Team Chevelle banner
  • Hey everyone! Enter your ride HERE to be a part May's Ride of the Month Challenge!

Status
Not open for further replies.
1 - 20 of 20 Posts

·
Registered
Joined
·
32 Posts
Discussion Starter · #1 ·
Well i went out and bought a 12 bolt for my 71. It is a 3 series carrier (3.08 gears) right now. I want to get the gears done before i put it in and am having a hard time deciding what to get. Will i loose all my drive ability with 4.11's? Also how much faster would it be with them then say a 3.73?

My car now is a good runing 350 with a big cam, intake, & headers. It starts runing good at about 2500 and gets realy good power from there up. I am also planing on puting a 2500 stall converter in when i swap the rear end.

How much does tire size effect the cruse RPM's

Someone give me some pointers on where to go with this i dont want to get the 4.11's and regret it, or regret no geting them.

Thanks
 

·
Premium Member
Joined
·
987 Posts
You'd probably be happier with 3.73s. 4.11 really get your RPMs up on the interstate. Going from a 3.08 to a 3.73 you'll really feel the differance if you stay with the same size tires.

------------------
Joe Yoder
BADBU68
LSE Motivated
 

·
Registered
Joined
·
1,525 Posts
4.11 is a big jump from 3.73. If you dont do any 50+ mile highway drives, and keep it "around town", you could be OK with 4.11's.

Tire size has a big effect on your overall gearing. E.G., I have 28" tires mounted for cruise, when I put the 25.5" tires on for go, it effectively take my 3.55 gear to a 4.06.

Check tech reference off the TC home page for gearing formulas. Get your calculator out run some numbers.

------------------
Member #62 Gold/ACES 03112
67 SS396(427-3X2)
Be Big, Be a Builder
 

·
Premium Member
Joined
·
13,692 Posts
I am running 3.73's with 28" tall tires and it is borderline monotonous,I drove it to Springfield,Mo. to the street machine nationals last night(50 miles one way)with the drive up and back,a little cruising,and an occasional jumping on the throttle,I have 1/8th tank of gas left


------------------
Bob West
1972 Malibu 454+.030
350 turbo-3.73's
[email protected] 1000ft.track
[email protected] mph 1/8th mile
 

·
Registered
Joined
·
1,749 Posts
Put a 2004R tranny in and then the 4.11's are fine. You need to look at this as an entire package; motor, tranny, rear gears. Yes, it will cost more up front but, 18 MPG against 9 MPG will pay for the tranny in 20,000 to 30,000 miles in just cost of fuel. When you start considering a new motor due to the huge additional wear caused by high RPM cruising, the actual return on investment is probably between 15,000 and 20,000 miles.

So,base your decision on how many miles to drive while you own the car.

------------------
Redrum (or Mike)
68 Corvette - 383 CI 427 HP
69 SS Chevelle being updated to Pro-Touring
97 Z-28

[This message has been edited by Redrum (edited 09-16-2001).]
 

·
Registered
Joined
·
1,314 Posts
Hello,

I bought a brand new 68 Z-28 back in 68. It came with 4.11 gears. I found someone with a 68 Z who had 3.73 gears and wanted to trade. I was much happier with the 3.73.
 

·
Registered
Joined
·
2,306 Posts
If you stay off the freeway 4.11s are alright. I even ran 4.56s on a driver once {stupid} but like everyone says mileage is lousy and parts wear out much faster.
 

·
Registered
Joined
·
4,647 Posts
I run 4.10's in my daily driver with no problems at all. I have a 700R4 tranny and 25" tall rear tires for 2500 rpm cruising at 65 mph.

------------------
67 Nova 3475# daily driver
10:1 406, 700R4, 224° Comp cam, RPM and a Q-jet - 11.76 @ 116
64 Chevelle Road Racer in the works
67 Nova Wagon under construction
65 Corvette Road Racer
 

·
Premium Member
Joined
·
27,698 Posts

·
Registered
Joined
·
3,545 Posts
Here are a couple of automotive math formulas that I have commited to memory:

1) (mph X gear ratio X 336) all divided by tire diameter = engine rpm

2) (rpm X tire diameter in inches X 2.96) all divided by (gear ratio X 1,000) = mph

Now by themselves these formulas are useful, where they get interesting is when you take into account you chassis dyno results. What, you haven't done a chassis dyno pull yet? If you haven't, then you are just taking a wild as$ guess as to what gear you should choose.

In very general terms a 26" tire vs a 28" tire will make about 8% difference in rpms.

One thing that I have noticed when neophyte hot rodders start talking about gear ratios is that few will take tire diameter into consideration. This is particularly important because drag tires/slicks tend to be taller then street tires (longer footprint = more traction).

Now let's go back to the word "mild", which you did not use, but probably would if you were honest with yourself. A 2,500 rpm stall is mild - some factory applications are not that far away. "Starts pulling at 2,500 rpm" - what carbed street application doesn't? If you are going to call a cam "big" you should spell out the specs because I have no idea what you consider "big".

4.11's with no overdrive trans is not too much gear, unless you dislike limiting long distance highway driving to about 55 mph, or buzzing your engine for higher highway speeds.

I have an overdrive trans that will soon be going into the Bomber, along with 3.73 gears. I did not want to change out the gears until the overdrive trans was in place because I still like to cruise at 80 to 85 mph on long drives.

Most people who have been in the Bomber never would have guessed that it was burdened with a lowly 3.08 gear. Sure it hurts the 60' and 1/4 mile e.t.'s, but on the street a few tenths go mostly unnoticed by all but the most hard core.

Best of luck with whichever you choose, Thomas.


------------------
"Bomber" '67 El Camino, Beater comes back to life.
Was 350/TH350 14.90 @ 93mph, 360,000+ miles on car
Now 406 roller, 340rwhp, more hp coming, 3.08 gears
Street radials, left in drive, 13.20 [email protected] mph
8/1/01 added Plum Mist '67 to collection
*New* 468 on its way - going Big Block!
 

·
Registered
Joined
·
32 Posts
Discussion Starter · #13 ·
Sorry for the vauge description of my set up. What i ment was that it has a noticable jump in power at about 2500-3000, below that it sorta sucks, and it also lopes quite a bit at idle, and gets about 10 INs/Hg at idle on my vac gauge.
 

·
Registered
Joined
·
279 Posts
<BLOCKQUOTE>quote:</font><HR>Originally posted by onovakind67:
I run 4.10's in my daily driver with no problems at all. I have a 700R4 tranny and 25" tall rear tires for 2500 rpm cruising at 65 mph.

<HR></BLOCKQUOTE>

Isn't that a LOT of gear for a 700r4? A 700r4 has a 3.06:1 first gear... compared to the 2.52:1 of the th350 and 2.48:1 of the th400. It also has a lower second... so wouldn't you be better off with 3.42's or so? A 700r4 with a 3.08 rear end would compare to a th350 with a 3.73 rear end... just a thought, been reading a lot about gearing lately.

To answer the question first ask: if the car is daily driven, DO NOT GO WITH 4.10s. This is primary reason I'm trying to sell my car. You know how bad it feels to get passed by a Festiva on the freeway when you know you can run a 12?


------------------
kenny

85 El Camino 355ci
350 turbo - 4.11's
best run so far 12.92
My Page

[This message has been edited by ? (edited 09-16-2001).]
 

·
Registered
Joined
·
3,545 Posts
'71 Chevelle,

Specs buddy, I want specs
Sorry, but your clarification did little to tell us about your car.

What carb, size and style?
What intake, single plane, dual plane, etc?
What cam, lift, duration, lobe separation angle?
What heads, valve size, any porting?

In lieu of chassis dyno results, how about drag strip results (and I do not want any computer simulation - I want real track results).

Don't worry if you do not know the answers to all of these questions - doing the work to find the answers will teach you a lot.

One step at a time and Team Chevelle will help you build the car of your dreams - well o.k., we can only supply encouragement and collective wisdom.
 

·
Registered
Joined
·
4,647 Posts
Originally posted by ?:
Isn't that a LOT of gear for a 700r4? A 700r4 has a 3.06:1 first gear... compared to the 2.52:1 of the th350 and 2.48:1 of the th400. It also has a lower second... so wouldn't you be better off with 3.42's or so? A 700r4 with a 3.08 rear end would compare to a th350 with a 3.73 rear end... just a thought, been reading a lot about gearing lately.

I have a 9" Ford rear in my Nova, and have 3.50, 3.70 and 4.10 gearsets. The 4.10's allow me to reach 6200 rpm in the lights for a speed of 116+. I haven't tried the 3.70's with the 406 yet, but I'll predict only 5600 in the lights and a slower elapsed time. I like the low first gear, my 60's are high 1.6's with stock gas shocks. I'm going to experiment with some looser shocks to get my 60's down in the 1.5 range, then 11.50's should be on the horizon.

------------------
67 Nova 3475# daily driver
10:1 406, 700R4, 224° Comp cam, RPM and a Q-jet - 11.76 @ 116
64 Chevelle Road Racer in the works
67 Nova Wagon under construction
65 Corvette Road Racer

[This message has been edited by onovakind67 (edited 09-16-2001).]
 
G

·
4:11 is a starter gear for a strong small block or a 427. It's those wussey 454s that can stand the rpm!

More gear means better off line performance and less wheel spin. I like a 4:88 for the street with a nice tall tire and my adjustable torque converter, clutch, and a slick shifting M22.

[This message has been edited by Wally (edited 09-17-2001).]
 

·
Premium Member
Joined
·
13,692 Posts
<BLOCKQUOTE>quote:</font><HR>4:11 is a starter gear for a strong small block or a 427. It's those wussey 454s that can
stand the rpm!<HR></BLOCKQUOTE>

thanks for the compliment Wally,454's CAN stand the rpm??? lol...actually 454's don't need the gears a small block needs,they do it all with torque,they don't need a crutch,like 4.56's or 4.88's ....if you don't believe me ask that guy with a red 68



------------------
Bob West
1972 Malibu 454+.030
350 turbo-3.73's
[email protected] 1000ft.track
[email protected] mph 1/8th mile
 

·
Registered
Joined
·
279 Posts
<BLOCKQUOTE>quote:</font><HR>Originally posted by onovakind67:
I have a 9" Ford rear in my Nova, and have 3.50, 3.70 and 4.10 gearsets. The 4.10's allow me to reach 6200 rpm in the lights for a speed of 116+. I haven't tried the 3.70's with the 406 yet, but I'll predict only 5600 in the lights and a slower elapsed time. I like the low first gear, my 60's are high 1.6's with stock gas shocks. I'm going to experiment with some looser shocks to get my 60's down in the 1.5 range, then 11.50's should be on the horizon.
<HR></BLOCKQUOTE>

How tall of tires do you run? I was just guessing but seemed like you'd be hitting redline before you went through the traps because of the lower first and second. Man that car has to SCREAM out of the hole. Wish I had a 700r4 and Ford 9, I would definitely be keeping my car.

------------------
kenny

85 El Camino 355ci
350 turbo - 4.11's
best run so far 12.92
My Page
 

·
Premium Member
Joined
·
28,597 Posts
<BLOCKQUOTE>quote:</font><HR>Originally posted by Wally:

More gear means better off line performance and less wheel spin. I like a 4:88 for the street with a nice tall tire and my adjustable torque converter, clutch, and a slick shifting M22.
<HR></BLOCKQUOTE>


I like 4.10's with 28" tall tires myself!


------------------
1970 Chevelle SS396/M20/4.10 My 70 SS396
Engine pic
1970 Chevelle SS454My 70 SS454
1968 Oldsmobile Cutlass convertible
1982 Oldsmobile Cutlass 350 Olds,TH350(daily driver)
Chris Corwel,TC Member 785
 
1 - 20 of 20 Posts
Status
Not open for further replies.
Top