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tire/gear

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by bennevis, Jul 12, 2001.

  1. bennevis

    bennevis Registered Member

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    Just looking for opinions on the following combo.
    33's 4.56 700r4 350
    Anyone have this setup, rpm's on highway, mpg, power???
     
  2. MudFrog

    MudFrog 1/2 ton status

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    I would think 4.56 would be too low for 33's even with the 700R4... 4.10's would be better.

    89 K5 Silverado
    <A target="_blank" HREF=http://mudfrog.rockcrawler.com>http://mudfrog.rockcrawler.com</A>
     
  3. 2Dogs

    2Dogs 1/2 ton status Premium Member

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    That setup will be perfect for 35s..... Do it!

    Dave

    Beauty is in the eye of the beer holder.
     
  4. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    MudFrog why do you say that. With that combo (4.56/700r4/33's) he should be running ~2200 RPM's at 65. With 4.10's he would be running ~1950 RPM's at 65. With a high stall converter (most stock are around 1800) he could generate way to much heat and fry the tranny. In my opinion 4.10 are too low for a 700R4 unless you run under 30" tires. A stock vehicle with 31 inch tires, 3.08 gearing, and a TH350 or TH400 is running ~2230 RPM's (even more than the 4.56/700R4/33's). You also want the rpms above 2000 with a 700R4 for highway driving at 65 (especially if you tow) in order to keep the line pressure up to keep it from burning up. The biggest killer of the 700R4 is too high gears (low numerically) and/or too big of a tire diameter. It keeps the RPM's and throttle too low (and the TV cable which controls line pressure is controlled by throttle position).
    I was told the biggest misconception of the 700R4 is the huge gas mileage increase it will give on the highway. I was told that you can regear with 700R4 swap in, but not to lower the highway RPM's too much because of the line pressure/burn-up issue. It will give you a huge boost in acceleration between it's lower first gear and then a swap in of lower (higher numerically) ring and pinion. Around town you should see a big increase in mileage due to not having to press the go pedal as hard to get moving. Especially for members of this board, most of us use our rigs as second vehicles for around town trips and weekend warriors and this is where the 700R4 will benefit. It will also benefit the pavement pounders but not as much. If you do want to go with lower RPM's on the highway (say under 2200) or tow then spend the $85 and get the "super overdrive servo" not the corvette one (the corvette isn't much better than stock) from <A target="_blank" HREF=http://www.transmissioncenter.net>http://www.transmissioncenter.net</A>. You don't even have to drop the tranny to put it in. If you do have the tranny out I would also suggest getting the 13 vane pump ugrade to help extent the tranny life. Please don't flame me here and say you have this and that and it's lasted x years. You can say it, just don't flame me. I live down the street from a performance tranny shop and visit quite frequently, and they come to the house some nights after work, and we have discussed this every which way. They have seen and rebuilt many 700R4's and know what works and what doesn't. I just thought I would pass on the information to members of this board that has been passed on to me.
    P.S. They say big coolers never hurt (with any tranny), and it is almost a must on the 700R4.

    If you didn't build it yourself, how can you call it yours.......?
     
  5. MudFrog

    MudFrog 1/2 ton status

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    I said I would think [​IMG]... not that I'm right. I just figured 4.10's are ideal for 33's and 4.56's are ideal for 35's.

    89 K5 Silverado
    <A target="_blank" HREF=http://mudfrog.rockcrawler.com>http://mudfrog.rockcrawler.com</A>
     
  6. 6.2Blazer

    6.2Blazer 1/2 ton status

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    I really don't think you should have any problems with this combo at all. The 0.70:1 ratio of the overdrive of the 700r4 would effectively make the final gearing about 3.20 (4.56 x 0.70 = 3.19) when cruising down the highway. I'm sure if somebody had a non-overdrive transmission (th350 or th400), most people would be telling them that 3.20 gears were way too high for 33's.
    I currently have 4.10's (stock ratio with the 3/4 ton axles) with 35" tires and the 700r4. If/when it gets a gear change, I would probably get 4.88 gears..........4.56 at the absolute minimum.
     
  7. 84_Chevy_K10

    84_Chevy_K10 Banned

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    I agree with the above. I have 4.10s and 35s and I wish I had just a little more gear as well. 4.56s would be nice, but if I were to change them, I'd go with 4.88s and get 36" tires. That way I could even go with 38s if I wanted.

    Tim
    '84 Chevy K10, lifted, loud, fast, and 3/4 ton axles
     
  8. CCRider

    CCRider 1/2 ton status

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    I agree as well!! i'm running 4:56 gears and 37"ssr's and could use at least 4:88's!! 33's and 4:56's will work out great , and you,ll probably end up with bigger tires eventually!! Everyone does!! CC

    1991 Fullsize 5 1/2"lift, 37"ssr's,10Bolt8 lug , 14Bolt ff, 4:56 Detroit rear, 12"fr. 14"r Bilstein remote res.350 P.F.I , 700r4 , 241c W/ sye Thanks to Leadfoot for the link!! Just ordered a "wake up"kit for my 700r4 , what if anything did you get from them, and how is it working ? Any advice? Thanks CC
     
  9. gokartergo

    gokartergo 3/4 ton status Staff Member Moderator

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    That is the exact setup I am running and I love it...Not sure what my gas milage is because my speedo is so far off now. I should have that fixed next week. I just did the gear swap about 6 weeks ago.Rpm's are supposed to be 2200 at 60 But my tach is showing about 1970 at 60.......Dan

    <P ID="edit"><FONT SIZE=-1>Edited by gokartergo on 07/12/01 10:09 PM (server time).</FONT></P>
     

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