is this true? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

1968GMC · 08-09-2005, 09:47 AM

I met a guy that say hes gota th350 with 2.73 gears rear end and he say he reves at 2200rpm at 60. I forgot to check his tire size but they looked like 17" rims. I on the other hand rev at 3200 rpm at 60 and its anoying. ppl pass me on hiway and if i got there speed i rev 4000 rpm, way to hi for my liking.

Bill72BB · 08-09-2005, 09:53 AM

Try this. if he is running 25-26 " tires http://richmondgear.com/streetcalculators.html

1968GMC · 08-09-2005, 10:13 AM

ty bill. Last year l got a new differencial gasket put on and while it was apart l got the mecanic to tell me what gear ratio l had. There was numbers writen by a yelow marker on the gears and with that he did some calculation and came up with 3.6964257 something like that so i assumed it was 3.73. Acording to the chart you gave me. it seems like i have 4.56 gears. My truck was originaly a 250 6 cyl with 3 spd colum shift. Does that sound correct?

Bill72BB · 08-09-2005, 10:18 AM

I only have the 72 ,spec's it shows 3.73 as standard for the C10 , and 4.57 for the C20 .

ckhd · 08-09-2005, 10:43 AM

Quote:

Originally Posted by 1968GMC

he did some calculation

Maybe he's changing gaskets because he's not good with math.

jack one wheel up and turn it two full revs while counting how many times the driveshaft rotates. That's your ratio.

Of course if you have posi, jack both wheels up, and rotate it once and count the times the drivesaft turns and that's your ratio.

tomatocity · 08-09-2005, 11:11 AM

I had a 1995 Camaro Z28 with 2.73's and a 4L60E and turned 2000 RPM's at 77 MPH so that sounds correct if you adjust for the OD transmission.

Longhorn Man · 08-09-2005, 07:06 PM

Here is my old GMC.
350/TH350, 3.07 rear gears, and 28 inch tall tires.

71meangreenc10 · 08-09-2005, 07:13 PM

He is correct, I am running 2.76 (bought them to replace my 3.73) and Iam running about the same, 2.73 or 2.76 is just like having an od trans, dont know how it is with the automatic (probably sweet) but the 3 speed aint too bad, only bad thing is with the 3 speed it has weak take off in 1st gear.....but i dont plan on pulling any more boats with mine.

Smitty

1968GMC · 08-09-2005, 09:03 PM

ty guys andy you got proof there. Im glad, Ill just replace the gears insted of replacing the tranny to a 700r4. Way cheeper.

**special-K** · 08-10-2005, 08:02 AM

You`ll lose that get up`n`go feeling.Not so w/overdrive trans.It seems every short Stepside 6cyl/3spd I`ve seen has had 4.10s originally.

1968GMC · 08-10-2005, 10:11 AM

Quote:

Originally Posted by special-K

You`ll lose that get up`n`go feeling.Not so w/overdrive trans.It seems every short Stepside 6cyl/3spd I`ve seen has had 4.10s originally.

ya l know i hope that wont bother me too much. i dont drive like l use to annymore. l drive more like grand-pa lol.

gator2511 · 08-10-2005, 10:34 AM

I'm running 2200 rpm at 70 mph with a 3.73 ratio. 3.73 is good for the four wheeling in the woods. I just put a GV OD on it and I get the best of both worlds. Kinda expensive though. I figure I'm gonna keep this truck for a long time and I can tow my tt and go in the woods, so it suits me fine. Don't get me wrong, I don't tow my travel trailer in the woods.

farside847 · 08-10-2005, 11:08 AM

Hey gator2511 - how did you set up your GV overdrive? I was looking into this too...

68Stepbed · 08-10-2005, 01:37 PM

I know i tell people this alot, but I would go with a 3.42 gear. You get good pull off the line and good highway rpm's.

My 3.07 gear with a 28"tall tire with a TH350, I ran about 2200 at 60mph and 2550 at 70mph. I put 3.73's in last month and turn 3200rpm at 70 mph.

gator2511 · 08-10-2005, 02:59 PM

Hey farside847! I changed the tranny from a th350 to a th400 and that required a new adapter. I also had to change the transfer case input shaft and gear which required some machine shop work to bore out the case. The rear tranny crossmember had to be re located cause the th4oo is longer than the th350. Lots of other little things besides. Then the GV unit bolted up to the rear output shaft on the transfer case. The front driveshaft had to be lengthened and the rear had to be shortened. If you have a two wheel drive truck all you have to do is pull the drive shaft, run the wiring, bolt the GV unit on the back of your tranny( You have to remove the rear tranny tailshaft cover but thats easy) and shortened the drive shaft. GV can tell you all the info you need to understand what you need for your truck. The only complaint I have is that is shifts hard unless you let off just as it shifts. I'm going to put some photos on my photo albums soon. Oh yeah, I'm running 32" tires on 15x10 rims. The neat thing is you can set the controls for automatic or manual control. On automatic it shifts in and out of od automatically. On manual you can kick it in anytime you want. That makes your three speed tranny a six speed. Great for towing in hills or mountains and you still keep your zoom off the line!

08-09-2005, 09:47 AM	#1
1968GMC love my truck Join Date: May 2001 Location: aylmer QC Posts: 648	is this true? I met a guy that say hes gota th350 with 2.73 gears rear end and he say he reves at 2200rpm at 60. I forgot to check his tire size but they looked like 17" rims. I on the other hand rev at 3200 rpm at 60 and its anoying. ppl pass me on hiway and if i got there speed i rev 4000 rpm, way to hi for my liking.

08-09-2005, 09:53 AM	#2
Bill72BB Thats the Hillbilly way Join Date: Jul 2001 Location: Torrance,Ca Posts: 5,980	Try this. if he is running 25-26 " tires http://richmondgear.com/streetcalculators.html __________________ BILL Torrance Calif 90504 Member DUF Club Member Old Farts Club 72 3/4ton Custom Camper BB402/400 trans Dynomax Cerama-coat headers , Hei distributor ,Edelbrock 1411 air,ps,pb,leafsprings ,98 chevy 60/40 seat,S10 shoulder belts tilt,3.54 Dana 60 rear. 16" Eagle wheels with LT265/75 16 tires,Gaylord Lid,H4 headlights with 100W relay conversion. " If I knew I was going to live this long I would have taken better care of myself " Marriage changes passion...suddenly you're in bed with a relative. A GUY'S PRAYER.... Lord, I pray for a nympho with huge boobs who owns a liquor store and likes to fish and hunt and has a Harley .Amen , Last edited by Bill72BB; 08-09-2005 at 09:55 AM.

08-09-2005, 10:13 AM	#3
1968GMC love my truck Join Date: May 2001 Location: aylmer QC Posts: 648	ty bill. Last year l got a new differencial gasket put on and while it was apart l got the mecanic to tell me what gear ratio l had. There was numbers writen by a yelow marker on the gears and with that he did some calculation and came up with 3.6964257 something like that so i assumed it was 3.73. Acording to the chart you gave me. it seems like i have 4.56 gears. My truck was originaly a 250 6 cyl with 3 spd colum shift. Does that sound correct? Last edited by 1968GMC; 08-09-2005 at 10:15 AM.

08-09-2005, 10:18 AM	#4
Bill72BB Thats the Hillbilly way Join Date: Jul 2001 Location: Torrance,Ca Posts: 5,980	I only have the 72 ,spec's it shows 3.73 as standard for the C10 , and 4.57 for the C20 . __________________ BILL Torrance Calif 90504 Member DUF Club Member Old Farts Club 72 3/4ton Custom Camper BB402/400 trans Dynomax Cerama-coat headers , Hei distributor ,Edelbrock 1411 air,ps,pb,leafsprings ,98 chevy 60/40 seat,S10 shoulder belts tilt,3.54 Dana 60 rear. 16" Eagle wheels with LT265/75 16 tires,Gaylord Lid,H4 headlights with 100W relay conversion. " If I knew I was going to live this long I would have taken better care of myself " Marriage changes passion...suddenly you're in bed with a relative. A GUY'S PRAYER.... Lord, I pray for a nympho with huge boobs who owns a liquor store and likes to fish and hunt and has a Harley .Amen ,

08-09-2005, 11:11 AM	#6
tomatocity Registered User Join Date: Jun 2005 Location: Sacramento CA Posts: 1,255	I had a 1995 Camaro Z28 with 2.73's and a 4L60E and turned 2000 RPM's at 77 MPH so that sounds correct if you adjust for the OD transmission. __________________ Got bored, sold everthing. Got bored, looking for a 1960-66 C-10. Want to build my last truck.

08-09-2005, 07:06 PM	#7
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Here is my old GMC. 350/TH350, 3.07 rear gears, and 28 inch tall tires. Attached Images

08-09-2005, 07:13 PM	#8
71meangreenc10 Its a Truck Thing...... Join Date: Dec 2004 Location: Sierra Vista, Arizona Posts: 3,159	He is correct, I am running 2.76 (bought them to replace my 3.73) and Iam running about the same, 2.73 or 2.76 is just like having an od trans, dont know how it is with the automatic (probably sweet) but the 3 speed aint too bad, only bad thing is with the 3 speed it has weak take off in 1st gear.....but i dont plan on pulling any more boats with mine. Smitty __________________ 71 C10 283/3SPD Full Resto 71 GMC 1500 Sierra Grande http://67-72chevytrucks.com/vboard/s...d.php?t=518599 70 C10 Suburban Former military GSA truck. 72 Chevy Blazer 4X4, Sloppy Jo, Mountain Climber. Wife says no more trucks. http://67-72chevytrucks.com/vboard/s...d.php?t=707378 72 GMC 1 Ton Motor Home, wife said no more trucks until she saw this one. Gen 3 6.0/4L80E 4.10 http://67-72chevytrucks.com/vboard/s...d.php?t=761110 68 GMC Suburban was 3/4 ton, now 1/2.Wife shook her head 71 C30 Wrecker 71 C20 Scott-Bilt As weird as it gets..BB Cheyenne AC Truck 68 GMC Long Stepside. They keep following me home 71 C20 Longhorn/Ole Yellor 69 C30 Former Motor Home, Flat Bed time

08-09-2005, 09:03 PM	#9
1968GMC love my truck Join Date: May 2001 Location: aylmer QC Posts: 648	ty guys andy you got proof there. Im glad, Ill just replace the gears insted of replacing the tranny to a 700r4. Way cheeper.

08-10-2005, 08:02 AM	#10
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,861	You`ll lose that get up`n`go feeling.Not so w/overdrive trans.It seems every short Stepside 6cyl/3spd I`ve seen has had 4.10s originally. __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~

08-10-2005, 10:34 AM	#12
gator2511 Registered User Join Date: Mar 2005 Location: tampa florida Posts: 776	I'm running 2200 rpm at 70 mph with a 3.73 ratio. 3.73 is good for the four wheeling in the woods. I just put a GV OD on it and I get the best of both worlds. Kinda expensive though. I figure I'm gonna keep this truck for a long time and I can tow my tt and go in the woods, so it suits me fine. Don't get me wrong, I don't tow my travel trailer in the woods.

08-10-2005, 11:08 AM	#13
farside847 Registered User Join Date: Feb 2005 Location: Bay Area, California Posts: 995	Hey gator2511 - how did you set up your GV overdrive? I was looking into this too... __________________ 1971 Chevy C10 Shortbed Stepside, 307v8 3-on-the-tree

08-10-2005, 01:37 PM	#14
68Stepbed Registered User Join Date: Mar 2005 Location: 10-Uh-See Posts: 5,609	I know i tell people this alot, but I would go with a 3.42 gear. You get good pull off the line and good highway rpm's. My 3.07 gear with a 28"tall tire with a TH350, I ran about 2200 at 60mph and 2550 at 70mph. I put 3.73's in last month and turn 3200rpm at 70 mph. __________________ Matt 68 C10 stepside, LS1/700R4, TCI Engineering suspension system

08-10-2005, 02:59 PM	#15
gator2511 Registered User Join Date: Mar 2005 Location: tampa florida Posts: 776	Hey farside847! I changed the tranny from a th350 to a th400 and that required a new adapter. I also had to change the transfer case input shaft and gear which required some machine shop work to bore out the case. The rear tranny crossmember had to be re located cause the th4oo is longer than the th350. Lots of other little things besides. Then the GV unit bolted up to the rear output shaft on the transfer case. The front driveshaft had to be lengthened and the rear had to be shortened. If you have a two wheel drive truck all you have to do is pull the drive shaft, run the wiring, bolt the GV unit on the back of your tranny( You have to remove the rear tranny tailshaft cover but thats easy) and shortened the drive shaft. GV can tell you all the info you need to understand what you need for your truck. The only complaint I have is that is shifts hard unless you let off just as it shifts. I'm going to put some photos on my photo albums soon. Oh yeah, I'm running 32" tires on 15x10 rims. The neat thing is you can set the controls for automatic or manual control. On automatic it shifts in and out of od automatically. On manual you can kick it in anytime you want. That makes your three speed tranny a six speed. Great for towing in hills or mountains and you still keep your zoom off the line! Last edited by gator2511; 08-10-2005 at 03:10 PM.

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