Sherlock9c1 finally gets an Impala
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As I get older, I’m getting more aware of my own biorhythms. Some days I can just get stuff cranked out, and other days I go 30 minutes and need to take a 2 hour nap. Today is one of those days. BUT… it’s a Saturday and it’s time to get things done.
@95wagon it turns out that some of the bolts were serrated flange cap bolts, so no loctite. And I guess I need to get back to the gym.
I hate these cooler lines. Someday when I have time, I’m figuring out how to adapt the newer style cooler line fittings to my wagon, because these suck. And the base fittings started turning when I put my 5/8” crows foot socket on them, so I had to double-wrench it, which is tricky by yourself. I’m definitely NOT inviting these fittings to my birthday party.
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And either I’m getting bigger or this quickjack is getting smaller. The newer QJs have 24” of ground clearance. 18” is barely enough.
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The sucky part is getting a fully dressed 4L60E on an off the trans jack while under the car.
@95wagon it turns out that some of the bolts were serrated flange cap bolts, so no loctite. And I guess I need to get back to the gym.
I hate these cooler lines. Someday when I have time, I’m figuring out how to adapt the newer style cooler line fittings to my wagon, because these suck. And the base fittings started turning when I put my 5/8” crows foot socket on them, so I had to double-wrench it, which is tricky by yourself. I’m definitely NOT inviting these fittings to my birthday party.
And either I’m getting bigger or this quickjack is getting smaller. The newer QJs have 24” of ground clearance. 18” is barely enough.
The sucky part is getting a fully dressed 4L60E on an off the trans jack while under the car.
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This is probably ultra nerdy for 99% of you, but here’s how to test the pressure regulator valve in the pump. Disassemble the pump, then pull a vacuum through the hole shown, and use a pencil eraser to seal the little port in the valve.
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A good valve should see well over 15” of vacuum, where 25” is ideal on the calibrated gauge.
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Well that’s the worst reading I’ve ever seen on the pumps I’ve checked. Likely culprit for the oscillating line pressure right there.
Let’s check the Sonnax 4L60E-LB1 o-ringed boost valve I use in all my transmissions. 23.5” of vacuum; a near perfect seal!
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Time for the Sonnax oversized PR valve. The original valve is up top. The primary wear is around the wide spool at the left end of the valve. Hard to see in this picture, but it’s very shiny, which means it’s been wearing against the bore quite a bit. Also shown is the new Sonnax pump slide pivot pin I’ll be installing.
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This is the reamer required to prep the bore for that valve. It ain’t cheap. Between the vacuum test equipment (which you can build yourself) and the reamer (which you can’t, but you can reBay it when you’re done), probably best not to try this at home. There’s also a knack to using this that’s not obvious and hard to explain.
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And there’s a TCC apply valve on the other side of the pump that may be leaky as well and also requires its own reamer. Bottom line, buy a remanufactured pump that specifically has the Sonnax oversized PR valve listed as a component.
A good valve should see well over 15” of vacuum, where 25” is ideal on the calibrated gauge.
Well that’s the worst reading I’ve ever seen on the pumps I’ve checked. Likely culprit for the oscillating line pressure right there.
Let’s check the Sonnax 4L60E-LB1 o-ringed boost valve I use in all my transmissions. 23.5” of vacuum; a near perfect seal!
Time for the Sonnax oversized PR valve. The original valve is up top. The primary wear is around the wide spool at the left end of the valve. Hard to see in this picture, but it’s very shiny, which means it’s been wearing against the bore quite a bit. Also shown is the new Sonnax pump slide pivot pin I’ll be installing.
This is the reamer required to prep the bore for that valve. It ain’t cheap. Between the vacuum test equipment (which you can build yourself) and the reamer (which you can’t, but you can reBay it when you’re done), probably best not to try this at home. There’s also a knack to using this that’s not obvious and hard to explain.
And there’s a TCC apply valve on the other side of the pump that may be leaky as well and also requires its own reamer. Bottom line, buy a remanufactured pump that specifically has the Sonnax oversized PR valve listed as a component.
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Once I got the bore reamed out, I thoroughly cleaned it and then installed the valve with the pinhole facing the same way so it can be plugged for testing. If you’re installing the Sonnax boost valve with the o-rings, make sure to pack the o rings with TransJel or Vaseline to protect them during installation. Sonnax recommends smoothing the bore with a wire brush, or IMHO you could chamfer the edges with fine sandpaper if you clean it out real good after.
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Next is the snap ring. Make absolutely sure it’s fully seated in the groove. The boost valve will move in maybe 1/16” after that snapring is fully seated. Otherwise it’ll pop out after you start the car and you won’t have reverse, or much of any line pressure at all.
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Wow, look at that! Now 23” of vacuum (out of 25” possible). That ought to help out this line pressure issue.
Next to replace the pump slide pivot pin. After removing the pump guts, I measured the old pin.
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New pin:
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Huh. Only 0.001” difference. Does that matter? I don’t know, this is my first time measuring one. But after all the agony of removing the transmission, be assured I’m putting a new one in. Sonnax sells them in 5-packs and I’ll be putting one in every build I do from now on.
Next is the snap ring. Make absolutely sure it’s fully seated in the groove. The boost valve will move in maybe 1/16” after that snapring is fully seated. Otherwise it’ll pop out after you start the car and you won’t have reverse, or much of any line pressure at all.
Wow, look at that! Now 23” of vacuum (out of 25” possible). That ought to help out this line pressure issue.
Next to replace the pump slide pivot pin. After removing the pump guts, I measured the old pin.
New pin:
Huh. Only 0.001” difference. Does that matter? I don’t know, this is my first time measuring one. But after all the agony of removing the transmission, be assured I’m putting a new one in. Sonnax sells them in 5-packs and I’ll be putting one in every build I do from now on.
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and/or an air gauge - then you can do the bores too.
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That's what the vacuum tester does. It measures air leakage around the valves in the transmission.
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Something like this...
When you need to hold spool/bore clearances in the millionths - Probably overkill for an automatic transmission
When you need to hold spool/bore clearances in the millionths - Probably overkill for an automatic transmission
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Related factoid - I was helping a buddy recently change his oil, and his car took 0w-16 oil. Some of the 2023 models are now requiring 0w-12.
I'm managing three teams at the moment, and having programmatic/staffing challenges on all three. I wish buying parts was actually harder than working on cars... but alas.
Since the trans is out and in pieces, I ordered a 4L70E 3-4 clutchpack, which is seven .067" frictions and six 0.095" steels. The stock setup GM put in these cars was six frictions and five .106" steels. If everything is working properly, that's sufficient for a stock application. When I originally built the trans, I added the Sonnax 74140-01K heavy-duty 3-4 clutch backing plates, but I just threw an extra thin steel in the middle of the stack and sent it. It shifted fine with proper line pressure, but while I'm in there...
There is much debate about thin steels being more prone to warp during slippage in hi-HP applications, but my personal opinion is that would be caused by inadequate line pressure, not thin steels. If that were true, the Raybestos Z-pack would be a stupid design, but it's widely accepted as a good solution. Additionally, the clutches would wear out fast anyway with poor line rise, so whatever. If I was building a trans for way more power, I'd probably use a Z-pack, or far more clutches, but not here.
I'm managing three teams at the moment, and having programmatic/staffing challenges on all three. I wish buying parts was actually harder than working on cars... but alas.
Since the trans is out and in pieces, I ordered a 4L70E 3-4 clutchpack, which is seven .067" frictions and six 0.095" steels. The stock setup GM put in these cars was six frictions and five .106" steels. If everything is working properly, that's sufficient for a stock application. When I originally built the trans, I added the Sonnax 74140-01K heavy-duty 3-4 clutch backing plates, but I just threw an extra thin steel in the middle of the stack and sent it. It shifted fine with proper line pressure, but while I'm in there...
There is much debate about thin steels being more prone to warp during slippage in hi-HP applications, but my personal opinion is that would be caused by inadequate line pressure, not thin steels. If that were true, the Raybestos Z-pack would be a stupid design, but it's widely accepted as a good solution. Additionally, the clutches would wear out fast anyway with poor line rise, so whatever. If I was building a trans for way more power, I'd probably use a Z-pack, or far more clutches, but not here.
NO IT IS NOT! The problem with thin steels is if they overheat once, it's the beginning of the end for the 3/4 clutchpack. For most daily drivers, thick or thin steels doesn't matter. For more HD applications thick seems to be the better solution.
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OK @tayto, be respectful in my thread. If you want to make your own 4L60E thread, you are totally welcome to.
Let’s start by defining “overheating” because it’s been distorted by those trying to make a buck. There’s general transmission temperature, and then there’s instantaneous clutch pack temperature during shifts. It’s the latter one that kills clutch packs, and the former one that accelerates oxidation of fluid (although now it’s a non-issue with Dexron VI).
I’m speaking theoretically here, but the counterpoint to your thin steels argument is that the only way to increase total torque capacity in 4L60E 3-4 clutch pack is to add pressure or add clutch surface. So you do everything to max the line pressure and the feedhole size during the shift.
With that much clamping, now you’re dealing with clutch distortion due to insufficient support. That can be fixed with either an aftermarket input housing (Sonnax SmartTech or 4L79) or the Sonnax 74140 backing plates. Otherwise, simply raising pressure becomes self-defeating.
Once that’s been optimized, the next step is to decrease clutch and/or steel size to get more surface area. Peformabilt uses an 8-clutch setup in their high-end units. Their website does not list which steels they use; I’m sure we could figure it out with math.
After all that, If you have sufficient line pressure and sufficient clutch area, the shift will be quick enough not to cause instantaneous overheating of the clutch pack. And that’s independent of the steel thickness.
OK I’ve run out of words. Hopefully this makes sense.
Let’s start by defining “overheating” because it’s been distorted by those trying to make a buck. There’s general transmission temperature, and then there’s instantaneous clutch pack temperature during shifts. It’s the latter one that kills clutch packs, and the former one that accelerates oxidation of fluid (although now it’s a non-issue with Dexron VI).
I’m speaking theoretically here, but the counterpoint to your thin steels argument is that the only way to increase total torque capacity in 4L60E 3-4 clutch pack is to add pressure or add clutch surface. So you do everything to max the line pressure and the feedhole size during the shift.
With that much clamping, now you’re dealing with clutch distortion due to insufficient support. That can be fixed with either an aftermarket input housing (Sonnax SmartTech or 4L79) or the Sonnax 74140 backing plates. Otherwise, simply raising pressure becomes self-defeating.
Once that’s been optimized, the next step is to decrease clutch and/or steel size to get more surface area. Peformabilt uses an 8-clutch setup in their high-end units. Their website does not list which steels they use; I’m sure we could figure it out with math.
After all that, If you have sufficient line pressure and sufficient clutch area, the shift will be quick enough not to cause instantaneous overheating of the clutch pack. And that’s independent of the steel thickness.
OK I’ve run out of words. Hopefully this makes sense.
i have been running a 7 HE thick clutch pack with thin steels in a 700R4 I built almost 15 years ago. It works i was not denying that. i guess it wasn't clear that I was talking about the Z-pak. There seems to be a lot of internet lore that somehow the Z-pak is superior. it isn't.
I guess you're using performabuilt as your bench mark. Fairly sure frank hasn't used the Z-pak in his units for close to 15 years. Save your money on expensive clutches, the hydraulics are more important.
I guess you're using performabuilt as your bench mark. Fairly sure frank hasn't used the Z-pak in his units for close to 15 years. Save your money on expensive clutches, the hydraulics are more important.
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Points of clarification:
- I'm only citing Performabilt as a reference, not as a benchmark. My position on them is neutral.
- If by Frank you're referring to Frank Cahall (who passed away 12/3/2019 but his wife continues the business), his bigger builds use the 4L79 drum with a proprietary 8 friction / 8 steel clutchpack.
- Fair enough on your point on the Z-pack. I didn't use it on the Impala; I have one leftover from when I was building in the 2010 timeframe. If I ever get my cars done I might take on some side work but that wouldn't be until fall 2023 at the earliest.
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