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700R4 into my M1009

four_by_ken

four_by_ken

1/2 ton status
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Allenton, MI
I am thinking about swapping the TH400 out of the M1009 for a 700R4.

The OD should be real nice for fuel mileage as this is my daily driver.

What torque converter should be used?

I want to just find a 700R4 and 208 set up. Hmmm... wonder what the length difference is?
 
You'll need the diesel convertor, it has a lower stall speed and has 6 mounting lugs instead of three. You'll also need the TV cable, TV cable bracket at the IP, and I believe there is also a TPS at the IP involved (for TC lock/unlock)

I think there is also a diesel specific governor or something in the trans...which get's it to shift before the 6.2 hits max rpm at WOT.

Rene
 
tRustyK5 said:
You'll need the diesel convertor, it has a lower stall speed and has 6 mounting lugs instead of three. You'll also need the TV cable, TV cable bracket at the IP, and I believe there is also a TPS at the IP involved (for TC lock/unlock)

I think there is also a diesel specific governor or something in the trans...which get's it to shift before the 6.2 hits max rpm at WOT.

Rene
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Rene is right on all points. The TPS mounts in place of the TH400 vacuum switch on the IP. If you can find a 700R4 from an '87 or later model diesel you will be ahead of the game.
 
Have you upgraded the gear ratio from 3.08's yet? The 700R4's overdrive gear will be useless if you run 3.08's and 31's... even worse with 33's.
 
I just finished collecting all the parts for this swap. Had originally gotten a hydro 465 and was going to swap that in, then afghanistan decided to destroy my left knee.... Here is what you need. Low stall torque convert, call any transmission shop and they should be able to get you the right one. I went with Oregon Performance Transmission, cost $120. You will need a flywheel for the 700, that cost me $45. You will need the TV cable bracket and cable, i got that for $35 from some guys on www.thedieselplace.com, go to the 6.2 section and ask for one, a couple guys have them over there. I had to get a diesel governor for the 700r4, that was $45. Also you need to get something to lock up the torque converter. BowtieOverdrives can hook you up with one, less than a hundred bucks. The length of the 700r4/208 is within a 1/4 inch of the 400/208 combo. Stock driveshafts will work. Also, the trans lines off the TH400 fit right into the 700, so you wont have to change those out.
 
Haha, find me a NV4500 or NV3550 and I'll give you mine.
 
kennyw said:
Have you upgraded the gear ratio from 3.08's yet? The 700R4's overdrive gear will be useless if you run 3.08's and 31's... even worse with 33's.
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Ditto. With 3.08's in the axles the OD of the 700r4 would be pretty worthless unless you were going 80+ mph on the highway
 
Good thing to know,that the TH400/NP208 setup is within a 1/4" overall length of the 700R4/NP208 setup..I was thinking of getting a TH400/NP208 setup for my '85 Suburban K10 rather than fix its ailing 700R4..losing overdrive wouldn't bother me any,I rarely go far,and even if I did,we managed just fine years ago when the TH400's and TH350's were all we had,right??..I'd rather have a beefy tranny ,seeing I will be using it to plow some ,and I could put bigger tires on it if it seems to low geared..I can buy a TH400 & NP208 for far less than fixing the 700T4,I just dont know what other issues I'll encounter doing so--at least now I know the shafts and cooler lines can be re-used..

In fact,I have a TH400 from a '74 Monte Carlo that had a BBC,the short tailed version..(no bolt on yoke)--and a spare NP208 transfer case with a TH400 32 spline input & adapter ,like my '82 K2500 has in it..it would be cool if the two of them would bolt together and I could use what I have,without buying any more parts--but I'm thinking the output shaft on the short tail TH400 might be a tad too long to let that happen..
 
I disagree here. The 700R4 has a steeper first gear, which would make the off the line acceleration better. Which is where the truck is at its worst.

I have plenty of power at highway RPMS. I cruise at 65 and its about perfect. A 700R4 would bring me to 70mph and be right at home.

Its been done before with the M1009s and it worked out real nice.

I just have other projects that I think I will do first.... like my bogger.

Pretty sure I will go to 33s when I need to get new tires though. That will help on the mileage some too.
 
four_by_ken said:
I disagree here. The 700R4 has a steeper first gear, which would make the off the line acceleration better. Which is where the truck is at its worst.

I have plenty of power at highway RPMS. I cruise at 65 and its about perfect. A 700R4 would bring me to 70mph and be right at home.

Its been done before with the M1009s and it worked out real nice.
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Going from the 1:1 TH400 to the 0.70:1 700r4 makes a lot bigger difference than that for highway cruising. If you take the rpm you are spinning with the TH400/31" tires at 65 mph and then calculate the speed at the same rpm but with the 700r4 you would going 90+ mph.

I do agree with the comment about better low end acceleration with the lower 1st gear in the 700r4. Sure, people got by with the TH350 and 400 for years but it was always a compromise between low-end power and highway cruising. Gear the axles down for low end power and towing and you sacrifice highway cruisng and fuel mileage. Gear it for highway cruising and mileage and you give away low end and towing power.
 
Keep in mind the 6.2's seem to operate most efficiently at around 1800 rpm. lugging the motor lower than that can actually hurt fuel economy. A quick search online for "rpm calculator" will allow you to check gearing, tire size, and transmission ratio's to hit the sweet spot.

http://www.csgnetwork.com/multirpmcalc.html

example: with a TH400, 31 in tires, and 3.08 gears, going 65mph, should be turning the motor at 2170 rpm. swapping to the .70 overdrive in the 700R4 would put that rpm down to 1519.

for the record, the other danger of turning the engine that slow with the 700R4 is that IIRC you loose line pressure at lower rpms, causing slippage, increased operating temp, and premature wear of the clutch packs.

upping the speed to 80mph would put you in the sweet spot at 1869 rpm. putting 33in tires on there would drop that rpm to 1756. But with both, the 80mph headwind would most likely offset your increased operating efficiency.

with 31 in tires, 3.73 gears and the 700R4, youd cruse at 65mph at 1839rpm. this is the route i would go for a daily driver, and fuel economy. (although id do an NV3500 over the 700R4 personally). the smaller the tires, the less mass to spin, the less work the engine does, the less fuel it needs to burn. the deeper axle gears and deeper first gear of the 700R4 would make off the line acceleration dramatically better (more than double the gear ratio you currently have). and the combination would net easy high mileage highway crusing.
 
oh, and just to cover this point. larger diameter tires do not always net higher mpg. in theory, their circumference effectively lowers gearing, and rpms at any given speed, but they also have more frontal suraface area, more mass to rotate, and often the larger diameter nets a wider tire for more contact area with the ground and thus more friction.

We run into this allllll the time on the TDI forum I frequent. and these guys are mileage fanatics. present company included. (personal best 931 miles on a single tank before the fuel light came on. about 62mpg) so many of us would like to ditch the 15in steelies and go to a pretty alloy rim of 17in or 18in diameter. but its become accepted that when you do this you can expect a drop of a few miles per gallon. all the top mileage guys are running the factory steelies and small tires.

Again, for daily driving duty, and best fuel economy. My suggestion would be keep the 31in tires, and swap out the gears and trans.
 
Its been proven on Steel Soldiers that with the M1009s... going to a 33 inch tire will either give you equal or a tad better mileage. Anything larger and you drop off quickly.

I am NOT changing axle gears, period. This is my commuter and I am really happy with the 18mpg I have been getting. Going with a numerically higher ratio will kill the mileage. Lower and I dont think it could get out of its way.

The truck will handle an OD trans... this has also been proven on SS. Guys get consistent low 20s with a 700R4 and 33s.



But, for keeping it simple... I am thinking more and more to just go with 33s and be done with it.
 
interesting point on the tires. im personally running 33's, never thought they were helping my economy. good to know.

I would still check regarding rpms for those 700R4's. like i said, i think turning em too slow hurts em.

I agree, for the cheap and easy, upgrading to 33's is the best bet.
 
K5dreamer said:
interesting point on the tires. im personally running 33's, never thought they were helping my economy. good to know.

I would still check regarding rpms for those 700R4's. like i said, i think turning em too slow hurts em.

I agree, for the cheap and easy, upgrading to 33's is the best bet.
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And to test... I will just get some used 33s and make sure it works for my truck.
They are strange that way.. .one truck something is a great fit and works... the next its the opposite.
 
Regarding changing to larger tires vs. MPG the above post hits it on the head. It all depends on whether the change in RPM and thus the fuel economy improvement can overcome the added rolling resitance and other factors that can decrease fuel economy.

Guess I will have to start only relying on Steel Soldiers to answer all of my 6.2 questions;). Honestly I chuckled a little bit when it says "proven on SS....".

All I can see if that I daily drove a K5 with the 6.2/700r4 combo for years with both 32 and 33" radial tires with 3.73 gears and know how it acted. OD was only used when running 65+ mph on the freeway and it would need to downshift to maintain speed on anything more than a mild grade. 35" radials with 4.10's and the OD was pretty useless. This was with a well running and low mileage (under 70k) engine, and I will say that the power rating of a later model C-code like my '90 was likely very comparable to the earlier J-codes (the power rating slightly and steadily increased over the years).
 
6.2Blazer said:
Regarding changing to larger tires vs. MPG the above post hits it on the head. It all depends on whether the change in RPM and thus the fuel economy improvement can overcome the added rolling resitance and other factors that can decrease fuel economy.
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I had a '96 Ford Ranger 4x4 with the 4.0L and the 5 speed stick. 3.27 gears! Came with 29" tires but had 31's on it when I got it. Drove okay but was clearly geared too high and got 11-12mpg all day long.

I had it regeared with 4.56's and put narrow 33's on it (255/85R16's to be precise) and I immediately started seeing 14.5-15mpg around town.

Regearing can work...but only in a certain "window" for each vehicle/powertrain combo.
 
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