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Just Purchased 90 3/4T Suburban and I have questions...

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Wheeling Arizona, Jan 19, 2002.

  1. Wheeling Arizona

    Wheeling Arizona Registered Member

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    Hi all,

    I'm a Jeep guy with a just purchased '90 3/4T Sub. So I thought I would sign up here and start asking questions. So here they are:

    1) Looks like a 10bolt front and a 14bolt rear...is that correct?
    2) The t-case is a 241 slip yoke...opinions? Thing is leaking like a faucet and I hate slip yokes. Looks similar to the 231's they put on Jeep's now-a-days. Is ATF that is in there?
    3) The suspension is ROCK HARD! This thing has a rougher ride than my Jeep ever had! And it has a long wheelbase! I here that the Skyjacker lift kits ride fairly nice? Opinions?
    4) It is an automatic w/ tow package...what tranny is in there?
    5) I think the front left automatic hub is blitzed. It will make a grinding noise (ocassionally) and then release when I stop. I have ordered some Warn premiums for it...do I need any kind of conversion kit to go with it?
    6) Any tips on improving fuel economy a bit on this hog?

    Thanks,
    Steve
     
  2. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Welcome to CK5 Steve,

    1) Looks like a 10bolt front and a 14bolt rear...is that correct?


    Yes, either a FF 14 bolt or a SF. Both are strong diff's.

    2) The t-case is a 241 slip yoke...opinions? Thing is leaking like a faucet and I hate slip yokes. Looks similar to the 231's they put on Jeep's now-a-days. Is ATF that is in there?

    It is the 231's bigger brother...very similar except it uses a 6 gear planetary instead of the smaller 3 gear version found in the 231. SYE kits are readily available. Yes it does use ATF...

    3) The suspension is ROCK HARD! This thing has a rougher ride than my Jeep ever had! And it has a long wheelbase! I here that the Skyjacker lift kits ride fairly nice? Opinions?

    There are several soft ride kits out there that will help the ride and give good articulation. BDS, Tuff Country, etc all offer soft ride kits. ORD also offers greasable bushing kits that have a dramatic affect on ride.

    4) It is an automatic w/ tow package...what tranny is in there?

    Should be a 700R-4. If it doesn't have one install the largest cooler available. If you tow do not tow in OD...

    5) I think the front left automatic hub is blitzed. It will make a grinding noise (ocassionally) and then release when I stop. I have ordered some Warn premiums for it...do I need any kind of conversion kit to go with it?

    Straight swap...

    6) Any tips on improving fuel economy a bit on this hog?

    Just the standard stuff...a good tune up and new filters, make sure the tire size versus gearing is in the right range so it doesn't lug. Other than that you'll have to take into acount you're moving 3 tons of 'barn' down the road...[​IMG]

    Rene

    <font color=green>Dyslexics of the world...UNTIE!</font color=green>
    <a target="_blank" href=http://coloradok5.com/gallery/project_T2> tRusty pics...</a>
     
  3. wayne

    wayne 3/4 ton status

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    1. Probably correct. 10 and 14bolt.
    2. 241, good t case. Good low range and can be converted to a fixed yoke output.
    3. I would recommend BDS.
    4. If it is auto with overdrive, th700r4. Lots of upgrades available.
    5. You don't need any conversion kit as fas as I know. I believe you are referring to the part time kit for a 203 t case.
    6. Keep you foot off the skinny pedal.[​IMG]

    See <a target="_blank" href=http://coloradok5.com/gallery/Waynes-Toy>Project Mighty Mouse</a> here.
    <font color=blue>Wayne<font color=blue>
    <font color=blue>Happy Trails<font color=blue>
     
  4. Thunder

    Thunder 3/4 ton status

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    Answers:

    1. sounds right

    2 yup it is a 241 and that is ATF in there. its a good x-fer case.

    3. Kinda strange, the ride is rock hard. Most subs ride pretty good. Does it have add a leafs? Not sure what lifts are good for a Sub but I like <a target="_blank" href=http://rough.roughcountry.com/>Rough country products</a> my self

    4. Your tranny is a 700r4. A good trans but they dont like heat. Make sure you have a good trans cooler. And change the fluid. OFTEN!

    5. Get rid of the auto hubs they are nothing but trouble. Replace them with a good set of manuals( Superwinch, Warn premimums) No conversion is needed. Unless the auto hubs have 3 bolts holding them on instead of 5. If they have 3 bolts there is a spindle kit you need (I think)

    6. As for the fuel economy make sure it is in good tune, Keep the air pressure up in the tires. A K&amp;N filter and good flowing exahust will help.

    <a target="_blank" href=http://coloradok5.com/gallery/Thunders-Blaze> Blazer pics</a>

    <font color=blue>Nevada... Where the pavement ends and the west begins
     
  5. chvyhs

    chvyhs 1/2 ton status

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    I just bought the same model in Nov. I had a problem with my ride being too rough too. It turned out be the front spring bolts and the upper and lower shackle bolts were too tight.

    <a target="_blank" href=http://community.webshots.com/user/chvyhs>WebShot Pics</a>
     
  6. Burbinator

    Burbinator 1/2 ton status

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    Are you and Thunder sure about the 700R4 tranny? Since it's a 3/4 ton, shouldn't it have a 4L80E?

    Just curious, because my '91 has that trans (4L80E)...

    Haze gray and underway...<font color=blue>or blue, in my case.</font color=blue>
    <a target="_blank" href=http://community.webshots.com/album/26246038MbQsYWKcbo>U.S.S. Nimitz II</a>
     
  7. 89GMCSuburban

    89GMCSuburban 1/2 ton status

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    To see if its a 700R4, look at the driver's side of the tranny. If there's a 4 prong plug going into it, it's a 700R4. On a 4L80E, it will have one huge plug going into it. Is it a 4 speed trans? Didn't some 3/4 ton burbs come with 3 speed auto trans?

    Red 1989 GMC Suburban SLE V1500 - TBI 350, 700R4 w/ shift kit, Quad-shock front, 31/10.50/15 Pro Comp MT, 4.10 gears, Duals off cat
     
  8. Burbinator

    Burbinator 1/2 ton status

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    I'd be willing to bet it's not a 700...

    A TH400 has been known to reside in some 3/4 ton Burbs.

    Haze gray and underway...<font color=blue>or blue, in my case.</font color=blue>
    <a target="_blank" href=http://community.webshots.com/album/26246038MbQsYWKcbo>U.S.S. Nimitz II</a>
     
  9. Wheeling Arizona

    Wheeling Arizona Registered Member

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    Just cleaned the tag on the tranny and it says:

    Turbo Hydra-matic
    9201
    90-LWA-1132

    Can one of you guys decipher for me?

    Thanks,
    Steve
     
  10. Wheeling Arizona

    Wheeling Arizona Registered Member

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  11. Thunder

    Thunder 3/4 ton status

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    Oops i forgot they used th400s in 3/4 tons up till the early 90s
    I dont think they came out with the 4L80e till 1991.
    The TH400 and the 4L80e have the same pan so.........
    If it is a 3 speed auto it is a TH400
    If it is a 4 speed with over drive then you have a 4L80e




    <font color=blue>Nevada... Where the pavement ends and the west begins<P ID="edit"><FONT class="small">Edited by Thunder on 01/19/02 11:50 PM.</FONT></P>
     
  12. Sparky87k5

    Sparky87k5 1/2 ton status

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    Rear axle is 14B semi floater 9.5" ring gear. Full floaters were not available in Suburbans that year. Trans is a T400. Surprised it rides "rock hard", try different shocks.

    87 K5, 427BBC,D60 & 14BFF, NV4500, NP208, TSM disc's,
     
  13. Burbinator

    Burbinator 1/2 ton status

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    Here's a definitive way to ID your tranny...now I have time to list an explanation.

    A TH350 pan is a square with one corner cut at a 45 degree angle.
    A TH400 pan looks similar to the state of Texas.

    If you have overdrive, disregard the above and look for the following:
    A 700R4 pan is a perfect square.
    A 4L80E pan is a rectangle, rounded at the rear.

    Another sure fire way is to look up the RPO code (sticker is inside the glovebox) <a target="_blank" href=http://www.wiu.edu/users/muwtj1/rpocodes.htm>here</a>. The code listed for my 91's 4L80E is "MT1".

    Axles should be 10 bolt front, 14 bolt 9.5" SF rear...look up the RPO's with the above link.

    The leaking slip yoke can be sealed. Someone told me on here that there is a zerk type fitting on the inside of the yolk closest to the t-case that works its way loose or falls out. Either tighten it or JB Weld it. Mine was leaking as well and still intact, so I tightened it. No more leaking.

    Hope that helps!

    Also, welcome to CK5! Fill out you profile, too!

    Haze gray and underway...<font color=blue>or blue, in my case.</font color=blue>
    <a target="_blank" href=http://community.webshots.com/album/26246038MbQsYWKcbo>U.S.S. Nimitz II</a>
     

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