3.42 Gears but NO converter
01-22-2011, 05:03 PM
#21
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I am going to look into prices now. Should I just pick up a Z06 diff in the parts FS section? Do I just ask to buy the diff? Any other parts needed or is this just a swap out/in process? What should I look for in terms of wear/tear?
I do need to do a bit more research on the converter though, as to what RPM and Yank vs Vigilante. I am going to do a search and read up a little bit on recommended converters and what not. Since the rear end is dropped at the time, I most likely will do the converter at the same time. I know later on I will want heads/cam so its best to do it now.
I do need to do a bit more research on the converter though, as to what RPM and Yank vs Vigilante. I am going to do a search and read up a little bit on recommended converters and what not. Since the rear end is dropped at the time, I most likely will do the converter at the same time. I know later on I will want heads/cam so its best to do it now.
01-22-2011, 05:18 PM
#23
It seems a lot of people here have no clue what a high stall converter does. It has nothing to do with a car at a stop period any converter will be stalled at a stop light it has to do with what happens as the car reaches the "power band" the converter really loads up as it "flashes" to the stall speed and totally engages usually causing a hard acceleration at that point. Since engines tend to develope more HP & torque higher in power band you can see it will just put more torque to the rear at that point. I have never cared for having my neck snapped so a slightly higher (2200-2500) is good enough for me. I do not like buying tires....
"Stock cars have anywhere from 1,000 to 1,400 RPM stalls from the factory. The reason a stall converter works is simple; an engine at 1,200 RPM is only making about 80 or so horsepower (on average), but at 2,500 RPM it could be making 150 to 200HP, and obviously trying to get a car moving using 150-200HP is going to be much easier than one trying to launch at 80HP or so. Most performance engines don't make power until 3,000 or so RPM, hence why when you have a higher horsepower engine with a big cam, you need a higher stall speed so the engine is closer to it's "power band" when taking-off from the line, otherwise it will fall on its face and be a turd off the line."
The higher the stall the more need for a tranny cooler as they get hot from the higher stall.
"Some people believe that "stall" means the car won't start moving until the engine reaches that particular RPM, and that isn't even close to being true. We build race cars with 6,000 RPM stall converters and when you put the car in gear and let it idle, it WILL roll along at 5 - 10 MPH, just like any other car will when put in gear and with the brake off. In fact, we usually cruise through the pits with the car simply in gear and idling, so if a 6,000RPM converter means that the car won't start moving UNTIL that RPM, then we'd have to have the engine wound-out to 6,000 RPM to putt along through the pits at 10-15 MPH, and that simply isn't the case. Stall means when the car is on the starting line, (with say a 4,500 RPM stall converter), and the trans brake is on, (which locks the transmission in first and reverse at the same time), and you hit full throttle, the engine will wind-up to 4,500RPM with the car just sitting there, so when you slip your finger off the trans brake button and the tranny engages out of reverse, the car instantly launches at 4,500 RPM, and a race motor at 4,500RPM is pretty much at it's peak torque curve when leaving the line, hence the big wheelies you see on some drag cars or the incredibly low 60 Ft. times when traction is good. Race engines make no power at low RPM's, and are usually shy on torque, so the nastier the engine, the higher the stall speed needs to be (in general anyway). Again, cubic inches, torque, vehicle weight and gear ratio have a big factor in this. Now, this doesn't get into the "flash" effect which is where a stall converter will "flash to" when your finger comes off the trans brake button. Typical 3,000 RPM converters can flash up to 5,000 RPM or so once you've launched the car. It's a bit more complicated and I am yrying to keep this simple for you, so we'll skip that area right now"
http://www.badasscars.com/index.cfm/...d=78/prd78.htm
"Stock cars have anywhere from 1,000 to 1,400 RPM stalls from the factory. The reason a stall converter works is simple; an engine at 1,200 RPM is only making about 80 or so horsepower (on average), but at 2,500 RPM it could be making 150 to 200HP, and obviously trying to get a car moving using 150-200HP is going to be much easier than one trying to launch at 80HP or so. Most performance engines don't make power until 3,000 or so RPM, hence why when you have a higher horsepower engine with a big cam, you need a higher stall speed so the engine is closer to it's "power band" when taking-off from the line, otherwise it will fall on its face and be a turd off the line."
The higher the stall the more need for a tranny cooler as they get hot from the higher stall.
"Some people believe that "stall" means the car won't start moving until the engine reaches that particular RPM, and that isn't even close to being true. We build race cars with 6,000 RPM stall converters and when you put the car in gear and let it idle, it WILL roll along at 5 - 10 MPH, just like any other car will when put in gear and with the brake off. In fact, we usually cruise through the pits with the car simply in gear and idling, so if a 6,000RPM converter means that the car won't start moving UNTIL that RPM, then we'd have to have the engine wound-out to 6,000 RPM to putt along through the pits at 10-15 MPH, and that simply isn't the case. Stall means when the car is on the starting line, (with say a 4,500 RPM stall converter), and the trans brake is on, (which locks the transmission in first and reverse at the same time), and you hit full throttle, the engine will wind-up to 4,500RPM with the car just sitting there, so when you slip your finger off the trans brake button and the tranny engages out of reverse, the car instantly launches at 4,500 RPM, and a race motor at 4,500RPM is pretty much at it's peak torque curve when leaving the line, hence the big wheelies you see on some drag cars or the incredibly low 60 Ft. times when traction is good. Race engines make no power at low RPM's, and are usually shy on torque, so the nastier the engine, the higher the stall speed needs to be (in general anyway). Again, cubic inches, torque, vehicle weight and gear ratio have a big factor in this. Now, this doesn't get into the "flash" effect which is where a stall converter will "flash to" when your finger comes off the trans brake button. Typical 3,000 RPM converters can flash up to 5,000 RPM or so once you've launched the car. It's a bit more complicated and I am yrying to keep this simple for you, so we'll skip that area right now"
http://www.badasscars.com/index.cfm/...d=78/prd78.htm
ButWhat your saying is that with a stock stall and a cam lets say 23*/24* 615/615 112 or 23*/23* 600/600 112 u can run a stock stall and have absolutely no problems when I am at a stop light, or anything of that sort right?
You also forgot to explain the fact of lock up speed, when driving around and how when the converter doesn't lock up lets say till about 55mph or lower (45) depending on the converter is open and tends to run hotter transmission temperature than you would with a stock converter, why it's recommended to run an independent transmission fluid cooler than the stock. stall.
I understand about the power band and track use, and helping with track times, but am sure the op was talking about daily drive ability rather than track usage. If am wrong then my apologies.
01-22-2011, 06:01 PM
#24
Drifting
I'm glad you explained it properly. I have a 3.42 ready to go in my car in the spring. I do not race so I decided I don't need/want a stall converter. That reply above alarmed me...I feel I should be fine without it and can enjoy the upgrade to 3.42 gears this summer.
You don't need STALL CONVERTERI have 50 K on my 3:42 gears and A4 since I did the swap. Car drives great no problems, Idles at 600 rpm with the a/c on. There are way to many people here on this forum that have not done this swap but will be sure and give your their opinion. FYI 12.5 is pretty slow. If you did want to do a converter swap do a search on Mike Mercury post on this. What you will read will surprise you and save you a lot of money.
01-22-2011, 07:15 PM
#25
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I am going to look into prices now. Should I just pick up a Z06 diff in the parts FS section? Do I just ask to buy the diff? Any other parts needed or is this just a swap out/in process? What should I look for in terms of wear/tear?
I do need to do a bit more research on the converter though, as to what RPM and Yank vs Vigilante. I am going to do a search and read up a little bit on recommended converters and what not. Since the rear end is dropped at the time, I most likely will do the converter at the same time. I know later on I will want heads/cam so its best to do it now.
I do need to do a bit more research on the converter though, as to what RPM and Yank vs Vigilante. I am going to do a search and read up a little bit on recommended converters and what not. Since the rear end is dropped at the time, I most likely will do the converter at the same time. I know later on I will want heads/cam so its best to do it now.
Also, there is a company on ebay selling brand new converters around $600 or less...looks very professional.
01-22-2011, 07:52 PM
#26
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Too Much misinfo
Too many guys just pop off with "you need a new/ diff TC"
Depends on how you use the car.
Stock TC you are not going to be pushing thru stop lights unless you're idling at 1200 rpm
Quite a few Muscle car guys running 700R4s (same as A4 but not electronic) use the Vettes TCs. Big Blocks with up to 600 hp and loads of torque.
Keep in mind that higher stall TCs make more heat and heat will kill a tranny. A TC slips until stall speed (simple explanation) until it locks up the TC.
The more slip the more heat = killed tranny.
You'll notice that lot of guys that went with high stall TCs when they did gears ended up doing a tranny rebuild not long after.
This is not always because they had so much power they killed the tranny it's that the added heat of the TC slipping killed it.
The key is to raise the line pressures to firm up the shifts. (smooth shifts are, by design, from slipping) which is OK on a stock HP motor which they are set up for but add more power and the "smooth" is excessive and yep more heat.
If you plan on tracking you car the the high stall will help your times a little but if your looking at 99% street driving probably not needed.
btw. I did a gear change 3.42s with a Blower and kept the stock TC.
That was 3 years ago and the tranny is still perfect.
Too many guys just pop off with "you need a new/ diff TC"
Depends on how you use the car.
Stock TC you are not going to be pushing thru stop lights unless you're idling at 1200 rpm
Quite a few Muscle car guys running 700R4s (same as A4 but not electronic) use the Vettes TCs. Big Blocks with up to 600 hp and loads of torque.
Keep in mind that higher stall TCs make more heat and heat will kill a tranny. A TC slips until stall speed (simple explanation) until it locks up the TC.
The more slip the more heat = killed tranny.
You'll notice that lot of guys that went with high stall TCs when they did gears ended up doing a tranny rebuild not long after.
This is not always because they had so much power they killed the tranny it's that the added heat of the TC slipping killed it.
The key is to raise the line pressures to firm up the shifts. (smooth shifts are, by design, from slipping) which is OK on a stock HP motor which they are set up for but add more power and the "smooth" is excessive and yep more heat.
If you plan on tracking you car the the high stall will help your times a little but if your looking at 99% street driving probably not needed.
btw. I did a gear change 3.42s with a Blower and kept the stock TC.
That was 3 years ago and the tranny is still perfect.
01-22-2011, 09:08 PM
#27
time-wise, i cant really say what the 3.42s did for me since i havent been to the track since then, but my 3400 fuddle converter and transgo HD2 shift kit install helped out big time!
intake, full exhaust, tune, 2.73 gears on drag radials/skinnies 11.91@116.8xmph 1.80 60'
same mods plus the converter and shift kit 11.41@118.98mph 1.60 60'
im sure i wouldve hit a 11.3x something on a 1.5x 60' but i got booted bc i didnt have a rollbar
the only difference i noticed with the gears is way less traction on the street, unless im running dr's out back. with street tires, my traction control kicked in on the on the 3-2 downshift and then on the 2-3 upshift @ wot. on the track im thinking maybe .15 to .2 second
intake, full exhaust, tune, 2.73 gears on drag radials/skinnies 11.91@116.8xmph 1.80 60'
same mods plus the converter and shift kit 11.41@118.98mph 1.60 60'
im sure i wouldve hit a 11.3x something on a 1.5x 60' but i got booted bc i didnt have a rollbar
the only difference i noticed with the gears is way less traction on the street, unless im running dr's out back. with street tires, my traction control kicked in on the on the 3-2 downshift and then on the 2-3 upshift @ wot. on the track im thinking maybe .15 to .2 second
Last edited by 98tadriver; 01-23-2011 at 03:04 AM.
01-23-2011, 01:16 AM
#28
3:42 no converter
I did the swap from 2.73 to 3.42 gears and it is a huge difference. car will lose traction everywhere. I have some boltons...lt headers, ls6 intake, msd wires, larger air bridge and throttle boddy, vararam,dyno tune.. and the 3.42 gears. the car just screams and will blow the tires off at will. You dont want to hook too hard unless you are willing to pay for expensive repairs... it could happen at any time...I would rather have my tires spin instead of blowing out my rearend or tranny. I plan to put a supercharger so wheel spin will be even more of a problem but i need to keep ahead of the junk coming out in these new cars... 5.0 coyote and ls3's.. it's hard for a c5 to keep up with the crowd if you dont mod... and a blower is cheaper than head and cam plus more power with a broader torque curve.. fyi. I should run 12.5 right now and I should run under 12 with blower installed. I just dont want to get in the habit of breaking parts so i will proceed with caution.
01-23-2011, 10:50 AM
#29
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St. Jude Donor '05-'06
ButWhat your saying is that with a stock stall and a cam lets say 23*/24* 615/615 112 or 23*/23* 600/600 112 u can run a stock stall and have absolutely no problems when I am at a stop light, or anything of that sort right?
Absolutely as long as you have a low enough idle. obviously some set ups require a higher idle to keep the engine running if too high it may hit stall speed. Only then a higher stall might be a good idea.
You also forgot to explain the fact of lock up speed, when driving around and how when the converter doesn't lock up lets say till about 55mph or lower (45) depending on the converter is open and tends to run hotter transmission temperature than you would with a stock converter, why it's recommended to run an independent transmission fluid cooler than the stock. stall.
I did mention a higher stall causes higher tranny temps. Lock up is different than stall speed it is controlled by the TV cable in 700r4 and electronically in the 4l60e and usually set ~42 mph and has nothing to do with engine power or rpm.
I understand about the power band and track use, and helping with track times, but am sure the op was talking about daily drive ability rather than track usage. If am wrong then my apologies.
Last edited by Redeasysport; 01-23-2011 at 10:55 AM.
01-23-2011, 11:42 AM
#30
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So basically daily drivability will be close to the same when starting slowly other than the added heat from a higher stall converter. When the pedal is mashed there is a slight delay in a high stall till the engine hits higher power before it really starts pulling and gives you the feeling of more power( tires break loose,neck snaps) that doesn't happen with a lower stall because it starts grabbing at a lower rpm. As stated you get a higher stall you need a cooler to go with it. All in all a waste of time and money for a street only car unless you want to impress someone with your burn outs. Actually pretty much the same for the rear end swap too. You loose MPG for the ability to do burn outs. To each there own but I like my 2.73's for that reason. I have a fast car that gets good mileage and don't have to buy tires every year. The perfect world for me. Now if I were going to track the car...........
01-23-2011, 01:02 PM
#31
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So basically daily drivability will be close to the same when starting slowly other than the added heat from a higher stall converter. When the pedal is mashed there is a slight delay in a high stall till the engine hits higher power before it really starts pulling and gives you the feeling of more power( tires break loose,neck snaps) that doesn't happen with a lower stall because it starts grabbing at a lower rpm. As stated you get a higher stall you need a cooler to go with it. All in all a waste of time and money for a street only car unless you want to impress someone with your burn outs. Actually pretty much the same for the rear end swap too. You loose MPG for the ability to do burn outs. To each there own but I like my 2.73's for that reason. I have a fast car that gets good mileage and don't have to buy tires every year. The perfect world for me. Now if I were going to track the car...........
I do not want to do this for burnouts. I simply want to feel the power better, something the 2.73s are not as good at, compared to the 3.42s.
well im in process of doing this swap (gears and converter), and i don't think its a waste of money, i hate the fact that my 2:73 rear makes my car a pooch. if i had 3:15's i would prob leave them in, but the 2:73's are a joke. i don't think its about doing burnouts all the time, its more just wanting to feel the power? so ill take my 2 mpg loss, and i don't think i need a car that tops out at 180mph, it will be plenty fast
01-23-2011, 01:18 PM
#32
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St. Jude Donor '05-'06
Like I said guys to each their own it's your car. I got plenty of power for my usage. I had a C4 with 3.15's 2800 stall Transgo shift kit it was fun for a while tires spun at 2nd gear shift at WOT. I think hitting the drive train with more torque from it all is not necessarily a good thing. Shortens the life of the tranny (my C4 had a radically rebuilt tranny I had done) unless you get it tweaked too. It is a slippery slope but if ya got the money.......
01-23-2011, 02:15 PM
#33
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Like I said guys to each their own it's your car. I got plenty of power for my usage. I had a C4 with 3.15's 2800 stall Transgo shift kit it was fun for a while tires spun at 2nd gear shift at WOT. I think hitting the drive train with more torque from it all is not necessarily a good thing. Shortens the life of the tranny (my C4 had a radically rebuilt tranny I had done) unless you get it tweaked too. It is a slippery slope but if ya got the money.......
01-23-2011, 02:22 PM
#34
id recommend running drag radials if you wanna hook up on the street @ wot- like when you step on it to pass someone, not racing 
also if you plan on going over 130 mph on a "closed course," youll need a retune so it shifts into 4th @ wot
also if you plan on going over 130 mph on a "closed course," youll need a retune so it shifts into 4th @ wot
01-23-2011, 06:42 PM
#35
Melting Slicks
Hope this helps clear some confusion.
Being a (strictly) Corvette mechanic, I can share some of my knowledge and experience.
You can remove the differential with out removing the driveline/transmission. Its simply done by dropping the rear cradle and unbolting the differential from the transmission. You can even do it with out removing the mid-pipe and tunnel plate as long as you support the trans. correctly. For someone using a lift and proper equipment/experience it could be removed and replaced in just 3-4 hours.
To replace the torque converter the drive-line/transmission would need to be removed from the car. This means removing the mid-pipe (and LTH's if you have them), tunnel plate, shifter, and unbolting the tube from the flywheel cover. Based on my experience to remove the drive-line, separate the torque tube from the trans., replaced the torque converter, and reinstall everything, it could be done in 8-10 hours.
That is twice the labor and twice the cost to replace the torque converter VS just the diff. My labor times are also based on someone who has done it before, working at a swift pace. It could take another hour or two for a slower tech. Don't forget fluids, alignment, and brake bleed.
I have seen automatic C5's with a 3.42 diff. and stock converters. There really shouldn't be any problems. Get a tune done as well for the new diff. and improved shift times.
Being a (strictly) Corvette mechanic, I can share some of my knowledge and experience.
You can remove the differential with out removing the driveline/transmission. Its simply done by dropping the rear cradle and unbolting the differential from the transmission. You can even do it with out removing the mid-pipe and tunnel plate as long as you support the trans. correctly. For someone using a lift and proper equipment/experience it could be removed and replaced in just 3-4 hours.
To replace the torque converter the drive-line/transmission would need to be removed from the car. This means removing the mid-pipe (and LTH's if you have them), tunnel plate, shifter, and unbolting the tube from the flywheel cover. Based on my experience to remove the drive-line, separate the torque tube from the trans., replaced the torque converter, and reinstall everything, it could be done in 8-10 hours.
That is twice the labor and twice the cost to replace the torque converter VS just the diff. My labor times are also based on someone who has done it before, working at a swift pace. It could take another hour or two for a slower tech. Don't forget fluids, alignment, and brake bleed.
I have seen automatic C5's with a 3.42 diff. and stock converters. There really shouldn't be any problems. Get a tune done as well for the new diff. and improved shift times.
01-23-2011, 08:16 PM
#36
Heel & Toe
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stall
I owned a 78 Pace for 26 years and about midway I bumped the car to 525 hp. With stock (added) 3.70 gears, a factory 3 speed auto and a 3000 stall, it drove like a ***** cat in traffic. The stall will only delay converter lockup meaning you may have to give it more gas pedal to start moving. In 15 years or so I never had my engine stall at a stop or have it push thru either. Uh oh, being new here I occasionally forget to check the date of the previous posting. If I am a light year or two behind, excuse me.
I said before " unless you want to take it to the track" a higher stall may give you lower ET's..... or not depends on the pedal pusher
01-23-2011, 09:34 PM
#38
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The closest track to me is a good 2 hours at least, given that there is no traffic. Occasionally, my buddies go up there and this year, I will too. I dont expect to go up there every weekend and do a million passes, but I do expect to do probably half a dozen at least. All of which will be scattered throughout the spring/summer. This is why I am so skeptical about this whole torque converter thing and if it is really worth it.
I think someone said I can expect to run 12.5's or so with bolt ons and 3.42's. How much would a torque converter shave off my et's? Probably low 12's?
01-23-2011, 09:51 PM
#39
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high stall
Ok, here is the scenario. At the track, maybe even with slicks, the light changes and you floor the pedal. With an auto and stock converter and even 3.42 gears you are going to have to wait for rpms to rise to get your self moving. With a higher stall, the instant you punch the gas, the rpm's are going to that converter speed, say 2800 and you will have an instant say 300hp instead of the 160 at 1700rpm. It is that simple.
It is the quickest way for an auto to pull away from a stop with a manual car. Anytime you kick it real hard, the rpm's are going to 2800 and corresponding hp.
It is the quickest way for an auto to pull away from a stop with a manual car. Anytime you kick it real hard, the rpm's are going to 2800 and corresponding hp.
