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08-07-2003, 01:24 AM
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#1 |
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Registered User
Join Date: Jan 2003
Location: Star Prairie WI
Posts: 392
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gear ratio questions
I have an '89 GMC Sierra Z71 with the stock 10 bolt and was wondering what size gears it has in it? I found this link on the board gear ratio chart and according to what it says: sinse my truck runs about 2600(give or take a bit)rpm@65mph with 33" tires in 4th gear I should have anywhere from 3.91 gears to 4.11's. Is this correct???? From what others are saying i should have gears like 3.08's or something small like that in my truck. Any help is wanted (IM VERY CONFUSED:p ) Thanx in advance, DK
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08-07-2003, 08:32 AM
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EZEKIEL 25:17
Join Date: Oct 2001
Location: Springfield IL USA
Posts: 984
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GEAR RATIO =RPM X TIRE DIAMETER DIVIDED BY MPH X 336
DONT FORGET YOU HAVE OVERDRIVE SO MULTIPLY BY .70 THE FORUMLA ASSUMES 1 TO 1 FINAL DRIVE LOOKS LIKE THE 3.08s TO ME
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68 CHEVELLE(HORSESHOE) 69 LONGHORN 396 70 NOVA 454(FOR SALE) 71 SWB 307 71 EL CAMINO 383 72 GMC JIMMY 350 87 BLAZER 350 WIW? http://blog.360.yahoo.com/blog-r5CJt...9_6Orzim4L5uWM Gun control, the theory that 110lb. women have the "right" to fistfight with 210lb. rapists. The reason animal rights activists are more passionate about fur than leather is because it's safer to harrass rich women than bikers... |
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08-07-2003, 08:37 AM
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EZEKIEL 25:17
Join Date: Oct 2001
Location: Springfield IL USA
Posts: 984
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DO YOU HAVE A AUTOMATIC....IF SO THEN MULTIPLY BY .70
IF YOU ARE RUNNING A MANUAL THEN CHECK SPEED AND RPM IN FOURTH GEAR
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68 CHEVELLE(HORSESHOE) 69 LONGHORN 396 70 NOVA 454(FOR SALE) 71 SWB 307 71 EL CAMINO 383 72 GMC JIMMY 350 87 BLAZER 350 WIW? http://blog.360.yahoo.com/blog-r5CJt...9_6Orzim4L5uWM Gun control, the theory that 110lb. women have the "right" to fistfight with 210lb. rapists. The reason animal rights activists are more passionate about fur than leather is because it's safer to harrass rich women than bikers... |
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08-07-2003, 12:31 PM
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#5 |
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Registered User
Join Date: Dec 1999
Location: Old Mission, MI, USA
Posts: 2,510
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If the gears haven't been changed, you can tell from the RPO codes on the sticker inside the glove box.
GU4 = 3.08 GU6 = 3.42 GT4 = 3.73 GT5 or GT8 = 4.10
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Tim |
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08-07-2003, 01:08 PM
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#6 |
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Registered User
Join Date: Jan 2003
Location: Star Prairie WI
Posts: 392
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the gears gould have been changed but im not sure. Thanx for the codes! I'm going to go check them right now
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08-08-2003, 07:59 AM
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#10 |
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Registered User
Join Date: Dec 1999
Location: Old Mission, MI, USA
Posts: 2,510
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3.73s with 35s is far from ideal with the O/D tranny, but it will work. I ran 33s with 3.42s on a Suburban for a while and it was OK. You will not want to use O/D except when you are on the highway going 65 mph or over. Just put it in D for normal driving. 4.10s or even 4.56s would be better for 35s with a 700R4/4L60.
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Tim |
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'89 GMC Sierra Z71 -"Scream'n Demon" 
Linear Mode
