3.42 or 3.73 ?

Project-Z28

Member
Apr 22, 2012
81
Newfoundland
I just picked up a good use carrier it came with a set of 3.42 on it . But I have a set of 3.73 gears as well . Which would be better for an all around street and sometimes strip car ?
 

Randy S

Veteran Member
Mar 27, 2008
164
NELA
What size tire are you planning to run? Do you have a target RPM for say, 70MPH? Does the wear pattern on the 3.42 ring and pinion look ok?

I'm running a tire that's right at 27" tall and wanted to be around 2200 RPM at 70MPH, so I'm running 3.42's.
 

grzewnicki

Veteran Member
Lifetime Gold Member
Dec 9, 2009
3,717
Gordon from Jacksonville Fl
I imagine your running an auto or 4 speed, something with no overdrive? 3.73 in my car at 65 MPH was over 3000 rpm, hard to tolerate for long drives. Now in my 73 I had many years ago I was running 4.10 but the area I lived I never much went on a freeway/highway. I'm loving 3.42 and a 5 speed now though. I think anyone that takes there car out for long drives or sees a bit of freeway travel can tell you how much of a blessing having a 5 speed is.
 

legierk

Veteran Member
Jun 11, 2014
762
Waskom, TX
I'm with the Floridian. 3:73s in mine with a big block screams over 3000 rpms down the freeway (with a 4 spd). That's a lot of steel spinning around. Not recommended. 3:42s safer choice.
 

Randy S

Veteran Member
Mar 27, 2008
164
NELA
Randy S said:
What size tire are you planning to run? Do you have a target RPM for say, 70MPH? Does the wear pattern on the 3.42 ring and pinion look ok?

I'm running a tire that's right at 27" tall and wanted to be around 2200 RPM at 70MPH, so I'm running 3.42's.

Should add that this is with a 4L60E that has a .70 overdrive.

Here's a good RPM calculator that might help - RPM Calc.
 

Coadster32

Veteran Member
Lifetime Gold Member
Oct 2, 2013
2,356
Milford,CT
If you have an OD tranny...3:73 definatly. If you plan on limited highway use....3:73. If you don't want to get smoked by a crappy little Honda with a really loud and obnoxious exhaust pipe....3:73's. If you're on the highway a lot, and have a 3/4 speed and are concerned about fuel mileage.....3:42, or sell the car :)
 

Rich Schmidt

Veteran Member
Mar 27, 2010
4,285
Denville NJ
Randy S said:
What size tire are you planning to run? Do you have a target RPM for say, 70MPH? Does the wear pattern on the 3.42 ring and pinion look ok?

I'm running a tire that's right at 27" tall and wanted to be around 2200 RPM at 70MPH, so I'm running 3.42's.


I am running 3.08's with 28" tall tires and am running about 3000 rpm at 75 mph. I cant see how you will accomplish your goal without and overdrive.

edit. I didnt know you had an overdrive.
 

Double J

Veteran Member
Jan 23, 2008
413
Michigan
I have 1972 Camaro 3:42 gear M20 4 speed 26" tires taching at about 2600rpm at 60 mph. Great combo the M20 gets the car out of the hole quickly and the 3:42 does not tach to high at highway speed.

Highly Recommended............
 

Rich Schmidt

Veteran Member
Mar 27, 2010
4,285
Denville NJ
Double J said:
I have 1972 Camaro 3:42 gear M20 4 speed 26" tires taching at about 2600rpm at 60 mph. Great combo the M20 gets the car out of the hole quickly and the 3:42 does not tach to high at highway speed.

Highly Recommended............


Haha,you dont live in Jersey. Anything under 75 mph will get you run over by little old ladies going to church,even if you are in the slow lane. Even with the 3.08's and 28" tall tires,I cringe at how high I have to spin just to keep up with traffic in the middle lane. I drive my car 60 miles round trip to work every day during the rush hour commute into down town NYC,so basically I need to fly at about 80+mph just to not get run over,until I get within 10 miles of the city,then sit in stop and go 5mph traffic for an hour. An overdrive trans and lock-up convertor are on my list of soon to be upgrades.
 




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