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Discussion Starter #1
Well, out of the blue, literally, the tranny took a large dump. 1 miles from home, no more forward movement. Prior to that, it shifted wierd, made lots of noise and generally caused the desire to pray. Anyhow, the suburban is now sitting in front of the general mechanic. At this point, I really am not sure what to do.

So, here are the options that I can think of:

1)Rebuild the 400 with a *****in' shift kit. This requires a competent tranny mechanic, one who wants to warranty their work, and one who is cost effective.

Upside: Truck is back on road fast with reliable tranny and low cost
Downside: stuck with 3 speed and bad mpg.

2)Replace with factory tranny
Upside: None
Downside: expensive-bending over

3)Replace with *****in 700r4

Upside: Tranny that she was meant to have. Good MPG. Long life. total happiness...

Downside: $2000. I don't know where to start. Who do I buy from? Where do I go? What about the drive shafts? What about......???????

Oh, I am trying to buy a house right now, so I have limited funds. That might help your decision....thanks. Chris
 

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you have either blown your stator or your planetaries. My vote is THM 400(they don't build them any stronger) and the cost should not be much. I usually charged $700 w/install and trans-n-go shift kit. My next suggestion is either a gearvendors or a USG/doug nash OD. Yes, the upfront is a little higher, but it is a bulletproof combo. I have GV's in my service trucks, would go USG the next time. THM 700 is a good trans, but not for heavy work like a THM 400 is for. Remember, you may save a few pennies today, but be spending more dollars tomorrow on a THM 700.
 

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First post here. I too have a TH400 that's on its way out. No real noticable shifting problems, but when I changed out the fluid, I found a bunch of needle bearings in the bottom of the pan:( . Figure it is only a matter of time now. This is where my dilema coincided with Chris's post - MPG vs. Cost. I thought about going to the 700R4 to get the overdrive, but after calling around to a tranny shops and getting the same advice Towcat gave, I've decided to stick with the 400. Calling around for quotes on a rebuild I'm getting around $1000+ average (Wish I'd called Towcat). I can get a rebuilt TH400 at the auto parts store for around $500 plus a core, so I'm thinking of going that route and changing it out myself. Beyond making sure I have a transmission jack so that I don't drop the thing on myself, does anyone have any advice that might not be included in my repair manual? Anything else that should be replaced while the tranny is off? Any questions that I should ask the parts shop about the rebuild?

Thanks, Robert
 

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There are guys that can rebuild 700R4's to be pretty strong. You can have a guy rebuild your 400 and still walk away with a piece of junk, it really depends on whos rebuilding with what parts.

if you go 700R4, you'll have to swap driveshafts..and since your 4x4 I think both.

I think each mod pushes things further and further to the rear of the truck.

since yours is a 1983 truck, consider yourself lucky you had a 400 to begin with. the first generation 700R4's were not nearly as good as the end years.

if you go 400 with a o/d unit, you'll still be swapping driveshafts I beleive.
 

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both of the OD's hang off the rear of the transmission or transfer case. So, yes...the rear driveshaft does need to be shortened. Yes, there is alot of gee-wiz stuff that you can put in to bulletproof a THM700, but that will drive the price up quickly. I've done them to the tune of 1800 when its all done. If you want a really strong torque convertor, that will add $$$$ too. I do have a THM700 behind a 6.5 in the "asshauler" but that combo is put together to do nothing else other than haul butt. No towing is going to be done whatsoever. I have other trucks for that job. But if there is a load involved, a THM400 that is built right will plenty of comfort cushion for reliability.
 

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Discussion Starter #6
Well, I just go off the phone with Columbia Transmission here in Portland Oregon. Here is what they are quoting me:

Basic Rebuild: $900
Upgrade Rebuild: Upgrades converter, transgo shift kit, road test etc. etc. $1200 or so.

good deal? Bad deal? Normal deal?
 

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Hard to say. Depends on the going rate up there. Down in the SFbay area its about average. As long as they are rebuilding YOUR trans, its OK. there are very desirable high-element clutch drums inside your trans. But even if your internals are not reusable, the standard THM400 stuff is pretty hard to break.
 

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Stay with the 400 for durability, to change to a 700 will require a different flex plate, different input gear for the transfercase, drivelines will work with either, very close in overall length. 700 will also require new transfercase to trans. adapter.
 

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when my 400 went out in my 89 I priced my local guys and for about the same money I got one from TCI With a new converter and a +2 pan.
 

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I hate the TH400 in my 6.2L Burb. It really kills the whole 'economical diesel' theme. Luckily its on its death-bed.

I agree on the TH700.... the trans it *should* have come with. It's too bad it its such a costly route.

I will be installing a 465 manual trans instead. Certainly more work, but accumulating the parts has, thus far, been cheap. I expect similar economy figures to the TH700.
 

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"I will be installing a 465 manual trans instead. Certainly more work, but accumulating the parts has, thus far, been cheap. I expect similar economy figures to the TH700"

I may be missing something here but, how would the economy figures be close to the 700 when it's an O.D. and the 465 is direct drive in top gear? The convertor slippage plays a slight role in overall fuel usage but would it be enough to offset the overdrive ratio at highway speeds?

I know, for a fact, the 700 increased the mileage from the 16mpg average I was getting with the 400 to over 20 on the highway in my Suburban.
 

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Portland Suburban, check with Transtar on 50th and Division, (800)345-7500 (don't know the local number). I buy lots of parts and have bought transmissions from them. They're dependable and prices are comparable. Ask for "Mike" in the shop.
 

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I may be missing something here but, how would the economy figures be close to the 700 when it's an O.D. and the 465 is direct drive in top gear? The convertor slippage plays a slight role in overall fuel usage but would it be enough to offset the overdrive ratio at highway speeds?
My apologies. The part missing is I re-geared to a 3.21 axle ratio.:eek::

Even with 33" tires and the 4.10 ratio, I'd only managed 11-15mpg (incl. tire size correction).

I'm not a fan of the TH400 for lower-powered engines. Some drag racers claim it's a 50hp penalty over a TH350. That tells me there's more to the loss equation than the just TC slippage.

In effect, my 1:1 top gear is now a .78 OD. :muahaha:
 

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I may be missing something here but, how would the economy figures be close to the 700 when it's an O.D. and the 465 is direct drive in top gear? The convertor slippage plays a slight role in overall fuel usage but would it be enough to offset the overdrive ratio at highway speeds?
I may be missing something here, but didn't the 700R4 generally come equipped with a lockout torque converter?
 

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Yes, the TH700 has a lockup TC.

Just for trivia's sake, so does a TH350C (started in the 80's)
 

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That would explain the power loss of the TH400 vs. the TH350. To sum it all up, the 700R4 is the best for fuel economy, the TH400 for towing.
 

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You should be able to get a th400 rebuilt for $500, i recently had one done and two different places quoted me the same amount. I did the instal myself, it was not hard at all.
-Paul
 

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I have use jake's trans. in hillsboro at 569 se baseline 503-648-9196 for trans jobs. for me it has been parts for 700r4's to rebuild it or other misc. stuff. I like the one horse shops because you can look them in the eye. Or better yet use Dave's trans action 3627 pacific av forest grove. I also used him over the last 15 years or so for parts and advice. email me and leave a number if you want to talk.
 

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That would explain the power loss of the TH400 vs. the TH350.
No... that's power loss with the non-lockup TH350... mind you lockup would only really be a factor on highway economy.

The TH400 is a fairly cheap rebuild. One consideration is it can be built with different 1st gear ratios. This can be useful if you are trying to improve the highway economy (i.e. bigger tires, or ratio change) and don't want to sell out on your low-end torque.
 

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U2, I get it now, the gear change. High Sierra, I meant the slippage would affect the overall mileage because you spend a lot of time without the convertor locked up.

Yes, the lockup is an "must" when towing with a 700. I've pulled convertors from 1/2 ton pickups with 6.2's that turned the convertor "Blue" because the lockup didn't work. The muddy fields knocked the wiring plug off the connector and the owner "just didn't have time to fix it, too busy moving irrigation pipe."

I do own a 350C. My '81 Jimmy came with it, it doesn't work at present. Somebody "rewired" it after an engine fire. I haven't sorted that out yet.
 
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