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Old 12-17-2010, 02:03 PM   #1
K20-69-POS
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Gearing w/35s

Would 4.56 gears with an sm465 and an NP205 (all in a 1969 K20 with a 292) be too tall of gears (33-35" tires)?

*The truck will never be driven on the highway, only in off road situations and the occasional towing of a boat 40 miles on back roads. It might take one 200 mile trip to the outerbanks.
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Old 12-17-2010, 02:37 PM   #2
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Re: Gearing w/35s

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Originally Posted by K20-69-POS View Post
Would 4.56 gears with an sm465 and an NP205 (all in a 1969 K20 with a 292) be too tall of gears (33-35" tires)?

*The truck will never be driven on the highway, only in off road situations and the occasional towing of a boat 40 miles on back roads. It might take one 200 mile trip to the outerbanks.
A 4.56 should be good for you with the uses you listed. If you said highway use, I'd go with a 4:11.

Since first is 3.58 on the 465 compared to the 2.48 of the 400, and 2.52 of the 350 you can get away with a slightly smaller gear without overly negative effects.

I'm building a truck with a 465, and 35" tires myself, and am going to be using 3.42 gears. Partly because it is what I have laying around... Also because I want to do more highway. I'm just going to get my extra reduction out of the T-Case when needed. Not ideal, but eh.
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Old 12-17-2010, 05:41 PM   #3
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Re: Gearing w/35s

Roger that, I was going through your build thread and I gotta ask- How long did it take to wire wheel your frame?
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Old 12-17-2010, 06:26 PM   #4
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Re: Gearing w/35s

Well, I only had to do about from the tranny crossmember back. In front of that had a nice oil/grease coating to keep it from rusting. Without the bed in the way though, I'd say it took me about a hour, maybe a hour and a half. Didn't really time it. The frame mainly had surface rust. Cleaned up easy.
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Old 12-17-2010, 10:30 PM   #5
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Re: Gearing w/35s

I think you meant 2nd is 3.58 in the SM465? Although now that I think about it, the 80's trucks listed 1st as L and 2nd as 1st? Either way, the SM465 gives you plenty of gear with it's granny gear.

4.56 and 35's is a great choice for a truck that never sees the far side of 60.
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Old 12-18-2010, 02:10 AM   #6
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Re: Gearing w/35s

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I think you meant 2nd is 3.58 in the SM465? Although now that I think about it, the 80's trucks listed 1st as L and 2nd as 1st? Either way, the SM465 gives you plenty of gear with it's granny gear.

4.56 and 35's is a great choice for a truck that never sees the far side of 60.
Yes, sir. The "First" gear in the muncies is a unsynchronized low-range. Not really practical for every day driving. And split between L-1 is terrible (6.55 Low). Most people consider the gap in 1-2 bad. Haha.
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Old 12-18-2010, 02:23 AM   #7
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Re: Gearing w/35s

I have a 350/350/np205 combo and 3:73 gears, i went to 33's back around 93' and i'm pretty glad i didn't buy 35's, its a bit labored off the line, but low rpm's on the freeway. I often wanted to go to 4:11's but could mever come up with the justification on spending the coin.....yet
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Old 12-18-2010, 09:04 AM   #8
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Re: Gearing w/35s

On that 4.56:1 truck,that came with 7.50-16s originally,by going to 35s you'll end up with right about 4.10:1 at the road/ground.It's a good ratio,especially with a 4spd.I like 4.10s with 35s because I'm on the road way more than 4 wheelin.With that you end up with right about 3.73s running 35s.I do fine off road with that.
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