Has anyone....????? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Angelse68cal · 12-20-2006, 07:18 PM

Has Anyone converted over from a th350 to a th400 in there K5 or Jimmy?

pharcyde05 · 12-21-2006, 02:01 PM

I changed mine out

gmcman7202 · 12-21-2006, 02:01 PM

not that a big a deal to do.

hotrodhomi · 12-21-2006, 02:02 PM

mine has a th400

Angelse68cal · 12-21-2006, 03:18 PM

I am talking about changing it in a 4X4! Oh yea and wht is Axel Wrap?

gmcman7202 · 12-21-2006, 05:08 PM

still isnt a big deal, i am not sure what t case adapters you might need, or if the splines match, since i dont know the specs of the 2 off hand, as gm made the needed adapters, as the t case used is gona be diffrent for diffrent years, ect...

JimKshortstep4x4 · 12-23-2006, 06:29 PM

We don't have a TH 400 in a Blazer but we have one in a short box 4x4. Since the TH 400 is longer there are some mods to be made in addition to the transfer case adapter, (the NP 205 is the same for both tranny's). The longer TH 400 requires a longer front drive shaft, a shorter rear drive shaft and the crossmember needs to go rearward. The side mount for the transfer case has to be relocated. The transfer case shifter has to be bent in an "S" shape to move it forward. The shift linkage is different, also.

Jim

jaros44sr · 12-24-2006, 09:12 AM

Hey Jim, thanks for the heads up and info. Just picked up my TH400 and was not sure what was involved, sounds pretty strait forward, I have a floor shift so no problem there, but how do you bend the transfer case shifter. Just heat and bend around a suitable mandrel?

Merry Christmas, J.

MNorby · 12-24-2006, 10:46 AM

another thing the th400 will have a 32 spline output whereas the th350 has a 27 spline output so you'll either have to change the input gear into the case or swap t-cases

JimKshortstep4x4 · 12-24-2006, 10:51 AM

We just heated and bent the shift lever. It was a lot of bending and the shift lever is pretty short by the time you get it into the right position.

We use the truck for towing a car trailer and the TH 400 works great!

Jim

jaros44sr · 12-24-2006, 11:28 AM

Quote:

Originally Posted by MNorby

another thing the th400 will have a 32 spline output whereas the th350 has a 27 spline output so you'll either have to change the input gear into the case or swap t-cases

Does anyone make an adapter 32-27 spline? Isn't there a coupling between the trans and transfer cs.

MNorby · 12-24-2006, 12:13 PM

Quote:

Originally Posted by jaros44

Does anyone make an adapter 32-27 spline? Isn't there a coupling between the trans and transfer cs.

If your going to run a TH400 to a NP205 its just the input gear into the t-case. on a 205 if you are going from 27 to 32 you will need the 32 gear and to have a machine shop bore out the bearing hole. I had that done to convert my 10 spline 205 to 32 spline for my doubler. NWF sells input gears http://northwestfab.com/ Also you'll need the adpater from the tranny to case and that adapter can be $$$ since was a rare fatory option. I believe NWF mills them too and you can sometimes fond them on ebay for around $150 or so. You could go with a th400 into a NP208 or 241 alot easier/ cheaper too since that was a very common setup. I have a 241 sitting here just collecting dust.

JimKshortstep4x4 · 12-24-2006, 10:07 PM

You may want to check this place out. They have an input shaft for the TH 400 to the NP 205. I am not sure if their part has any complications so you would want to talk to someone.

Here is the link: http://www.drivetrain.com/

Click on Transfer Case parts. The part number is ALT 13929 and lists for $104.

Jim

jaros44sr · 12-25-2006, 04:45 PM

Quote:

Originally Posted by JimKshortstep4x4

You may want to check this place out. They have an input shaft for the TH 400 to the NP 205. I am not sure if their part has any complications so you would want to talk to someone.

Here is the link: http://www.drivetrain.com/

Click on Transfer Case parts. The part number is ALT 13929 and lists for $104.

Jim

Thanks that might work. I see a heavy duty listed as well. I'll go with the bigger bearing and bore out the case at the same time. J.

Angelse68cal · 12-27-2006, 01:48 PM

Advance adapters in northern California Has everything you need to make the conversion. Also I dont have a bench seat so I Dont have to Bend the t case Shifter. Really I noticed it moved it back like 3 inches. So I am going to have to Weld up the old Hole on the trans cover and cut a new one.

www.advanceadapters.com

vtblazer · 12-28-2006, 07:49 AM

Quote:

Originally Posted by Angelse68cal

Has Anyone converted over from a th350 to a th400 in there K5 or Jimmy?

Why do you want/need a th-400 when a properly built th-350 could work just as well?

Shift points are different, first gear is higher and they rob more power from the drive train.

Flame suit on

12-20-2006, 07:18 PM	#1
Angelse68cal Cochino_Racing_909 Join Date: Oct 2006 Location: California Posts: 280	Has anyone....????? Has Anyone converted over from a th350 to a th400 in there K5 or Jimmy?

12-21-2006, 02:01 PM	#2
pharcyde05 Senior Member Join Date: Mar 2006 Location: modesto CA Posts: 239	Re: Has anyone....????? I changed mine out __________________ http://www.cardomain.com/ride/2461088

12-21-2006, 02:01 PM	#3
gmcman7202 Active Member Join Date: Oct 2006 Location: wi Posts: 190	Re: Has anyone....????? not that a big a deal to do.

12-21-2006, 02:02 PM	#4
hotrodhomi Registered User Join Date: Apr 2004 Location: Sacramento Posts: 3,737	Re: Has anyone....????? mine has a th400 __________________ '72 2wd blazer, bagged w/ watts link & EDC '72 C10 "Lowered Farm Truck" STOLEN 5-18-11 '66 impala ht

12-21-2006, 03:18 PM	#5
Angelse68cal Cochino_Racing_909 Join Date: Oct 2006 Location: California Posts: 280	Re: Has anyone....????? I am talking about changing it in a 4X4! Oh yea and wht is Axel Wrap?

12-21-2006, 05:08 PM	#6
gmcman7202 Active Member Join Date: Oct 2006 Location: wi Posts: 190	Re: Has anyone....????? still isnt a big deal, i am not sure what t case adapters you might need, or if the splines match, since i dont know the specs of the 2 off hand, as gm made the needed adapters, as the t case used is gona be diffrent for diffrent years, ect...

12-23-2006, 06:29 PM	#7
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Re: Has anyone....????? We don't have a TH 400 in a Blazer but we have one in a short box 4x4. Since the TH 400 is longer there are some mods to be made in addition to the transfer case adapter, (the NP 205 is the same for both tranny's). The longer TH 400 requires a longer front drive shaft, a shorter rear drive shaft and the crossmember needs to go rearward. The side mount for the transfer case has to be relocated. The transfer case shifter has to be bent in an "S" shape to move it forward. The shift linkage is different, also. Jim

12-24-2006, 09:12 AM	#8
jaros44sr Registered User Join Date: May 2006 Location: Philadelphia, Pa. 19454 Posts: 9,452	Re: Has anyone....????? Hey Jim, thanks for the heads up and info. Just picked up my TH400 and was not sure what was involved, sounds pretty strait forward, I have a floor shift so no problem there, but how do you bend the transfer case shifter. Just heat and bend around a suitable mandrel? Merry Christmas, J. __________________ Semper Fi...Uncle Sam, you da man All parts offered to help are free, unless otherwise noted Dont try this stuff in my build thread, unless you have 55 years of mechanical OTJ training SAFETY FIRST AS usual, off topic They say your mind goes second, can't remember the first Jim

12-24-2006, 10:46 AM	#9
MNorby Registered User Join Date: Aug 2006 Location: Powell, Wy Posts: 135	Re: Has anyone....????? another thing the th400 will have a 32 spline output whereas the th350 has a 27 spline output so you'll either have to change the input gear into the case or swap t-cases

12-24-2006, 10:51 AM	#10
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Re: Has anyone....????? We just heated and bent the shift lever. It was a lot of bending and the shift lever is pretty short by the time you get it into the right position. We use the truck for towing a car trailer and the TH 400 works great! Jim

12-24-2006, 10:07 PM	#13
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Re: Has anyone....????? You may want to check this place out. They have an input shaft for the TH 400 to the NP 205. I am not sure if their part has any complications so you would want to talk to someone. Here is the link: http://www.drivetrain.com/ Click on Transfer Case parts. The part number is ALT 13929 and lists for $104. Jim

12-27-2006, 01:48 PM	#15
Angelse68cal Cochino_Racing_909 Join Date: Oct 2006 Location: California Posts: 280	Re: Has anyone....????? Advance adapters in northern California Has everything you need to make the conversion. Also I dont have a bench seat so I Dont have to Bend the t case Shifter. Really I noticed it moved it back like 3 inches. So I am going to have to Weld up the old Hole on the trans cover and cut a new one. www.advanceadapters.com



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