Downside to installing the Corvette Servo?

[livingez_123]

I install them on all of my 4l60e rebuilds and I have never had one come back for harsh shifting and there is no downside. If anything they increase the life of the 2nd gear band....less slippage equals less heat.
And most tuners can adjust the firmness of the shift without getting your hands dirty.

 

[BentleyArnage]

After building thousands of these transmissions in the last 40 years, I'll tell you how this works. The Vette servo doesn't really make it shift harder. It just has a lot more holding power. The Sonnax servo has even more holding power. You get harder shift feel through the accumulator and the hole size in the separator plate. Think of it this way. Back in the day, they made a T 400 with as little as 3 direct clutch plates and 5 forward plates. In a Cadillac, truck and in Rolls-Royce they would put 6 plates in the forward and 5 in the direct. You think that made it shift harder? No. Not at all. That is accomplished in the separator plate.

Watch for snake oil ideas in transmissions. Us guys who know them laugh when we hear this crap. As far as engineering, GM did an absolutely lousy job with this trans over the years. It took the greats like Sonnax, Transgo and Gil Younger to figure them out and fix the problems created by the experts. In fact, we're still sorting out GM engineering problems with the new transmissions. But that's for another part of this forum.

 

[BentleyArnage]

I've always wanted to install one, cheap and easy upgrade. BUT, I have had TWO (2) Tahoe's shatter the sun shell's without any modifications. Both were factory transmissions 4wd's. One was a '98 with the manual shift 4wd, and one was a '99 with the push button 4wd. The '98 Tahoe grenaded the the sun shell at 209,000 miles. The '99 grenaded the sun shell at 217,000 miles.

The '98 towed a quad on a 5X8 box trailer maybe 10 times at most. The '99 never towed anything. Both came with the tow package and factory trailer hitch mount. I noticed the '98 searching in overdrive on the tach going from 1300 rpm to 1400 rpm for a year or so before the reverse gear went, and an hour later the whole trans quit (sunshell cracked apart).

Both were purchased used with low miles around 90-110,000 or so, and factory bone stock as far as I know. My wife and I babied both of them the whole time...maybe that was the problem. So now, I fear the 4l60's will strand me. Both were sold as is with blown trannys, the shop out here in our small town wanted 2,600$ to rebuild the trans in either one. So we sold them.

I figured I got over 100,000 miles out of both of them, and paid exactly the same for each $2,500. So I guess I got my money's worth. Then my wife finds another one, and I find a Yukon, both '99's for the same price $2,500 again! Kinda wierd, but we took the chance. Probably going to end up with the same scenario. But this time, I changed the trans filters and complete drain and fill with valvoline max. Installed a drain plug on each truck, and installed larger trans coolers on both. But until I get the upgraded sun shell, I don't think I will install a servo or shift kit. Call me tranny shy!

The sunshell problem was caused by the brake to shift modification shoved up our collective asses by government fiat in 1993. They never broke before then. Locking the brakes and applying 1st gear, many times when cold, high RPM during warm up is what tears them up. This isn't the only trans with the issue.