give me your opinion on rear gears

[ryes 69]

what gear ratio do you have and do you like it with your motor,tranny?I'm trying decide on 3.07 or 3.73.I like the burnout and 2nd 3rd chirp but not hwy with the 3.73s. but I'm not sure how the 3.07 would be off the line? not a drag racer just want the best of both oh I have 350 4spd.

[cableguy0]

if u want somewhat decent highway but still be able to get off the line get like 3.55 rears.

[batboy]

I like the way the Cableguy thinks. If you had an auto, then maybe the 3.07 gears would be ok, but for a truck using a manual 4 speed, that's too high of a gear ratio (too low numerically) in my humble opinion. Personally, I like the 3.73 gears, especially if you have tall tires and ever plan on doing any hauling or towing. Otherwise, the 3.55 gears would be a nice compromise.

[Patrick Sullivan]

4.10's are fun - "Those are the longest rubber marks I've ever seen!"..

[Bill72BB]

ryes ;

I replaced the 4.10 in mine with 3.54 ,still has some spunk off the line and can cruse the freeway at a reasonable RPM .
If you want to keep the 3.73 ,think about going to a larger tire size.
This site will help.
http://www.prestage.com/carmath/calc_Gears.asp

Bill

[Fast68Chevy]

you can find 3.40 ratio in some 76 trucks i know, some other years also too, if you have too short of tires with 3.73 thne your rpms can suck, but 3.40 can help if you are bent on tires that are short enough to give you crappy rpms than if you got taller tires.

shorter tires with 3.07 would help to counter affect the crappy acceleration of 3.07 gears, and taller tires on 3.,73 ratio would help counter affect the crappy rpms on freeway, you have to give alittle to gain something else when it comes to axle ratios, eithe ryou want fast or yuo want a cruiser, hard to have both unless you sit down and calculate tire size with ratio to get rpm you want yet acceleration you like and also cruising rpm you like,

personally, 3.73 with 29.5: tires is badassed acceleration and is my preference of all ratios GM made, unles engine is super badassed strip drag motor or something, and is not horrible rpm, thats roughly 2850, which i think is fine for a chevy ergine, it wont hurt the motor to cruise at 2850, its not even working it, id give up a few cruising rpms for some fun acceleration anyday

good luck

[Longhorn Man]

I have 3.07's, a 350/350 combo, and it will barley get out of it's own way.
3.73.

[ryes 69]

thanx guys,so the 3.07 would kinda bog off line with the 4spd?I want to get a 5 lug rear and he has the 3.07or3.73.I have 6 lug 3.73.just trying to get "help" deciding which one to get.but maybe I could a 3.55 gearset hmmmm!!

[RodC]

What No Poll? I'm really disapointed with you guys.....

I like the 3.73s but 1/2 of my driving is highway towing a camper. I have 3.37 with a 350/350C and 29" tires

Yes that is a 350C with a locking Torque converter, and it is wired to work with my vacuum, talk about somethig that will give you 3-4 more mpg and give you some engine breaking in 3rd gear, you gota get a tranny with a locking Troque converter. I don't know how I drove this thing on the highway without one before. I don't have a tac but I lost lots of RPMS and you dont have that mushy feeling of a Auto once it is locked up.

[Longhorn Man]

Onless your verter is slipping at that RPM, you should only lose about 200 - 300 RPM.
I don't see how you can get that kind of MPG increase, and it is actually supposed to come out of lock up when you take your foot off the throttle.

[RodC]

Check out how they were wired 80-81 the only thing that will take them out of lock up is:

Low eng temp
High Vacuum
Stepping on brake

The circuit was pretty simple, temp sensor, brake switch and vacuum switch.

Only the lockups that were controlled with ECMs would unlock due to lack of throttle.

Keep in mind I am comparing the 350C RMPs not locked up vs locked up. The 350Cs actually slip more when not locked up in 3rd than a normal 350. (I read this on some tranny co. website, I'll try to find it again) They also warned that running a 350C without the lockup working would cause more heat than a standard 350 and we all know what heat does to auto trannys.


I guess I should have said, if you have a 350C, better hook up the Lock-Up You will notice a difference. When I bought mine the prev owner did not have it wired. I ran it a while before I hooked it up, I wish it was the first thing I did.

[68 with 350 TPI]

I have 4.11 gears in my truck and I would not change it for anything

But I would also be happy with a set of 3.73 gears.


There are a few easy things to do to help out the highway gas millage though.

1) drive slower so the people can look at the cool old truck
2) put on taller tires to help the 3.73's act more like 3.55's
3) get a trans with a overdrive.

[Longhorn Man]

Rod, cool deal. I did not know that.
You are right that I am thinking of computer controlled trannys there.

[Mountain Man]

I had 3.73 gears in my 67 until 3 weeks ago. RPMs were insane at 60mph, because I have 26" tires (255/60/15)

You could lay tracks any time, but could not cruise at all.

Opted for a new auburn posi with 3.08 ratio. I lost some acceleration, but it is not that bad with 26" tall diameter, and I love my top end, the truck will do 135mph+

I wanted a cruiser thou, and if you are more concerned about your 0 - 60 acceleration then I would stick with 3.73's

By the way, I have my original 3.73 gears and differential available if someone is interested in them.

[ryes 69]

I don't want to be able to do 135mph cause' I'll DO just that!! so 3.73s it is.I think? (135mph hmmm how fast is a cop car?)