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tranny Qs

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 90K5, Oct 8, 2000.

  1. 90K5

    90K5 1/2 ton status

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    I have a 700R4 and I already have a cooler in it. I need to know how hard it is to put a B&M megashifter in it. Has anyone done this? Also how much does a deep pan really help if you already have a cooler? I have a deep pan butg its chrome and rusting, so I was thinking about putting the stock one back on.

    90K5
     
  2. ken

    ken 1/2 ton status

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    Chrome retains heat, so put your stock one back on, it'll run cooler!

    ken
     
  3. Blue85

    Blue85 Troll Premium Member

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    The main advantage of the deeper pan is to hold more fluid. It doesn't help with cooling nearly as much as an oil cooler, especially if you are not moving very fast.

    Chrome can always be polished and waxed for protection, though.

    '85 JIMMY
    '90 paint/grill/trim 5"susp 33/12.5/16.5
    Fresh 350 B&M '87 TH700
     
  4. blazen91

    blazen91 1/2 ton status

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    I just had my 700r rebuilt and he put in a Corvette servo instead of a shift kit. It works great!! Another CK5 guy did it also, and liked it. See post "Ya'll with shift kits...".

    blazen91
     
  5. ken

    ken 1/2 ton status

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    A good reason NOT to put in a Corvette Servo, or a shift kit for that matter, in a 700r4... (from the drivetrain page):

    Alter Shift Quality, When, and If It is Needed
    By Example: The 700R4, and Why I Do Not Recommend Shiftkits in 700's...
    Some transmissions do have shift quality problems that need to be dealt with. For example, the 700R4 transmission has a nasty habit of burning the 3/4 clutches. To "fix" this problem, many rebuilders add an "Alto" kit (or another brand of clutch pack, that are thinner, providing room for more clutches), and drill out the apply hole (which makes the clutch pack apply more quickly). In addition, to make the transmission shift harder into second gear, they change to a Corvette servo piston, which has more apply serface area. The 700R4 3/4 clutch pack usually burns up, as a direct result of a few different problems, all of which are not addressed by most technicians. Number one: the 2nd gear band must release when the 3/4 clutches apply, to produce a 2nd to 3rd shift, so, when they increase the apply area of the band,(to make the 2nd gear shift harder), they also make the band release more slowly, and, together, with the 3rd apply hole, they drilled out, to make the 3/4 clutches apply more quickly, they produce a "bind up" in the 700 which causes the 3/4 clutches, and the 2nd gear band, to burn up, prematurely, due to excessive heat. (Remember, the original problem with a 700R4 is premature 3/4 clutch burn up, which has just been made worse by the technician who "improved" the unit). In addition, the 700 has a couple other weak points that include a weak sungear shell, and a weak input sprag, which both hold up fine, unless they are "hammered on" by harsh shifts. Installing a shiftkit in a 700, to produce firm shifts, will CAUSE transmission failure. GM has found, by smoothing out the shifts, that the input sprag, and sungear shell, are very reliable components. GM has also found that by INCREASING the thickness of the 3/4 clutch steels (rather than decreasing the thickness, like the Alto kit does), the clutches can dissipate more heat, sucessfully, without burning up the clutches, and make the 3/4 clutch pack last longer. In addition, many rebuilders have found, including myself, that increasing the size of the 3/4 release hole to .078" (I got this trick from a shift kit, so I must admit that shiftkits can be a "good thing" if the correct things are altered, for the right reasons), which tends to help the 3/4 clutches release during a 3rd to 2nd downshift, eliminating "bind up" in this condition, as well as replacing the servo accumulator check ball capsule (the capsule wears severely, and can be the CAUSE of 3/4 clutch failure, in many cases, and drilling the 3rd clutch apply hole to around .090", can all help make the 3/4 clutch failure a "thing of the past", in most cases. One more interesting comment about 700 "common repair mistakes": I have never seen a problem with the 2nd gear band overheating, due to a soft 1st to 2nd gear shift....So why does everyone want to install the Corvette servo piston that has more surface area. The corvette uses a specially calibrated valvebody and separator plate, designed with the special servo piston in mind, so it does not produce a tremendously hard shift, into second; installing the Corvette servo in a transmission that does not have a valvebody and separator plate designed with the Corvette servo piston in mind, produces a harsh shift that causes premature failure of the sungear shell, and input sprag.


    ken
     
  6. River

    River 1/2 ton status

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    Ken is this your opinion or did you find the text on a webpage?
    If it`s your opinion a would like to ask you a view questions about what is a good shift kit or about wich parts to install from a shift kit.
    If it`s not your opinion from who did it come can i ask him the questions.

    Greetings from Amsterdam,

    River `90 K5, 350, TH700R4, NP241, "33, 3.08, 10 bolt F, 10 Bolt R(GOV-Lock)
     
  7. ken

    ken 1/2 ton status

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  8. getsome

    getsome 1/2 ton status

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    I understand that the early 80's 700r4's had a bad reputation for premature failer and that this was corrected in the late 80's. Is this what GM did on the later year 700r4 to get them more reliable? A long time ago I was reading about a shop that would rebuild your 700r4 with the enhancements of the late 80's 700r4 to make it almost bullet proof. What are the upgrades that make the late 80's 700r4's so much better the the early 80's?

    Getsome
     
  9. Derf00

    Derf00 1/2 ton status

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    Ken,

    That is a great transmission web-site, it should be required reading for anyone with an automatic transmission.
     
  10. ken

    ken 1/2 ton status

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    Yeah, I especially like the comment that the writer makes that the GM Engineers must've had a great sense of humor when they decided on tow ratings for 1/2 ton trucks with OD trannys!!

    ken
     
  11. Blue85

    Blue85 Troll Premium Member

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    The upgrades from the early 80's to the late 80's include:
    New front and rear sprags (tougher)
    A 10-van oil pump instead of a 7-vane
    Different 3-4 clutch pack

    Somebody help me out because I can't remember any more right now.


    '85 JIMMY
    '90 paint/grill/trim 5"susp 33/12.5/16.5
    Fresh 350 B&M '87 TH700
     
  12. ken

    ken 1/2 ton status

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    All I know is that I'm on my FIFTH one in 220,000 miles in my 1990 Suburban that sees ZERO towing!!! If that doesn't qualify as junk, I don't know what does!

    ken
     
  13. blazen91

    blazen91 1/2 ton status

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    That's good information. Thanks. The shop that did mine installed a 7 disk clutch in it and said they offered a 13 disk clutch(I think??),but DID NOT recimind it for the reasons above, however did recimind the 7 disk. Any input on that? The guy who owns the shop has a K5 with 14b and 35's, and claims his trans is exactlly the same as mine except he has the stronger sprag.

    blazen91
     

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