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Tranny poop

Discussion in 'OffRoad Design' started by **DONOTDELETE**, Jan 22, 2001.

    What building tips can you offer in creating a bombproof TH700R4? What have you done and what is proven? I know about JET, B&M, and TCI, but is there an ORD alternative? I have a 495 lbs.ft. HD 6.2L turbo diesel, and am taking the next step of installing a heavy duty tranny. Y'all have one hell of a product line, and it makes my burban crawl. Thanks for you support.

    '85 K20 suburban-rear 10.5"FF, front GM 8.5"
    6.2L HD Detroit Diesel-turbo
    5.5"combined lift
    35"BFGs
     
  1. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    This may be a topic for the diesel page, but what did you do to the 6.2 to get 495 ft-lb? Jim Allen's dyno sheets on his turbo's 6.2L K5 only showed 385 with all the tweaking he could come up with. That's at the rear wheels, and in Denver (high altitude) but that's still a pretty good difference!

    Now, for the guts of the question!
    My trans has lived behind the 383 since about 1990 or '91. The last 4-5 years of that have been fairly hard on it, the first couple were basically just hard street driving. Also keep in mind my built 383 probably never put out more than 350lb-ft at the flexplate due to altitude.
    We took a brand new GM trans, disassembled it and put in the full B&M kit. It's the one that adds extra clutches, etc, about $350-$400 if I remember right. That's all. It was a late 80's or early 90's version trans that we started with, so it had a lot of good upgrades already.
    I've run a gauge and big cooler on it the whole time and make sure to tame things down when it gets over about 210.
    That's about it.
    Art Carr is going to build my next trans, they have a lot of cool stuff for the 700 like new sun gear shells and other goodies. We're starting to deal their line, so I have pretty good confidence in their parts.
    My crewcab is keeping the TH400 and getting a Gear Vendors behind it to have overdrive. That way I can split all the gears.
    Hope this helps

    Making the world better, one truck at a time.
    [​IMG]
    SW-ORD
     
  2. For the monster torque, I used Peninsular Diesel's 19:1 compression pistons in conjunction with a Gale Banks turbo, 105 gpm water pump, dual thermostats, a gear drive, blah blah blah. It's a ground up diesel taken from a military CUCV 5/4 ton pickup. It was balanced, ported and polished, and bored .030 over stock. It surprises a few folks. I made a few calls to local tranny shops that build automatics for top fuel dragsters, and they all use aftermarket kits like the ones you suggested and apply them to a later model trans. Since diesels develop everything around 1900 rpm, I'm not worried too much about the famous 3-4 shift point since I'm turning nearly 2400 at that time. What concerns me is the first and second gears when I'm climbing a hill or crawling over something. Has anybody else done this before, or am I the lone pioneer? I am in fact a member of the dieselpage, and am posting there too. Getting all the facts before I write the check! Thanks.

    David
     
  3. RUSS84K5

    RUSS84K5 1/2 ton status

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    You might want to look into replacing the forward sprag unit with a "machanical diod" it a self contained ratchetting assembly made my Reybestos. I got mine from TransStare Inc.
    You should be able to find a local dealer on the web. Cost was 70-80 bucks
     
  4. ken

    ken 1/2 ton status

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    All I gotta say is thats gonna be one spectacular bomb going off under your truck when it "sees" 495 foot pounds!!! Sorry for the wasted post, but I TOTALLY DISDAIN 700R4 trannys and would NEVER EVER have another in a truck again...after having gone thru 6 of them. (I spent the weekend yanking the 700 and installing what should have been in there in the first place, a TH400!!).

    ken
     
  5. Stephen

    Stephen 1/2 ton status Moderator Vendor

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    Not sure what to tell you on the trans. You're a little over what most people recommend for torque capacity on a 700R4, but there are some companies making new parts that change the old rules. And if the vehicle is set up and driven right, you can be a LOT easier on the trans.
    I'd like to do the full diesel buildup, but I got a complete already built motor with a turbo for my crewcab, so it's just going in. Maybe a sqeeze of propane? I know the 6.2 is marginal for that, so I'll probably just take what I can get.
    But, I have considered dropping that diesel into the K5. Especially after a couple of long desert trips and living with gas motor milage, grrrr. hate to carry extra fuel for a 31 gallon tank and still run out before the end. But that's what the big truck will be for now. with 40 gal of diesel and maybe a 31 gal K5 tank also, it should be OK.

    Making the world better, one truck at a time.
    [​IMG]
    SW-ORD
     
  6. A co-worker has a 6.5 GM crate with a Banks turbo and he's been through 4 T700's in 2.5 years. That's with using the best shop around.'83 K25 3.73's and 33's isn't a stressful combo. He's fed up and is going to swap to a 4L80 when he get's the ATS propane. As it turns out there is 3 options to control it: factory GM 6.5&4L80 computer from a bone yard, Jet controller, and the one I found yesterday on pg 170 in GM Perfomance Parts catalog a controller for use in a non computered engine(4L60 and 4L80).
     

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