only as good as the dealer attempting to get the coverage. So yes they can potentially void the warranty based on you gross weight. The answer is they don’t know what range you were in when the failure occurred or what the actual weight the vehicle was.

I am not advocating untruthful activity in anyway. You have to do the job and take the risk that they may not pay a warranty claim.