NP 205 29 spline observations

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NP 205 29 spline observations

Postby CumminsPower59 » Mon Feb 24, 2014 11:04 am

I had a 29 spline unit apart and did some measuring, in the case to show everyone what is involved in converting a 23 spline unit to a 29 spline unit.


For the hard parts, you'll need:

29 spline input shaft.
Large input shaft front bearing and outer snap ring, and small (super thick) front bearing retaining snap ring.
29 spline coupler.
Input shaft seal (dual lip)
Front adapter gasket, might want to use a thick one here.

Quad 4x4 makes a "kit" with all the needed parts included:
http://www.quad4x4.com/cgi-bin/commerce ... key=662001


Disclaimer: I used one of my el cheapo dial caliper, I would recommend measuring all the new parts and what not with a proper metal dial caliper and depth gauge. My measurements are a rough estimate as to what's all needed.


Machining to be done:

Input bearing bore on the case will have to be machined to approximately 3.550" to accept the larger bearing. The input shaft front bearing is 3.543" in diameter. It doesn't have to be a tight/press fit, but don't want it loose either. It should take light persuasion from a soft faced hammer.

Front adapter or "bowl" as Bill and I call it, will have to be machined to accept the larger seal, bearing and two snap rings.
Large outer snap ring groove, 3.775" to a depth of 0.100".
Bearing groove, 3.550" to a depth of 0.200".
Small (thick) snap ring groove, 3.050", to a depth of 0.350".
Seal bore to 2.685"
The cost for each bowl to be machined was $50.
I didn't get a quote to get the case bored, I would guesstimate somewhere between $50-$150.


Now here's where it gets a little interesting. I recently had two small input bowls machined out to the large bowl specs. No biggie there, buuuut where the input seal rides. Most of the casting is machined off, leaving just a small, sharp lip. One of the bowls was off my 91, and it had about 0.300" of material remaining. The other bowl I had was off a 85 W400, it had 0.250" to .0.270" of material remaining. The dual lip seal has a thickness of 0.500". The big input bowl has a seal surface of 0.800" for the seal to ride in.


Pictures.
Image

Image

Outer snap ring groove
Image
And depth
Image

Bearing groove
Image
And depth
Image

Bearing retaining snap ring groove
Image
And depth. NOTE: this depth is from the land above it, need to add 0.200" to it to get the total depth.
Image

Seal surface
Image

Small (thick) snap ring
Image
Bearing
Image
Large snap ring
Image

This shot shows how much of the snap ring would protrude from the case, and how much DOESN'T go into the bowl, hence the need for the thicker gasket
Image

Another shot of the bearing and two snap rings
Image

Original big input bowl seal surface
Image
Machined out small input bowl to big input bowl specs, notice the input seal surface
Image

Inside of big input bowl, and how much material is there
Image
And inside of machined out small input bowl
Image

Case input bearing bore
Image

That's all for now, I got to head to work, I will update this some more when I get some time tomorrow morning...

Enjoy!!! :mrgreen:
Last edited by CumminsPower59 on Tue Feb 25, 2014 10:08 am, edited 3 times in total.
Ike

91 W350 SRW, 3.07's, NV4500, 370's, THD LPPP, Super HX40, 2nd gen IC swap, BHAF, Isspro's, 2" lift, 285's on 3rd gen 17"'s.
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Re: NP 205 29 spline observations

Postby bgilbert » Mon Feb 24, 2014 5:45 pm

Sticky material 8) . Sorry Ike, I couldn't wait til you added more info before replying :lol: . My two cents:

Mark Nixon mentioned on another website he found a narrower input seal for the newly machined bowl. I don't know if it was a narrower double lip seal or single lip. He also mentioned he forgot the part number :lol: . Ike and myself feel we can just Loctite the siht out of the double lip seal instead of running NO seal and having to run the same lube in both the tranny and t-case as many others have done after this modification. I currently have a couple of these bowls at my machine shop waiting to be done. Until I get my hands on one, I won't know how the double lip seal feels in the modified bowl, Ike? I have good bearing/seal shop in town, when I get some time I will take the double lip seal there and see if they can find another option. IMO, we really only need to keep oil IN the t-case. Assuming your manual transmission's rear seal is fresh and not leaking. So a single lip seal would be fine.

Great write up. I haven't seen one before. I know trashingcows or the like on dtr has mentioned he was gonna do a write up on the same thing. Maybe he did one on a 205 rebuild and didn't go into details on the machine work.
Bill Gilbert
85 D350 crew with 90 6BT intercooled Getrag 3.07's
93 D350 single cab Getrag 3.54's.
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Re: NP 205 29 spline observations

Postby CumminsPower59 » Tue Feb 25, 2014 10:06 am

I put a few more small tidbits of info I forgot in the original post up in there...

I found a seal that may work. National #3173, and I believe it is a single lip seal.

Specs:
Shaft 1.937"
Housing bore 2.686"
Outer diameter 2.69"
Width 0.304"

Normal, dual lip National #710928
Shaft 1.938"
Housing bore 2.68"
Outer diameter 2.685"
Width 0.5"

For what it's worth, it may be a viable option.
Last edited by CumminsPower59 on Tue Feb 25, 2014 10:19 am, edited 1 time in total.
Ike

91 W350 SRW, 3.07's, NV4500, 370's, THD LPPP, Super HX40, 2nd gen IC swap, BHAF, Isspro's, 2" lift, 285's on 3rd gen 17"'s.
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Re: NP 205 29 spline observations

Postby CumminsPower59 » Tue Feb 25, 2014 10:18 am

bgilbert wrote:IMO, we really only need to keep oil IN the t-case. Assuming your manual transmission's rear seal is fresh and not leaking. So a single lip seal would be fine.


The only issue I can see is that if there is anything other than a Getrag in front of the NP 205, as with conversions, a lot of times the rear transmission seal is pulled to facilitate clearance for the output shaft to transfer case input shaft coupler, and the "bowl sump" gets some transmission lube in it. I don't think much lube would push it's way past a single lip seal that far up, the only instance I can see is if the transmission gets pretty hot and can't vent for whatever reason and a little pressurized lube gets past the seal and into the transfer case. Even then, NP 205's are pretty tough, the only ones I've seen killed off are from sled pulling and running out of lube.
Ike

91 W350 SRW, 3.07's, NV4500, 370's, THD LPPP, Super HX40, 2nd gen IC swap, BHAF, Isspro's, 2" lift, 285's on 3rd gen 17"'s.
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Re: NP 205 29 spline observations

Postby ellis93 » Tue Feb 25, 2014 10:26 am

Ike I applaud you :)
Keep going on this tho,the more info the better. I plan on doing a few more writeups in the future and will focus on some of those common problem areas like brakes and electrical or maybe a/c idk. Seems there are a lot of questions that pop up often that are usually asked at least oncea month.
Take for instance the voltage regulator woes that befall the 91 and back guys,there is a ton of info on how to fix that.....in about 50 different treads and about 5 different fixes. Someone needs to break out a writeup on that.
93 D250 ,5 speed,4.11s,k&n autometer tach pyro trans boost guages,GDS 60mm h1c 14cm,honed 5x10,hplp/reg,1/8 timing,M+H M2 fuel pin, tims cooler tubz
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Re: NP 205 29 spline observations

Postby CumminsPower59 » Tue Feb 25, 2014 12:19 pm

Thanks Ellis. I need to do the voltage regulator thing, as my volt gauge constantly swings. It drives me nuts. :scratch: Its even a blue Mopar unit. :mad:
Ike

91 W350 SRW, 3.07's, NV4500, 370's, THD LPPP, Super HX40, 2nd gen IC swap, BHAF, Isspro's, 2" lift, 285's on 3rd gen 17"'s.
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Re: NP 205 29 spline observations

Postby ellis93 » Tue Feb 25, 2014 1:36 pm

You could search out bobS' post.....he had several "fixes" or diagnosis for it. Hell I think Levi fixed his....somehow,I didn't pay attention because it doesn't apply or effect my truck.
93 D250 ,5 speed,4.11s,k&n autometer tach pyro trans boost guages,GDS 60mm h1c 14cm,honed 5x10,hplp/reg,1/8 timing,M+H M2 fuel pin, tims cooler tubz
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Re: NP 205 29 spline observations

Postby CumminsPower59 » Tue Feb 25, 2014 1:56 pm

I will do some digging, I got plenty of electrical issues to deal with once it gets above freezing...
Ike

91 W350 SRW, 3.07's, NV4500, 370's, THD LPPP, Super HX40, 2nd gen IC swap, BHAF, Isspro's, 2" lift, 285's on 3rd gen 17"'s.
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Re: NP 205 29 spline observations

Postby bgilbert » Tue Feb 25, 2014 5:42 pm

CumminsPower59 wrote:I put a few more small tidbits of info I forgot in the original post up in there...

I found a seal that may work. National #3173, and I believe it is a single lip seal.

Specs:
Shaft 1.937"
Housing bore 2.686"
Outer diameter 2.69"
Width 0.304"

For what it's worth, it may be a viable option.

Ike, I googled it. I'm pretty sure you nailed it. It came up, Advance Auto Parts, and it 'fit's my vehicle! I plugged in a 89 W250 CTD. Shows for the 205 transfer case and the most important part we've been talking about, 2 required per vehicle. So Philip was right on, even the big bore bowl came with two seals back to back. One to keep oil in the tcase, one to keep oil out. In all the gasket/seal/rebuild kits, a single double lip seal is included. At .304 is should fit fine in your .300 machined bowl.

Not everyone gets a chubby talking about tcase machine work and seals. Maybe if we were talking about 'murdering' our trucks, 3rd gen towing mirror installs, or some other way to further rice out our truck it would get some love :lol: ..
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Re: NP 205 29 spline observations

Postby dazedandconfused » Tue Feb 25, 2014 6:07 pm

Very good info Ike.
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Re: NP 205 29 spline observations

Postby CumminsPower59 » Tue Feb 25, 2014 6:34 pm

Thanks guys! We all know that there is an abundance of 23 spline units and 29 spline units can be hard to come by. And with all the auto to manual swaps being done, the supply is limited. With this info we can save money by not paying $1000-$1300 eBay prices on these things, and still get the product we need. Think about it, that 23/29 spline coupler is $175 and on back order, its $450 for the Quad 4x4 conversion kit. So a bit more than double, but you now have the strength of the larger input. I figure one could have about $600 in the kit and machining, still not bad. Unless you stumble on a craigslist find like I did recently, or buying a whole donor truck to get parts from, this is a viable option.
Ike

91 W350 SRW, 3.07's, NV4500, 370's, THD LPPP, Super HX40, 2nd gen IC swap, BHAF, Isspro's, 2" lift, 285's on 3rd gen 17"'s.
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Re: NP 205 29 spline observations

Postby Philip » Thu Feb 27, 2014 5:55 pm

Ike me and Bill have talked about this many times. I have a 23 spline bowl out being modded also. Its being done slowely by the shop that has it. He said a couple of weeks ago he is getting tired of having his surface plate tied up by that adapter bowl. So he might move a little fast now. :lol: :lol:

When mine gets done I'll add it to this thread showing how it is modded with pic's.
93 W350 Club/cab w/duals, buckets & console, B&W flatbed, G56, 6 spd, 3:07 rears, gages, HX40/16, 4" exhaust, 6X.018 sticks, rear air ride suspension
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Re: NP 205 29 spline observations

Postby bgilbert » Thu Feb 27, 2014 6:12 pm

CumminsPower59 wrote:...$450 for the Quad 4x4 conversion kit.

Quad4x4 is insane!! I picked up the input shaft and coupler from Zbag for about a 1/4 of that! The bearing is ~$25. Then the two snap rings could be tough to source? I haven't tried to find them yet.
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Re: NP 205 29 spline observations

Postby CumminsPower59 » Fri Feb 28, 2014 6:35 am

I am well aware that they are VERY proud of their parts :roll: I was looking into building another NV4500, I could buy a whole, brand new NV4500 for LESS than the sum of all the parts I need. No thanks. If it is a last resort, I would buy some small parts from them, large parts, nooooo thanks.
Ike

91 W350 SRW, 3.07's, NV4500, 370's, THD LPPP, Super HX40, 2nd gen IC swap, BHAF, Isspro's, 2" lift, 285's on 3rd gen 17"'s.
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Re: NP 205 29 spline observations

Postby Philip » Sat Mar 01, 2014 6:48 am

Quad doesn't have or will ever have anything I need. I bought from them one time. That was enough.
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