Super OD

Inside Hughes Performance's 4L80E Overdrive Transmission

Andrew Schear Mar 17, 2005 0 Comment(s)

Every hot rodder with a Gen III motor in their machine can imagine the frustration of blowing up a $2,500 4L60-E. Whether it's a '69 Camaro or a Silverado 5.3, the end result is the same, lots of dollars spent for a new transmission.

While casually taking a few photos of Brian Zacuto's late-model blown Silverado roasting the hides we accidentally grenaded his modified 4L60--a little oops on our part. Feeling slightly at fault, we made it our mission to outfit his truck with the ultimate four-speed automatic overdrive. As luck would play a part in our decision, Jim Hughes, of Hughes Performance happened to view our unfortunate transmission explosion. While still contemplating how to get Brian's truck back to Los Angeles, Hughes casually mentioned that he could build us an overdrive that would take all the abuse we could throw at it. Naturally, this sounded like a challenge. Kind of like two third graders eggin' on the second grader to break a car window. We told Hughes he was on.

Three weeks later our "bulletproof" beast was ready for pick up and installation. Seeing as we had a terrible itch to install the 4L80 and do a few burnouts, we made the 500-mile trek to Phoenix, Arizona, to pick up the 4L80 first hand. We also thought it would be wise to have a look at the facilities which might produce such a mean shiftin' gear box.

Despite what the average hobbyist might think the install was only a tad more complicated than removing one transmission and installing another. In addition to the 4L80 from Hughes and the piggyback harness from Speartech, the installer also must find a competent local fabricator to lengthen and gusset the cross member and shorten the driveshaft.

The internals of a Hughes (25-1) 4L80 differ significantly from a stock unit. After the case and hard parts have been inspected, hot tanked and repainted, the transmission is reassembled using Alto Red Eagle clutches, Kevlar bands, and Kolene steel where applicable. In addition to the list of new internals the OE valvebody is reprogrammed and the pump overhauled with a tighter degree of tolerance. Behind the 4L80 sits a (25-30L) 10-inch 3,000-rpm stall converter. The loose converter utilizes a full roller bearing design combined with a forged sprag and race. This new combination of parts will live indefinitely at the 1,000hp limit, according to Hughes. The way we figure, any transmission that can handle the rigors of indefinite magazine testing is top notch for the weekend street warrior. Check it out!

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Alas, our Hughes 4L80 is ready for pick up. There's nothing like a brand new, shiny transmission in cellophane.

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Each and every transmission that leaves Hughes' facility is tagged and numbered, a system, which is always helpful when diagnosing a would-be problem.

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The use of a smaller, lighter torque converter is a must for performance. The 4L80 is naturally designed as a heavy-duty unit, hence the 13-inch 65-pound stock converter. The 10-inch, 3,000-rpm Hughes unit catches the revs better and reduces overall weight.

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Before that actual installation certain changes must be made to insure the connectivity between the transmissions and the in car/truck computer. A second speed sensor is used on the 4L80, unlike the single speed sensor on the 4L60.

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An extension for the transmission cooling lines must also be added. Be sure to use actual transmission fluid tubing. Traditional rubber hose will not suffice.

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When connecting a 4L80 in place of a 4L60 an inline harness manufactured by Speartech must be used. It too has a provision for the second speed sensor.

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Project "R" installers Warren and Jeff survey the situation before attempting to connect the new 4L80. With the additional weight and size, the mating of the transmission to the back of the motor is a two-person job.

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The new piggyback is mated between the harness and the transmission.

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To our delight, the stock starter fit perfectly with the new 4L80 size.With the transmission firmly in place our next goal was to modify the cross member. In our case, the mount was off approximately three and a half inches.

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By sectioning and moving the mounting point back, our fitment problems were fixed, however strengthening the modified cross member was our next order of business.

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Once tacked, the cross member was removed for welding.

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Now gusseted and painted the cross member was ready for installation. Don't let the Hughes sticker throw you, it isn't a Hughes part, not yet anyway.

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The converter bolts are torqued and double checked.

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The converter cover can be bolted in place.

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During the driveshaft shortening process, the yoke is replaced with a larger diameter TH400 yoke and larger U-joints. The rearend of the driveshaft remains the same.

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The driveshaft can now be installed, be sure to inspect your U-joints at the back of the driveshaft, it's an easy time to make the change.

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The forward portion of the exhaust system can be reinstalled, cat in all.

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With your new Hughes 4L80, you'll never have to worry about making a face like this ever again.

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