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#24489 11/23/2003 2:28 AM | Joined: Oct 2002 Posts: 60 Wrench Fetcher | | Wrench Fetcher Joined: Oct 2002 Posts: 60 | took the pig/pumpkin out of a 1968 chevy 20 series 3/4 ton today , has 32 teeth on ring gear has 7 on pinion gear . if you divided 7 into 32 you get 4.571428
didn't 1951 chevy 3/4 ton come with a 4.57 rear end?
I have not removed the 51 pig yet hoped the 68 would give me highway speed without high rpms
what year pig pumpkin do I need for 3.90 or low 4.00 ratios? Or am I going the wrong way should I be looking for 3.00s or 5.00s ratios? thanks Bill
Bill 1951 3/4 ton 5 window pick up
1955 GMC 1/2 ton longbed automatic
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#24490 11/24/2003 1:44 AM | Joined: Jul 2003 Posts: 55 Member | | Member Joined: Jul 2003 Posts: 55 | As far as the specific years go, I couldn't help. If you want to cruise on the highway with low RPM's then get a high gear (numerically low) around 3.08 or so. Also, most gears below 3.50 are ok for cruising. The only drawback will be the loss of power on takeoff. Hope this helps. John
1968 Chevy C-10, 250 and 3 speed on floor, Hedman headers, Offy intake, Edelbrock 600cfm 4 barrel, HEI
1966 Chevy C-10, motor and tranny went into the '68. Waiting to be restored.
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#24491 11/24/2003 1:56 AM | Joined: Jun 2000 Posts: 2,773 'Bolter | | 'Bolter Joined: Jun 2000 Posts: 2,773 | Pumpkin needs to be from a 64-72. Most will be 4.57, the next largest quantity was 4.10, with 3.73 running a very distant, and next to impossible to find, third. You can also use the carrier you have found and buy a new 3.90 set from Randy\'s Ring & Pinion but they aren't cheap.
Fred
52 3600
69 C-10
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#24492 11/24/2003 2:05 AM | Joined: Jul 2003 Posts: 101 Wrench Fetcher | | Wrench Fetcher Joined: Jul 2003 Posts: 101 | From 1967 to 72,Chevy 3/4 tons (and I think 1-tons) with automatic, came with 4.10 ratios. The sticks came with 4.57. They're hard to find. Junkyards ask around $250-300 for the 4.10 pumpkin.
With 31" tires and 4.10's you would be running about 2670 RPM at 60 MPM. With 4.57's you would be running 2970 RPM at 60 which is on the high side if your 51 has the stock 216. | | |
#24493 11/24/2003 2:41 PM | Joined: Oct 2002 Posts: 60 Wrench Fetcher | | Wrench Fetcher Joined: Oct 2002 Posts: 60 | well the 67 to 72 GM 3/4 ton automatic is the only easy 2 hour pig/pumpkin swap gets you from 4.57 to 4.10
There are kits avable to change the ring & pinion gears to get you in to the 3.s
there is a( rear end swap and what to use)on the chevytrucks.org site full of info.
thanks to all for the help and good luck to the all who diecide to change gear ratios. thanks Bill
Bill 1951 3/4 ton 5 window pick up
1955 GMC 1/2 ton longbed automatic
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#24494 11/24/2003 7:27 PM | Joined: Mar 2002 Posts: 9,115 'Bolter | | 'Bolter Joined: Mar 2002 Posts: 9,115 | If you go Randy's route, you will want to get the information straight from them. I have had one conversation with them and I still don't have it straight. There is a thread on here somewhere where it was stated that Randy's can make some custom parts to allow the use of the 3.90 in the 1951 carrier. I don't understand the details at this point. | | |
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