2004 Z71 Suburban 2.0

C.I.TR3

New member
Hello All,

Long time lurker who, after many years, finally has a vehicle to do some back country exploring with my family. For most of you this vehicle will be very familiar since I have purchased Travis' 2004 Suburban well documented at http://forum.expeditionportal.com/threads/162238-I-got-here-as-fast-as-I-could-07-Suburban-Z71. Travis has been great to deal with throughout this whole purchase answering my numerous questions. I am excited for his new vehicle endeavor and wish him the best of luck.

My goal for the vehicle is to have something that my son and I can take on trips to explore the Pacific Northwest's beautiful forests and mountains, bird hunting trips to Eastern Washington, and surfing trips to the coast. We will also do some extended trips as a family to more parts of the west and into British Columbia. I don't envision any technical four wheeling nor do I have any experience in doing that.

Anyway, just wanted to say hello. I love following these forums and am amazed by the builds done here and the amount of help that is offered. I look forward to participating.
 

C.I.TR3

New member
Transmission Decisions

If you have read this thread (http://forum.expeditionportal.com/threads/174964-Friends-it-s-a-sad-day) you know that the first order of business for the Sub is a new transmission. I consider myself to be in the beginner to intermediate range when it comes to vehicle mechanics and a large part of my goal in getting a GMT800 Suburban was the idea that it is something my son and I can wrench on and learn together. Something a little newer, reliable, easy to work on, can seat at least 4 with the ability to sleep in the back were my criteria for purchase. Having said that, I do not think a transmission swap (and the associated cost) is where I want to start my mechanical education. I think this is too far out of my reach at this point.

So, I spent a lot of yesterday calling around and would love some advice on how best to proceed. Here are the options I have found:

The local Chevy dealer will R&R with a remanufactured GM 4L60E for $3800 and give me a three year warranty.

I found a shop that apparently does some work for the local offroad community. They R&R with either a Jasper or TRC remanufactured transmission for $3500 - $3800 depending on which transmission I choose. Also has a three year warranty.

Local transmission shop quoted $2800 to rebuild it with a two year warranty. No idea of their reputation or quality.

I could purchase a used or rebuilt transmission myself and take it to a local (non-licensed) mechanic who will R&R it for $300. Obviously no warranty and if I get a used transmission I would have no idea of its condition and would worry about reliability.

I found a lot of references to a local speed shop that does engine/drivetrain work. They seem to have a GREAT reputation online and have built lots of 4L60Es for high horsepower applications. He was great to talk to and quoted me $2600-$2800 depending on what kind of improvements I wanted to make. Two year warranty.

This last option is the route I am leaning towards. Not only is it the cheapest, but I feel good about the reputation of their shop and my conversation with him. I see people quoting rebuilds for $1200-$2000 on all kinds of boards (including this one) but have not found that in my area. I have tried to stick with shops that are more well known so maybe I need to call around more.

I know a number of people also recommend swapping in a 4L80E but I could not find a single person that has done this or would do it. If this is strictly something I would have to do at home thing, then I do not think this is an option.

Oh, one more piece of relevant information is that I do not plan on doing a lot of towing right now. My wife and I have looked at trailers but that is probably a few years down the road. Even then we want something pretty small like in the 5,000 lb range empty.

Any other suggestions out there? Any input on the best route to take? Thanks for the help!
 

Martinjmpr

Wiffleball Batter
When my transmission went out last year I went on a couple of local boards and asked for recommendations for local shops. Found one that came highly recommended (even from some on this board.) They rebuilt the transmission with stronger parts (as I understand it, there are some poorly made parts in the transmission that are prone to breaking and these get replaced with much better metal parts) and the cost was $2k with a 12 month/12,000 mile warranty - but the shop owner even said to me that they wouldn't be "sticklers" about the warranty and if I had problems to bring it back.
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6 months later I noticed I was dripping a small amount of fluid from the T-case, so I took it to him and he fixed it at no charge, even though I'm not even sure it was actually a transmission issue.
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To me this is the big advantage of going to a local shop that has a reputation to protect.
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I'm pretty sure that in a large metropolitan area like Seattle there must be a lot of transmission repairs done, particularly on Chevy transmissions. I'd find a local shop with a good reputation and go with them.
 

Martinjmpr

Wiffleball Batter
WRT the advice to 'drop in' a 4L80, I've seen a few write-ups on that over on the Tahoe/Yukon message board. It's not a "drop in" by any means, particularly on a 4x4, since the 4L80 is longer and requires relocating the Transfer case, shortening the rear driveshaft and lengthening the front, and other mods as well.
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By the time you factor in the cost and the time of doing the 4L80 swap, you could probably buy at least a couple of 4L60's. ;) Really I think if you need a 4L80 the best way to get one is to buy a truck that already has one in it.
 

ClovisMan

Observer
Pulling a 4l60e is not that bad. I would pull it and take it in the be rebuilt. In Texas they are a dime a dozen and can be rebuilt for 700.00. Here's a little secret. Most of the reputable big name shops don't rebuild the transmissions you bring in. They take them to the guy Downtown that has couple of employees that don't speak english. He charges them 600-700 to rebuild and then they turn around and charge you 1100-1200. Then they charge you 75 an hour to pull and replace. Highway robbery. I just happened to have found that guy in my city that rebuilds everyones transmissions. It was kind funny because he had them all over his shop stacked up and they were all tagged by the shop that brought them in for rebuild.
 

rayra

Expedition Leader
Make the deal with the $300 guy, buy the warrantied monster 4L60E and have it shipped to you or even the shop, have him put it in.


It's really a simple operation, with a couple helpful tools, like a transmission cradle on a floor jack. And some extra hands. It's a little heavy and a little awkward. But the operation is dead simple. You simply drop the driveshafts, remove the transfer case - a few bolts and electrical connection and it slides off the output shaft of the transmission. Drain the trans. Get the jack under the trans, support its weight, unbolt the trans mount from the trans and raise the trans slightly. Remove the transmission mount frame cross brace. Remove trans dipstick and dipstick tube (one bolt at the base of the dipstick tube), pull the trans cooler lines - be prepared to capture draining fluid. Pull the electrical connection(s). Removing the upper transmission bellhousing to ending bolts. Lower the trans slightly, so its bellhousing will clear the firewall. Support the engine under the oil pan, preferably with another floor jack. Slide the trans back off pulling its input shaft out of the torque converter. Or alternately first pull the access cover(s) and unbolt the torque converter from the flywheel. The later method is an easier removal and install but a lot more weight to juggle.

Once it's out, you transfer your bellhousing from the dead transmission to the new, if necessary.

Been a long time since I did it with the THM350 in my pickup. When that one went out ~180k miles later, I was flush at the time and paid IIRC $1300 (in 2011) for a well regarded local shop to do the rebuild. These cited prices in the Seattle area are a damned ripoff, even today.

If the vehicle doesn't have to immediately be road-worthy, I would suggest it is exactly the sort of father-son project you want. It's a dead simple technical process, little more than unbolting and bolting things together. The only skill involved is the experience that will prevent you dropping or breaking things, or smashing something while wrestling it around. Could be done in a weekend. I think book time is only a few hours for a pro.

The Haynes manual for the GMT800s is #24066 and it has a detailed section on removing this transmission, with lots of illustrations.


eta on second thought, skip doing it yourself. Start with smaller stuff. But when you progress to tackling stuff this size you'll laugh about how easy / straightforward it is.

eta2 it's also a prime opportunity to put a new transmission (rubber) mount in.
 
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C.I.TR3

New member
Finally picked up the Suburban this past weekend and had it towed to the shop. Travis was absolutely great to deal with and I thank him for spending so much time with me showing me all the things he had done as well as some ideas for plans in the future.

After many more conversations I decided to go with local builder. He was so knowledgeable about these transmission and will do all the necessary upgrades. Essentially I think it will be a 4L65E or close to it when he is done. Cost will be a little more than doing it myself but not that much once you factor in some tools I would need, miscellaneous parts, and shipping the core back. Plus, we are hoping to do a maiden voyage in September.

Now to start planning my next steps. Travis took great care of the rig so other than an oil change it is ready to roll. I want to get a bluetooth ODBII dongle to monitor transmission temp and other items (unfortunately I am an IOS person), thinking about new keys in the front and a 2" spacer in the back, adding a second battery, and maybe the fuel pump as a preventative measure. Mostly need to start planning some interior sleeping and storage mods.

Here she sits waiting for help.

At Speed Secrets.jpg
 

rayra

Expedition Leader
I've had good experience with an OBDII bluetooth reader marketed under the brand name Panlong. There's a bunch on Amazon, all translucent blue plastic, under a bunch of brand names, ~$13.
I'm using it with a 7" Android tablet and the Torque app. In a dash mount I fabricated. I later paid the $5 for the full version of Torque, to gain access to Transmission temp readings. And you can create a custom 'dashboard' of gauges / readings.

tabletbracket16.jpg
tabletbracket15.jpg


http://forum.expeditionportal.com/t...ablet-GPS-mounts-please?p=2075866#post2075866


I'm still in the middle of fiddling with transmission cooling and gauge solutions. My attempt to 'add' the missing factory trans temp gauge was only partially effective and suspect my circuit board soldering connection failed. That will be revisited once I find a source for the gauge step motor pin spring clips.
Meanwhile, next up is a much larger trans fluid cooler.
https://www.amazon.com/dp/B0060NKA1U/_encoding=UTF8?coliid=I36GK72XBDJSDZ&colid=QWZ1BSZYG6VW

There's another version of that cooler that has some sort of a thermal valve in it, which constrains the flow until operating temps are achieved. Costs $10-15 more. In cold climes it's probably a good idea.


The 4L60E seems to have a real intolerance for high heat. Push it over ~~275F - especially with high mileage - and that seems to be the death knell for it. So for sure do something to at least monitor its temperature. And if you travel in warmer climes, boost the cooling. You planned 'HD'/4L65E improvements will go a long way towards making those problems less likely.
 

Martinjmpr

Wiffleball Batter
The 4L60E seems to have a real intolerance for high heat. Push it over ~~275F - especially with high mileage - and that seems to be the death knell for it. So for sure do something to at least monitor its temperature. And if you travel in warmer climes, boost the cooling. You planned 'HD'/4L65E improvements will go a long way towards making those problems less likely.
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Good Lord, I'd hate to think what you'd have to do to get the 4L60E up to that kind of temp! :Wow1: Maybe pull a 6000lb trailer out of Death Valley in mid-Summer?
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I've been using the SGII on my 'Burb since I bought it in 2015 (the SG was in my 3rd gen 4runner and then in my 4th gen - I've owned the SG longer than I own most of my vehicles!) The hottest temps I've ever seen were ~ 210 and that was pulling a 2000lb trailer over a 10,000' pass in mid-Summer. Other than that it rarely hits 200 and even then it only hits it for maybe a couple of minutes. And this is with the factory cooler (towing package.)
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By contrast, my 2007 (V6) 4runner would hit 200 any time I ascended a mild grade or even if I had a strong headwind while pulling the trailer. Hottest temp I ever saw was about 269 and that was going over the pass from Panamint Springs over to the Owens Valley while pulling our small teardrop (~1000lbs) in July of 2015.
 

mccustomize

Explorer
I swapped in a mileage-unknown 4L65E about 7 years ago in my truck, put a huge dedicated trans cooler on it and the only thing I have had to do was replace the 2-3 shift solenoid, when I did that I also put a deep Hughes pan on it. It's been rock solid for me with 37s and a 7400# truck.
 

rayra

Expedition Leader
I've broken 200F a couple times this summer, racing around Socal highways in 100F+ days. But I drive too hard / fast, still. It's made me leery enough that my next mod is the bigger trans cooler.

I often go over the I-5 'Grapevine' grade, it's only a 4000' summit, but it's a looong grade northbound and a very steep one southbound and a car killer all over, year-round. Roadside seems to always have someone steaming, especially on holiday weekends. That and some future towing considerations and the life stage of my trans and I definiteyl have to up the cooling.
Have also been considering the above mentioned bigger (and finned) pan, too.

And being in SoCal I really don't need the in-radiator loop, don't need the trans 'warm up' function of that and would rather divorce the trans cooling from the engine heat load. Especially until I retrofit some electric fans. Not sure about that though. The factory loop with towing package is trans -> into radiator -> out to external trans cooler -> trans. I'll probably just first replace the tiny factory trans cooler and leave the rest alone, so I can get a better appreciation of any cooling improvement. Just change one factor at a time.
 
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C.I.TR3

New member
Spoke with the transmission shop yesterday. He said the front planetary assembly bearing let loose and destroyed the assembly (not a transmission person so I hope I am getting the name of the parts correct). We talked about the rebuild and upgraded parts and I feel confident I made the right choice. He is clearly very knowledgable about how to beef up the 4l60e; at least as far as I can tell based on my google knowledge. He is also going to take a look at the rear main seal and oil pressure sending unit o-ring before he puts it back together. Hoping to get it back this Friday or early next week.
 

rayra

Expedition Leader
Yep, that's s common failure, pump too. Something about differential heating of steel and aluminum, when the trans gets heat-stressed.

Ordered my trans cooler upgrade. I should be installing it weekend of the 1st
http://www.ebay.com/itm/Tru-Cool-Ma...ash=item4b0628c625:g:xW0AAOSwZVlXt1iJ&vxp=mtr
About $25 less than Amazon

There's another version with a thermal bypass (thermostat sort of thing) that would be better for those in cold / freezing conditions. It prevents the cooler from operating until the trans reaches normal operating temp.

SHould be an easy install since I've already got that small factory external cooler, part of the factory tow package. I'll be detailing it in my build topic. Already putting notes and related vids there.
 

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