Ring gear count for 4:56 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

*wolfthing2000* · 11-08-2004, 11:17 PM

Does anyone happen to know the ring gear tooth count for a 4:56 ratio rear axle for the 69 3/4 ton corporate style (Eaton?) that has the 3rd member drop out ( quick change style carrier)......??????
Thanks,
Dave

BLAZERMAN · 11-08-2004, 11:31 PM

Should be 41-9

BLAZERMAN · 11-08-2004, 11:32 PM

Sorry, thats 41 teeth on ring gear and 9 on pinion.

*wolfthing2000* · 11-08-2004, 11:47 PM

Thanks for the numbers. Makes it so much easier.
Dave

67ChevyC10Stepside · 11-09-2004, 02:08 AM

41 / by 9 is 4.555555555555555555555556

*wolfthing2000* · 11-18-2004, 01:07 AM

For the record on this board::: The front axle on the 69 says 4.56 and when pulling out the rear 3rd member I have discovered that the ring gear is a 32 and the pinion is a 7 for a 4.57 ratio which is slightly lower gear ratio than the 4.56 making the front tires pull ahead slightly faster theoreticaly keeping them in front or the leader on slick surfaces Thus the truck stays in a straight ahead position rather than the back end coming around in front.
However I have proven beyond any doubt with my CJ5 Jeep with the same gear set ups that the rear end will pass the front end up with little more than a blip of the throttle at the wrong time!!!! Believe me it can be quite entertaining whether done intentionaly or by accident!!

Passengers love it too!!!!!!!!!!!!!!
Dave

1969 GMC · 11-18-2004, 01:13 AM

Yeah the Eatons are weird like that. 4.11s, not 4.10s...4.57s, not 4.56s...5.14s, not 5.13s. My dana 60 will get 5.13 gears up front. My dad thought it was really weird that GM did this from the factory, but most people say that such a small difference wont even be noticed.

**Stocker** · 11-18-2004, 09:45 AM

Quote:

Originally Posted by wolfthing2000

The front axle on the 69 says 4.56 and when pulling out the rear 3rd member I have discovered that the ring gear is a 32 and the pinion is a 7 for a 4.57 ratio which is slightly lower gear ratio than the 4.56 making the front tires pull ahead slightly faster theoreticaly keeping them in front or the leader on slick surfaces

I've heard of this before, never checked it out, and in theory it makes sense. But if the front is geared slightly lower, it will turn the tires more slowly than the rears, not faster. Hmmmm....

**JIMs70GMC** · 11-18-2004, 11:59 AM

I think to have any noticable difference you'd have to have like 3.73s up front and 4.11s in the back with the same size tires. There was a truck like this in a magazine and it was strickly for mud bogging.
The reason for the slight variations between front and rears in production vehicles is probably more a function of design constraints between the different manufacturers. Really between 4.09 and 4.10 the difference is like 0.25% hardly noticable. You could have more variation between the tires than that. The only vehicle I had that the front and rears matched was a scout II with front and rear Dana44s.

11-08-2004, 11:17 PM	#1
wolfthing2000 Account Suspended Join Date: Oct 2004 Posts: 1,276	Ring gear count for 4:56 Does anyone happen to know the ring gear tooth count for a 4:56 ratio rear axle for the 69 3/4 ton corporate style (Eaton?) that has the 3rd member drop out ( quick change style carrier)......?????? Thanks, Dave

11-09-2004, 02:08 AM	#5
67ChevyC10Stepside Registered User Join Date: Mar 2004 Location: Butler PA Posts: 3,032	41 / by 9 is 4.555555555555555555555556 __________________ 67 c-10, 400 SB, TH350, 4.10 gears, Blazer tank,camaro tach, sidemarker fuel fill (soon) WTB: stepside parts, 67 front end parts, 67 small window cab. posi for 3.73 or 4.10 for 12 bolt and 10 bolt.

11-18-2004, 01:13 AM	#7
1969 GMC Registered User Join Date: Feb 2003 Location: The Rubber City Posts: 5,498	Yeah the Eatons are weird like that. 4.11s, not 4.10s...4.57s, not 4.56s...5.14s, not 5.13s. My dana 60 will get 5.13 gears up front. My dad thought it was really weird that GM did this from the factory, but most people say that such a small difference wont even be noticed. __________________ 1969 GMC K2500 1996 Honda Accord 2007 Kawasaki KLR 650

11-18-2004, 11:59 AM	#9
JIMs70GMC user # 2756 Join Date: Jun 2001 Location: Chesapeake, Virginia Posts: 4,612	I think to have any noticable difference you'd have to have like 3.73s up front and 4.11s in the back with the same size tires. There was a truck like this in a magazine and it was strickly for mud bogging. The reason for the slight variations between front and rears in production vehicles is probably more a function of design constraints between the different manufacturers. Really between 4.09 and 4.10 the difference is like 0.25% hardly noticable. You could have more variation between the tires than that. The only vehicle I had that the front and rears matched was a scout II with front and rear Dana44s. __________________ 1970 K25, 8' stepside bed 350/465/205 44 up front, 60 in the rear 4.10s rolling on 33" Dunlop MTs 1986 K5, 350/465/208 Dana 60/14 bolt from a cucv 36" Super Swampers TSL/SX 1983 K20 w/ CUCV axles, 350/700R4/208 sitting on 37" Goodyears 1986 M1031 6.2 diesel, TH400/NP205 locker in the rear and a LS in the front, all stock for now..... 1986 K30, 350/400/205 dana 60 and 14 bolt. I kept the drivetrain. Body/bad and chassis are gone. 1981 K30, 350/465/205 dana 60 and dually 14 bolt. Has a G80, and a flat bed. Going to replace the flat bed. 1985 K20, 350/400/208 10 bolt and SF 14 bolt. I wonder where I can find some 1 tons. Hmmmmm

11-08-2004, 11:31 PM	#2
BLAZERMAN Currently Blazerless Join Date: Apr 2000 Location: St. Joseph Mo. Posts: 4,829	Should be 41-9

11-08-2004, 11:32 PM	#3
BLAZERMAN Currently Blazerless Join Date: Apr 2000 Location: St. Joseph Mo. Posts: 4,829	Sorry, thats 41 teeth on ring gear and 9 on pinion.

11-08-2004, 11:47 PM	#4
wolfthing2000 Account Suspended Join Date: Oct 2004 Posts: 1,276	Thanks for the numbers. Makes it so much easier. Dave

11-18-2004, 01:07 AM	#6
wolfthing2000 Account Suspended Join Date: Oct 2004 Posts: 1,276	For the record on this board::: The front axle on the 69 says 4.56 and when pulling out the rear 3rd member I have discovered that the ring gear is a 32 and the pinion is a 7 for a 4.57 ratio which is slightly lower gear ratio than the 4.56 making the front tires pull ahead slightly faster theoreticaly keeping them in front or the leader on slick surfaces Thus the truck stays in a straight ahead position rather than the back end coming around in front. However I have proven beyond any doubt with my CJ5 Jeep with the same gear set ups that the rear end will pass the front end up with little more than a blip of the throttle at the wrong time!!!! Believe me it can be quite entertaining whether done intentionaly or by accident!! Passengers love it too!!!!!!!!!!!!!! Dave



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