[bluechevelless]

Right now Im running with a 2 series 2.56. I want to have a mid gear for my car. Im have a 3000 stall and the 2.56s are killer with it keeping the trans temps hot. The 3.42s are about $20 bucks cheaper than the 3.55s.
My car is street driven daily driver. I will occasionally take it down the strip but not often. Please help with my decision.
My tires are 25.5" Tall, I will stay with around a 26" tire.

 

[sonk]

Im no expert but i dont think you would notice any difference between the 2...either one would feel alot better than what you have..Sean

 

[mr 4 speed]

Go for the 3.42's

 

[norvalwilhelm]

Go for the 3.42's

Without overdrive I would not go to the 355's in a daily driver. On the open road they suck and being a bigblock you don't want to rev it all the time.
Even the 3.42 suck on the open road.
Given the 2 choices I would pick the 3.42 but how about 308's?

 

[mn65bis]

I've had 308 331 355 373 390 410 433 gears. The gear I liked with the best overall performance with tire size you have is the 355. If you plan on installing a 4spd some day I would opt for the 355's. I agree with sonk. You will never be able to tell the difference it's only about 3%. Either way you will love the change, but when cruising down the highway you will be looking to see if it is in drive instead of second gear.

 

[Steve70SS396]

I'm going to go with the 3.55 but I have a 28" tire.

 

[SWHEATON]

Without od trans & being a daily driver with alomst no strip time i would opt for used 3:31's or the 3:42 gear at max for street,no 3;55's.

With no strip time and being a daily driver 3:55's are not nedded IMHO and used 331's or new 342's (MAX) will be more street friendly rpm wise since this is not a pure perf car. The 402/bbc trq will handle the 331 or 342 gear just fine with good perf when getting into it vs streetability for cruise rpms.

I just saw a used set of 331s go for $130 on ebay,the 331s i bought used from ebay are still fine 3yrs later and cost me $125.

Scott

 

[98drags10]

I just went with 3.42 but mine will be more of a driver and does have a auto trans.

 

[bluechevelless]

what rpm do you run at, at 75mph?

 

[Dave]

I had 3:73's with a BB and TH400, sucked driving on the freeway. Now, I'm switching to 3:08's in hope's of a little more comfort, and less wear and tear on the Drivetrain. In my first Chevelle many years ago, I had a SB, M-22 with 3:31's, was the best all around combo I ever rode in.

 

[big gear head]

3.42

 

[Chief fat nutz]

regardless of driving style a mid 3 range gear is great. 3.42's for my vote even though i have 3.73's.

 

[bluechevelless]

where can I get 3.31s except ebay?

 

[SWHEATON]

No where,331's are not produced NEW anymore.

My friend and myself both bought used sets of 331s a few yrs ago for approx $125 off ebay and have had no problems after having them installed by a qualified shop,not everyone selling on ebay is a thief unloading junk.

I just saw a good looking set of 331s sell on ebay last wk for $130 and i see used 331s pop on ebay every 1-3 months so just kee watching.

I have seen 2-3 NEW GM NOS 331 ring & pinion sets sell for approx $250-$325 on ebay over the last 1.5-2yrs.

IMHO 331s are the best all around gear for perf vs streetability GM put in a muscle car that doesnt have some kind of an O/D trans.

So be patient and you will eventually find a good used or NOS set of 331's on Ebay or maybe even here in the T/Chevelle sales section,its worth the wait.

Scott

 

[radz]

I voted 3.42 since you said it is a DD. Here are my results.

I have 3.55 in mine, but I like a lot of gear, I actually prefer a 3.73; but I do need to drive on the highway. I did the calculations for you so you can compare the 2 different gears. I used a 26" tire as the standard, and a 5500 redline.

3.55 Gear :
1st gear redline: 48 mph
2nd gear redline : 81 mph
3rd gear redline : 120 mph
60mph rpm : 2750..... 55mph rpm : 2550

3.42 Gear :
1st gear redline : 50 mph
2nd gear redline : 84 mph
3rd gear redline : 124 mph
60mph rpm : 2650......55mph rpm 2450

Here is the link I used to do the calculations, you can play with it and find what you think you may like. http://www.f-body.org/gears/ Let me know if you need to know the gear ratios for a th400. - Mike R

 

[bluechevelless]

Thanks the 3.42s seem appealing, I might see if I can get a tad bigger tire.

 

[SWHEATON]

Mike,no disrespect but the rpm cal your using is not accurate,it shows rpms too low for sure.

For example,when i was running the stock setup 307 gear/m20,and 26" tires like you used for your calc my motor turns 2,400 rpm @ 60mph and your calc is 2,450 rpms (only 50 rpms more)for 342's @ 60mph with same tires and a lot more gear,thats incorrect.

When i changed to 331's with correct speedo gear,26" tires & m20 the rpm is 2,600 @ 60mph and you state 355 is less rpm 2,550 @ 60mph with more gear which is incorrect.

I have the correct speedo gear installed for each ring & pinion i was running so i know that was correct.

Again,my rpm #'s are real world what i got with same 26" tires with the correct speedo gears & M20 for each of the 2 gear ratios i used & i know my speedo is correct because i also clocked it against my wifes new car a while back and we were 1mph dif @ 60mph.

I calc the rpms for 342 & 355 gear @ 60mph with 26" tires and here is what got which i feel is right on or very close within 50rpm + - @ 60mph.

342 @ 60mph = 2,650 rpm

355 @ 60mph = 2,750 rpm

355 is too much gear for a daily driver with todays fuel prices IMHO. Even the 342s are pushing it for a daily driver esp with bbc that has good trq and can easily handle gear like 331 which is what gets my vote,but 342 max without an overdrive trans for daily use & even thats pushing it.

Scott

 

[1969 Chevelle Dude]

I voted 3:42's because that what I just put in my Camaro. In my ElCamino I have 3:73's hate it on the highway I should have put 3:42's in it.

 

[bluechevelless]

Im thinking the 3.42s might be the highest gear I get but it also depends on what I decide with the tranny later on. Id like a 5 or 6 speed overdrive manual but they seem pricey to swap.
I had 4.10s for a while and I could only go on the highway at 60 for about 3 miles before engine temps started climbing high.

 

[artmalibu]

I got 3.42s with a 28 inch tire its a little much on the open road.