Urgent help! Th350 to th400 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

INSIDIOUS '86 · 09-05-2012, 02:25 AM

So we are swapping a th350 and 305 combo out for a 454 an th400. PROBLEM! Th400 had a bolt on yoke. It's from a suburban and the truck is a 81 shorty. What can we do about the driveshaft? It has to be cheap and quick though if possible
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KQQL IT · 09-05-2012, 02:33 AM

Slip on goes on a bolt on style.
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INSIDIOUS '86 · 09-05-2012, 02:57 AM

So what do we need? I know it needs slip in the driveshaft. The th350 is a long shaft trans and the th400 Is shorter.
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xrcr · 09-05-2012, 07:29 AM

Look at this and see if it helps http://www.maliburacing.com/auto_tranny_id.htm
You need to get a slip in yoke and have at least 1" in the tailshaft maybe 3/4 but I don't know. I put a 350 in a 4 speed truck using a driveshaft that was behind a 700r. had to change to a 9" tail on the 350

**old Rusty C10** · 09-05-2012, 08:41 AM

I have always had long bed pickups . The driveshaft with a th400 was always a slip in like on the th350, however the shaft on a 400 was always a two piece. UNfortunately when you are customizing things, its never cheap or easy. IIRC the tailshaft on the th400 is either long or short tail much like the th 350. the short tail is the one with the bolt on driveshaft. the vast majority of the short tail ones were in vans and those van cab truck body trucks they make. Im thinking your only way out is to have a driveshaft custom made.. Also every th400 ive seen in the pickup has a carrier bearing that needs to be installed on the frame..

KQQL IT · 09-05-2012, 09:23 AM

You will need a th400 slip yoke and a drive shaft shop to shorten the drive shaft and attach the new yoke.
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KQQL IT · 09-05-2012, 09:28 AM

http://www.drivelinesnw.com/
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INSIDIOUS '86 · 09-05-2012, 01:20 PM

Alright so I can either convert the trans to slip yoke or have a new driveshaft made basicly.

Can't gO two piece cause that will be too weak for a truck like this that will see track time
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INSIDIOUS '86 · 09-05-2012, 01:22 PM

Quote:

Originally Posted by KQQL IT

You will need a th400 slip yoke and a drive shaft shop to shorten the drive shaft and attach the new yoke.
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Also are you saying that a bolt yoke trans will take a slip yoke if we got a longer slip yoke to go in?
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KQQL IT · 09-05-2012, 01:55 PM

Track time? Well the U joints will need to be 1330s if not 1350s. Which means a brand new shaft...
id guess a 305 t350 would be 1310 ujoints.
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Desert1957 · 09-06-2012, 01:52 AM

http://ls1tech.com/forums/automatic-...questions.html

http://www.chevelles.com/forums/show...put+shaft+yoke

This is the best web site I can give you, It list ALL the available yokes for 400 Turbos.

http://www.dennysdriveshaft.com/c8_t...lip_yokes.html

Desert

Desert1957 · 09-06-2012, 02:19 AM

I think this is the one you need to replace a bolt on yoke, with the short output shaft splines on the tailshaft.
http://www.dennysdriveshaft.com/p108...ine_th400.html

Desert

INSIDIOUS '86 · 09-06-2012, 02:24 AM

Going to have my buddies at Drivelines nw build a driveshaft that will adapt to the trans. Eventually this th400 will be built for a 600hp bbc and have a gear vendor on it or he may go the 700r4 route. Either way we just need to get it moving though.
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09-05-2012, 02:25 AM	#1
INSIDIOUS '86 Registered User Join Date: Jul 2009 Location: washington Posts: 4,178	Urgent help! Th350 to th400 So we are swapping a th350 and 305 combo out for a 454 an th400. PROBLEM! Th400 had a bolt on yoke. It's from a suburban and the truck is a 81 shorty. What can we do about the driveshaft? It has to be cheap and quick though if possible Posted via Mobile Device __________________ 377 sbc thumpr cam autogear m23 muncie 3:73 Detroit trutrac 3''spintech prostreet mufflers xpipe 1 3/4 headers build thread !http://67-72chevytrucks.com/vboard/s...d.php?t=577217 Iroc gauge threadhttp://67-72chevytrucks.com/vboard/s...d.php?t=554511

09-05-2012, 02:33 AM	#2
KQQL IT At the body shop. Join Date: Aug 2009 Location: Land of fruits and nuts. Posts: 5,260	Re: Urgent help! Th350 to th400 Slip on goes on a bolt on style. Posted via Mobile Device __________________ " That didnt make it any newer " " Dont antique the equipment "

09-05-2012, 02:57 AM	#3
INSIDIOUS '86 Registered User Join Date: Jul 2009 Location: washington Posts: 4,178	Re: Urgent help! Th350 to th400 So what do we need? I know it needs slip in the driveshaft. The th350 is a long shaft trans and the th400 Is shorter. Posted via Mobile Device __________________ 377 sbc thumpr cam autogear m23 muncie 3:73 Detroit trutrac 3''spintech prostreet mufflers xpipe 1 3/4 headers build thread !http://67-72chevytrucks.com/vboard/s...d.php?t=577217 Iroc gauge threadhttp://67-72chevytrucks.com/vboard/s...d.php?t=554511

09-05-2012, 07:29 AM	#4
xrcr Registered User Join Date: Dec 2008 Location: Foristell, MO Posts: 418	Re: Urgent help! Th350 to th400 Look at this and see if it helps http://www.maliburacing.com/auto_tranny_id.htm You need to get a slip in yoke and have at least 1" in the tailshaft maybe 3/4 but I don't know. I put a 350 in a 4 speed truck using a driveshaft that was behind a 700r. had to change to a 9" tail on the 350

09-05-2012, 08:41 AM	#5
old Rusty C10 Robert Olson Transport Join Date: Oct 2002 Location: recent transplant to NC USA Posts: 20,313	Re: Urgent help! Th350 to th400 I have always had long bed pickups . The driveshaft with a th400 was always a slip in like on the th350, however the shaft on a 400 was always a two piece. UNfortunately when you are customizing things, its never cheap or easy. IIRC the tailshaft on the th400 is either long or short tail much like the th 350. the short tail is the one with the bolt on driveshaft. the vast majority of the short tail ones were in vans and those van cab truck body trucks they make. Im thinking your only way out is to have a driveshaft custom made.. Also every th400 ive seen in the pickup has a carrier bearing that needs to be installed on the frame.. __________________ Bob 1951 International running on a squarebody chassis "If a man's worth is judged by the people he associates himself with, then i am the richest man in the world knowing some of the fine people of this board" http://67-72chevytrucks.com/vboard/a...t.php?f=25&a=9 (you can review the site rules here!) PM Me for your vehicle/parts hauling needs in the North East US or see my Facebook page Robert Olson Transport Live each day to the fullest.. you never know when fate is going to pull the rug out from under you... I hate cancer!!

09-05-2012, 09:23 AM	#6
KQQL IT At the body shop. Join Date: Aug 2009 Location: Land of fruits and nuts. Posts: 5,260	Re: Urgent help! Th350 to th400 You will need a th400 slip yoke and a drive shaft shop to shorten the drive shaft and attach the new yoke. Posted via Mobile Device __________________ " That didnt make it any newer " " Dont antique the equipment " Last edited by KQQL IT; 09-05-2012 at 09:46 AM.

09-05-2012, 09:28 AM	#7
KQQL IT At the body shop. Join Date: Aug 2009 Location: Land of fruits and nuts. Posts: 5,260	Re: Urgent help! Th350 to th400 http://www.drivelinesnw.com/ Posted via Mobile Device __________________ " That didnt make it any newer " " Dont antique the equipment "

09-05-2012, 01:20 PM	#8
INSIDIOUS '86 Registered User Join Date: Jul 2009 Location: washington Posts: 4,178	Re: Urgent help! Th350 to th400 Alright so I can either convert the trans to slip yoke or have a new driveshaft made basicly. Can't gO two piece cause that will be too weak for a truck like this that will see track time Posted via Mobile Device __________________ 377 sbc thumpr cam autogear m23 muncie 3:73 Detroit trutrac 3''spintech prostreet mufflers xpipe 1 3/4 headers build thread !http://67-72chevytrucks.com/vboard/s...d.php?t=577217 Iroc gauge threadhttp://67-72chevytrucks.com/vboard/s...d.php?t=554511

09-05-2012, 01:55 PM	#10
KQQL IT At the body shop. Join Date: Aug 2009 Location: Land of fruits and nuts. Posts: 5,260	Re: Urgent help! Th350 to th400 Track time? Well the U joints will need to be 1330s if not 1350s. Which means a brand new shaft... id guess a 305 t350 would be 1310 ujoints. Posted via Mobile Device __________________ " That didnt make it any newer " " Dont antique the equipment "

09-06-2012, 01:52 AM	#11
Desert1957 Registered User Join Date: Apr 2009 Location: New Freedom Pa. Posts: 1,335	Re: Urgent help! Th350 to th400 http://ls1tech.com/forums/automatic-...questions.html http://www.chevelles.com/forums/show...put+shaft+yoke This is the best web site I can give you, It list ALL the available yokes for 400 Turbos. http://www.dennysdriveshaft.com/c8_t...lip_yokes.html Desert Last edited by Desert1957; 09-06-2012 at 02:15 AM.

09-06-2012, 02:19 AM	#12
Desert1957 Registered User Join Date: Apr 2009 Location: New Freedom Pa. Posts: 1,335	Re: Urgent help! Th350 to th400 I think this is the one you need to replace a bolt on yoke, with the short output shaft splines on the tailshaft. http://www.dennysdriveshaft.com/p108...ine_th400.html Desert

09-06-2012, 02:24 AM	#13
INSIDIOUS '86 Registered User Join Date: Jul 2009 Location: washington Posts: 4,178	Re: Urgent help! Th350 to th400 Going to have my buddies at Drivelines nw build a driveshaft that will adapt to the trans. Eventually this th400 will be built for a 600hp bbc and have a gear vendor on it or he may go the 700r4 route. Either way we just need to get it moving though. Posted via Mobile Device __________________ 377 sbc thumpr cam autogear m23 muncie 3:73 Detroit trutrac 3''spintech prostreet mufflers xpipe 1 3/4 headers build thread !http://67-72chevytrucks.com/vboard/s...d.php?t=577217 Iroc gauge threadhttp://67-72chevytrucks.com/vboard/s...d.php?t=554511



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