Max fuel economy for the 6.5TD

[Robyn]

Towing a big trailer is a scary thought with a 700 R handling the gears..
Yeah...I am very much down on the 700R
After breaking several in the 80's/90's it soured me.

Then being into them with bunches of hands on reinforced my dislike....

YES....RIGHT PARTS, TOP NOTCH SHIFT KIT (SET ON KILL)

A top notch converter with furnace brazed fins on the Turbine, pump and stator.
Better sprag in the stator....A much better converter clutch.

The converter is small in these and with the clutch in there it takes up space that needs to be used for pump and turbine.

An oil pump with more vanes in the rotor.......More oil volume available.

Big azz cooler out front

Transgo Dash2 shift kit installed on the stoutest settings.

The Input shaft reinforcing sleeve on the drum.....

5 planet carriers....The beast sun shell....Super duty 2-4 band.
Corvette servo......

A few other goodies.....The late units with the late style case (4L60E) with the tow haul option.....This will really help when working it hard.

One thing to remember....These boxes have a nasty little thing they do....

THE 2-3 and 3-2 SHIFT CLUNK (Light to mid throttle)

The 2-4 band has to be released....and the 3-4 clutch applied to make 3rd gear....


During the shift the output shaft goes into a reverse torque condition when the band is released and then the 3-4 clutch is applied.

The slack in the drive train (Especially the 4x4 rigs) is all taken up CLUNK....Very annoying and will scare the hell out of the unknowing owner....

Another thing

The T case in your Blazer/Tahoe has a 32 spline input shaft at the coupler with the tranny.

The 4l60 uses a 27 spline....Either swap the shaft or scare up a different T case...

The T case adapter is different too....Not sure about the frame cross member and rear mount.

Drive shafts will be different length due to the different tranny.

All doable.

The ECM PCM will likely need some massaging.
Not sure about the wiring harness that connects to the tranny.....I think these are different too.

Scaring up a similar year rig with a 5.7 gasser for a parts goat....might be a good ideal...
Somebody offers a kit to do this swap....

A bunch tougher than in the old days.....Build the gear box, bolt it in and swap drive shafts...Good to go

Probably have to massage the T CASE shifter too.....

The 700R converter has a smaller bolt pattern...The 4l80 has the large pattern.

Most 6.5 flex plates have 6 bolts.

Since the 6.5 never had a 700R the holes may need to be added to allow the small converter to bolt up.

Fun stuff.....

[More Power]

... clip...

Probably have to massage the T CASE shifter too.....

The 700R converter has a smaller bolt pattern...The 4l80 has the large pattern.

Most 6.5 flex plates have 6 bolts.

Since the 6.5 never had a 700R the holes may need to be added to allow the small converter to bolt up.

Fun stuff.....

The swap from a 700 to a 350 was so popular back in the 1980's that the aftermarket made a trans/txcase adapter just for that swap, that made it really easy. The adapter allowed joining the TH350 to the original transfer case used behind the 6.2. Didn't have to change the position of the transfer case or cross-member.

Swapping to a 350 during the 1980's didn't have a lot of downsides - mostly upsides... The national speed limit, even on Interstates at that time was a snail's pace 55-mph. I swapped back to a 700 when the national 55-mph speed limit was lifted. The TH350 made the 6.2 unusable for anything other than back roads... because 70-mph meant 3000-rpm in a 4.10 geared truck. Our speed limits were even higher - they are 80-mph now. The TH700R4 had a 0.71 OD. In my 3.42 geared truck, that TH700R4 OD produced about 1800-rpm at 65-mph, which was heavenly after 200,000 miles of having no overdrive.

Another big advantage of the OD was that the diesel rattle practically disappeared at 65-mph and over. Then, there was the fuel economy advantage... I saw a change from 17 to 24-mpg during my 50-mile commute. All combined, I was very happy with the TH700R4.

Going to a 4L80-E in a non-computerized truck means buying a computer and wiring harness (about $1200) in addition to the cost of the transmission. It also means engine sensors (TPS - ESS). I installed a 4L80-E and computer and wiring harness and engine sensors in a non-computerized truck. I did it for the power handling capability.

Someday, if the DS4 or existing 4L80-E in Sarah's Blazer ever give up, I'll be highly temped to swap in a TH700R4 and mechanical DB2. There's no reason this engine can't deliver low to mid 20's in fuel economy instead of the 15-17 it does now.

There are two flexplate options for the 6.2/6.5 - "light duty" and "heavy duty". The only difference is TC bolt circle - both use 6 bolt TCs. The TH350 and TH700R4 share the same smaller bolt circle, and the TH400 and 4L80-E share the same tiny bit larger bolt circle. The difference isn't very much. From a short distance away, I doubt many could tell the difference in size between a pair of TCs or flexplates made for each transmission.

Here's a pic of Howard's 1987 1500 Suburban and his 36' Airstream... There's a TH700R4 in that Banks 6.2 powered Suburban. He was from New Jersey. That pic was taken here in western Montana.