confusion on the corvette servo upgrade and billet 4th apply piston and cover.
04-26-2014, 04:54 PM
#1
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confusion on the corvette servo upgrade and billet 4th apply piston and cover. I'm planning on firming up my shifts with the corvette servo upgrade. I noticed that some people also get the billet 4th apply piston and cover?
What I'm wondering is(and I searched a lot here) are the two things the same thing, one is just billet?
can both be used at the same time?
What I'm wondering is(and I searched a lot here) are the two things the same thing, one is just billet?
can both be used at the same time?
04-26-2014, 06:18 PM
#2
The Corvette servo is the 2nd servo while the billet 4th is, well, not 
They can both be used at the same time, when my v6 Firebird's 4L60E dumped out on me last summer and I rebuilt it, I decided to go crazy with the build and build a stupidly strong 4L60E just because, and I am running the Corvette servo/Sonnax billet 4th servo combo in my transmission.
That aside, the billet 4th servo is as you said, billet vs the stock non-billet. It also has a larger apply area, so there's more holding power on the 2-4 band.
They can both be used at the same time, when my v6 Firebird's 4L60E dumped out on me last summer and I rebuilt it, I decided to go crazy with the build and build a stupidly strong 4L60E just because, and I am running the Corvette servo/Sonnax billet 4th servo combo in my transmission. That aside, the billet 4th servo is as you said, billet vs the stock non-billet. It also has a larger apply area, so there's more holding power on the 2-4 band.
04-26-2014, 06:47 PM
#3
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Oh I see. makes sense now. I ordered both, the transgo separator plate, sonnax pinless accumulators.(1-2 2-3, and forward) and sonnax 1-2 accumulator springs. oh, and the 0.500" boost valve.
Anything I'm missing?
Anything I'm missing?
04-26-2014, 09:10 PM
#5
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You have ordered a good set of parts; but see below for one addition.
IMHO, the billet 4th servo piston is unnecessary unless you are running WOT in 4th, e.g. over 120 mph or are towing heavy loads in a truck. But at $70 it sure doesn't hurt and adds a nice appearance to the outside. Note that billet 2nd servo pistons are also available, e.g. from Sonnax.
Drill the separator plate according to the Transgo HS2 instructions:
https://ls1tech.com/forums/automatic...questions.html
I generally suggest (when using a Corvette or Billet 2nd servo):
2nd apply hole: .093
3rd apply hole: .093 or as much as .125
I recall builder and member BPA also suggesting drilling the 4th apply hole bigger, but don't remember his exact size. Pro builder eLiT3SnIpEz probably has a suggestion for that too.
Since you are removing the valve body, the Sonnax HD 2-3 shift valve is highly suggested if you are drag racing. With this part, when you put the shifter in [D3], the overrun clutches are applied in all gears which reduces the strain on the somewhat-weak forward sprag. Without it in [D3] the overrun clutches are only applied during the 2-3 shift and steal fluid away from the critical 3/4 clutch at a bad time. Without this part, drag racing should therefore be done in [OD], but the strain on the forward sprag will be higher. Here is a good thread on the subject of the HD 2-3 shift valve:
https://ls1tech.com/forums/automatic...ure-flare.html
IMHO, the billet 4th servo piston is unnecessary unless you are running WOT in 4th, e.g. over 120 mph or are towing heavy loads in a truck. But at $70 it sure doesn't hurt and adds a nice appearance to the outside. Note that billet 2nd servo pistons are also available, e.g. from Sonnax.
Drill the separator plate according to the Transgo HS2 instructions:
https://ls1tech.com/forums/automatic...questions.html
I generally suggest (when using a Corvette or Billet 2nd servo):
2nd apply hole: .093
3rd apply hole: .093 or as much as .125
I recall builder and member BPA also suggesting drilling the 4th apply hole bigger, but don't remember his exact size. Pro builder eLiT3SnIpEz probably has a suggestion for that too.
Since you are removing the valve body, the Sonnax HD 2-3 shift valve is highly suggested if you are drag racing. With this part, when you put the shifter in [D3], the overrun clutches are applied in all gears which reduces the strain on the somewhat-weak forward sprag. Without it in [D3] the overrun clutches are only applied during the 2-3 shift and steal fluid away from the critical 3/4 clutch at a bad time. Without this part, drag racing should therefore be done in [OD], but the strain on the forward sprag will be higher. Here is a good thread on the subject of the HD 2-3 shift valve:
https://ls1tech.com/forums/automatic...ure-flare.html
04-27-2014, 02:24 PM
#7
Wouldn't it firm up the 3-4 shift in normal driving? I've thought about doing this ever since my first converter install, as that shift is so soft as to be almost unnoticeable. I'm not interested in a harsh jolt, just in feeling the band grab the drum.
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04-27-2014, 03:23 PM
#8
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The shift firmness is related to the gear ratio that the shift went to. So, all things being equal (which they never are), the 1-2 shift into a 1.625 gear will feel 2.33 times firmer than the 3-4 shift into a .696 gear.
Next, when the engine speed after the shift is well below the converter's stall speed, the shift will feel soft. And of course the shift feel depends upon the line pressure which depends upon the throttle position. So unless your 3-4 shift is at WOT (120+ mph), it probably will feel soft.
I don't have the info right now, but PBA suggested drilling the 4th apply hole bigger to firm up the 3-4 shift. It may be .093 or bigger, but I cannot find his post right now.
In short, yes the 4th billet servo will firm up the shift, but due to the physics of the gear ratios it will never come close to the 1-2 shift.
Next, when the engine speed after the shift is well below the converter's stall speed, the shift will feel soft. And of course the shift feel depends upon the line pressure which depends upon the throttle position. So unless your 3-4 shift is at WOT (120+ mph), it probably will feel soft.
I don't have the info right now, but PBA suggested drilling the 4th apply hole bigger to firm up the 3-4 shift. It may be .093 or bigger, but I cannot find his post right now.
In short, yes the 4th billet servo will firm up the shift, but due to the physics of the gear ratios it will never come close to the 1-2 shift.
04-27-2014, 11:41 PM
#9
Looking over my "modified" HD-2 instructions from PBA, I don't find a designated 4th apply hole (unlike 1-2 & 2-3) but there are a couple of feed holes he specs at .110. The original Transgo spec is .093. Transgo also calls for modifying the 4th gear accumulator.
I understand that 3-4 will never feel like 1-2; proportionally, it's a descending scale from 1-2 on down. But maybe increased pressure would yield a more positive 3-4 shift? After my converter install, that shift became ultra-soft, and I understand why, but my thought is that the billet servo might restore some of the feel. I guess I could buy one and find out. I've been thinking about it off and on for years now.
I understand that 3-4 will never feel like 1-2; proportionally, it's a descending scale from 1-2 on down. But maybe increased pressure would yield a more positive 3-4 shift? After my converter install, that shift became ultra-soft, and I understand why, but my thought is that the billet servo might restore some of the feel. I guess I could buy one and find out. I've been thinking about it off and on for years now.
05-11-2014, 06:50 PM
#10
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OK, so I installed the corvette servo and its great. But when I installed the billet fourth, I lost fourth gear. Putting the stock 4th brings it back though. I bought a longer pin to see if that makes it work. It has 3/8"+ end play with the pin that was in it.
05-12-2014, 01:38 PM
#11
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The end play should be between .075 and .125 (about 1/16" to 1/8"). 3/8" is way too much and you are lucky to even have 2nd gear.
Whose 4th billet piston are you using?
How many miles are on the trans?
I now wonder if there are too many miles and your band is nearly worn out.
IIRC, with a very worn band, a stock setup will first lose 2nd gear, but a billet setup will first lose 4th gear.
Whose 4th billet piston are you using?
How many miles are on the trans?
I now wonder if there are too many miles and your band is nearly worn out.
IIRC, with a very worn band, a stock setup will first lose 2nd gear, but a billet setup will first lose 4th gear.
05-12-2014, 01:41 PM
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Well, I just had it repaired under warranty. It lost 2nd gear. Now I wonder if the cause was this extra play on the servo rod. I'm going to put a longer pin and try the billet fourth and cover again. They are sonnax.
05-13-2014, 08:08 AM
#16
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I would then suggest following the Sonnax instructions for grinding down your pin until you have .100 end play; note that they suggest rounding the end so that it solidly and consistently engages the band.
05-03-2015, 01:23 PM
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Sorry for reviving this tread. I am planning on installing the 2nd and 4th super hold sonnax servos, how much do i need to grind off from the pin that comes with the servo?
Last edited by ozzy77; 05-03-2015 at 02:32 PM.