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33" Tires and the 700r4

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by woodpecker, Jan 16, 2001.

  1. woodpecker

    woodpecker Registered Member

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    Hey Guys,

    Well, as is part of my usual day, I've been sitting here browsing the message forum, and came across some postings that scared me. Now granted, I'm easily scared b/c I'm a VERY novice mechanic. But . . .

    Someone posted that they had put a new GM 350 in their K5 w/ some new 33"s. Promptly thereafter, their tranny blew.

    I've got an '86 K5, 305 w/ 108K miles on it. According to most here, I'm hoping to get the "usual" 180K+ miles from it and the tranny. But long before the motor/tranny blow, I'd like to swap out the stock 31"s and put on some 33"s. I've got 3.73 gears and am wondering if this sounds like the recipe for disaster to any of you more experienced out there. I know that the 700r4 has a shady history, especially the earlier ones. I've recently checked the tranny fluid, smells/looks good (red and not burnt smelling). Will 33" tires send my 700r4 to an early grave?

    Any input would be appreciated.

    woodpecker
     
  2. gokartergo

    gokartergo 3/4 ton status Staff Member Moderator

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    Re: 33\" Tires and the 700r4

    I hope that is the recipe. Because that is what I plan on doing. I have a 86 blazer also. With 107000 miles on it. The 700r4 was rebuilt at 100000 miles and I put in the crate 350 at 105000 miles. I am currently running 3.08's with 32 tires. I think that is what took the tranny out the first time (before I owned it). I plan on putting the 4 in lift at the end of this month . Then hoping the tires hold out long enough for me to save the money to put the 33's on with the 3.73 gears.At the same time. I hope some more people have some insight on this. I don't do any major off roading just some hunting.

    Become one with nature...........Then marinate it..
     
  3. Espen88k5

    Espen88k5 1/2 ton status

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    Re: 33\" Tires and the 700r4

    It will be allright if you dont use the overdrive in town or when driving at slow speeds. And when highway cruising I shift down before starting a hill-climb. If I leave it in OD it sounds like it waits to long to downshift, and when it finaly does the rpm shoots upp and it slams down hard.

    I'm no mechanic, but thats what I've been told.

    <A target="_blank" HREF=http://www.espen88k5.coloradok5.com>http://www.espen88k5.coloradok5.com</A>
     
  4. 4GUNZ4X4Z

    4GUNZ4X4Z 1/2 ton status

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    Re: 33\" Tires and the 700r4

    Espen is pretty much right. I've got 36" tires with 3.08gears and I really dont have to much of a problem. My first 700 lasted over 100,000miles w/33's and hopefully my 2nd last just as long, but I really think to do that I need to get some lower gears to spin 36's.
    I think 3.73's w/33's you shouldn't be to worried. Just my 2cents

    <font color=blue>Professional <font color=red>JEEP EATER</font color=red>, it's a population control thing.</font color=blue>
     
  5. johnny reb

    johnny reb 1/2 ton status

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    Re: 33\" Tires and the 700r4

    hmmm....It appears that you've read my post. My tranny blew up a day after I put on 33" tires and 2 weeks after I put in a new 350. However, from the responses I received, it doesn't appear that my taller tires had anything to do with the tranny blowing. I think my tranny blew because the fluid wasn't being cooled properly, not because of the larger tires.
     
  6. MICHIGAN BLAZER

    MICHIGAN BLAZER 1/2 ton status

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    Re: 33\" Tires and the 700r4

    I've been driving my 89 with 33's for 1 year and 35's for 1 1/2 yrs and who knows how long before i owned it and i never had a problem with it shifting when i didn't want it to. And I probably used my overdrive more than i should have....but like i said it never upshifted or downshifted unless i wanted it to....oh yeah i've got 3.42's. Of course maybe i shouldn't be giving advice....my blazer is sitting in the yard with a cooked tranny too......but it does have 168,000 miles on it....so not too much to complain about

    <font color=red>MICHIGAN BLAZER
    <font color=green>89 Fullsize Blazer
    87 Cherokee
    65 IH Scout
     
  7. 6.2Blazer

    6.2Blazer 1/2 ton status

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    Re: 33\" Tires and the 700r4

    There's really no reason a tranny would just "blow up" after putting 33" tires on. Now if the tranny was on it's very last legs, the additional stress of larger tires might push it over the edge a bit faster. The same goes with installing a new engine, there's no reason this will cause the tranny to fail by itself. Again, if you put a built engine (a lot more power than stock) and then go out and flog it, it could cause an already sick tranny to die.
     
  8. Wheels

    Wheels 1/2 ton status

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    Re: 33\" Tires and the 700r4

    You asked for any input...I've been looking at converting my TH350 over to a 700R4 and in my research, the 3.73 ratio was the bottom end of the gear spectrum they recommend. They prefer 4.10 or 4.56 gears with 33" tires. My experience with the 700R4 was in two different vehicles. Both recommended that when driving around town to keep the tranny out of OD. The OD shift point is right at 45 mph. When driving around town at or around 45 mph, the tranny was always trying to shift into and out of OD at 45. This I was told would cause premature wear on the tranny and cause early failure. Both vehicles went in excess of 150,000 without a tranny problem. They were traded in for newer vehicles (IROC Z-28 183,000 and S-10 Blazer 162,000)
     
  9. JimmyDie6.2

    JimmyDie6.2 1/2 ton status

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    Re: 33\" Tires and the 700r4

    I have 33s, a 700, and 3.42s. no problems, I did add a tranny cooler though. and I use overdrive at 65 and higher on the highway, I have about 15,000 miles on the trans......js
     
  10. HarryH3

    HarryH3 1 ton status Author

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    Re: 33\" Tires and the 700r4

    I ran 33's on a stock '87 with 3.73 gears. Put them on at around 70K miles. Traded the truck at 125K miles. Never had a problem with the tranny. I did manage to waste the 10-bolt rearend with my rather "spritied" driving style. [​IMG] But the 700r4 never complained.

    <font color=black>HarryH3 - '75 K5</font color=black>
    <A target="_blank" HREF=http://ThunderTruck.ColoradoK5.com>http://ThunderTruck.ColoradoK5.com</A>
     
  11. 90K5

    90K5 1/2 ton status

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    Re: 33\" Tires and the 700r4

    My tranny got rebuilt at 91K, and it had 32" BFGs until about 112K, when It got some 33s. i bought it at 124K, and its got 135K on it now, with 3.42s. i always drive in D until i hit about 70, and then shift down to D to pass of go up a hill. The reason they brak earlier is they are always hunting for the righ gear in town, when your speed is right around 45. this builds up a lot of heat. 33s should be no problem for it...just make sure the fluid id in good shape, and you may want to put a cooler on there just to be sure.

    90K5

    See my truck at <A target="_blank" HREF=http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502>http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502</A>
     
  12. woodpecker

    woodpecker Registered Member

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    Re: 33\" Tires and the 700r4

    Hey Wheels,

    Where do you find info like the stuff you mentioned as "research?" I'd like to get my hands on info like that.

    woodpecker
     
  13. johnny reb

    johnny reb 1/2 ton status

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    Re: 33\" Tires and the 700r4

    Like I said, I think the reason my tranny died was because there was a problem with my cooling system not because I put on 33" tires. Every time I would climb a hill the temp. gauge would go up to about 240. Then it would cool off. When I put the new engine in 2 weeks ago, I also put in a new thermostat and water pump. I didn't put in a new radiator because mine is only 2 yrs. old. So now I have to figure out why my engine was overheating.
     

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