I have a 700R-4 trans in my 69, with 3.22 rear gears and 25" rear tires. My fairly torquey 383 turns about 2,000 RPM at 65MPH. With your set up, here is what you can expect:
***
MPH RPM (in Gears)
****
1 2 3 4
****
5 484 258 158 111
10 968 516 316 221
15 1452 773 474 332
20 1936 1031 633 443
25 2420 1289 791 554
30 2904 1547 949 664
35 3388 1805 1107 775
40 3872 2062 1265 886
45 4355 2320 1423 996
50 4839 2578 1582 1107
55 5323 2836 1740 1218
60 5807 3093 1898 1328
65 6291 3351 2056 1439
70 3609 2214 1550
75 3867 2372 1661
80 4125 2530 1771
85 4382 2689 1882
90 4640 2847 1993
95 4898 3005 2103
100 5156 3163 2214
105 5414 3321 2325
110 5671 3479 2436
115 5929 3637 2546
120 6187 3796 2657
You might want to consider either changing to a smaller tire, or a numerically higher rear end gear ratio.
With a 3.42 rear gear:
****
MPH RPM (in Gears)
****
1 2 3 4
****
5 606 323 198 139
10 1213 646 396 277
15 1819 969 594 416
20 2425 1292 792 555
25 3031 1615 991 693
30 3638 1938 1189 832
35 4244 2261 1387 971
40 4850 2584 1585 1109
45 5456 2906 1783 1248
50 6063 3229 1981 1387
55 3552 2179 1526
60 3875 2377 1664
65 4198 2576 1803
70 4521 2774 1942
75 4844 2972 2080
80 5167 3170 2219

With your 2.73s and a 25" tire:
****
MPH RPM (in Gears)
****
1 2 3 4
****
5 561 299 183 127
10 1123 598 367 253
15 1684 897 550 380
20 2246 1196 734 506
25 2807 1495 917 633
30 3368 1794 1101 760
35 3930 2093 1284 886
40 4491 2392 1468 1013
45 5052 2691 1651 1139
50 5614 2990 1835 1266
55 6175 3289 2018 1392
60 3588 2201 1519
65 3887 2385 1646
70 4186 2568 1772
75 4485 2752 1899
80 4785 2935 2025
85 5084 3119 2152
90 5383 3302 2279
95 5682 3486 2405
100 5981 3669 2532
105 6280 3853 2658
110 4036 2785
115 4219 2911
120 4403 3038
Options to consider. I get the feeling that your 5.3L won't be very happy at such low RPM. Here's the link to the calculator that I used. It's fun to play with.
Gear and Shift Point Calculator | GTSparkplugs

 

Xten, lots of good information (except it confirms my concerns). 1328 RPM at 60 MPH won't work. My Vortec was out of an '04 Tahoe which had a 3:73 ratio and a 30.6" tire which would be 1700 RPM at 60 MPH according to the calculator.
Again, thank you very much for the insight.

 

I'm glad it helped.

 

here is another calculator for rpm's an speed.

Gearing Analyzer with Shift Tracer

Enter gear ratios, tire and diff ratio to analyze RPM vs velocity at shift points with tracer

www.blocklayer.com

 

The calculator that you linked is very cool.

 

That gear calculator is absolutely awesome!

 

The 700r4 and the 4l60e are essentially the same transmission as far as the gear ratios are concerned. I would imagine that with a 29 inch tall tire a 3.42-3.73 would be in the neighborhood you’d want to be in. 4th gen Camaro’s were available with 2.73, 3.23, and 3.42 axle ratios but the tire diameter on a 275/45/17 is 26.7 inches.

 

Thanks Thug. I bought the rear, first gen Camaro, cus of the cheap price and great condition but primarily the needed 60" width.
This is a poverty, non-Nova build and it requires the 29" tire to fill the well.
I think I'll get the PCM programmed to the 2:73 gear and get it on the road and see what happens. I can always throw a $200 R&P in it if necessary.
Thx all

 

I'm on to a new project and I've never had a 4L60 before. So, here's the combination and question:
3000 pound vehicle, stock, 295 HP 5.3 with a stock 4L60E, stock converter, 2:73 rear gear and 29" tire.
This not a performance build, t's a "reacher"......I'm going to highway drive it all over the place, (probably down to Az and have a beer w/ Jim).

4L60's have an 0.69 OD 4th gear. With the 2:73 ratio I'm wondering if it will shift into 4th at a reasonable speed?.
I have not had the PCM reprogrammed yet and I'm sure the tuner will take the tire size and rear gear into account but as it stands this thing is going to be very high-geared. I don't want to drive around in 3rd, I want to take advantage of overdrive.
Can any of you LS guys shed any light?
Thx in advance.

Well Thank you , John . . . . . . . (but, there's more than one - " Az . . . . w/ Jim ) .
plus, you could always stop by and 'pick-up my Friend xten57 - Gerry . . . ' & have someone ridin'
Shotgun . . . . .
I would just have too Figure-out if I can "remove my face - mask" too enjoy that those beers .

COME on Down . . . . . AZ ani't going anywhere . .
" Road Trip "

(and I'm only 30 miles off of I-40 @ Ashfork, Az )

 

(ps - nothing to do with u'r o.d. trans . . . . . but = )

you can re-late



later , jim

 

OK, I sent the PCM off for reprogramming and asked the tuner about the very high rear gear and he confirmed the trans will never see overdrive. Additionally, setting the shift points in the ECM would be a challenge. So, I broke down and bought a 3:73 R&P, a ring gear spacer for the 2 series carrier and a brg kit.
The last thing I want to do right now is to "dial-in" a new set of gears.....makes me wish I had a 9-inch so I could just go buy a new pumpkin.

 

How about an Ford 8.8 from an Explorer..? They typically are equipped with 3.73’s, posi, disc brakes, and a Ford bolt pattern..

 

Yeah, Thug......I'm kinda kicking myself. I have already welded on the correct perches, striped, painted and plumbed the thing.
My $150 8.2 will just have to be a $450 rearend.

 

 

$450 is not too bad. The axle will have new gears with the correct ratio for your application.

I had to swap out the axle in my 64 a couple of weeks ago. I figure the hose from the body to axle deteriorated internally and roasted the brakes so bad I the drums were literally red hot. The brake shoes and springs were totally wasted.. Fortunately, I had picked up another 8.2 back in March and it was ready to go..

 

I have an LS6 from a 2003 Z06, a 4L65E trans, Ford 8'' with 2.79 gears and a 25.46'' tire. The 2003 Corvette with an automatic trans came with a 2.73 gear and a 25.34'' tire. Think you need to run a smaller tire or a little taller gear.