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bverd
07-25-2001, 12:37 PM
Okay... Looking for a little advice here. Turns out that the transmission in my Suburban has gone out and I am currently in the process of getting it rebuilt. I guess traveling all over the place with the X hasn't helped.

My question is "should I do anything special to ensure that this transmission lasts as long as possible, as well as any special maintenance that should be done" The rebuild is not cheap and I want to beaf it up as much as possible. They are putting in a high stall torque converter. Is there anything else I should be looking to do as well. This is a 3/4 ton Suburban (1996, I love this truck)with the 454 package, the transmission (I have been told by the technician) is the largest GM makes short of the allison, it is the same one in the Hummer. This truck was built for towing, I just want to make sure I am not cutting any corners now that I will have to pay for later.

Thanks in advance... Brad

Looped
07-25-2001, 01:23 PM
bverd,
Look into a tranny cooler if you don't already have one. For my stinkin Lincoln Mark viii I was told to throw in a cooler and change from Merc 3 to Merc 5 for transmission fluid. I'm not too sure if GM has a better fluid than stock like the Ford upgrade I did but you could go to a synthetic tranny fluid too.

Just a thought,
Craig

Woodsy
07-25-2001, 01:30 PM
I don't know if I would put a Hi-Stall converter in a truck I was using for towing. Hi-stall converters are usually used in street/strip cars where you don't have a low idle due to the hi-performance camshaft. It effectively allows your engine to rev higher before you begin to move. I would use a stock converter and have them put in a mild shift kit. What the shift kit does is it allows the trans to shift into gear a lot harder instead of slowly (think feathering a clutch) shifting ino gear. This eliminates alot of wear on the transmissions clutch plates. I would also install a big transmission cooler and mount it low on the radiator in front. Someplace where it will get some clean airflow. Heat is a big killer of automatic transmissions, so the cooler it runs, the longer it runs. I might even be tempted to install a thermostatically controlled engine ouil cooler as well. My Ram 2500 came stock with all of this except a shift kit. I have had no problems to date @ 80K. Of course, I just probably jinxed myself as the Dodge is known to have tranny problems!! Hope this helps!!

Dave

bverd
07-25-2001, 01:42 PM
The high stall converter was suggested because I am running oversized tires on the truck. Now they aren't HUGE by anymeans, but they are larger then the small stock ones. I was told this would help with the strain on the tranny with the bigger tires. --Brad

Looped
07-25-2001, 02:16 PM
bverd,
You may think of replacing the stock u-joints with beefier ones if that is you plan. High stall converter, larger tires, BBC torque & maybe a shift kit can really put a strain on the u-joints.

Just another thought!
Craig

Forrest
07-25-2001, 03:04 PM
GM R700 most likly. Real nice tranny. Mine's been "rebuilt" twice in the last four years. One thing you have to watch out for with transmission shops is that they will try to get away with just fixing what's wrong and not really do a complete overhaul - then tell you that it was completely rebuilt. Many of the transmission guys are just too fast to suit me, especially on a come back. Good luck.

bverd
07-25-2001, 03:31 PM
Forrest - yeah, I have been there on a daily basis inspecting the progress and seeing the work getting done. They are doing anything but getting it done fast. It is on day 4 right now and the technician says normally on a job this size it is minimum of a week.

olredalert
07-25-2001, 06:08 PM
Bverd,
Ive managed to put 125000 miles on my 93 3/4 ton Sub and have never had the trans out.At least 80000 of those miles were towing my 10000lb (loaded) race trailer.The key to making a 4L80 trans (what you have)live is to keep the fluid as clean and cool as possible.I dont trust any kind of after market converters,especially higher stall.Your convertor is a computer controled lock-up style converter and the only modifications needed to either the converter or the trans are in the computer.Get a modified chip,add the biggest cooler you can fit on your truck and change the fluid every 5000 miles and you should never have a problem.Call me direct if you want to get a chip.My guy is the best in the industry,and can tailor your chip to your personal desires.He can put in firmer shifts(less trans heat build-up).He can also keep the lock-up locked up longer(less RPM hunting).Im not sure by your brief description whether Id even trust your chosen trans guy.Hes given you bad info on a couple of things.My number is 810-326-0490,name is Bill.I should be around!............just......tired ol red!

Shanghied Again
07-25-2001, 06:46 PM
Brad

When I returned from Kentucky, My Trannie blew. Talk about luck? I made it home. I had the trans rebuild in my dually and they put in a quick shift kit. Boy what a world of difference. I pull the boat with no problem at all. Are you going to Jackson Marine poker run? I will be there Saturday August 11th. I have a Donzi meet Sunday August 12th in NJ at the Waters Edge. :)

Formula Jr
07-26-2001, 12:30 AM
Every 5000 miles? Boy, am I in trouble now........

BERTRAM BOY
07-26-2001, 05:52 AM
Brad,
I had the TH400 rebuilt in my truck last year. The owner of the transmission shop told me that some of the new synthetics work so well, that in some lighter towing applications, a cooler isn't needed.
Since I already had a cooler installed, and swithed to Mobil 1, I feel pretty confident that it won't let me down. I would at the very least switch to synthetic fluid.
:D
BERTRAM BOY

Rootsy
07-26-2001, 08:32 AM
if you can do it.. change the chip so that it keeps the converter locked up while towing anywhere above about 1200 rpm or so.. the biggest killer of transmissions is people towing loads in Overdrive where the RPMs are usually less than that of the lock up point of the converter. Stock converters usually lock up anywhere from 1800 to 2200 depending on the torque output of the motor. when you reach cruising speeds and take some of the load off the converter and then get back on it to accelerate or climb a hill, etc you can get converter slippage and that gets the fluid hot and you end up smoking stuff, and it only takes one time. just something i once learned from experience.

olredalert
07-26-2001, 10:11 AM
Jaroot is 100% correct.Keeping the convertor locked up as much as possible keeps temperatures low,thereby prolonging trans life...........just.....cool ol red!

MOP
07-26-2001, 06:20 PM
Hi I recently found out from a fleet manager buddie that they use Mobil One trans fluid, it has cut operational costs by over half. That and a tranny cooler should be the hot ticket.

Phil Long Island NY

boldts
07-26-2001, 10:33 PM
Jaroot, Ol Red,
I have a question about the Overdrive in the GM trans. I am leasing a 99 Chevy Tahoe, so not wanting to do anything wrong, I read the owners manual cover to cover. In there, it says that while towing, OD should be used. Is GM looking to sell more trans rebuilds? I also thought that OD should not be used until reading this. It is a lease vehicle and I plan on returning it every 3 years, but I also want to get the most for it when I turn it in. I really like the ride vs the smaller S10 version of this truck. Thanks for your info.

olredalert
07-26-2001, 11:39 PM
Boldts,
Scot,I have way more knowledge about 4L80s than what I think you are referring to,a 4L60 or,basicly,a computerized 700R.These new series of trucks are out of my territory.The button for towing on the shift arm and all.My first thought when they came out was"uh oh,another gimmick".But I have at least heard posotive things about the new trucks in light tow situations.No direct knowledge though.Cant afford to get rid of what I spent so much time developing(my present 93 Suburban"duallie",with a 502 monster torque motor in it).Hopefully,sometime soon Ill have a boat to tow behind it to one of the great events you guys are putting on.It couldnt happen too soon!........Just.......boatless......ol red!

Formula Jr
07-26-2001, 11:49 PM
Do you guys know that you have just put out more relevant information about transmissions than Trailer Boat Magazine has in the past five years! I'm impressed!

Rootsy
07-27-2001, 08:46 AM
The new Chevies and GMC's have a Tow/Haul mode. when you activate it, it locks the converter up and changes the shift points in the trans. So yes you can tow in OD if you have the HP and with that 4.8 and 5.3 you DEFINITELY have enough! Now take my 98 F150 4X4 Offroad... you have to put it in 3rd to pull so you dont smoke the trans and at 70 mph you are crankin 3000 rpm and that little 4.6 has just about enough power to go that fast with 5000 lbs hangin off the receiver. I always have been a Ford man BUT i've come to realize, they are just wussified...

Anyone one want a big blue ford? Exceptionally good condition.. 68,000 miles.... new rubber and shocks.

CRAVING a NEW Chevy!!!!