Spin off to the Klune vs. Doubler

[wayne]

Stephen, when looking deeper into this I thought it might be good to do some comparing. The big thing is cost issues for a lot of people when doing an upgrade like this. In comparison we will leave driveshaft mods out because all options will most likely require modifications.

Atlas- will cost anywhere from $2100 to $2500. I believe it is a bolt in for most applications.

Klune- cost is around $1500 to $1800 and the 2.7/1 is a bolt in for quite a few applications.

Doubler- Kit price is $740, shifter is $250 for the triple stick. Most will need t cases and we will use my set up as an example but you will have to fill in the cost.

th350 203- easy to find and cheap. We will figure $100 for the case.

Cost to change the input shaft to bolt it to a th400/208=?
Cost to redrill the case=?

Can I use my factory adapter and if not cost=?

SM465/205- cheep and easy to find in fixed rear yoke= $100
Input shaft=?
modifications needed to use in this combo=?
32 spline front output conversion=?

I think I got it all and if not I'm sure you can fill us in. Also could the back yard mechanic do any mods himself easily like redrilling the 203? Shipping t cases will really drive the cost up. Let me know what you think and this would be starting with a th400/241 combo with an SYE kit.

 

[Stephen]

Hi Wayne, starting at the top:
The Atlas doesn't bolt into anything GM. AA is a jeep shop and thus the Atlas comes with a jeep bolt pattern and that's it. They could very easily build it with the GM bolt pattern on the front but chose not to forcing you to do custom work or buy their adapter housing to bolt the trans to t-case. I doubt you would have to change the trans output shaft.

The Klune has a head start on the Atlas since they actually build it to bolt up to the GM round pattern so you don't have to buy an adapter for it. The Klune does have the disadvantage in shifting, there are no provisions for shifting the NP205 at all and it has one shift rail buried behind the housing like the Doubler does which makes it kind of a pain. You also have to adapt the round pattern to the common 205 fig8 bolt pattern.

So I guess for a good Klune vs. Doubler comparison you have to look at buying or building a shifter either way you go and converting the 205 to a 32 spline short input gear, along with checking which adapters are necessary to bolt it together.

OK, now down to your example:
I wouldn't pay more than $150 for a 203 gearbox for sure, $100 is a good middle of the road price.

A NP203 32 spline input gear runs $150
Modifying the 203 gearbox to bolt up to the GM round pattern is a pretty simple process that can easily be done on a drill press. It is a decent number of small steps but not of them are difficult:
You need to line up the adapter feet on the Doubler adapter and on your 400/241 adapter and mark the holes to drill. One will fall on the edge of the 203 face so you'll have to move it around on the adapter and the 203 face just a bit. On some we can just egg the existing hole in the adapter and make it work out, with others we just drill a new hole. Once they're marked just drill and tap the case to 3/8" coarse thread and you're ready to clean up and re-assemble the case.
Use some small allen set screws and generous amounts of locktite to plug the existing holes, then we usually dimple the edge of the hole and the screw just to make really sure they're going to stay in the there.
We like to bolt a flat steel tab into the half flat on the idler shaft to keep it from spinning if it ever comes loose. This is what NP did with the ford 203's where the adpater didn't cover the idler shaft.
The bearing retainer will need to be matched up to your adapter housing so it could require some clarance grinding on the small tabs on the face of the retainer and you may need to clearance grind some room for the bolt heads in the adapter housing. Using 12 point or allen head bolts for the bearing retainer really helps. None of this is precision work, the case indexes into the adapter with the OD of the bearing retainer and that's a good fit to start with so all you're doing is making room for it to go together.

The NP203 input bearing bore is the same for all applications so the input gears all bolt in without case modifications.

This is tedious but simple to do with minimal tools. This will have your 203 gearbox ready to bolt to the factory 400/241 adapter housing. We usually charge $60-$70 to so this to a case.

For the 205, you'll need the same 32 spline input conversion no matter which gearbox you choose. Modifying the 205 involves taking the 205 completely apart, taking the case to a machine shop with the new bearing and the old bearing, boring the 205 to fit the new bearing just like the old bearing fit, then putting it all back together. Conversion kit cost is $200 and that includes the input gear, input bearing and a full seal and gasket kit for the 205. If you want to do a full rebuild, the cost is $330 and that adds the bearings and small parts to rebuild the 205. We charge $60 to do the machine work and inspect the case, check holes, etc. I typically don't recommend shipping the case to us so your local price may vary.

So, there you go. You should spend about $1000 to put a 203 gearbox in. This is assuming you're modifying the 205 either way and ignoring shifters since you'll have to address that problem with either gearbox also.

The 32 spline front output swap for the 205 is a different subject since it has to be done anyway. At this point we don't have a reliable supply of 32 spline front output shafts so price and availability vary almost day to day. Typical cost is roughly $125

And that's my book on this for the day, whew!