B52bombardier1

Hello,

I have a bone stock 5.3 truck motor and a 4L60E in a 70 El Camino with 2.73 gears in the back. I was advised by my local trans rebuilder five years and 20,000 miles ago that around town below about 45 MPH that I should stay in a manually shifted D3 gear to keep the RPM's up and the load on the 3-4 clutch pack frictions in the 60E down. And then only shift into OD on higher speed roadways such as the Interstate, etc. Since that rebuild, this transmission has been excellent loafing along at about 1800 RPM in D4 OD at 70 MPH sipping gas at 22-23 MPG. The vehicle is most definitely a cruiser that couldn't smoke a tire even if I wanted to.

Can I expect to see excessive wear in the D3 portion of my 4L60E anytime soon due to being in a manual D3 so much? I have a Pontiac Catalina convertible that will very soon have a similar setup.

Rick

Full Power

Ring n Pinion sets are cheap.
recommend installation of 3.73 gears as a YUGE improvement in driveability, acceleration, and ECONOMY.

B52bombardier1

I have thought about a ring and pinion change but I enjoy the fuel economy. And more to the point, I thought that a 3-series gear of that magnitude wouldn't fit inside my ten bolt differential.

Rick

FranksCustomTrans

Most certainly will fit and no driving around in D3 won't hurt anything

FranksCustomTrans

Also note while 373 might hurt a bit on the highway they most certainly would help fuel efficiency around town

2BFAST

iTrader: (11)

The F?

FranksCustomTrans

Yes I had same sentiment , Odd and pointless thing to tell someone . On top of that with 2.73 I don't see it going in 4th much below 45 anyway , I know i have 3.08 and mine does not . So not sure of the builder reasoning. Maybe if it was an old 700R4 they used to sometimes go into OD at speeds to low and lug but even then it was usually because TV cable was wrong or converter set up to lock in 4th.

RPM WS6

iTrader: (3)

Are you certain this engine is running correctly?...such as fuel pressure and A/F ratio? I ask because, even at stock power for a 5.3 (LM7s are like 270-300hp stock, correct?), there should be no issue getting a one-tire-fire going - even with 2.73s (I mean, unless you have a huge M/T ET Drag tire on the rear or something).

My '74 Cutlass has a stock Olds 350-4, it's 200hp with dual exhaust option, 2.56 gears with a TH350 (mild 2.52:1 1st gear, vs. 3.06:1 in your 4L60E), and it's a ~4,000 pound car. The engine hasn't been rebuilt since leaving the assembly plant in April of 1974, but I can still get some tire spin with a 215/70/14 tire out back. You should be making at least 70hp more than my '74, more torque as well, and have much more 1st gear mechanical advantage with 2.73 x 3.06 1st gear.

Beyond that, I will buck the trend here and NOT recommend more gear. If you like the 2.73 fuel economy on the highway then don't change anything with the axle. Instead, consider a higher stall speed torque converter. Even a stock LM7 can benefit from a bump in stall speed. Keep it mild, around 2600-2800rpm, get a top shelf unit (Yank, FTI, etc.) and you'll barely notice it around town unless you stomp on the pedal. On the highway, with lockup it will turn the exact same rpm as it does currently - no loss in MPG.

B52bombardier1

The engine seems to be running well. No codes, very low STFT and LTFT and 58 PSI at the fuel rail. Plugs are a nice tan color, and all cylinders are at 165-170 PSI for compression. Cold oil pressure is 50 PSI and hot idle oil pressure is 35 PSI. The motor only has 170,000 miles and it had both heads rebuilt 23,000 miles ago. Two Blackstone oil analysis reports indicate very low wear metals and no fuel in the oil. And low silicon . . . good air filtering.

The 4L60E torque converter stall is stock for whatever the donor 1999 GMC Sierra 1500 had - I'm thinking 1800 RPM. The TC also got rebuilt when the transmission got rebuilt. The hottest temperature that I've ever seen in the fluid at the trans cooler was mid-summer here in Louisiana at 190 F.

I must say that I have never tried to smoke a tire in my El Camino. That's what my 2013 six speed manual SS Camaro is all about but even that is a rarity. Teaching my grandson and niece how to drive this manual LS3 Camaro caused more tire smoke than I've caused in years.

All in all, I'm happy with the motor but I will consider a higher stall TC.

Many thanks,

Rick