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post #1 of (permalink) Old 05-18-2001, 11:03 PM
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how big can I go??

Howdy!! I have a 86 s10 blazer 2.8 tbi 4x4. I was wondering what was the biggest size tires I can put on there with my stock gears..Problem is, I don't know what gears I have, can anyone give me an estimation of what they may be?? I plan to do a 3" body lift as well as cranking the T bars and adding shackles as well. I would like to put 31's on, does anyone have any suggestions and/or forsee any problems with this setup? Thanks,


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post #2 of (permalink) Old 05-19-2001, 12:58 AM
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Re: how big can I go??

the 31's will throw of your speedeo a little but other then that not enouph to need to get into gear upgrades for the axels other then that I know someone that had the same setup and it worked fine


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post #3 of (permalink) Old 05-19-2001, 06:53 AM
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Re: how big can I go??

to find out what gears u have, look in your glove compartment at the sticker that says "do not remove" it has all the part codes on it. Towards the middle, look for GU then the number. EX. i have GU6 which means i have 3.42 stock gears. GU5=3.23 GU4=3.08 GU3=2.93 GU2=2.73 GU1=2.41. 3.42 are the minimum for 30" tires. IF you want 31" than upgrade your gears to 3.73 or better yet, get a better axle front and rear. Also with a 2.8 you definatly want the minimum to run a certain tire. with a 4.3 you could possibly run a smaller gear but with alot of power loss. I suggest if u want 31" tires get biger gears or better axles.

Thanks to the guys at i could answer this question. =]

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post #4 of (permalink) Old 05-19-2001, 07:19 AM
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Re: how big can I go??

<font face="Comic Sans MS">First try to get the fill plug out of your rear differential. Nail it with penetrating fluid, wait a while, smack it with a hammer a bit (the plug itself not the housing, you can get an extension for a ratchet, put it in the square hole on the fill plug and whack the extension with the hammer if need be). When you get that out, put it back in snugly (not too tight). Now run to the parts store for either some RTV (my choice) or a gasket for the 7.5" ring gear Corporate 10 bolt rear end. While you're there, grab some gear lube (I would say at least 3 containers of GL 5 (a few spares couldn't hurt just in case), 80w90 or realistically anything in that general range is ok). Pull the rear cover off the diff (by removing 10 bolts, also treating them the same way you did with the drain plug, penetrating fluid and some whacks with a hammer) but when you do, be sure to have a decent sized drain pan centered under the cover, and pull (carefully) the bottom of it out first. It drains better with the fill plug out. It helps to have the rear end raised up and supported by jack stands, so you can rotate the tires easily. Rotate them until you can see the numbers stamped into the ring gear. The ones you're interested in are written like a ratio. Example: 41:10 which equals a 4.10 ratio. Just divide the first number by the second and you get your ratio.

The reason I'm recommending this procedure to procure your gear ratio is actually two reasons. The first reason is that your axle will thank you for it, considering this is an 86 and I'd doubt it's been changed in forever(although it's just an assumption). The second reason is that someone might have swapped gears in it to a different ratio and the glovebox would be lying to you...

Just a thought...

Oh, about the tire size thing, you can fit whatever tires you want... With a sawzall and a willingness to drop in a 350cid V8 or larger... [img]/wwwthreads_images/icons/laugh.gif[/img]

With my 3.73 diff ratio, 235/75 15's are about the tallest I'd go... [img]/wwwthreads_images/icons/crazy.gif[/img] That's with a carbuerated 2.8L and the Borg Warner Non world class T5 manual transmission...</font>

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