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Standard transmission in a rock buggy?

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Nikwho

Active Member
Joined
Apr 10, 2023
Messages
26
Hey all,
I get it that auto's are easy. VERY convenient. But I just like shifting gears! Plus, an SM465 has what, a 6.55:1 1st gear? That's LOW! So, I was thinking of putting an SM465 transmission into my rock buggy. Anyone else have one in a buggy/truggy?

Now, I need to figure out my axle gearing. I'm thinking that I'd like my buggy to be able to hit 65 MPH. That feels plenty fast for playing in the desert, driving between trails. My buggy will have a basically stock 5.3 LS based engine. Headers, holley EFI intake, mild camshaft and mild tune. Looking for reliability. Shooting for 400-450 HP. I want the SM465 behind that, followed by my NP203/Dana 300 doubler that's geared 1.96/4:1. If I run 4.56's, I'll have a 234:1 crawl ratio. With both cases in high range, and transmission in 4th, I'd run 65 MPH at roughly 2,500 RPM, wich is a pretty comfortable cruising RPM. BUT, if I run 5.38 R&P's, I'd still be under 3,000 RPM at 65, and have a final crawl ratio of 276:1.

Thoughts? I've never even ridden in a tube rock buggy. I'm trying to find the right balance in gearing.
 
Im guessing you are out west, so maybe that deep of a gear will be usable. Unless you spend for an aftermarket 300, I dont believe it will hold up to LS power and that gearing. I would install a hand throttle to help with missing a 3rd leg.
 
paradisepwoffrd said:
Im guessing you are out west, so maybe that deep of a gear will be usable. Unless you spend for an aftermarket 300, I dont believe it will hold up to LS power and that gearing. I would install a hand throttle to help with missing a 3rd leg.
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Yes, I live in Arizona. Rig will be run primarily in Moab, Rubicon Trail area, Colorado and Johnson Valley. Yeah, I've been torn on saving up for an Atlas. They're sure pricey, though!
 
An NV4500 would be great, being a 5 speed! I have a 4:1 + a 2:1 doubler. But, I reall6 like the low range of the first gear in the SM465! BUT, I really appreciate all of the personal experience! Would you prefer your higher gearing and overdrive, over a lower first gear?
 
Nikwho said:
An NV4500 would be great, being a 5 speed! I have a 4:1 + a 2:1 doubler. But, I reall6 like the low range of the first gear in the SM465! BUT, I really appreciate all of the personal experience! Would you prefer your higher gearing and overdrive, over a lower first gear?
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As a non-three pedal guy for off-road purposes, that would depend on your overall usage.

If you think there would be a fair amount of road driving/highway speeds (think Ultimate Adventure road days of a few hundred miles), the over drive would be ideal since you could use the tcases to gear down for better crawling.

If your road driving/highway speeds would be limited/not all that often (think 20-50 miles getting from place to place in Moab etc) then the lower first gear and higher engine rpms wouldn't be too bad.
 
I had a 465 in a yota truck and my biggest complaint about it was the way it shifted. It felt about like rowing a boat. I would personally want something with a shorter throw.
 
Having wheeled with t18 & np435, I agree with boat rowing. Slamming between reverse and 1st can be cumbersome.
Having shorter throw and OD would be ideal, nv4500, zf 5 etc
 
My man!
I built my rig with a Sm465 for stupid reliability. I actually bought and had a th400 rebuilt but never put it in cause I love the man tran.
I got a build thread on here. Go knock the cobwebs off the thread and check it out.
 
I'm stock LS, sm464, np205, rockwells, 43s and first gear is awesome for crawling. If anything I might be too low. But I like it
 
I'm running a mild 351w with a np435 and a 205, running 5.13 gears and the granny gear is great at crawling. 1st is party gear. Don't think I've ever hit 3rd lol.
 
Eddyj said:
I'm stock LS, sm464, np205, rockwells, 43s and first gear is awesome for crawling. If anything I might be too low. But I like it
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May I ask what your final crawl ratio is? I've never had a crawl ratio lower than my CJ7 (79.45:1). I could definitely go lower!
 
Nikwho said:
An NV4500 would be great, being a 5 speed! I have a 4:1 + a 2:1 doubler. But, I reall6 like the low range of the first gear in the SM465! BUT, I really appreciate all of the personal experience! Would you prefer your higher gearing and overdrive, over a lower first gear?
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Gm had a nv4500 some time around 93-95 that had the low first gear equal to the sm 465 first gear, was only available in the GM version,
 
I have two crawlers one with 351W SM465, NO205 456 gear with 44 boggers it'll get rowdy on high side not sure on top speed tho? The other 4.3 vortec SM465 NP205 513 it's a lil sluggish on high side.dam thing crawls good. No Way I could go with a slush box. I added a drift brake handle to handle the 3 foot shuffle. With a 4 speed can always find a gear with to get home
 
1tonrenegade said:
I have two crawlers one with 351W SM465, NO205 456 gear with 44 boggers it'll get rowdy on high side not sure on top speed tho? The other 4.3 vortec SM465 NP205 513 it's a lil sluggish on high side.dam thing crawls good. No Way I could go with a slush box. I added a drift brake handle to handle the 3 foot shuffle. With a 4 speed can always find a gear with to get home
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Drift brake sounds like a mighty good idea.
 

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