Comparison
4L60E vs 4L80E for an LS swap: which one should you run?
Torque ratings, gear ratios, weight, length and the parts that change with each one, so you buy the right transmission the first time.
Short answer
Run a 4L60E (or the stronger 4L65E/4L70E) behind a mild, near-stock LS in a light car: it is smaller, lighter and has a deeper first gear. Run a 4L80E for big torque, boost or a heavy car: GM rates it at 440 lb-ft, but it is longer and heavier and needs a 32-spline yoke and 4L80E flexplate.
How do the 4L60E and 4L80E compare at a glance?
| Spec | 4L60E | 4L80E |
|---|---|---|
| Ancestor | 700R4 (TH700-R4) | TH400 |
| GM factory torque rating | About 360 lb-ft stock; 4L65E and 4L70E rated higher | 440 lb-ft (4L85E: 460 lb-ft) |
| Gear ratios (1st / 2nd / 3rd / 4th) | 3.06 / 1.63 / 1.00 / 0.70 | 2.48 / 1.48 / 1.00 / 0.75 |
| Weight (with fluid, no converter) | About 160 lb | About 180 lb |
| Overall length | About 31 in. for the 1998-up LS version | About 1.5 in. longer (GM spec sheets, 4L85E vs 4L65E/4L70E) |
| Bellhousing | Removable on 1996-up cases | Cast into the case |
| Converter bolt pattern | 11.062 in. (LS version) | 11.5 in.; needs a 4L80E-pattern flexplate |
| Output shaft | 27-spline | 32-spline |
| Controller | Computer required | Computer required |
| Our mechanical speedometer options | Speed kit ($850), tail housing kit ($850) | Speedometer kit ($900), tail housing kit ($900) |
Ratings, ratios and weights from the TCI chart in Street Muscle, LSSwapBible and Gearbox Insider. Published 4L60E ratings vary by source and year (roughly 360 to 380 lb-ft), so treat them as a guide, not a guarantee.
Which is stronger, the 4L60E or the 4L80E?
The 4L80E. It descends from the TH400 and GM rates it at 440 lb-ft of engine torque, against roughly 360 lb-ft for a stock 4L60E. The 4L65E and 4L70E closed some of that gap with stronger internals. If your LS makes close to factory power, a healthy 4L60E-family unit is the common choice. If you plan on boost, a big-inch build or a heavy car, the 4L80E gives you margin. Compare your engine's torque to the transmission's rating, not its horsepower. Our LS engine and transmission pairing guide lays out where each LS lands.
How do the gear ratios differ, and does it matter?
The 4L60E has the deeper first gear (3.06 vs 2.48), which helps a heavy car or a tall rear gear get moving. The 4L80E's overdrive is a little shorter (0.75 vs 0.70), so at the same rear gear and tire it turns slightly more rpm on the highway. Neither change affects the speedometer: speedometer gears are driven off the output shaft, so only tire diameter and rear axle ratio set the tooth count.
Will a 4L80E fit in my car?
Plan for it before you buy. The 4L80E is longer and heavier, its mount sits in a different place, and most swaps need a different crossmember or tunnel clearance work. Measure your tunnel and mount location first. The 4L60E-family case is the more compact package, which is a big part of why it is so common in older cars.
What changes on the driveline?
- Flexplate and converter: the LS-version 4L60E uses an 11.062 in. converter bolt pattern; the 4L80E uses 11.5 in. and needs a 4L80E-pattern flexplate (LSSwapBible).
- Yoke: 27-spline for the 4L60E, 32-spline for the 4L80E.
- Driveshaft: measure for length with the engine and transmission in their final position. Don't assume the original shaft will work.
- Crossmember: expect a swap-specific crossmember for either, and almost certainly for the 4L80E.
Can both keep a mechanical speedometer?
Yes. Both report speed through a VSS and have no cable drive as GM built them, and we make mechanical options for both. For 1998-and-newer 4L60E, 4L65E and 4L70E cases there's the speed kit, a 30-minute bolt-on that uses a billet adapter on the stock 6-bolt case so a standard 4-bolt tail housing bolts up, or the machined tail housing kit. For the 4L80E there's the 4L80E tail housing kit, built for builds running the 4L80E behind a big-inch LS or a blown small block, and the 4L80E speedometer kit. See the full walkthrough in how to keep your mechanical speedometer with an LS swap.
So which should I choose?
Pick by torque, vehicle weight and space. Near-stock LS, lighter car, tight tunnel: 4L60E family. Boost, big cubes, heavy car or towing: 4L80E, with the crossmember, flexplate and yoke budgeted in from the start. Whichever you choose, the original speedometer can stay.
Frequently asked questions
Is the 4L80E stronger than the 4L60E?
Yes. GM rates the 4L80E at 440 lb-ft of engine torque, against roughly 360 lb-ft for a stock 4L60E. The 4L65E and 4L70E are rated higher than the original 4L60E but still below the 4L80E.
Is a 4L80E longer than a 4L60E?
Yes. GM's spec sheets list about 1.5 inches more overall length for a 4L85E than a 4L65E/4L70E, and the 4L80E's mount sits in a different place, so most swaps need a different crossmember and a driveshaft measured for the new length.
Do the 4L60E and 4L80E use the same flexplate?
No. The LS-version 4L60E uses an 11.062-inch torque converter bolt pattern, while the 4L80E uses an 11.5-inch pattern and needs a 4L80E-pattern flexplate.
How many splines does a 4L80E output shaft have?
The 4L80E uses a 32-spline output shaft and slip yoke. The 4L60E uses 27 splines.
Can I keep a mechanical speedometer with either transmission?
Yes. Southwest Fabrication makes mechanical speedometer kits and machined tail housings for the 4L60E, 4L65E, 4L70E and 4L80E. The tail housing kits and the 4L60E speed kit retain the VSS, and the 4L80E speedometer kit does not interfere with stock electrical configurations.
Talk to the shop
Every housing and speed kit is machined in Caddo Mills and ships with gears cut to your tire diameter and rear axle ratio. Questions about your combination? Call 903-527-2006, Monday to Friday, 7am–3pm Central, or email [email protected].
Shop the kitsGear calculatorSources
- Street Muscle: Spotter's guide to the 4L60E (TCI length chart and ratings table)
- LSSwapBible: LS swap transmissions compared
- Gearbox Insider: 4L60E to 4L80E swap guide
- Novak: The GM 4L60-E (late style) transmission guide
Kit details come from Southwest Fabrication's own product listings. Outside technical figures are linked above; check them against your exact parts.
