darrensls1

I'm trying to determine what gears I can go with. I've got a 408 motor being built and I want to run a Performabuilt Lvl 3 4L60E or something similair so keep in mind this will be a $2500 built transmission. Can I rev 6800? 6500? stay 6000 or it'll die?

I figure I might trap as high as 135 on spray so when I ran some gear calculators I found out that third gear tops out at:

6,000 rpm + 3.73 = 123 MPH
6,500 rpm + 3.73 = 133 MPH
6,800 rpm + 3.73 = 139 MPH

I've always heard that RPM's are second only to heat for being 4L60E killers. Can a built 4L60E handle 6800 RPM's or do I need to look at 3.42 gears as an alternative?

Any input is greatly appreciated.

Z28LS1camaroguy

iTrader: (3)

well how fast are you wanting to go??? if you want to get over 150 mph then go with 3.42s but if you are making this a track car then go with the 3.73s. also at that high of RPMs something is more bound to go wrong with the motor than with a built up tranny. what size stall you gonna run also??? plus you can always get a tranny cooler.

darrensls1

I said in my first post that I may trap as high as 135 so I guess 136 would be good

Well like I said in my first post I'm having a 408 built. So the 408 is forged internals with the ability to handle up to a 300 shot of N20 (although I will only run a 150 and only on a rare occasion). So motor strength is not a concern.

It is a track mostly car but like I showed the 3.73's do not allow me to cross the traps in third gear unless I can spin 6800 rpm's. I know the motor can handle it but I'm not 100% sure about the transmission.

See my sig. I all ready got a 3500 stall and a tranny cooler.

Sunset'01Z

iTrader: (10)

why dont you ask the guys that built it?

performabuilt

iTrader: (25)

Good idea well unless its the something similar , I am comfortable with our units to 7000 rpm , I say this because I have run them in excess of that in the past on many occasions. RPM is only and issue because of the pump slide colapsing which we deal with in two ways, lube and centrifial apply of the 3-4 in the lower gears causing premature 3-4 clutch failure which we also deal with in the build, A tight tolerance 4l60e should be able to handle that with no great problem.
Thats my answer, The only request we make from a tuning standpoint on our units is that the presure be returned to the stock setting, Shift points can be set as you please

darrensls1

I'm really looking for something reliable and stable since I go to the track twice a month and run as many as 10 times per visit. That's a lot of stress on a transmission after a 40 minute drive to the track. This is why I am going with a forged 408 with a relatively small shot of N20. I'm only looking at maybe 475 rwhp on motor and 600ish on spray.

So do you think your lvl 3 4L60E under 600 RWHP and spinning say 6700 rpm's can handle 20 track passes a month for six months straight? Then add to that mix that I want to see a transmission that can last at least 2-3 seasons. It's a tall order to fill which is why I have been on the fence between a built 4L60E or a built 4L80E.

darrensls1

Because I also want to hear from people who are using and abusing these transmissions the way I intend to. I have no doubts that Rossler, FLT and Performabuilt all make a very stout 4L60E. I am leaning towards Performabuilt because they are close to me geographicly, they have a good reputation and they spend a lot of time here answering questions. The fact that they jumped into this thread so quickly with an answer speaks volumes for thier customer service.

But still it is a 4L60E and it does have limits. I'm just wondering if my application will test those limits or be well within it. As much as I respect the knowledge of the builders I also understand they are trying to sell me thier product.

Which brings me back to the reason for this thread. If I can "relatively safely" rev my motor to say 6700 rpm's then I want 3.73's and a built 4L60E. If not then I would rather stay on the safe side and rev 6200 rpm's with 3.42's.

Ragtop 99

iTrader: (7)

I spun my built A4 to 6800 rpm on a regular basis for a couple years.

6-Speed Terror

iTrader: (4)

i have also seen a friend localy that spins it to 6800 for over 2 years already has big cooler and hasnt had any problems.

N4cer

iTrader: (11)

And then what happened to it though?

performabuilt

iTrader: (25)

Well eventually everything tears up even a 4l80e nothing is indestructable , Perhaps its still going Perhaps not, But if he got several years of that and it held up well I would think he would be very pleased, I know turbo guys whos 3000 dollar turbos dont last that long and they seem to think thats just part of the price you pay . Honestly in a way though I do spend most of my time in the auto trans forums several , I do also spend time looking around other parts of the forums and it does amaze me how much stress people get into about spending a grand or two on a trans yet when it comes to power adders They will throw the bucks out no problem lol. Just something I have noted from 1000s of hours reading post since well this is what I do. all day every day 7 days a week

Ragtop 99

iTrader: (7)

Tranny broke as I was leaving at a traffic light at about 5% TPS. Several suspect causes emerged, but none appear to be tied to rpm.

DrkPhx

iTrader: (15)

I rev my Stage IV FLT to 7000. Only about 6,000 miles and 6 track runs with no problems.