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.

Towing in OD w/700R4 ?'s

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Hossbaby50, May 4, 2003.

  1. Hossbaby50

    Hossbaby50 3/4 ton status

    Joined:
    Sep 1, 2001
    Posts:
    8,972
    Likes Received:
    0
    Location:
    Peoria, AZ
    Towing in OD w/700R4 ?\'s

    Ok, it looks like I am moving back to AZ in a few weeks. I will be hauling a 4x8 uhaul trailer behind my K5 on the way back. It won't have much weight in it. A futon bed, 1 set of mounted tires, and other little crap. Here is my questions and dilemma's:

    Specs: '85 K5, crate 350, 4.56 gears, GM cert rebuilt 700R4, stacked plate trans cooler, trans temp gauge, and I should have a remote filter kit installed with a 1 qt filter on before I leave.

    I have searched and read on towing in OD. Some say ok on flats and bad in hills (duh)

    My dilemma is to run my 32's or 35's. I would like to run the 32's because they are an AT vs. MT, are under warranty, and the 32's make the truck easier to stop. But if I have to run in D the 35's will help keep RPM's down with the 4.56 gears. (65mph=300Rpm)

    All comments, thoughts, and experience are welcome. Thanks

    Harley
     
  2. Can Can

    Can Can Pusher Man Staff Member Super Moderator

    Joined:
    Feb 17, 2000
    Posts:
    15,552
    Likes Received:
    136
    Location:
    Cochrane, Alberta, Canada
    Re: Towing in OD w/700R4 ?\'s

    To put it simply:

    If the engine feels like it's lugging or the tranny is trying to downshift, put her in drive. I always tow in D regardless but I never tow anything under 3000 lbs.

    32s and 4.56 will make your OD feel a lot more like D. Because of your gearing I would be less concerned. If you really want to be sure that your 700 is staying cool I would recommend that you install a tranny temp gauge before your trip. That's the only way to ensure that you don't overheat the sucker.
     
  3. Hossbaby50

    Hossbaby50 3/4 ton status

    Joined:
    Sep 1, 2001
    Posts:
    8,972
    Likes Received:
    0
    Location:
    Peoria, AZ
    Re: Towing in OD w/700R4 ?\'s

    Actually I already have a B&M trans temp gauge installed. I am going to install a Perma Cool Remote Trans filter before I leave that will give me some more fluid capacity and also alot more filtration. I bought the 1 quart Napa Gold Filter for it the other day.
     
  4. jwduke

    jwduke 1/2 ton status

    Joined:
    Aug 25, 2001
    Posts:
    721
    Likes Received:
    0
    Location:
    Ice Cream Capital of the World, IA.
    Re: Towing in OD w/700R4 ?\'s

    Harley, if it gets to doing that "gear hunting", you know going back and forth from 3rd and 4th, then run it in 3rd (Direct). Thats when you get your major heat build-up. Good luck in moving!
     
  5. wrathORC

    wrathORC 1/2 ton status

    Joined:
    Apr 27, 2002
    Posts:
    908
    Likes Received:
    0
    Location:
    Hancock, MI
    Re: Towing in OD w/700R4 ?\'s

    As long as the torque converter stays locked up you'll be alright in overdrive.
     
  6. Hustler

    Hustler 1/2 ton status

    Joined:
    May 14, 2001
    Posts:
    326
    Likes Received:
    0
    Location:
    St. Peters, MO
    Re: Towing in OD w/700R4 ?\'s

    I wouldn't worry about it unless you are down shifting all the time. Then, just put it in D, not OD. I tow mine all the time and always keep it in OD.
     
  7. JustHorsinArownd

    JustHorsinArownd Registered Member

    Joined:
    Mar 20, 2003
    Posts:
    77
    Likes Received:
    0
    Location:
    Flagstaff, Az.
    Re: Towing in OD w/700R4 ?\'s

    Not for nuthin but I've always been told to never tow up hills in OD always downshift to third then once you get back to flat or downhills it's up to you. Good luck on the drive.
     
  8. Chris_T

    Chris_T 1/2 ton status

    Joined:
    Mar 17, 2001
    Posts:
    718
    Likes Received:
    0
    Location:
    Saskatoon, SK
    Re: Towing in OD w/700R4 ?\'s

    Since you're towing and have the OD, I'd run the 32's for the reasons you stated: better tread pattern, and braking (important even with a light trailer). The 300 rpm probably won't make a huge mileage difference, but may be enough to keep your 700R4 locked in OD vs. hunting - depending on your speed of course.

    I drove my 72 K5 (350/700R4/4.56) 1800 miles on 235/75R15s because it was winter and those were my ice tires (vs. 35" BFG MTs)and the rpms were not a real killer.

    I think you'd be fine in OD. I know that I am in my 94 when I tow a light trailer (canoe trailer) but not with the 17 foot camper I had (kept it in D). If you have a tach, watch the rpm vs. speed on the flats and going up hills, slight grades, strong headwind/etc. to see if the convertor is slipping (unlocking) under load and use your best judgement based on that and trans temp. I think you'll find the 32s to be a much better towing tire. On my 35s, I have to keep my speed above 65 mph or they don't really like it - for example, at 60 mph on the 35s, the rpms I run start to bog the truck down in 4th up a long hill (my convertor is manually switched and won't unlock) because they're not in the right powerband. At 70 mph, you wouldn't even know there's a hill there.

    Your number one concern should be tranny longevity, and you can monitor that with the temp guage, maybe see if it runs cooler in D or OD (remember the trans pump spins faster in D) over a stretch of similar road. Secondary to that is efficiency/economy, which you can get a pretty good "seat of the pants" feel for. If the truck sounds like it's working hard (bogging, lugging, downshifting, requiring a heavy right foot, etc.) then it's probably not running very efficiently (sub-optimal rpm range, convertor slippage .. blah blah blah). But you've got all the right stuff for you to make that decision once oyu get on the road because your truck won't behave the same as mine or someone elses that doesn't have all the same equipment. Good luck, I'm sure you'll have no problems.

    C
     
  9. Hossbaby50

    Hossbaby50 3/4 ton status

    Joined:
    Sep 1, 2001
    Posts:
    8,972
    Likes Received:
    0
    Location:
    Peoria, AZ
    Re: Towing in OD w/700R4 ?\'s

    I do have a tach, and I think I have nailed lockup on my converter to around 1700-1800rpm. Cruising at 65 with the 32's is roughly 2200-2300rpm which should keep it locked up. I do notice the difference in power around town between the 2 sets of tires so I will definilty run the 32's to get home.

    Thanks for all the input everyone.

    Harley
     
  10. Chris_T

    Chris_T 1/2 ton status

    Joined:
    Mar 17, 2001
    Posts:
    718
    Likes Received:
    0
    Location:
    Saskatoon, SK
    Re: Towing in OD w/700R4 ?\'s

    Best of luck!
     
  11. wadinator

    wadinator 1/2 ton status

    Joined:
    Dec 18, 2001
    Posts:
    233
    Likes Received:
    0
    Location:
    NW Iowa
    Re: Towing in OD w/700R4 ?\'s

    Hey guys.

    Where can I get a tranny temp gage for my 87 burb with a 700R4? I've always wanted one, but I thought there wasn't a plug on the tranny that'll support a temp gage's sensor. /forums/images/graemlins/ears.gif /forums/images/graemlins/thumb.gif
     
  12. outlaw612

    outlaw612 1/2 ton status

    Joined:
    Feb 11, 2001
    Posts:
    2,342
    Likes Received:
    0
    Location:
    Springfield, Illinois
    Re: Towing in OD w/700R4 ?\'s

    You can buy a gauge from Summit and just have the bung for the sender welded in the pan.
     
  13. heavy4x4

    heavy4x4 1/2 ton status

    Joined:
    Aug 28, 2002
    Posts:
    3,270
    Likes Received:
    0
    Location:
    Delafield, Wisconsin
    Re: Towing in OD w/700R4 ?\'s

    I've got an Autometer tranny temp gauge in my truck. I drilled the pan, tapped it with a 1/4" pipe tap, and then JB-welded the sender in too. Pics are in my Webshots (link below). I bought mine from a local 4x4 store, but I believe Summit carries them.
    You can also get a B&M tranny temp gauge which comes with a T-fitting to plumb into the tranny lines.
     

Share This Page