Trans fitment questions... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

73CheyenneSuper20 · 01-15-2009, 12:50 AM

My th400 went out, it's behind a 454 big block... I've been looking around for a replacement, and I've been wondering...

Are all the bell housings the same? As in, a th400 bolted behind a 350 small block will also fit behind a big block? Will the 4 speed manual bolt up behind the big block with just a change in flywheel, and add the clutch? (And clutch pedal and linkage etc)

Thanks in advance....

b454rat · 01-15-2009, 03:04 AM

All Chevy V-8s have the same bell pattern. The clutch stuff too, but the 454 uses it's own flywheel....

Walts_restoration · 01-15-2009, 03:11 AM

nope, one piece rear mains are different bolt pattern iirc. Also, i believe the 400s were by themselves, being they were externally balanced. But yes, using your current flywheel and torque converter, getting the correct th400 trans it will bolt right in.

Prong · 01-15-2009, 07:27 AM

You got the 400 engine info backwards. It's the flywheel/balancer that's different, not the bell pattern.

James McClure · 01-15-2009, 02:32 PM

All chevy v8 engines have the same bell housing bolt paterns. Flywheel or flexplate bolt paterns change with one piece rear main seal. You could bolt a powerglide behind that 454 if you had one. Back in the 70's GM came out with what they called a "corporate case". It would fit any engine in any of the GM lines. It came in 350, 200r4, 700r4 and 400 flavors. If you have one of these hold on to it. Be aware, the clutch packs inside the tranny have fewer clutches from a 350 eng to a 454. jim

73CheyenneSuper20 · 01-15-2009, 08:55 PM

Is there a difference between long tail and short tail? I have a long tail, if I get a short tail, would I be able to just bolt my long tail on?

Thanks again for all the info and experience that's on this board...

sierra4x4 · 01-15-2009, 09:03 PM

In order to change the tailshaft you have to pull all the guts out of the trans to get the tailshaft out. But it can be done.

asphaltburner · 01-15-2009, 09:15 PM

Yo! I had to do this very thing,...change out the output shaft,...to accomodate the NP205 and required spacer/mount. The TH400 came with the short shaft to mount to the NP203 due to it's SHORT spacer/mount, and the NP205s LONG spacer/mount required a long output shaft.
Wish I could tell you more about the big block to TH400 but I'm unfamiliar with the "dark side"!
Todd.

01-15-2009, 12:50 AM	#1
73CheyenneSuper20 Registered User Join Date: Nov 2008 Location: San Bernardino, CA Posts: 92	Trans fitment questions... My th400 went out, it's behind a 454 big block... I've been looking around for a replacement, and I've been wondering... Are all the bell housings the same? As in, a th400 bolted behind a 350 small block will also fit behind a big block? Will the 4 speed manual bolt up behind the big block with just a change in flywheel, and add the clutch? (And clutch pedal and linkage etc) Thanks in advance.... __________________ '71 C25 Camper Special, 402, TH400, Longbed, Power Loc axle, Figuring out the rest of the details.... '10 Dodge Charger SXT - DD '91 Kasel M101A2 3/4 ton trailer (It has Chevy rims!)

01-15-2009, 03:04 AM	#2
b454rat Senior Member Join Date: May 2004 Location: Binghamton, NY Posts: 3,469	Re: Trans fitment questions... All Chevy V-8s have the same bell pattern. The clutch stuff too, but the 454 uses it's own flywheel.... __________________ 2000 GMC CCSB 454/4L80 6” lift SAS 1999 Chevy CCSB 454/NV4500 4” SAS 1999 GMC Yukon 350/4L60 6" SAS

01-15-2009, 03:11 AM	#3
Walts_restoration Real Projects never die Join Date: Jan 2007 Location: Lawrence, kansas Posts: 1,508	Re: Trans fitment questions... nope, one piece rear mains are different bolt pattern iirc. Also, i believe the 400s were by themselves, being they were externally balanced. But yes, using your current flywheel and torque converter, getting the correct th400 trans it will bolt right in. __________________ Ill put it this way, ive got a few lawn ornaments My name tag says Ryan KansasTwister On other forums Last edited by Walts_restoration; 01-15-2009 at 03:11 AM.

01-15-2009, 07:27 AM	#4
Prong Registered User Join Date: May 2007 Location: CO Posts: 475	Re: Trans fitment questions... You got the 400 engine info backwards. It's the flywheel/balancer that's different, not the bell pattern.

01-15-2009, 02:32 PM	#5
James McClure One shot, one kill. Join Date: Dec 2007 Location: Saratoga Springs NY Posts: 859	Re: Trans fitment questions... All chevy v8 engines have the same bell housing bolt paterns. Flywheel or flexplate bolt paterns change with one piece rear main seal. You could bolt a powerglide behind that 454 if you had one. Back in the 70's GM came out with what they called a "corporate case". It would fit any engine in any of the GM lines. It came in 350, 200r4, 700r4 and 400 flavors. If you have one of these hold on to it. Be aware, the clutch packs inside the tranny have fewer clutches from a 350 eng to a 454. jim __________________ 1984 K20 350M engine with 465,000 miles. Well, it's finally done!! Almost 2 years of work, but it was really worth the effort. Little stuff left to do is mount winch, wet sand & buff out and build belly pan\running boards. Body work takes lots and LOTS of beer!!!! God, Guts and Guns made America and God, Guts and Guns will preserve it! The worst thing you could do is get into my sights, but that don't matter, you'll never know it, cause you'll never hear the shotJim or Paladin whichever you choose.

01-15-2009, 08:55 PM	#6
73CheyenneSuper20 Registered User Join Date: Nov 2008 Location: San Bernardino, CA Posts: 92	Re: Trans fitment questions... Is there a difference between long tail and short tail? I have a long tail, if I get a short tail, would I be able to just bolt my long tail on? Thanks again for all the info and experience that's on this board... __________________ '71 C25 Camper Special, 402, TH400, Longbed, Power Loc axle, Figuring out the rest of the details.... '10 Dodge Charger SXT - DD '91 Kasel M101A2 3/4 ton trailer (It has Chevy rims!)

01-15-2009, 09:03 PM	#7
sierra4x4 Registered User Join Date: Jan 2009 Location: Canada Posts: 308	Re: Trans fitment questions... In order to change the tailshaft you have to pull all the guts out of the trans to get the tailshaft out. But it can be done.

01-15-2009, 09:15 PM	#8
asphaltburner Registered User Join Date: Jul 2008 Location: Ault, Colorado Posts: 862	Re: Trans fitment questions... Yo! I had to do this very thing,...change out the output shaft,...to accomodate the NP205 and required spacer/mount. The TH400 came with the short shaft to mount to the NP203 due to it's SHORT spacer/mount, and the NP205s LONG spacer/mount required a long output shaft. Wish I could tell you more about the big block to TH400 but I'm unfamiliar with the "dark side"! Todd. __________________ '78 3/4 ton 4x4 custom "Todd-built" FRANKENTRUCK!



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.