Burb Needs a New Transmission

[bad_idea]

Hello All.

The time has come. The 700r4 in my Suburban is about done. I would like to replace it (doing the work myself) with a quality rebuilt 700r4. I have looked into swapping in a 4L80E and cannot justify the cost. My planned use for the vehicle is a mild lift with 33x12.5s, occasional towing a car trailer, and hauling the family through mild trails and down the beach. Can you all recommend a good shop to get the transmission from? Thanks.

 

[Dutch Rutter]

I've been down this road with my k20 twice now. First time I had the original 700r4 rebuilt. $3200. Lasted about a year and a half. Shop went out of business so no warranty, and they didn't really rebuild it correctly which lead to the second breakdown.

This last time I took it to a shop and they recommended replacing it with a rebuilt unit, $3400. So far its been alright, pump has started getting a little groan when warm and under 40mph but it still has another two years of a warranty. That shop won't be closing so I should be good there.

All that being said. Looking back, I would have been better off spending the $3400 once to do a nv4500 swap or a 4l80e swap and not worry about it ever again. A burb with a nv4500 would be pretty sweet imho.

Might also be worth looking into swapping in a th400 if you don't need overdrive.

 

[bad_idea]

That seems awfully high. Monster Transmission sells 700r4s starting at $2099, rated at 500 horsepower. Again, I'm not racing this thing or thrashing it on trails. Just looking for a good rebuilt unit.

 

[Matt69olds]

Stay away from Monster Transmission. Their customer service sucks, their technical assistance sucks, and all they sell is repackaged parts from other venders.

I don’t understand how transmission shops today have trouble building 4l60 transmissions for mild engines. The 4L60 has been around since 1982, and GM constantly updated abd improved it right up until it was discontinued. You would assume a shop that has been around for more than a couple years would be very familiar with them.


Have your transmission built with a Sonnax drive shell, upgraded dual cage input sprag, wide band, upgraded servo, upgraded 3-4 clutch kit, a good shift kit, make sure the TV cable is adjusted correctly, properly built there is no reason the 700 won’t last behind a mild big block, even more so a small block.

The drive shell is a well known weak area, the Sonnax part fixes that problem. The servo, wide band, and 3-4 clutch parts help add enough friction area to hold under heavy use. The shift kit will fix the hydraulic problems and provide enough clamping force for the frictions to do their job. The dual cage input sprag adds a little durability.

Keep in mind, a trans with durability upgrades won’t have the girly man soccer mom shift that GM designed into these transmissions. At the same time, you don’t need a transmission that shifts hard enough to knock the dash out of the truck! A transmission that shifts with a good solid thud is a good compromise between acceptable clutch/band life, and driver comfort.

 

[bad_idea]

So, you're saying I need to take it to a local transmission shop and have it rebuilt? Any recommendations on finding a good shop? AMMCO a good one?

In regards to Monster, I put their stage 2 clutch in an 02 Z28 about 10 years ago and it performed well. I did have a minor issue where they forgot to send me the alignment dowels. When I called them on it, they gave me attitude and were difficult about it. I chocked it up to one jack ass on the phone. Thanks for the heads up, I'll avoid them.

Absolutely fine with a crisper shift. I want longevity and reliability. Besides, a crisp shift reminds you you are in an antique. If I was after a gentrified ride, I wouldn't be putting together a 30 year old diesel Suburban.

 

[yevgenievich]

33" tire and occasional towing with trails to me means 4l80e is needed. But if built correctly 700r4 should hold.

 

[Bextreme04]

I am a big fan of the 4L80 swap.... but probably not even close to necessary for what you are going to do to it. Look for a shop that has been around for a long time and has a good name in the area. I wouldn't go to a place like AAMCO, a big chain business like that can have a wide variety in quality and can stay in business because they are a big chain. Do your research, talk to some hotrod and 4wd shops in the area and ask for their recommendations for a good trans builder. You will likely hear good and bad things about several places, and have one or two names that consistently come back(from multiple sources) as the go-to builder. Then go in and talk to the builder, tell him what your application is and what you use it for and ask for his advice on upgrades and a quote. It will be MUCH cheaper if you pull the trans yourself. A quality shop will likely want to at least inspect the installation afterwards to make sure the TV cable is properly adjusted in order to honor a warranty. I would expect many shops will flat refuse to honor a warranty on a 700R4 that they didn't install though, since it is so easy to destroy a new 700R4 that is not properly installed and set up.

 

[Matt69olds]

AAMCO is a acronym for

All

Automatics

Must

Come

Out!!!


I would agree with the above advice, find a independent shop that’s been around awhile.

My only experience building a Monster in a box transmission was for a C6 Ford going behind a stroked (565 inch) big block Ford wagon making 800 plus hp. Guess he felt he needed to get those groceries home quick!! The guy bought the rebuild kit from them directly, in typical Ford “let’s change things” way of manufacturing nothing was right for that particular model year trans. It took far more phone calls and waiting on the correct parts to finish than the “convenience” of ordering a complete kit was worth.

I have repaired a couple monster in a box transmissions, as I mentioned they are just repackaged parts from other venders.

 

[Dutch Rutter]

That seems awfully high. Monster Transmission sells 700r4s starting at $2099, rated at 500 horsepower. Again, I'm not racing this thing or thrashing it on trails. Just looking for a good rebuilt unit.

Prices in my area are pretty stupid high. Especially in older stuff. Shops seem to think that means you need to ask a premium price for anything, and that's if they'll even touch it.

Better to cry once and not worry about it again imho. And that's the route I'll be going when this new unit goes out on me.

 

[bad_idea]

I am open to doing a 4L80 swap, if it can be done reasonably. Can you all give a rough break down of cost and effort associated with the swap? I would like to build this truck as a reliable driver to make memories with the family in.

 

[SquareRoot]

Buy once, cry once. It only seems expensive until you're replacing the 700 for the third time.

 

[Bextreme04]

Going from a 700R4 to a 4L80E is going to be expensive and a PITA. Especially since you are 4x4. You'll need a different transfer case and adapter, or at least to change the input shaft on your current transfer case. The transfer case you have now will be for a 27 spline output shaft from the trans. The 4L80 has a 32 spline output shaft. It's possible the standard 4L80e adapter would bolt up to your current transfer just fine, but at a minimum you would need to change the input shaft.

They are also different overall lengths and you would likely need to adjust front and rear driveshaft lengths.

Then you would need to worry about electronic controls. You can do a full manual control, but that will make it run full line pressure all the time. The 91 3/4 ton burbs with a diesel had a 4L80E running on a standalone controller and harness. You could try to mimic that harness/controller or buy one of the standalone controllers that are currently out there, or even make your own standalone controller using an LS computer from a 2000-2004 vehicle. I got my engine

If you want easy, wallet friendly, and reliable for family trips and occasional towing I would say just get the 700R4 rebuilt by a reputable local company with a good warranty and put the biggest trans cooler you can find in front of it. I would recommend a Tru-Cool 40k.

 

[Dutch Rutter]

What bextreme said above is all true. Which is why I suggested the nv4500 5 speed option. If your open to a manual trans it makes ALOT of sense.

It's the same length as the 700r4 so no relocating cross members, or re working drivelines. You do still need to change the input shaft of the transfer case (assuming you have an np208) it can be done easily and cheaply (high-impact sells the shafts). The nv4500 also has no controller to worry about. But you would need to source the brake pedal/clutch assembly (can be hard to do, and can cost $300+). If wanting a clean looking swap, I'd recommend picking up a steering column from a manual trans truck while you're at it.

With those parts in hand, you can get a full swap kit to include the hard to find parts and other master/slave cylinder parts from high-impact.net. Last year they quoted me $3400 (same cost of my last rebuilt 700r4) for the whole shebang, minus the factory parts I mentioned above.

One of the things I like the most about this swap is that the year of gm nv4500 they sell has very close to the same gear ratios as the 700r4. And you'll break the engine, or axles before that trans breaks a sweat.

Side note: people on this forum are probably tired of reading me fanboy about this swap. But I've done alot of research in the topic and in my eyes at least, it's one the most straight forward and easiest options available.

Edit: The biggest downsides in my mind to this option is the needed cutting of sheet metal, and these transmissions do not shift fast (think big truck shifting speeds).

 

[SquareRoot]

What bextreme said above is all true. Which is why I suggested the nv4500 5 speed option. If your open to a manual trans it makes ALOT of sense.

It's the same length as the 700r4 so no relocating cross members, or re working drivelines. You do still need to change the input shaft of the transfer case (assuming you have an np208) it can be done easily and cheaply (high-impact sells the shafts). The nv4500 also has no controller to worry about. But you would need to source the brake pedal/clutch assembly (can be hard to do, and can cost $300+). If wanting a clean looking swap, I'd recommend picking up a steering column from a manual trans truck while your at it.

With those parts in hand, you can get a full swap kit to include the hard to find parts and other master/slave cylinder parts from high-impact.net. Last year they quoted me $3400 (same cost of my last rebuilt 700r4) for the whole shebang, minus the factory parts I mentioned above.

One of the things I like the most about this swap is that the year of gm nv4500 they sell has very close to the same gear ratios as the 700r4. And you'll break the engine, or axles before that trans breaks a sweat.

Side note: people on this forum are probably tired of reading me fanboy about this swap. But I've done alot of research in the topic and in my eyes at least it's one the most straight forward and easiest options available.

Edit: The biggest downsides in my mind to this option is the needed cutting of sheet metal, and these transmissions do not shift fast (think big truck shifting speeds).

Agree totally. I recently did exactly that. And yes, it was worth the effort.

 

[yevgenievich]

411 ecu can be set up as a stand alone trans controller. Drive shafts, tcase or tcase input shaft/speed sensor, Throttle body position sensor. Easiest path is finding 91 donor, but they are not that common.