Turbo and 700R4 donor?

[softboyled]

I have an m1010 with 4.10 gears in the rear and am still not too happy with the revs at highway speeds (I got it that way, so I don't know how the 4.56 gears are...). Also, I'm not too pleased with the hill climbing ability of this beast.

I've come across a possible donor vehicle for both a turbo and a 4-speed. It's a 1987 Suburban (6.2L) that's apparently running fine, but the price may be low enough to make this economically feasible.

I've read a bit about swapping the transmission, but has anyone here actually put a 700R4 in the M1010 or equivalent? What would I need in addition to what's already in the Suburban?

I'm assuming that the turbo swap would be pretty straightforward. Perhaps need to fab some exhaust parts?

Thanks for any thoughts,
Greg

 

[jblack6527]

As far as the 700r4, you shouldn't need anything that isn't in the suburban. I "think" they are the same length as a th-400, but I'm not sure about the splines on the d-shaft yoke, but that's an easy swap if they're different. I think you're on the right path with the turbo, but you may not even have to fab any exhaust parts, it may work with just some massaging.

 

[AJMBLAZER]

If you get the whole Suburban you should have all the necessary parts provided nothing is broken or damaged.

Talk to mangus on here, he's done the swap in a M1009.

 

[hndrsonj]

Should be an easy bolt in swap.

 

[Croatan_Kid]

I'm in the last stages of buttoning up my 700R4 before I swap it in. Lemme tell you, if you don't get a donor vehicle you'll play hell getting every little part you need! However, I have done it and am glad I have.

The output of a TH400 is 32 spline, the 700R4 is 27 spline, so a new transfer case is necessary.

You will need a flexplate, torque converter, transfer case adapter (tall style), transfer case, you may or may not need to swap the front output yoke on the transfer case, a TV cable, a TV cable bracket, some way to make the lockup converter work......

I've got 850 bucks in parts alone for the internals of the transmission. That includes a full rebuild with Kevlar clutches and band, quite a few valve body modifications, and some other beefy internals to boot. If I had been able to find a donor, I would have gone that route.

I still have 4.56 gears, but I lifted my M1008 and I am running 39 inch tires....I still need overdrive!

 

[Recovry4x4]

Is the burb AWD?

 

[Bozor1000]

Just make the 700r4 is the upgraded version. Some of the early 700r4 had a lot of internal problems with them. In my 84 K20 I had the 700r4 that was rebuilt. The original tranny went out in it.

 

[Taz]

Don't the M1010's have an NP 205 transfer case? if so, it will not bolt up to a 700r4. You could use the np208 out of the burb (assuming it is 4wd). Many would frown on this because the 205 is stronger. You can put a 205 behind a 700r4. You would need a 205 and adapter plate that was behind a TH350 trans and change the out put shaft of the 700r4. Advanced adapters makes a special, shortened one. Oh and you would need the coupler sleeve the conects the output and the input shafts. If your 1010 has the 208 T/case, you can directly swap out the th400/208 for a th700r4/208 with no driveshaft changes. there is some lingage for the throttle valve cable that you would need of off the burb. I have done the 700r4/np205 thing and my M1008 and M1009 have 700r4/208's in them. The 1008 has a Banks turbo on it as well. It really does help with pulling power! Good luck.

 

[AJMBLAZER]

Is the burb AWD?

In '87 it should have had a NP208 part time. The full time 203 went away by 80.

 

[mangus580]

Having the donor onhand will help alot.

Transmission is a different length, but the adapter for the tcase handles that problem. You dont need the new transfer case so much, as the input shaft out of the front of it. (which requires disassembly) Honestly, I would take the time to pull the t-case apart anyway, to check the internals out. The one I used failed me 2 years later (this past winter).

You should pretty much be able to drop the tranny/tcase assembly out of the donor, and lift it up in the new truck.

You will most likely have to have your rear driveshaft adjusted, as the wheelbase is different for the Burb.

I would suggest you put in an external tranny cooler, and possibly even a gauge (esp since you have the added weight of the ambulance body) to keep temps down.

Make absolute sure you get the 'TV' cable adjusted right, as you will fry the tranny quite fast if not.

The TCC wiring from the donor vehicle will be a big plus. If its done like the TH400 kickdown wiring, it should be a standalone harnes, plugging into the front of the fusebox. If you dont have it, you can make your own quite easy by searching the net.


As for the turbo... DO IT!

 

[CUCVFAN]

Don't the M1010's have an NP 205 transfer case?

Nope. NP-208 all the way. The shifter shaft is different. It points backwards and doesn't appear to be an NP208 shifter at first glancce, but it is.

 

[Croatan_Kid]

If, by chance, you do decide to run an 27 spline NP205 from behind a TH350 like I plan to, all you need is a spacer for a TH350?700R4 swap and you will need to cut a little bit off of your tailshaft. That or plan a rebuild and swap in the AA output shaft. There isn't a couple sleeve in a 27 spline NP205 like there is for the 32 spline unit found behind the SM465 and TH400, it's just a direct fit.

Either way you do it, you can't go wrong. The NP208s are suprisingly strong and I know a local guy that owns a 4x4 shop that runs one with a SYE kit and 54 inch Boggers. It'll hold up!

 

[softboyled]

What I think I heard:

The 1010 has the TH400 + np208.
The burb has the 700r4 + mp208.

The burb AT+tcase assy should drop in where my AT+tcase was.
I need to address TV cable issues.
I -may- need to mod d-shaft due to wheelbase difference.
I -should- inspect t-case internals.
I -should- ensure that 700r4 is 'upgraded' -- how do I determine that??
I -should- add a cooler and a temp gauge.

The turbo bits should bolt on easily.

Correct?

As for the resulting suburban hulk? What is its best outcome? Can I bolt the TH400+NP208 from the m1010 back on there? Is there anything special involved in 'un-turboing' the 6.2?

Thanks for all the info!

Greg

 

[Radioshop]

I say get the turbo, leave the transmission. Put in a Gear Vendor's overdrive or something like it. The Turbo 400 is way better for toughness than a 700r4 I just did a 700r4 conversion on a 77 Corvette and it was nothing but surprises. In all fairness it is working better than the 3 speed. I have had 700r4 trucks, I just don't think a stock 700r4 is really up to heavy towing etc. What you'll spend on rebuilding (beefing up) the transmission could be better spent on an overdrive.

 

[AJMBLAZER]

Ever priced one of those GV od's? I know a few folks who have run them, including one on a 80's C35 crewcab with a 6.2L and TH400, and none of the results enough to do it again.

A 700R4 can easily be upgraded to handle anything a 6.2L, even a turbo'd J model, can put out. They have a bad reputation due to GM's early failings and constant tinkering and overuse of the transmission but when properly built and used in the correct place they are great transmissions.



soft, if the Burb and your M1010 are in proper working order, driveshafts aside, you should be able to swap the stuff between the two of them fairly completely. If it comes off one truck and goes on the other the part it replaced should go back on the first truck in it's appropriate spot.

 

[Radioshop]

The GV overdrive is $3095, which is expensive. I paid $1k for the 700r4 in the Corvette. Now that might be expensive for a 700r4, but I am confident of the quality of the build. The 700r4 is a four speed with a final drive ratio of 0.70:1, the TH400 has a final drive ratio of 1:1. From what I gather of GV, they'll build to suit. Frankly the 4 speed is nice, but the gear vendor's is capable of splitting all three speeds in the TH400. If we're talking about a 50% split on the GV unit, we're talking about 0.50:1. Depending on how much highway driving you do, the cost could be made up pretty quickly.

 

[softboyled]

if the Burb and your M1010 are in proper working order, driveshafts aside, you should be able to swap the stuff between the two of them fairly completely. If it comes off one truck and goes on the other the part it replaced should go back on the first truck in it's appropriate spot.

Looks like that's the way I'm going to go. Think anybody'll want an '87 3 speed normally aspirated Suburban when I'm done?

Thanks!

 

[mangus580]

Yeah, actually AJM brings up a great point...

as you do the swap... swap it back, you will still have a driveable saleable vehicle!

 

[AJMBLAZER]

Well, all I know is I haven't actually met anyone with a big truck and the GV unit that really liked it. Great theory but in practice you're out thousands and it's practical uses are limited. As the guy with the C30 told me, "what do I need to split 2nd gear for?" He also said sometimes it seemed like the OD was almost too low.

 

[AJMBLAZER]

There's a good discussion over on www.ColoradoK5.com going on that has had some good info about the GV unit in it. I'm even less impressed than I was before.

http://coloradok5.com/forums/showthread.php?t=230696