Tranny swap in progress

[britannic]

Started on the TH400->TH700R4 conversion today. Sure is hard work without a helper, but invested in a transmission mount for my floor jack which really helped.

I was able to undo the bell housing top bolts by lying on top of the intake and reaching around the vacuum pump. Although it was more painful physically, it was a lot easier than going in with a universal joint and extensions - they were real tight in any case.

I installed a new GR starter and ring gear, almost finished but it got too dark to check the clearance between pinion and ring, so I'll finish that tomorrow.

I have a new NP208 with the correct input shaft and the transfer case mounting housing ready to go in behind the 700R4 - I can't wait to get this dialed in and finally get the revs down on the freeway, maybe even better MPG too.

I'm still trying to figure out what's best for the vacuum pipe (I don't have a blanking piece for the pump yet) - maybe cap it up by the IP so it won't suck any debris in and sieze the vac. pump - any ideas on that would be appreciated.

[ 08-13-2003, 10:00 PM: Message edited by: britannic ]

[Dieselboy]

If it's only temporary, then it sounds like plugging up the hole near the IP would be okay. I don't think it would be too different from plugging up an EGR line.

[ 08-14-2003, 10:07 AM: Message edited by: Dieselboy ]

[grape]

Can i purchase your old 32 spline input gear for the 208, i'm doing something similar 700 to a 4l80e.

[EWC]

Grape , have you figured out any details for the 4L80E swap ? ECM , mounts , wiring , etc .

[grape]

Unfortunately the answer is just throw my wallet on the table. I'm currently looking at two computer systems, the TCI and the COMPUSHIFT. The TCI system is a little less complex in the amount of tuning you can do and it requires a tach signal, which would take some figuring out on my old 82. The compushift version is a little bit higher in price but allows waaaay more adjustment and somehow doesn't need a tach signal.......don't ask me how they do that. There is 3" difference in length in the 4wd versions of both the 700 and 4L80E, so I am going to have to fiddle with the driveshafts and shift linkage. I was pleased to find out that the NP 208 will bolt up to the 4L80 which keeps my stock speedo cable for the stock speedometer in the truck. Try this link www.compushift.com (http://www.compushift.com)

[whatnot]

Isn't there any way to make a computer work out of a '92 or '93 truck that had a 6.5L mechanical injection engine?

[grape]

yes the box for the 91-93 trucks is $157.00 with a $110.00 core charge and the tach sensor is roughly $140. The kicker is that the harness assembly has been discontinued from GM.

[britannic]

I actually bought a whole new T-case to fit the new tranny, so I have the original 60,000 mile NP208->TH400 T-case to sell. I also have a brand new NP208 input shaft to fit the TH700 up for grabs.

[britannic]

I nearly have it all done now, just the transmission cooler lines (amazing how the simpler things are the hardest :mad: ) and the wiring/drive line pressure hose to install.

The cooler lines are a pain, because the 700R4 uses a slightly different angle for the return and output. I figure on using some subtle leverage to get them bolted in and the fine tune them to relieve any stress/chafing points.

Can't wait to get the beast back on the road - it's positively pawing the ground out there!!! :D

[ 08-16-2003, 09:35 PM: Message edited by: britannic ]

[Eric Deslauriers]

Britannic,

I just got my 93 TCU and harness from a yard in Nebraska. Can't remember the final price off the top of my head, but think it was $150 total shipped or somesuch. I can get you the details if you need.

As soon as the turbo is done, the electronic hacking will commence.

I'll still need a TPS, etc. What sucks is that the yards toss them with fragged motors and sell them with good motors and won't get me one off a fragged motor. Wish I had a buddy at a yard. Anyone?!

You can also check TransGo - they make a full manual shift kit for the 4L80E (my project) that bypasses electronics (still need vacuum TPS tho) and may make a similar kit for the 60e. Summit did not have the best pricing, but wasn't far off (tho backordered).

It is fully reversible and my backup plan if I run out of time and need my motorhome up and running when I do my 4L80E swap. Either way, I'll keep the shift kit component in it.

[tpitt]

brittanic,
When I switched mine from a 400 to a 700 I just made up a couple of short cooler lines around 3 or 4 inches long and was able to tie them in with the existing ones. It made life a lot easier. I just put the 400 back in it. I had one of the "infamous" raptors and it went bad. tpitt

[EWC]

Sorry for cutting in on your thread about your 700 Britannic but ...

I looked at the Compushift site and they stated that some diesels will not work with their TPS setup . I know that the 4L80E has a TPS that will bolt up to the older mechanical pumps , as I have one and did the swap on the pump , but not the rest of the swap .

The mechanical pumps ran up to 95 in the G vans and did come with a 4L80E . No ECM just a TCM . If you compare the wiring from a 91 R/V series to the 95 G vans , you will find very similiar schematics . These would be the 2500 and 3500 series . I found a wiring harness from a van and bought an ECM off Ebay for $80.00 .

The column shift rod linkage needs to be lengthened about 2" but the rest looks to be the same as a TH400 even though the parts book has a different number .

I'm working on an 83 CC dually and have picked up some parts for the swap . I have done a little research and this is what I've come up with .

[britannic]

I was able to reuse my old cooling lines with some judicious tweaking and a new position for the clip on the tranny dust cover. I did discover that my TH700R4 output and input nozzles were metric, so I had to swap them over for the TH400's.

I was also able to reuse the shift linkage, just a quick tweak on the bell crank to align it better.

Now I'm waiting for my supplier to come do the inspection, road test and adjustments to commence my warranty and I'm in business!

[ 08-17-2003, 09:08 AM: Message edited by: britannic ]

[Animal]

Originally posted by britannic:
I also have a brand new NP208 input shaft to fit the TH700 up for grabs. Britannic,

I'm interested in the input shaft if it's still up for grabs. E-mail me at acbarta@yahoo.com

Thanks

[britannic]

This is one great transmission! It's very strange to be at freeway speeds with just a muted exhaust note and 2100rpm or so in OD.

Fuel economy has jumped, I haven't run the actual figures yet, but suffice to say, I've never been at 1/2 full with over 200 miles driven since the last top off, usually I'm almost down to about 3 gallons at that point.

EGT is of course higher in OD locked up at lower revs, but I'm learning to stay in drive for the mountains and manually lock up when needed.

The furnace brazed TCC's 1650 rpm stall speed allows the torque to build up for lusty launches and locks up solidly. It shifts nice and firm with the precision of a Swiss clock.

Tranny temps are around 100-130F even with TCC unlocked on hills in 3rd, I have a 19,000gvw and 24,000gvw cooler in series after the radiator circuit (to properly warm the Dextron III and stop components getting brittle during some of our super cold mornings in the winter).

I fitted a TCC lock up brake cancel switch to extend clutch life and a manual 2nd and 3rd lock up switch for towing and driving the rougher trails.

There's no going back to my TH400, even though it's been a great tranny and is still as strong as ever - I'm addicted to that 700R4 .70:1 OD :D :D .

[wthif]

Britannic,
I was wondering if you had to shorten and lengthen the driveshafts and about how much did that cost? Thanks ;) Trying to figure out the cost of doing a buildup on my truck! :D

[britannic]

I left the drive shafts as they were. The 700R4 is only 1/2" difference in length at most, but the slip joints in the driveshafts can easily handle that, unless your truck has been lifted or lowered to the point it becomes an issue.

[Bobbie Martin]

Just a note on the trans computers for 4L80E's. The force motors in the valve bodies changed in 1994. You have to use a computer designed for your force motor. The newer ones operate at 614 Hz vs 292.5 Hz for the old ones. The 94-96 G vans and the 94-99 P chassis have the TCM's you need for the newer transmissions. You also need the engine speed sensor that mounts on the back of the engine and the TPS sensor on the DB2 pump for these TCM's. Engine speed sensors without the vacuum pumps are cheap used ($25 at Diesel Depot). TPS is almost $150 from the dealer. Connectors are available at the dealer for both, but around $20 each. It also wants a barometric pressure sensor. But its much cheaper than any aftermarket computer. You can get the TCM used for around $75.

[TimK]

Brittanic,

I think you saw my other posting I listed on getting a TH400 torque converter cover. Did you use the same TC cover from your TH400 on your 700R4 conversion? If not, do you still have the TH400 cover and is it for sale?

TimK