Long story short: We are putting a 2002 4L60E from a Tahoe (remaned in 2005 by American Transmissions, that came in our B4C Camaro (purchased in 2007)) and a Coan 3200 single disc converter behind an LS1 (which should be good for 400hp (+100 shot of nitrous)) into our Lemans wagon. Ultimately I would like to see the car run a 10.9; it is all in the link in the sig below.

Anyway, today I started to tear into the trans to install some Sonnax parts specifically:
Performance Pack (HP-4l60E-01)
2nd and 4th Gear Super Servos (779911-03K and 77767)

Here we go:

1. Setting the pin travel. Currently I have .065" of travel right out of the box measured at the servo cover, which is close to the low end of the recommended range of .075" to .125". Where should I seek place the pin length for best operation?

2. Servo parts. I added the Performance Pack Servo Cushion Spring (into the 2nd gear piston assembly) and the 4th Servo Return Spring, I trust this is fine (vs. reusing the stock truck-spec springs)?

3. TCC Regulator valve and end plug. According to the instructions this assembly (w/the VB separator plate plug) eliminates the PWM function, but still allows the TCC to function in an ON/OFF capacity (I will tune the car accordingly to support this concept). It also says it restricts the apply pressure to 100psi, is this sufficient pressure for a single disc converter that may get applied at the drag strip (I know this isn't the best idea)?

4. Sonnax 2-3 shift valve. Should I buy this thing (77754-41)? I really like the concept of using the overrun clutches.

5. Superior 3-2 downshift valve spring and valve stop. Same as above, seems like a worthwhile upgrade (K054). Yes/no?

6. Pump parts. Is worthwhile to remove the pump assembly to install the .490" Boost Valve and High RPM Pump Slide Spring included in the kit, or am I just asking for headaches for 13% extra pressure?

7. Reuse valve body gaskets. I managed to get them apart without any damage, is it safe to reuse them?

8. Drilling the separator plate. Any recommendations other than using the .093" bit across the board for a mildly stalled car?

Hopefully I didn't screw this trans up, it really worked well before:

 

I'll try to answer all your questions later today (busy now) but let me quickly answer a few; and perhaps our newly joined expert Kawabuggy will answer them too.

Your .065 servo pin travel is fine; that is exactly what I aimed for in my last rebuild, although I had to grind down the Sonnax servo pin a lot. The real test is that the reverse drum turns in both directions. In an assembled trans, test that you can turn the output shaft, noting that it turns easy one way and about 3x harder the other way; if its 10x+ harder, the band is too tight.

The Sonnax 2-3 HD shift valve is HIGHLY recommended as it reduces the load on the forward sprag and doesn't divert fluid pressure the overrun pistons during the critical 2-3 shift. (Because the overrun piston is already applied.) Here are two threads on it:

https://ls1tech.com/forums/automatic...-drive-od.html (Jake's confirmation)
https://ls1tech.com/forums/automatic...ure-flare.html

The pump does NOT need to be removed to install the boost valve. The Sonnax .490 boost valve is highly recommended for every performance build. For one thing, its O-ring design ensures the boost pressure is working and not leaking. After dropping the pan, it barely takes 3 minutes to install the better boost valve.

 

BTW - Sorry to say this, but IMHO you will likely tear up the internals before you get to 10.9. The '02 4L60E does not even have the heat treated sunshell, a weaker forward sprag and only 6 frictions in the 3/4 clutch. Any or all of them may fail before you reach your goal.

 

Thanks for your initial thoughts! I am looking for local price and availability on all of the parts.

Perhaps I should have been more clear. I by no means expect this transmission to last for very long behind the new engine, especially if abused. I just need it to get the car up and running for initial tuning and cruising. We'll either put a 4L80E or TH400/GV behind it for reliability down the line. I know all too well that even with extensive modifications these transmissions are on borrowed time, the RPM Transmissions "Level 5" 4L70E in our TBSS didn't last 6000 miles.

I appreciate the input thus far.

 

Glad you understand the limitations of the 4L60E.
Perhaps contributing to your Trailblazer SS failure is the weight of that vehicle.
Also, nitrous is very hard on any trans because it sudden engagement will cause a marginal clutch to slip or a marginal part to break; SC and TC are much easier on the drivetrain.

 

Oh, the TBSS is a pig. We ran it on Drag Week 2016 and they made me scale it - weighed 5100lbs. It was even heavier than that when I got it to go 11.9@116mph thanks to the kids' car seats going back in.

As for the internals of the 4L60E for the wagon, I cannot say for certain what is in it - or what American Transmission would have updated in 2005. What I have found thus far is it did have aluminum accumulator pistons in the 1-2 and 3-4 (case) locations, only the Forward (valvebody) was still plastic and in good shape.

I really needed to take a closer look at the instructions, it clearly shows how/where the boost valve is serviced. I feel bad. LOL.

 

Sonnax 2-3 Valve ordered (costs more than twice what it does in the US @ $70), along with some new VB gaskets (thankfully only $6/pr). Boost valve is done. VB holes drilled to .093", the 2-3 hole was already about .091".

I polished up the tip of the servo pin as it was kind of rough. Still at .073". The drag test on the output shaft is loose in one direction, and firm but not obnoxious in the other.

Odd thing is it is kind of squealing/squeaking when rotated; is this normal?

 

Yes, the squealing/squeaking is this normal. It’s the low roller clutch.

 

I would go one bigger on the 2-3 hole; somewhere around .100; some builders go to .125 but I have personally not gone that big.

The slight squealing is normal and you will not hear it from inside the car.

 

I have the 2-3 hole on mine drilled to either .110 or .125 (don't recall exactly) and even with all the other parts and tinkering the part throttle shifts are what I consider light from 2-3 (the torque converter lockup with a Yank SS3600 is more firm than a 2-3 shift).

At WOT though it is quick and firm.

 

Mine are .125 per the recommendation of Dana at ProBuilt and I would describe the shift similarly - maybe "somewhat firm."

 

Thanks for the help, guys!

I am not worried about shift feel, hard is fine by me - especially given the engine is solid mounted. Fast, accurate, and reliable is more important than comfort. I will take the 2-3 out to a larger size.

The trans is pretty much good to go other than the parts on order. Tee hee.

 

I think I double posted? ^^^

Opened up the 2-3 hole to .110"; we'll call it splitting the difference.

Granted the separator plate is still available on the bench to go further out if warranted.

 

I know that many drill right to .125, but I prefer to give somewhat conservative advice here.
Also, I have found it easier to drill a hole bigger than drill it smaller.

 

I sincerely appreciate that.

Have welder, will weld.

You know you have a good wife when she runs to the parts to store to pick up your order. But, then mentions how "two gaskets" and a "little thing" don't look like they are "worth $70". She's a keeper.

 

When opening the 3rd gear feed hole to .120", you must keep the band release hole at .082". If the band comes off too fast, you will have a "2-3 shift flare". This is with using the Corvette servo. Other servos require some changes here. If the transmission is apart, set the 3-4 clutch clearance at .020" - .035". Minimum of 7 clutches here, I like 8 or 9 of the Borg Warner Hi-Energy clutches. The BW Hi-E's come in apx. .080", .065" and .062" thicknesses. If you want to make it more bullet proof, you can block the 3-2 control valve inboard. First, remove the original spring. Second, install the valve. Third install a spacer to block the valve inboard. This will eliminate a lot of the 3rd gear circuit leak. The Sonnax reverse abuse vale setup helps here too. If you do this, (block the 3-2 control valve inboard) now you can open the 3rd gear feed hole (using the Corvette servo) to .135", and open the band release hole to .101". When using the Sonnax 2nd apply servo, you can open the 3rd gear feed to .140" - .155", band release hole to .104". 3-4 clutch clearance still .020" - .035".

 

Thank you for detailed info and suggestions Dana.

 

Thanks, Dana! I am sure many folks are going to benefit from the info.

The trans was buttoned up today with the Sonnax 2-3 Shift valve being the last piece. I used the Sonnax "plastic" ***** in all of the case and VB locations. I saturated the filter element with some fluid to avoid a dry start up (do the same thing with an oil change). Hopefully this thing works well for a while. Just have to top it off with some Amsoil ATL.

The rear "caged" check ball in the case was absent, tangs were not bent down or broken. Go figure.

One really interesting thing I noticed when cleaning up the stock parts was an extra ball bearing in behind the stock TCC spring. Looks like someone was looking to achieve less wear in the bore by increasing the tension back in 2005. Must have been the style at the time.

 

The missing rear caged check ball is not unusual - often removed to allow reverse to engage faster.

 

Cool, and thanks again for the help!