Transmission Recommendation - The 1947 - Present Chevrolet & GMC Truck Message Board Network

86-C10-V6 · 10-14-2003, 10:38 AM

My truck currently has a rebuilt 700R4 transmission. It was rebuilt in 1992 with 108K miles and I have used the truck mainly for hunting(pretty rough on the tranny) and hauling trash to the dump, it has 160K on it now and the transmission is whining and recently it refused to shift to high gear. The transmission mechanic that rebuilt the tranny said it probably had metal shavings in the pan and would cost about $1200 to rebuild including remove and install.
I am thinking of changing to a 350 or 400 transmission that does not require a TCC lock up.
The V6 seems have difficulty keeping the TCC locked in high gear and the added RPMs without the overdrive I think would help the response.
1)Which transmission would handle more abuse the 350 or the 400?
2)Which would be easier to install in the place of the 700R4?
3) What would be required for each of these swaps?
4) Should I just go buy a cheap rebuilt 700R4($550) and install myself and run it in 3rd gear.

**N2TRUX** · 10-14-2003, 11:10 AM

4) Should I just go buy a cheap rebuilt 700R4($550) and install myself and run it in 3rd gear. The going price for a rebuilt 700R4 is around $1200, so your mechanic is not off base with his price.
I'm not sure what you are getting for $550, but I would at least consider it, since you have the mechanical ability to do the swap. Just make sure it's a quality rebuild, and you aren't buying any headaches.

The TH400 is the stronger of the two TH transmissions, but the TH350 can handle any abuse than the 4.3 can dish out.

OK, with all that said, here's what I would do. "IF" the $550. tranny is a good rebuild, then go with it. Then I would spend the money saved and get rid of your 3.08 gears, for a set of 3.73's. That should help the 4.3 pull enough to handle the TCC lock up...

79BIG10 · 10-14-2003, 01:09 PM

One thing to consider is that the Th400 has a different spline that hooks up to the drive shaft. You would need to change this out. Also the TH400 is a different length. If you go with a TH350 then you would not have this trouble if the TH350 has a 9" tail shaft. the splines are the same count on the TH350 but the 9" is close enough to the 700r4 length you don't need a new D/S.

Cole's 87 · 10-14-2003, 01:47 PM

Brandons right the 350turbo would be an easier install.
Here are some numbers to play with.

350= 1st..2.52, 2nd..1.52, 3rd..1.00
400= 1st..2.48, 2nd..1.48, 3rd..1.00
700r4=1st..3.06, 2nd..1.63, 3rd..1.00, od..0.70

the 350 will make a little better use of your V-6 power
the 400 is geared higher and take more HP to run
the 700r4 has such a big spread between 1st & 2nd its like falling on your face. but is real nice for getting going in town.

1985K10 · 10-14-2003, 05:27 PM

I was told I could get my 700R4 built without the OD components. That would make it last longer, and it will fit no prob like you may have with a TH400 or TH350. My next tranny is gonna be a Level 2 or 3 from bowtie overdrives, www.700r4.com

MylilBowTie · 10-15-2003, 12:00 AM

I vote th350 for the 4.3. th400 will hold a lot of power. But its senseless to put a th400 behind a 4.3. The th350 will work fine.

crackajacka · 10-15-2003, 10:25 AM

yea i vote th350 ive had my truck for 3 years so far and it was a junk yeard throw together when i bought it. the only problem i have with my trans is the tcc lockup since i have the th350c its the biggest headache in the world but its a damn tuff trans. got the truck when i was 16(u know how 16yr olds drive) and ive drove it up n down the interstate at about 70-95+ and its always worked just fine.(that is when the vaccum's right)

soleeagle · 10-16-2003, 12:19 AM

I would replace it with a TH350 myself, screw the overdrive.

**old Rusty C10** · 10-16-2003, 08:49 AM

I cant ell you torque specs or gear ratios or things like that but i can tell ya i have a 1986 C10 with a 4.3 v6 and a th350 tranny. I drag around a boat sometimes with the truck and regularly pull dead cars with it and i love it. Ive had vehicles with a 700R4 trans and i kill them waay too easy the th350 seems to take more of a beating and is alot easier on the wallet to have rebuilt . My vote is to berid yourself of the 700R4 and go th350 it shouldnt be a hard conversion

10-14-2003, 10:38 AM	#1
86-C10-V6 Shadetree Mechanic Join Date: Oct 2002 Location: Youngsville, NC Posts: 100	Transmission Recommendation My truck currently has a rebuilt 700R4 transmission. It was rebuilt in 1992 with 108K miles and I have used the truck mainly for hunting(pretty rough on the tranny) and hauling trash to the dump, it has 160K on it now and the transmission is whining and recently it refused to shift to high gear. The transmission mechanic that rebuilt the tranny said it probably had metal shavings in the pan and would cost about $1200 to rebuild including remove and install. I am thinking of changing to a 350 or 400 transmission that does not require a TCC lock up. The V6 seems have difficulty keeping the TCC locked in high gear and the added RPMs without the overdrive I think would help the response. 1)Which transmission would handle more abuse the 350 or the 400? 2)Which would be easier to install in the place of the 700R4? 3) What would be required for each of these swaps? 4) Should I just go buy a cheap rebuilt 700R4($550) and install myself and run it in 3rd gear. __________________ Dave M. (Hacksaw) 86 C10 Scottsdale LWB, 4.3L, Edelbrock 1904, K&N, 700R4, 3.08 Auburn Performance 89 GMC S-15 Extended Cab 4x4, 4.3L, FI 98 K1500 Xcab, 5.7L, 3.43 Gov-Lok

10-14-2003, 11:10 AM	#2
N2TRUX Happy to be here Join Date: Mar 2000 Location: Cypress, TX Posts: 39,023	4) Should I just go buy a cheap rebuilt 700R4($550) and install myself and run it in 3rd gear. The going price for a rebuilt 700R4 is around $1200, so your mechanic is not off base with his price. I'm not sure what you are getting for $550, but I would at least consider it, since you have the mechanical ability to do the swap. Just make sure it's a quality rebuild, and you aren't buying any headaches. The TH400 is the stronger of the two TH transmissions, but the TH350 can handle any abuse than the 4.3 can dish out. OK, with all that said, here's what I would do. "IF" the $550. tranny is a good rebuild, then go with it. Then I would spend the money saved and get rid of your 3.08 gears, for a set of 3.73's. That should help the 4.3 pull enough to handle the TCC lock up... Last edited by N2TRUX; 10-14-2003 at 11:12 AM.

10-14-2003, 01:09 PM	#3
79BIG10 I'm back with 2nd truck! Join Date: Feb 2002 Location: Texas Posts: 3,775	One thing to consider is that the Th400 has a different spline that hooks up to the drive shaft. You would need to change this out. Also the TH400 is a different length. If you go with a TH350 then you would not have this trouble if the TH350 has a 9" tail shaft. the splines are the same count on the TH350 but the 9" is close enough to the 700r4 length you don't need a new D/S. __________________ 1979 Chevrolet Bonanza Big10 "Tootsie Roll" 1985 Chevrolet Silverado (wife's) Member of the Southern Bowties Club "Don't underestimate how sexy a fat man who drinks to excess can be." Homer Simpson

10-14-2003, 05:27 PM	#5
1985K10 Registered User Join Date: Oct 2003 Location: CT Posts: 315	I was told I could get my 700R4 built without the OD components. That would make it last longer, and it will fit no prob like you may have with a TH400 or TH350. My next tranny is gonna be a Level 2 or 3 from bowtie overdrives, www.700r4.com __________________ Anthony 07 Tahoe LT 70 Chevelle 450HP 383-TH400 77 GMC Royal Sierra~Resto in progress~

10-15-2003, 10:25 AM	#7
crackajacka Stylin Join Date: Sep 2001 Location: Tuttle, OK Posts: 620	yea i vote th350 ive had my truck for 3 years so far and it was a junk yeard throw together when i bought it. the only problem i have with my trans is the tcc lockup since i have the th350c its the biggest headache in the world but its a damn tuff trans. got the truck when i was 16(u know how 16yr olds drive) and ive drove it up n down the interstate at about 70-95+ and its always worked just fine.(that is when the vaccum's right) __________________ Ive been traveling for some time, with my fishin pole and my bottle of shyne. Most Girls like finished products and just dont understand what a good addiction does for you http://www.paulwall.us/

10-14-2003, 01:47 PM	#4
Cole's 87 Registered User Join Date: Nov 2002 Posts: 272	Brandons right the 350turbo would be an easier install. Here are some numbers to play with. 350= 1st..2.52, 2nd..1.52, 3rd..1.00 400= 1st..2.48, 2nd..1.48, 3rd..1.00 700r4=1st..3.06, 2nd..1.63, 3rd..1.00, od..0.70 the 350 will make a little better use of your V-6 power the 400 is geared higher and take more HP to run the 700r4 has such a big spread between 1st & 2nd its like falling on your face. but is real nice for getting going in town.

10-15-2003, 12:00 AM	#6
MylilBowTie Right turn Clyde Join Date: Nov 2002 Location: Cincinnati, Ohio Posts: 2,911	I vote th350 for the 4.3. th400 will hold a lot of power. But its senseless to put a th400 behind a 4.3. The th350 will work fine.

10-16-2003, 12:19 AM	#8
soleeagle Registered User Join Date: Sep 2003 Location: Shelbyville, Indiana Posts: 614	I would replace it with a TH350 myself, screw the overdrive. __________________ Chuck '85 Chevy Silverado 4X4 '91 Chevy 4X4 Suburban http://www.cardomain.com/memberpage/545941

10-16-2003, 08:49 AM	#9
old Rusty C10 Robert Olson Transport Join Date: Oct 2002 Location: recent transplant to NC USA Posts: 20,302	I cant ell you torque specs or gear ratios or things like that but i can tell ya i have a 1986 C10 with a 4.3 v6 and a th350 tranny. I drag around a boat sometimes with the truck and regularly pull dead cars with it and i love it. Ive had vehicles with a 700R4 trans and i kill them waay too easy the th350 seems to take more of a beating and is alot easier on the wallet to have rebuilt . My vote is to berid yourself of the 700R4 and go th350 it shouldnt be a hard conversion __________________ 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!!



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