Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

700R4 Problems ??

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by njonl, Jul 6, 2003.

  1. njonl

    njonl 1/2 ton status

    Joined:
    Jun 30, 2003
    Posts:
    128
    Likes Received:
    0
    Location:
    Northern CA
    Regretfully, I let a buddy borrow my '85 Blazer to go camping. He comes back and something is very wrong with my transmission. I have no third gear or overdrive. It slips really bad when trying to go into third. When it shifts from first to second, it shifts really hard. I checked the fluid level and it is actually too full. Is my transmission toast ? Is it even worth rebuilding ? Any idea of how much a rebuild would cost ? This is such a bummer because everything was going great. Thanks for any help or advice.
     
  2. bryguy00b

    bryguy00b 3/4 ton status

    Joined:
    Apr 7, 2002
    Posts:
    5,587
    Likes Received:
    0
    Location:
    Rochester, N.Y
    i would take it out and put a 400 in it..thats what i plan on doing to mine..when the time comes..but hopefully mine will last a while..was rebiult in 2001 and thers only like 500 miles on it since then..and i just bought a big a$$ 24,000 GVW B&M cooler for it..
     
  3. ken

    ken 1/2 ton status

    Joined:
    Feb 17, 2000
    Posts:
    1,244
    Likes Received:
    0
    Location:
    Anaheim, CA
    The same old story, 700s acting funny then blowing up. Sorry to hear it, but now's your chance to swap in what should be in there, a TH400. Oh yeah, boo-hoo, you won't have overdrive, but at least you won't be broke repairing 700s all the time!!!
     
  4. nevercomplete

    nevercomplete 1/2 ton status

    Joined:
    Dec 25, 2001
    Posts:
    309
    Likes Received:
    0
    Location:
    Beaufort, South Carolina
    Man, you really hate 700's dont you?

    Jon
     
  5. Bubba Ray Boudreaux

    Bubba Ray Boudreaux 1 ton status

    Joined:
    Jan 21, 2001
    Posts:
    20,716
    Likes Received:
    2
    Location:
    Undisclosed Location
    Don't think he does. Of course I'm sure all these trannys blowing up couldn't be attributed to the driver/maintenance issues. /forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gif

    Mine's been in for 11 years and as for mileage, I've put 90K on it since I've had it since '95.
     
  6. nevercomplete

    nevercomplete 1/2 ton status

    Joined:
    Dec 25, 2001
    Posts:
    309
    Likes Received:
    0
    Location:
    Beaufort, South Carolina
    Yeah, my tranny has over 150,000 miles on it and still no trouble out of it. Previous owner took care of it and so do I.
     
  7. Foy

    Foy Registered Member

    Joined:
    Oct 28, 2002
    Posts:
    34
    Likes Received:
    0
    Location:
    Raleigh, NC
    My 700 in a '90 Sub K1500 survived 80,000 miles by the original owner, virtually all around town in hot, hot, NC. The miles not in town were towing a heavy horse trailer to the NC mountains and down to SC. I then bought it and drove the heck out of it on trips, including some towing the 5000# boat, motor, and trailer, plus wife, sons, dogs, gear. I started to get some "fluttering" while towing, and about that time I first learned about the advice not to tow in overdrive. Towing, or even fast non-towing driving in overdrive (these pre-92s have the aerodynamics of a big cinder block, after all) causes the torque converter to pop out of lockup for long distances, such as all the way up long hills/mountain passes. That causes a large amount of heat buildup--the principal enemy of any auto trans. I wised up on the OD towing and became very attuned to listening for the torque converter unlocking and would feather the throttle such that it'd lock right back up, and I drove that gearbox to 159,000 miles before a professional rebuild. During that rebuild, I had the shop do some common tweaking designed to strengthen the torque converter, clutches, etc, and now she's got 180,000 and is going strong. Oh, I also had a Mongo-sized trans cooler installed then, plumbed directly to the trans rather than routing through the radiator.
    Seems to me that a combination of tall gears, tall tires, hot summers, fast driving with the torque converter unlocked, and maybe some poor maintenance (letting the fluid get low, or failing to change it more often than the book calls for) will lead to overheating, and it seems that the 700 may be more sensitive to overheating than other auto transmissions, so the pop more often, and are generally thought to be POS transmissions. Seems that some book learning and some TLC will get long life out of them, however.

    Case in point- there's a very interesting thread on the VMag Suburbans and Tahoes board where a guy installed oil temp, trans fluid temp, and rear axle temp gauges in his '96, then reported on the temp behavior over a lengthy trip, towing, if I recall correctly. The most telling fact was that his transmission fluid temp immediately went up by 20-30 degrees when the torque converter unlocked. Also interesting, since we're there, is that while driving through heavy rain, the trans fluid temp went DOWN BY 50 degrees. Makes me want a water reservior so toggle on to spray nozzles directed towards the transmission pan with something like a boat bilge pump while climbing passes.

    Foy- Destroyer of 2 700r4s and a TH 350, before he Saw The Light.
     
  8. bajaviking

    bajaviking 1/2 ton status

    Joined:
    Apr 10, 2002
    Posts:
    752
    Likes Received:
    2
    Location:
    Baja
    In the 3 years I've had my truck I have put 48,000 miles on it and no problems. This is my daily driver as well as my week-end toy, I have been waiting for something to happen to my tranny or engine to have an excuse to get a performance rebuild but I can't kill the damn thing. I change the oil and watch the levels but besides that I don't do anything special to keep it running. Unless you have a lot of engine power I don't see why you should not be able to run a 700 for a long time. I sure like the overdrive on the freeway.
     
  9. 75-K5

    75-K5 3/4 ton status

    Joined:
    Apr 28, 2002
    Posts:
    5,353
    Likes Received:
    0
    Location:
    Anderson, Indiana
    We just traded in our '89 G20 van with 175k on it. We bought it new and did absolutely jack to the transmission the whole time. Not one bit of maintenance. My dad treats all of his cars like sh1t, and this was his DD for 14 years. When we got rid of it, there were still no problems with it. It didn't shift as firm as it should have, but it was reliable. The woman who bought it from the dealer after we traded it is the bartender at a club my dad belongs to, so he still sees it every few days. It's still going strong and is her only car. Judging from this experience, I'd say a 700r4 can take a good beating. Granted, a 2wd van putting out 200 hp max is a little different from a built 350 on a K5 or burb running big meats, but strong nonetheless.
     
  10. Drewminator

    Drewminator Registered Member

    Joined:
    Jun 23, 2003
    Posts:
    14
    Likes Received:
    0
    Location:
    Grand Rapids, MI
    I've got a rebuilt 700r4 behind a 400 hp 406 and it's holding up fine. Yes, stock 700r4's are not as strong as a 400 but when you rebuild them right and maintain them they will hold up. It's my understanding that GM beefed them up some out of the factory after a certin year ('90 maybe). I'm not a transmission guy but had mine rebuilt by a guy I know that has his own trans shop and knows exactly what needs to be done to make them strong. After you rebuild them right & beef them up they are a great transmission. Yes, the overdrive is great, especially if you have bigger tires and low gears - I'm running 36's and 4:88's and still run about 2500-2700 rpm at 75 mph. in addition you have a great 1st gear ratio - much better than the 400 for crawling and such.

    Bottom line - if overdrive and a great 1st gear ratio are important to you find someone that can rebuild the 700 right and get a price on the rebuild. There are also aftermarketers out there that sell them already beefed up (I think Jet offers one). Get a price from both. Find a rebuilt 400 or a used one and get a price for a rebuild on that. Compair & make your decision.

    Think about adding a trans cooler to your rebuild or replacement what ever you choose - heat kills trannies. At least, put in a trans temp gage to make sure it does not get too hot - my sensor is right in the pan. I also added a B&M cooler with a thermostat controled electric fan as added insurance to my rebuild.

    Built right & maintained right both the 700 & the 400 will hold up to normal "abuse" from an off roader.
     
  11. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

    Joined:
    Aug 28, 2002
    Posts:
    9,097
    Likes Received:
    144
    Location:
    california
    HEY KEN, HOPE YOUR READING THESE POSTS. NOW WHO LOOKS DUMB!! /forums/images/graemlins/thumb.gif /forums/images/graemlins/thumb.gif /forums/images/graemlins/thumb.gif
     
  12. Drewminator

    Drewminator Registered Member

    Joined:
    Jun 23, 2003
    Posts:
    14
    Likes Received:
    0
    Location:
    Grand Rapids, MI
    Not everyone knows everything - just throwing in my 2 cents knowing it's worth what you pay.
     
  13. the professor

    the professor 1/2 ton status

    Joined:
    Feb 6, 2003
    Posts:
    130
    Likes Received:
    0
    For the guy about the TH400..

    I replaced a TH350/NP205 in my 1978 K20 with a totaly reconditioned TH400, new bushings everything to spec..I spent around $1100 in parts, on a trans out of a 1989 454 Suburban with 75,000 miles on it.. About the only thing I reused was the Torque Converter

    The TH350 ran behind my 454 for almost 6 years and 45,000 miles, doing burn outs, and would spin my 12.5x33" tires into second..

    The TH400 lasted exactly 5,530 miles before shredding the rear planetary.. One burn-out, less than 10 times "through the gears"

    The TH400's ultimate torque capacity is ONLY about 50ft.lbs. more than a TH350.. Its Orginal design was for SMOOTH shifts in Buicks, Cads and Oldsmobiles.I used a shift kit, the trans shifted no where near as hard as the 350, but a 400 will take no hard shifts..... GM uses the TH350 behind the 400 small block...

    The TH400 handles repeated slippy shifts without clutch failure better than a TH350..thats why it is used in heavy vehicles.. In actual practice, the weakest link in a TH350 is the 27 spline output shaft.. they take the very same torque coverter

    Why is this important, because the 700r4/4L60/4L60e are all based on the TH350..

    The 1986 and earlier 700's were originaly ONLY for V6's and 305's.. The TH350c lock up was used behind the 350's and Diesels, along with the 200..the 350c converter is the same as on some 200/700's

    The original design was weak and flawed, by 1987 vast improvements, finalized by 1989.... the design only got small improvements until the very latest "seperate bell housing 4L60E", and ALL the improvements are "backward compatable" to the 1987 and later trans...

    If you really want to abuse a TH700r4 / 4l60, parts are now available to handle up to 600+lb.ft. of torque, way MORE than a TH400.. the ONLY thing that will do more is a Powerglide...

    I have posted links to some of the places these parts are available before...

    Just like with the Q'jets, it is lack of knowledge that makes the 700 a demon... /forums/images/graemlins/cool.gif /forums/images/graemlins/truck.gif

    Oh yea, the TH400 is one of the most mechanicaly inefficient automatic transmissions on the market, and draws something like 35-50hp MORE than a 350 or 700..parasitic drag is spectacular, I noticed the difference immediately...

    Not to mention, that besides lacking a .7 OD, the TH400 has a 2.48:1 First gear vs. 3.0:1 with the 700.. Its like starting in second gear..

    And for my last trick, I am presently building a TH700r4/NP208 (want the lighter weight and syncro shifting, better ratios) from a 1988 for my 454.. I lucked out, its a 1991 case, Goodwrench rebuild in 1996.. has all the latest parts... We will see how long this one lasts...
     
  14. mrbill

    mrbill 1/2 ton status

    Joined:
    Jul 1, 2003
    Posts:
    170
    Likes Received:
    0
    Location:
    Sugar City, Idaho
    Searched this post on Trannys and had a few questions. :help: Having my 84 rebuilt engine (new crate 350) and tranny rebuilt. My shifter showed an OD but the mechanic says it was a TH350 and that I was lucky not to have the 700. Is that right? The rig will be duel use with lots of highway miles. Should I push for 700 or go with the 350?

    mr.bill -
     
  15. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,980
    Likes Received:
    189
    Location:
    Roy WA
    700 equipped truck would not have come with the "OD" indicator. Either its been swaped, or you've got a bad mechanic. Plenty of tranny ID pages so you can check for yourself.

    As to 700 vs 350, it is 100% entirely based on how you use the truck. Numerically high gears? Lots of off-roading? Heavy duty towing?

    As much as some hate to say it, try a search on 700 or 700r4 on this board, you'll get plenty of reading material.
     

Share This Page