Hi Folks. I have a 72 BB 4spd. It was restored with an non original 4:11 gears. I would like to change to 3:55's or 3:70's. Is it easier to just purchase a complete rebuilt rear end from a vendor or buy the parts and have it done? Thanks in advance, Ray
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Re: changing rear end gears
Ray-----
It depends. If the carrier case is original to your car and/or it's otherwise in superb condition and you don't want to part with it, then I'd suggest having it rebuilt with a new gear ratio. In addition to SERVICE parts, you'll need a ring and pinion set of the ratio you choose AND you'll also ned a new positraction unit since the "4-series" case won't work with "3-series" gears unless an adapter/modifications are performed.
If the carrier assembly is non-original to the car and/or you're not otherwise endeared to it, then you can simply send it off as a core and obtain a replacement, rebuilt unit of the gear ratio desired. You'll pay for the rebuild and, likely, an extra charge for a different gear ratio than the core returned.In Appreciation of John Hinckley -
Re: changing rear end gears
Ray-----
It depends. If the carrier case is original to your car and/or it's otherwise in superb condition and you don't want to part with it, then I'd suggest having it rebuilt with a new gear ratio. In addition to SERVICE parts, you'll need a ring and pinion set of the ratio you choose AND you'll also ned a new positraction unit since the "4-series" case won't work with "3-series" gears unless an adapter/modifications are performed.
If the carrier assembly is non-original to the car and/or you're not otherwise endeared to it, then you can simply send it off as a core and obtain a replacement, rebuilt unit of the gear ratio desired. You'll pay for the rebuild and, likely, an extra charge for a different gear ratio than the core returned.In Appreciation of John HinckleyComment
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Re: changing rear end gears
May I suggest you think in terms of a 3.36:1. It is almost a waste of time to drop from a 4.11:1 to a 3.70:1 in a big block. IMHO
If this car is a street car than all the more reason to skip the 3.70:1. The 3.55:1 is a great choice for the small block but that 454 has a lot more torque and will be very happy with the 3.36:1. I have a 396/425 with 4.11:1 and often consider swapping those gears.Comment
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Re: changing rear end gears
May I suggest you think in terms of a 3.36:1. It is almost a waste of time to drop from a 4.11:1 to a 3.70:1 in a big block. IMHO
If this car is a street car than all the more reason to skip the 3.70:1. The 3.55:1 is a great choice for the small block but that 454 has a lot more torque and will be very happy with the 3.36:1. I have a 396/425 with 4.11:1 and often consider swapping those gears.Comment
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Re: changing rear end gears
Swapped the 4:11 for 3:55 on my 67BB. The car still screams and can actually be driven on the streets now. The 4:11 gears were useless unless you want to drag race or get 5 MPG on the freeway. Plus, one hour of driving resulted in needless vibration of ones private parts and a significant hearing loss with off-road or side exhaust.
Plus, the lack of revs in normal driving save some wear and tear on the motor. As posted, you could go to econ (3:36) and still haul it to your liking. Recalibrating the speedo was no problem, conversion gears are available from GM restoration parts. I successfully followed Joe Lucia's advice, easy conversion.Comment
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Re: changing rear end gears
Swapped the 4:11 for 3:55 on my 67BB. The car still screams and can actually be driven on the streets now. The 4:11 gears were useless unless you want to drag race or get 5 MPG on the freeway. Plus, one hour of driving resulted in needless vibration of ones private parts and a significant hearing loss with off-road or side exhaust.
Plus, the lack of revs in normal driving save some wear and tear on the motor. As posted, you could go to econ (3:36) and still haul it to your liking. Recalibrating the speedo was no problem, conversion gears are available from GM restoration parts. I successfully followed Joe Lucia's advice, easy conversion.Comment
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