Gear ratio question ???

[houston_t]

So I have a 79 Monte that I just LS swapped. Car was an all original 35k mile car with the 4.4 and 3 speed trans, for the swap I went with a 2002 ls1 and 4l60e setup out of a trans am. Now that I have been driving the car I’m noticing I can get the rpm’s above say 3200 (unless I’m in neutral or park) I guessing the factory rear gear is the problem since I have a OD trans now. Has always been my plan to change out the carrier for a posi and new gear ratio, I’m trying to figure out what would be a good gear ratio to go with. Car will be a cruiser and will see highway time also I ride on 205/75/14 tires and don’t see myself changing that out anytime soon I want to keep the original look of the car. I plan on going with a setup from quick performance what would your suggestion be for a gear ratio ? Stock LS1 and stock converter with tire size listed earlier.

Thanks !

 

[airboatgreg]

373 is a nice all around gear

 

[houston_t]

Would the 3.73 be good on the highway with a small tire like I have ?

 

[69hurstolds]

Something else seems weird. My wife's long-gone 2002 Z28 with auto trans did not have any issue performance-wise getting the RPMs up on the highway (albeit a good rate of speed) and she had the standard automatic car 2.73 rear end. My 02 SS I once had came with the standard 3.42 with no other option, but it was an M6. Also without issue getting around at any RPM. Those were efficiency leaning gears, so you could go deeper without issue if gas mileage isn't a concern. 3.23 were optional for the auto I think.

Really depends on what you want to do with the car. 3.42 or 3.73 are good gear sets in general. Only about 100 rpm or so on the highway difference at cruising speeds. Depends on if your LS1 and trans set up is stock. Either way I'd sloppy up that torque converter a little if you go with .42 or .73s. Especially if you go .73. Say get something like a 3300 stall speed or in that range somewhere. Again, JMO. Personally with OD, I'd lean to 3.73. With only a 3 speed, I'd go 3.42. But your call.

Just think, the mid 80s G-body "performance" cars came with either 3.42 or 3.73 with OD transmissions. The gears helped immensely between stoplights (as well as they could anyway) but also weren't annoying on the highway.

 

[pagrunt]

Would the 3.73 be good on the highway with a small tire like I have ?

205/70R14 is about 24.5" diameter as the 215/65R15 which the MCSS used is 26" diameter so that .5" is nothing.

 

[SS_Malibu]

Google an RPM calculator. You can add MPH, tire size, rear gears and final RPM.

 

[79 USA 1]

Your stock ratio is probably a 2.29, both my 79 Monte Carlo's with the open rear and 267/turbo 350 combo's came equipped as such. Had a 79 Malibu Classic with the same engine/transmission set up but a limited slip rear, that had 2.41 gears.
3.42's were a great gear set with my first 79 Monte Carlo but that was with the 406/ turbo 350 transmission and a 26.5 inch (225/70/14) tire. Later went to 4.10's, while they were great for the track, they buzzed the 406 a little too much on the highway.
3.73's would be a better choice with the overdrive, would make it similar to the 85-88 Monte Carlo SS where the gearing would give life to the anemic 305.

 

[houston_t]

Something else seems weird. My wife's long-gone 2002 Z28 with auto trans did not have any issue performance-wise getting the RPMs up on the highway (albeit a good rate of speed) and she had the standard automatic car 2.73 rear end. My 02 SS I once had came with the standard 3.42 with no other option, but it was an M6. Also without issue getting around at any RPM. Those were efficiency leaning gears, so you could go deeper without issue if gas mileage isn't a concern. 3.23 were optional for the auto I think.

Really depends on what you want to do with the car. 3.42 or 3.73 are good gear sets in general. Only about 100 rpm or so on the highway difference at cruising speeds. Depends on if your LS1 and trans set up is stock. Either way I'd sloppy up that torque converter a little if you go with .42 or .73s. Especially if you go .73. Say get something like a 3300 stall speed or in that range somewhere. Again, JMO. Personally with OD, I'd lean to 3.73. With only a 3 speed, I'd go 3.42. But your call.

Just think, the mid 80s G-body "performance" cars came with either 3.42 or 3.73 with OD transmissions. The gears helped immensely between stoplights (as well as they could anyway) but also weren't annoying on the highway.

I’m hoping it’s just the gear ratio, mines is in the low 2’s as it was a 3 speed car.

 

[Rt Jam]

It A L L depends on what you want to do and get out of the car. Do you have a Grand National? They are mid 3 gearing with transmission ratios very similar to your 4L60E.
I see alot o f3.73 suggestions but that is pretty low for a tiny rear tire. The 1st gear ratio is 3:1, multiply that by 3.73 and consider the 14" white wall tire and there is zero chance you will be able to take advantage of that ratio during full throttle launch. So personally I do not see the need for a low rear gear.
Get a low 3's ratio to suit the car.

What are you getting from Quick Performance?

 

[69hurstolds]

The 14" tire isn't much difference in circumfrence than a 15" tire on a stock G-body. Width may be a tad different. Once you start having some fun and tear off the 14" tires with 3.73, you'll get fatter ones. Trust me.