Hey Diesel. I joined this forum just to make this post and ask you a few questions. I checked out your build too, by the way - its pretty amazing what you've done. Anway, I think I'm in the same boat as WildcatKit52, where I was in the basement looking at my spare 241 that had a bad output bearing and pump and was thinking to myself that the front planetaries are still in good condition. I did some quick research and figured out that someone makes a 231 doubler setup, so I figured why not see if I can rig something together. I made a post on Pirate and they led me to here.
Anyway, I know you mentioned something about making more doublers for your Moab trip and was curious about a couple things.
First - the part where you welded the shaved down 6-hole t-case adapter plate to the larger flat plate, what was stopping you from simply drilling those 6 holes into the larger flat plate?
The reason that I did this was because the transfer case indexes into that adapter and I my little lathe can't turn a piece as large as the adapter plate. Obviously I'm to cheap to pay someone to turn it for me, lol, so I just decided to use what was originally indexing it because it was there.
Second - I read somewhere that someone broke their adapter shaft on their D&D 231 doubler and the company made them a new one for $75 (versus the $225 you mentioned). I wonder if the 231 splines coming out of the planetary setup are the same as the 241 (since I know a lot of them are). Might be easier for some of us without access to a lathe and welder in the same location (I have access to a lathe but no welder at work, but my welder is at home).
The $225 was a guesstimate based on what a freind that has been in the business for years sells his for, $75 is cheap IMO, but it didn't hold up so it must not have been to much of a bargain. I would assume that the splines between the 231 and 241 would be the same because I believe I read that the planetaries will swap between them, but I am not sure. Again, I just did it this way because I could do it myself without paying to have it done.
Third - how many passes did you do on the intermediate shaft? It looks like two to me, but it also looks like you could have done a couple more, if nothing more than to increase the OD of the weld area and significantly increase the torque rating (even though I know you said it held up to 400 lb-ft and lots of weight - just curious).
On the first one I believe it was two passes and that's the one I ran it with behind the 6.5 that was making around 400 ft/lbs of trq and was using a 27 spline input gear on the second case. I rebuilt the shaft for the current setup for a 32 spline input on the second case since I more than doubled the torque input with the tuned Duramax, not to mention the lower gearing in the Allison, and I made a third pass on it tapering it from the larger portion to the 32 spline section. This engine should be putting out somewhere around 825-850 ft/lbs as it is right now and pulling a 24' bumper pull trailer with it with a moderate load of steel it will break the tires loose up to around 35 mph on dry pavement and the shaft is taking it fine. I had it out last month due to a rear transfer case failure (that I caused from a missing C-clip) at it looked great with no signs of stress. A good friend of mine that used to build a lot of axle shafts and stub shafts said that this welded shaft is probably stronger than one I could buy.
Fourth - how much would you say you've beat on in it double-low? I ask because if you've got the front case in low, it's multiplying the torque by 2.72 onto the intermediate shaft. Obviously if you're in single low, you'd want to use the rear-most case to limit the torque on the intermediate shaft, but have you done any tough stuff with the front case half in low? I only ask because this is going in a 6000+ lb truck and I want to make sure I don't leave myself stranded somewhere if the intermediate shaft breaks. Though I guess I could always make a spare one to bring along with me, just in case.
I haven't been able to beat on it much at all in double low as I really haven't had it ready to wheel much until recently and now I'm having an issue with the Allison, so I can't comment much here. I will always run the rear case in low before I engage the front case though for the reason you mentioned above. There is no reason to run the front one in low before the rear. My truck hovers just below 6K also, so we will be playing with the same fire from a weight stanpoint. This setup would most definitely be vulnerable to breakage, but I'm more worried about damaging it from contact with rocks than internally mainly because of my wheeling style. I'm very patient and practice good right foot control, seldom ever throttling it. The shear beauty of this setup is the cost IMO, if I did grenade the entire setup I have very little in it and a pile of 241's under the bench in the shop and the adapter plate is reusable. Cutting the side off and having the section of aluminum to fill the gap on the front case is all that would have to be done to have another one ready to go other than the intermediate shaft. Weight is another perk, my 203/241 doubler weighed a ton compared to this one. I have installed this entire setup in my truck, without using the lift or a jack, by myself.
I'm really excited to get this project going. I have a 2001 Silverado half ton with a Dana 60 up front and 14b 10.5" out back that I really need to run a new rear drive shaft on, so I figure now would be the time to add the doubler into the mix. Plus my front drive shaft is super unbalanced and I've been wanting to re-tube it, so now would also be a good time for that. Plus the angle is about as steep as I'd ever want it to be so lessening the angle is also a good thing. I just don't see any downsides to doing this other than cost.
The cost is the best part of this setup to me, I had the plate, the aluminum section and the factory adapter laying around, so I spent very little and these cases can be had for $75-$100 all day around here on CL. The lengthening of the front driveshaft is also an enormous plus for me too because of the suspension travel I'm dealing with. Mine really doesn't need the doubler at all with the engine/tranny I'm using, but the front shaft really need to be as long as it is with doubler to prevent binding. You'll be surprised how easy it is to pull off.
And I appreciate any advice you can give on this!
