Speedometer gears for a 4 speed SM465? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

bobs409 · 09-22-2009, 07:28 PM

I have a 71 C20 that has the 4 speed tranny. I think they call it a SM465?

My speedometer is reading about 8-10 miles per hour too fast.

Anyone know what kind of speedometer gears these take. Are they the same ones used in a turbo 350? Or a special kind and if so, where to buy?

Thanks,

Bob

bobs409 · 09-24-2009, 10:08 AM

bump

airdale94 · 09-24-2009, 10:18 AM

Sorry don't know the answer. I can't imagine why it would be off unless you made some considerable tire/rear end changes. This came up on Google. My NP435 has one. But the 2 SM465's I have do not.

http://cgi.ebay.com/ebaymotors/SM465...=p4506.c0.m245

**WorkinLonghorn** · 09-24-2009, 10:43 AM

My NP435 has that same type of gearbox between the case and the speedo cable. It says "666F and on next pad it says 1.1111 and it seems to INCREASE the speedo reading by that amount (.1) ie. 50MPH without it, 55MPH with it attached. So if you get one of these make sure that the value is correct for your needs. Someone else will know more I'm sure.

airdale94 · 09-24-2009, 02:57 PM

I also found this.

http://www.bethsbackyard.com/NP540GL...escription.htm

Evidently you buy different ratio reducers.

Scroll down to the speedometer section.

bobs409 · 09-24-2009, 06:54 PM

Thanks guys. I'll look into one of those.

Bob

**john** · 09-24-2009, 07:02 PM

Bob my speedo was 15 mph off at 60 mph. I had my local speedometer shop make an adapter as pictured and it is reads correct now according to the mile markers.

Tynee · 09-24-2009, 07:42 PM

I believe that the speedo gears are available through the dealer for a decent price. I did a little reading on this a while back on a chevelle forum, I've lost the link since then. If I remember correctly, there is a process by which you can determine how much higher or lower, numerically speaking, the new gear needs to be. This will reduce the amount of trial and error involved in getting the right gear in there.

BCOWANWHEELS · 09-24-2009, 10:01 PM

call atlanta gear and axle. they have different speedo gears for your sm465

09-22-2009, 07:28 PM	#1
bobs409 1969 Custom 30 wrecker Join Date: Sep 2001 Location: Pottsville, Pa Posts: 2,611	Speedometer gears for a 4 speed SM465? I have a 71 C20 that has the 4 speed tranny. I think they call it a SM465? My speedometer is reading about 8-10 miles per hour too fast. Anyone know what kind of speedometer gears these take. Are they the same ones used in a turbo 350? Or a special kind and if so, where to buy? Thanks, Bob __________________ Bob 63 Impala 283/PG/3.36 (under restoration) 66 Impala 327/PG/3.36 66 Chevelle SS 409/M22/3.55 69 Chevelle 307/PG/3.08 (future restoration) 69 C10 short stepside 454/TH350/3.73 69 Custom 30 tow truck 350/4 spd/4.10 (resto done, CRUISIN TIME!) 71 Cheyenne 20 fleetside 350/4 spd/4.10 71 Chevelle 6/PG/3.08 72 Chevelle 454/M21/4.10

09-24-2009, 10:08 AM	#2
bobs409 1969 Custom 30 wrecker Join Date: Sep 2001 Location: Pottsville, Pa Posts: 2,611	Re: Speedometer gears for a 4 speed SM465? bump __________________ Bob 63 Impala 283/PG/3.36 (under restoration) 66 Impala 327/PG/3.36 66 Chevelle SS 409/M22/3.55 69 Chevelle 307/PG/3.08 (future restoration) 69 C10 short stepside 454/TH350/3.73 69 Custom 30 tow truck 350/4 spd/4.10 (resto done, CRUISIN TIME!) 71 Cheyenne 20 fleetside 350/4 spd/4.10 71 Chevelle 6/PG/3.08 72 Chevelle 454/M21/4.10

09-24-2009, 10:18 AM	#3
airdale94 Registered User Join Date: Jan 2007 Location: Topeka,KS Posts: 778	Re: Speedometer gears for a 4 speed SM465? Sorry don't know the answer. I can't imagine why it would be off unless you made some considerable tire/rear end changes. This came up on Google. My NP435 has one. But the 2 SM465's I have do not. http://cgi.ebay.com/ebaymotors/SM465...=p4506.c0.m245

09-24-2009, 10:43 AM	#4
WorkinLonghorn Senior Member Join Date: Dec 2006 Location: Studio City, Calif. Posts: 2,886	Re: Speedometer gears for a 4 speed SM465? My NP435 has that same type of gearbox between the case and the speedo cable. It says "666F and on next pad it says 1.1111 and it seems to INCREASE the speedo reading by that amount (.1) ie. 50MPH without it, 55MPH with it attached. So if you get one of these make sure that the value is correct for your needs. Someone else will know more I'm sure. Attached Images __________________ '69 GMC C2500 Custom Camper, 8 1/2' bed, New GM 350, NP 435 Close Ratio 4spd. Trans., 3.73 Dana-60 open.Camper and Trailer wiring, PS, PB, AC, tach , three gas tanks, stereo speakers, 2nd owner, Work-Truck supreme.

09-24-2009, 02:57 PM	#5
airdale94 Registered User Join Date: Jan 2007 Location: Topeka,KS Posts: 778	Re: Speedometer gears for a 4 speed SM465? I also found this. http://www.bethsbackyard.com/NP540GL...escription.htm Evidently you buy different ratio reducers. Scroll down to the speedometer section. Last edited by airdale94; 09-24-2009 at 02:57 PM. Reason: add

09-24-2009, 06:54 PM	#6
bobs409 1969 Custom 30 wrecker Join Date: Sep 2001 Location: Pottsville, Pa Posts: 2,611	Re: Speedometer gears for a 4 speed SM465? Thanks guys. I'll look into one of those. Bob __________________ Bob 63 Impala 283/PG/3.36 (under restoration) 66 Impala 327/PG/3.36 66 Chevelle SS 409/M22/3.55 69 Chevelle 307/PG/3.08 (future restoration) 69 C10 short stepside 454/TH350/3.73 69 Custom 30 tow truck 350/4 spd/4.10 (resto done, CRUISIN TIME!) 71 Cheyenne 20 fleetside 350/4 spd/4.10 71 Chevelle 6/PG/3.08 72 Chevelle 454/M21/4.10

09-24-2009, 07:02 PM	#7
john member #16 Join Date: Dec 1999 Location: Yuba City Ca. Posts: 3,618	Re: Speedometer gears for a 4 speed SM465? Bob my speedo was 15 mph off at 60 mph. I had my local speedometer shop make an adapter as pictured and it is reads correct now according to the mile markers. __________________ john http://67-72chevytrucks.com/vboard/showgroups.php board vendors http://www.flickr.com/photos/1745471...7602865984234/

09-24-2009, 07:42 PM	#8
Tynee I miss this truck. Join Date: Dec 2001 Location: Lexington, KY U.S.A. Posts: 2,863	Re: Speedometer gears for a 4 speed SM465? I believe that the speedo gears are available through the dealer for a decent price. I did a little reading on this a while back on a chevelle forum, I've lost the link since then. If I remember correctly, there is a process by which you can determine how much higher or lower, numerically speaking, the new gear needs to be. This will reduce the amount of trial and error involved in getting the right gear in there. __________________ '07 GMC Acadia SLT. Sweet ride. '08 Crew Cab Z-71 short bed. Really like this truck A LOT.

09-24-2009, 10:01 PM	#9
BCOWANWHEELS Registered User Join Date: Nov 2006 Location: KINGSPORT,TN. Posts: 3,035	Re: Speedometer gears for a 4 speed SM465? call atlanta gear and axle. they have different speedo gears for your sm465 __________________ I BELIEVE IN JOHN 3:16



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