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Thread: Geartrain noise in 4L60E second gear causing "knock" retard

  1. #16
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    On a side note, I was driving home tonight with the windows down on the service road, next to an elevated highways retaining wall and ran it WOT from 0 through 75 mph. The whine I am hearing may even be accessory whine as its there in 1st gear too.

    Ramjet timing tables woke this pig up. Also noticed a strong correlation between the 0411 MBT map and the Ramjet maps. On 93 octane a vortec 350 should have no issue at 30-31° of timing.

  2. #17
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    Do you have an underdrive pulley laying around that you could install to see if that changes the sound and the knock? Are the belt and tensioner in good shape (maybe it is slipping)?

  3. #18
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    Quote Originally Posted by sherlock9c1 View Post
    Do you have an underdrive pulley laying around that you could install to see if that changes the sound and the knock? Are the belt and tensioner in good shape (maybe it is slipping)?
    Tensioner was replaced 23k miles ago with the engine and it has an underdrive pulley already installed. Belt was replaced with the underdrive pulley when the cam went in, about 1,000 miles ago. The clutch fan has already hit the spare parts shelf as well.

    I wonder if it could be that Duracrap alternator that I had no choice but to install in middle of nowhere USA when the original started discharging at idle.
    Last edited by Fast355; 04-15-2013 at 10:38 AM.

  4. #19
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    So I found something interesting looking at the knock sensor calibration.....Specifically Burst Knock. I am going to do some datalogging with it limited to 1° and see what I see. I notice many guys just disable it on the LS engine and my TBI/TPI/CPI always had it disabled

  5. #20
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    I am CERTAIN the knock sensor is lying to me though. At 3,500 rpm in 1st gear, heavy throttle PE @ 12:1 afr, commanding a mere 19° of advance, I was getting 7.8° of retard, that gradually tapered off as the rpm climbed, to less than 1° at 5,200 rpm.

  6. #21
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    Now I am getting somewhere. Removed 2° additional CTS compensation at 205+ and ran with the burst knock at 0. Only saw a few brief points of 2° retard and that was mostly in OD when the TCC locks. Going to need that 3.73 G80 sooner than later. Now that I have the P0128 code turned off, I'll stick my 170°F thermostat back in. That will safely bring me up from 24-25° of timing to 28-29° by keeping the engine and IATs lower.
    Last edited by Fast355; 04-19-2013 at 03:39 PM.

  7. #22
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    Speaking in terms of pure speculation I am going to say that your problem most likely isn't related to the noise you are hearing regardless of the source. This is based on your experiences with timing changes etc. It sounds to me like you are on the right track with tuning and lowering coolant temps etc. Just my 2 cents on the noise, if the trans does have a 2nd gear specific noise then it would probably be in the rear planet and/or captured bearing as well as sunshell flex. I understand your desire to upgrade to a 4L80E, but just remember that they are heavier, take more power to operate, and are relatively more expensive generally speaking. They also have their inherent flaws to deal with. If you can build a trans then I'd say build a solid 4L60E instead. You can throw upgrades that basically just increase pressures and clamping forces at the trans all day long. But, if you don't actually upgrade the internals and have stock frictions that have seen slippage and been abused, then nothing is going to improve the function of the trans and you might actually be worsening the problem.
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  8. #23
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    I like burst knock, especially on high advanced spark tables. It's a anticipated knock for like cruising highway speed lite throttle and a quick accelerate it will keep you out of knock. Does not effect WOT. Great for heavy rigs. So when you get this issue fixed don't rule out leaving it off.

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  9. #24
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    Quote Originally Posted by pmkls1 View Post
    Speaking in terms of pure speculation I am going to say that your problem most likely isn't related to the noise you are hearing regardless of the source. This is based on your experiences with timing changes etc. It sounds to me like you are on the right track with tuning and lowering coolant temps etc. Just my 2 cents on the noise, if the trans does have a 2nd gear specific noise then it would probably be in the rear planet and/or captured bearing as well as sunshell flex. I understand your desire to upgrade to a 4L80E, but just remember that they are heavier, take more power to operate, and are relatively more expensive generally speaking. They also have their inherent flaws to deal with. If you can build a trans then I'd say build a solid 4L60E instead. You can throw upgrades that basically just increase pressures and clamping forces at the trans all day long. But, if you don't actually upgrade the internals and have stock frictions that have seen slippage and been abused, then nothing is going to improve the function of the trans and you might actually be worsening the problem.
    I have made up my mind on the 80E and have a core to build already. The 60E is a TRASH transmission, I have had one built professionally by a reputable performance shop (killed it in 15K) and had 3 others that I built with good components. You hit a point where you end up destroying cases on them or other hard parts with relatively little power. You just cannot make them hold up in a 6,000 lbs vehicle making 450+ TQ with a 2.6 STR converter. 80E has better gear spacing and the durability is well worth the slight power loss. The build I am looking at copying on my 350 made 490 ft/lbs of torque at the flywheel. With a 2.6 STR converter I will be looking at over 1200 ft/lbs torque spikes to the input shaft. The 60E does not stand a chance against that.

  10. #25
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    Quote Originally Posted by EagleMark View Post
    I like burst knock, especially on high advanced spark tables. It's a anticipated knock for like cruising highway speed lite throttle and a quick accelerate it will keep you out of knock. Does not effect WOT. Great for heavy rigs. So when you get this issue fixed don't rule out leaving it off.
    It also subtracts timing in 1st gear on a WOT jab and right after WOT downshifts. I am not a big fan of letting the PCM predicte something that might happen 1 time in 50 events. Properly tuned spark tables including AFR, CTS and IAT along with properly timed PE will keep you out of knock ALL the time.

    I ALWAYS disabled Burst knock on my TBI engines. Never was a fan of it and never had issues without it. My 4.7 and Hemi engines had the same thing on them. I dropped nearly 2 tenths in my 60' in my Hemi Ram disabling, aka zero'ing out the TPS activated timing retard. Basically dodges version of burst knock. With the right timing and power enrichment delay bypassed never had an issue with knock either. Nothing like being heat soaked in hot weather, with a loaded trailer, high IATs and high CTS readings, A/C kicked on and hardly being able to move forward out of a traffic light due to all the unecessary timing retard.
    Last edited by Fast355; 04-19-2013 at 07:52 PM.

  11. #26
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    Quote Originally Posted by Fast355 View Post
    The 60E is a TRASH transmission
    I've built 700's for 502, supercharged 383's (600 rwhp) and nitrous cars... have had a couple issues, but they're still running....
    the planets are actually bigger than 4L80E, but the hard parts actuating things are different, and the 80E does have an extra planet in front for overdrive, it for sure is heavier duty. Will be good to know how stuff works out...
    Last edited by greggbruceauto; 04-20-2013 at 02:12 AM.

  12. #27
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    Quote Originally Posted by greggbruceauto View Post
    I've built 700's for 502, supercharged 383's (600 rwhp) and nitrous cars... have had a couple issues, but they're still running....
    the planets are actually bigger than 4L80E, but the hard parts actuating things are different, and the 80E does have an extra planet in front for overdrive, it for sure is heavier duty. Will be good to know how stuff works out...
    I tore the case lugs off the side of the case in one. Broke the "beast" sun shell in another and broke an aftermarket input drum in another. Each time it looked like a grenade had gone off inside. The weakest point gave out and when it failed, took the whole unit out. I had one that cracked in the bellhousing area as well on a stock 2.8 S-truck.

    I picked up the ATSG manual on the 4L80E and plan to build it myself. I will let you know how it works out. The beefier OD is one of the main things I am after, since I plan to swap either 4.10 or 4.30 gears into it and will be towing in OD.

  13. #28
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    Quote Originally Posted by Fast355 View Post
    I tore the case lugs off the side of the case in one. Broke the "beast" sun shell in another and broke an aftermarket input drum in another. Each time it looked like a grenade had gone off inside. The weakest point gave out and when it failed, took the whole unit out. I had one that cracked in the bellhousing area as well on a stock 2.8 S-truck.

    I picked up the ATSG manual on the 4L80E and plan to build it myself. I will let you know how it works out. The beefier OD is one of the main things I am after, since I plan to swap either 4.10 or 4.30 gears into it and will be towing in OD.
    very cool -- not too difficult to do, the 60's and 80's are easier than the other brands (engineered WAAAAYYY better)...and practice makes you better....
    I figured out on a couple of them the reverse boost valve "upgrade" made too much pressure and broke things.
    also the pressure regulator spring "upgrade" in some of the shift kits do the same thing. I lowered the pressure (stock spring) a little and hit the magic button, things stayed together better.....

  14. #29
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    Quote Originally Posted by Fast355 View Post
    I had one that cracked in the bellhousing area as well on a stock 2.8 S-truck.
    you know something is awesomely engineered when a ~125HP/~155TQ engine in a ~2700 lb vehicle can kill it.

    i've had bad experiences with 700R4s in the past.... not so sure i would want to deal with another or something that was derived from it.
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  15. #30
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    Gotta love it...Knock retard entirely in 2nd gear but absolutely none at the 2-3 shift. I ran it 107 mph in 3rd gear at 4,500 rpm with the converter force locking at 85 mph and had less than 2* of knock retard and was pushing 200+*F coolant temps. That was as fast as the brick would roll into the wind up a slight grade.
    Last edited by Fast355; 04-21-2013 at 07:10 AM.

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