So I would like everyone's thoughts on launching in second gear. What, if any, stress would this take off of the sprag or low roller? Would this reduce any drive line component stress? Would this add any stress to any component other than the 2-4 band? With my current gearing, I could potentially mph second gear out to 110mph. I'm sure that the 60' would suffer. I'm just looking at it from a hardware stress point of view. Not trying to set records. If this has been covered before I couldn't find it. Thank you.

 

What do you mean by 2nd gear. Modifying the trans to launch in 2nd gear or do you mean launching with the shifter in the D2 position?

 

I can modify my tune to start in second gear. Also in d2 it starts in 2nd as well so I guess either or. Either way starting from a dead stop in 2nd gear and launching wide open throttle.

 

Starting in 2nd gear with the shifter in D2 will engage the overrun clutch and therefore reduce the load on the forward sprag. It won't engage the overrun clutch if you tune for a 2nd gear start if you have the shifter in D4/OD as the hydraulics won't do it.
HOWEVER - why not implement a simple VB mod to always keep the overrun clutch engaged in 1st, 2nd and 3rd. Frank documents this in https://ls1tech.com/forums/automatic...-everyone.html

I will of course defer to the experts, but I don't think that starting in 2nd will help the transmission. There rarely is a post here about anyone losing 1st gear, unless the sprag failed. But plenty of posts about worn out bands.
(I only start in D2 when I want to do a long burnout and want to avoid excessive wheel spin in 1st and the shift. )

 

Do the 4th overrun mod. Launch it in OD dial your shift RPN/speed in and let the transmission do it's job!

 

That’s what I needed. Thanx guys. Now I can take away from this that launching in 2nd gear is no easier on the transmission than a 1-2 shift would be. Any of the over run clutch mods for the sprag should be enough to not worry about it. Sounds great. Thanks again.

 

I do not think the OVERUN clutch is on in manual second . It is on in manual 1 and d3-3 but off in manual 2 AND d3 -2 unless you have the the sonnax valve or the FT OVERUN MOD you linked to. Now I could be mistaken the manuals show it on in d2 and d3 2nd but we know its not on in D3 2nd. I will have to follow the path and make sure so I am not swearing on it just yet for D2 2.

But the FT overun mod would indeed make it be on in all manual positions and D4 (1-2-3) regardless of what he has the tune set to start in.

As for the band as long as its wide , good straight drum and corvette or larger apply area servo I do not think it would be an issue , To me the biggest strain here would be on the sunshell IMO.

 

I'll be happy to be corrected, but I think the Overrun clutch is on in 2nd gear when the shifter is in D2. Reason is that we have had several old posts where the OP obviously had a failed sprag, but could get the car up to speed by manually shifting from D1 to D2 to D3 and finally OD. If it were off in D2, he could not have accelerated above 1st gear.
But happy to get a definite answer.

 

I will study it tomorrow but I do not see how it would make any difference on or off as we know its off in D3 -2 and still continues to go . So in that way should be the same.
Ok I just looked and you are correct, It is fed via D2 oil I had not noticed that before. My bad I had not paid attention to the D2 - manual valve feeding it. Which is particularly bad because its one of the holes I block in my overun mod argh so had to have known just forgot . Now Im embarassed lol
I had to go look I could not wait till tomorrow lol.

 

I guess I should have listed my build specs for clarification, I just didn't want to get side tract. I hind sight it was or is relevant. So here goes:
GPZ 3-4 6 clutch pack (stock specs shimmed to .030 clearance at the time of assembly)
Tan Raybestos stock spec clutches everywhere else
Corvette Servo
Wide band with new drum
New hardened stock spec sunshell
New stock spec sprag
Used 4 pinions in good shape
HD-2 Shift kit set to shift 1-2 way too hard (I plan to correct this upon my first service)
1-2 .093
2-3 .120
3-2 .120
3-4 .135 (I think I could not find my notes. Seems in my memory I made this hole the biggest. Don't know why or cannot remember)
b-r .110
fwd/rev .093
2800 stall single disk converter
External cooler only. Temps usually ambient to 130*

That is what I can recall. Been close to 10k since rebuild.

 

Overrun clutch is on in D1 and D2
And it is on in D3 only when in 3rd gear
D3 1st and D3 2nd it is off

Sonnax Valve puts overrun clutch on anytime D3, D2, D1

Overrun clutch mod like I do or Frank does has overun clutch on in any fwd shifter position and gear EXCEPT 4th for obvious reasons

As for launching in 2nd...you'll be adding load to the fwd clutch and all other components connected to the powerflow. you're starting to move the same weight with less mechanical advantage. Now...will it cause harm? Doubtful.
As for low roller life...rarely do we see failures there. It's a quite stout piece and not a common cause for concern

 

Looks good, The only thing and bear in mind I run an OBD1 car so may be different, But In my car a maual second gear start is not possible. While it has a check box in the tune for it checking it does not yield the desired result instead it just stays in 1st on the 1-2 manaul shift. Not sure why and this was both with the trans in stock vigin build and after. I went to one of the LT forums and was told I would have to flash a whole tune from a truck that had that function for it to work no idea why and never pursued.

I do think you will need to do the FULL TIME OVERUN MOD SUCH AS I AND MAROON DO sorry caps lock to insure the sprag survives if you set up the d3 or d4 starts in second tune.

Setting the solenoids to be on correctly will not be an issue just checking unchecking boxes, You will need to turn off I think its code P0751 to avoid a solenoid stuck on or off code due to ratio being wrong in first. You can find my method of doing the full time overun mod in my tips and tricks thread. Its simple and easy to do when you address the harsh shift on 1-2 . Odd .092 would be harsh but then I do not use the transgo kit nor its accum set up , I find .092 and the stock accum springs with the VB accum also stock works out perfect. In fact I use it for all my hole sizes except 3rd its .100.

You also might consider the Drum cooling mod in the same thread while youre at it just incase the band slips some during the 2nd gear launches .

 

Yessir in my original tuning, the d2 position also started in 1st. I had change the shift pattern to yield a 2nd gear start. Doing it this way has not triggered any codes which is good and helps with traction. When at a dead stop, 1st gear just lights the tires and snaps 2nd shortly after. 2nd gear starting while a bit slower is easier to control and I always worry with that sudden snappy shift to second. Shoots the tire speed way up so the shock has to be tremendous. Or it could be nothing to worry about. I do drive around in d3 to keep the sonnax valve engaged as often as I remember to but I plan on doing the "All Position Mod" when I get to the service. I believe my harsh 1-2 comes from the accumulator setup. I'm sure I set it up with too many shims in my ignorance. Combo that with a wide band pls the vette servo and it is a banger. Rattle your teeth that thing. I haven't blocked the 3-2 circuit yet as I still am nervous about that for some odd reason. I don't know yet what hole sizing will yield a solid 3-2 and don't have a lot of time and money for testing so I just left it stock. It could work or it could flare/bind. Which means fixing it. If I screw up I'm gonna have to live with it for a while. Hence the 1-2 shift is still a problem for now. Now I have gotten off topic. Thanks again guys.

 

I just posted basically this same question. Didn't see this one because I was searching with 4l60e and I don't think it was mentioned here but that's what it looks like you're talking about.

Reason- teen 1/8 mile class that doesn't allow much for mods, and on hard tires.

I plan to set 1-2 shift speeds to 0 and 12 shift rpm to something low, like maybe 0 or 300 rpm. Is this all I need to do?

Would like to let him just launch in d4 so he won't have to shift, and it won't spin. This is a stock 5.3 4l60e in a 3100 pound ford ranger.

 

So you want a tune that will very very quickly shift into 2nd gear to prevent any spin?
Hopefully someone can confirm your ideas.

 

Sounds like he wants the trans to just start in 2nd gear
When in D4 shifter position

Setting the shift speed to 0 and the rpm low *should* do the trick

 

Start in second, no use of first at all, while in D4.

Yes exactly. I did it last night, shift speed to 0, downshift speed to 0, shift rpm to 300, also changed shift speed in cruise and hot just in case it would mess with it. It worked out perfectly, holds 2nd from a dig then shifts to 3rd normally. I did a couple 1/8 mile hits and it didn't even raise temp very much. I'd say this is workable for what we're trying to accomplish. We can't go faster than 9.0 in the eighth anyway, dragy said 10.0 last night. Can probably get that down a little bit more with some timing.

Now, is it going to trash the trans right away?

@MaroonMonsterLS1 If you are who I think you are, I messaged you a few weeks back looking for a th375 tailshaft for this project but gave up and went with the 4l60e, since it worked with the stock driveshaft.

 

Awesome! Mine still spins sometimes but that is more due to the one tire fire rear diff than anything else. Also I have noticed in just driving around like this, I sometimes feel like the 2-4 band slips a touch from a dead stop. It is so slight and so infrequent that I'm wondering if it is just my foot coming on and off the throttle a touch. Kind of an up and slide back down of the rpms. Like taking off with a manual transmission. Again I can never hear it when I'm looking for it so I dunno if it is real. 2800 stall doesn't help much either. Cannot confirm long term durability.

 

The 60e is the better fit. I remember chatting