When my 4l60E shifts from 2nd to 3rd it will making a loud bang that I can feel in the seat.
It only does it at light throttle. I think the shift happens around 1600 or so rpm and a little under 20 mph. If I give it enough gas to where the 2nd to 3rd shift happens after 2k rpm there is no banging. Could this be a fluid pressure related issue due to a clogged cooler or line?
There isn’t any banging when downshifting while coasting.

If has a 3,200 stall converter so I don’t know if that has anthing to do with it. When it was first installed it wouldn’t pull itself on level ground. But I believe that was because it was under filled. It pulls itself now though. I added more fluid until it would do so. The light throttle 2nd-3rd shift didn’t get any better though. It seems like if I could tune it to where it wouldn’t shift until it reached 2k rpm the problem would be solved. But I don’t know if I have someting else going on that’s causing it.

The low pressure theory stems from me thinking that the cooler or lines might be partially clogged. WOT shifts are good.

Or is it just the nature of the beast with higher than stock stall converter on the stock tune?

I’d also like to note that it doesn’t start banging until the fluid is up to operating temp.

 

I had a 3500 stall speed in my '00 WS6 with a 4L60E and stock tuning for about a year while I was waiting for LS1 Edit to be released (yes this was nearly 25 years ago). There was never any banging at low rpm shifts (or any other rpm range). It behaved quite well with stock tuning (other than a tiny bit of idle surge in gear due to the higher stall speed causing a change in load).

It shouldn't ever need more fluid than what the stock dipstick shows as full (unless you're using some kind of aftermarket dipstick setup that may or may not show an accurate "full" level). Mine pulled forward on level ground with correct fluid level, stock idle rpms, and a 3500 stall speed (it was a Yank converter).

 

Bummer. The transmission has been banging since it was installed. I wonder if it could be a flow issue?

 

Tell us more about your transmission. Was it a stock rebuild? Does it have a shift kit, if so which one?

 

It’s a @FranksCustomTrans Stage 1 4l60e.

The reason that I’m thinking that it might be a pressure related issue is because it shifts better with more throttle than less. Frank said that I might expirence a hard down shift while coasting but that’s not the problem that I have. Mine only makes a loud bang that you can feel in the seat when it shifts around 1500-1600 or so RPM from 2nd to 3rd below 20 mph. It’s a soft shift when it happens. It doesn’t throw you forward in the seat like it does when it shifts at a higher rpm. When it shifts hard enough to make your head go forward it doesn’t make a noise.

Maybe my trans cooler is clogged and it’s not getting enough fluid pressure at low RPM. I dunno.

 

Its mine he did initailly have low fluid missread dipstick or something he determined, I had unit back and it also showed damage expected with such.
I repaired and check over sent back. I was unaware he was having any sort of issue before seeing this thread today.
The build is I think stage 1 I would have to look . Using my shift kit. Pretty straight forward build WIDE BAND I think 7 friction 2-3 with .90 steels. .083 second feed. .093 3rd .
I would be curious if TCC is coming on ? I was in a car with a 3600 stall and the TCC came on early 273 axle and abruptly with 3rd gear at low throttle and speed and the feel was kinda a bang followed with a luging sensation. Something to look into partcular if rear ratio is high 2.73 to like 3.42 , I know with my own car and 308 rear with stock tune 2800 stall it would try and lock the converter at low speeds in 3rd and was not a pleasant feel , I raised it up to 4th only about 45 mph along with rasing all the PT shift points and fixed it. IMO is was up shifting way early 3 gear by 20ish 4th by 30-40 mph with very light throttle felt yuky (I was new to a stall at that time) but once those two were done felt fine. (I honestly initally did not like low throttle feel with the stall , but loved it when it hit lol)
I mention because he says does not do it with a bit more throttle and later shift.
To me at least the stall even the 2800 was not particulary pleasant with the stock tune and 2800 stall 3.08 gears in my impala ss.
My ultimate solution was raise the low part throttle shift points by 20 percent below 40 mph and less than 20 percent throttle and then made so lockup could not happen till above 45 mph period and only in 4th.
So to the OP I would sugest if possible something like ^ and see how it feels then .
I wish I had a better understanding of BANG as in hit s or an actual noise. While the trans would be unable to really make a noise if it is a bang noise I would look at mounts - torque arm bushings as at very low throttle you can get drive train backlash that can sound feel like a bang as regardless of build during the 2-3 at some degree because it involves releasing the band while applying the 3-4 clutch overlapping the load will release to some degree which is the equavalent of a momentary neutral during the shift otherwise it would be a what many perceive as a bind up (really momentary 4th gear) during the shift except with the overun clutch on which together would cause a momentary braking effect. But I dont think that is the case as it does not occur at a bit higher throttle and RPM .
So if you have ability I would try making the changes I have above and see where you end up.
Note if you do make changes always make sure you have original saved incase you want to go back .
Also note with any performance trans, You have larger feeds- more frictions and friction area- higher line . It will never feel exactly like stock , In fact if you look at your stock 2-3 shift adapt etc at least in my car origial OBD1 tune and even now with the torque head and OBD2 using a 2002 tahoe tune GM actually uses negative numbers during the shift , I assume to smooth this all out
And always feel free to contact me with any questions directly in messenger.
I do have HP tuners now also and can look at your tune and make changes of you would like to send in mesenger.

 

Wrong guy Frank. I never sent mine back, it’s still installed in the car.

We’ve messaged a few times about it after It was first installed though and you said that maybe I was expecting a smoothe shifting transmission. I think I have other issues going on though. Like possibly the TQ converter spacing is off which is reducing the flow or the cooler or lines are clogged. I asked if you were me would you have the transmission pulled so the converter spacing could be checked and you said that it wouldn’t be worth the labor to do so and that you’d just drive it until it breaks. I’m finally at the 500 mile “break in period” so I was trying to figure out my next move. Which would be either change the filter and keep driving it around until it breaks or to try and salvage it if it can be.

When yours was trying to lock the converter in 3rd was it happening right when it shifted? The kind of bang it’s making is the kind where someone would say, “Oh ****, did the rear end just fall out!?” It’s not subtle. How “unpleasant” was yours shifting prior to tuning? Was it so unpleasant that you thought your driveshaft fell out? That’s how mine is.

I have a 3.23 rear gear FWIW. If the fluid were too low would it runin the transmission in the first handull of miles? The loud bang first happened on the first drive home from the shop and it’s still doing it even with more fluid in it.

I’ve been reluctant to post about it again because the first time that I did after I got it home I got flammed by others on the site.

Would low flow cause a LOUD bang that you can feel in the seat when it shifts below 2k rpm from 2nd-3rd?

It only seems to do it when the fluid is warm.

 

^ I remember there being some issues with the shop that actually installed your new trans (something with a leak, etc.?) I still wonder if they didn't damage something with improper converter spacing at first (they may have "fixed" it and not told you, but the damage could have already been done if they first tried to run or drive it with improper spacing). It shouldn't need excessive fluid level just to pull forward on level ground. Again, I had a looser stall speed (3500) with the same gears (3.23) in the same general car (heavier actually, being a fully loaded Trans Am) with the same stock 550rpm idle speed. It was definitely able to pull forward on level ground at idle speed from day one with the new converter and stock tuning.

I wonder though if the banging, specifically, is a separate issue like Frank mentioned above. Something to do with other driveline components, meaning bushings or a driveshaft/U-joint issue even?

 

When I first got it back from the shop the guy left the tail shaft housing seal leaking. It’s since been replaced by a different shop.

The trans mount and the torque arm bushing are new. Even if they weren’t it seem like there’d be banging at WOT instead of at 1,600 rpm but there’s not. It only makes the God awful sound and feel on a light slow shift. It’s just the 2nd to 3rd shift when you’re taking off slow from a stop light (under 20 mph). It also doesn’t bang into gear when the fluid is cold.

 

I think my next plan of action is to disconnect the return line at the radiator to see how much fluid is pumped out in 20-30 seconds. If it’s barely pumping I guess I can assume there’s a clog.

 

Ah ok my bad , hmm weird , But ok then if you are not him then guess your not.
As for the shift / lock yes they hit dead on with each other, and yes it was unpleasant. Now a bit more throttle and it didnt happen. Thats why i decided to raise the shift point and move lockup to 45 mph 4h only, I just did car for the feel Im 3.08 and the car shifted IMO way early . Low speed was very clunky and really felt slippy . I just didnt care for it.
That said however I would not say it was like I was hit in the *** either. But then I have a 4400 pound car without me in it .
Now if a shift happens at any speed and lockup is allready on yes it will feel like someone hit you in the ***.
I think I said before I will be more than happy to look at it for you. My concern is more that you end up pulling the trans only to learn its something like the things I mentioned above .

Is the tune stock as far as you know ? Many times some tuners will run the particualry 2-3 presures way up . I had a guy I helped recently that sent his tune and first thing i noted was 95 95 95 95 95 in the 3rd gear row, I coied my tables and sent back to him and he was good .
If you do indeed have the ability to download and up load tune feel free to send it to me in messenger as I would like to help you solve it to your satisfaction.
And before I dont thing the intent was to flame you Certainly not on my part. But rather because you hadnt at that time contacted me first would be my guess.
I do not expect you to live with something you are unhappy with.That was not teh message I intended to send , I have never been like that. Now or in the past.

Let me know .

hmm now I need ot figure out who the other guy was , The only info he sent me was his return address and that he had run it low on oil but had figured it out and all was good .But then later contacted and said he thinks he damaged it and he had . not tarribly but you could see a l burnish on all frictions, I fixed and returned ,

I have only had like 4 returned fo repairs since I started this 3 years ago , two were converter failures one the shaft can out if a reman input drum which caused me to start pulling and inspecting those before I use any of them, And that one.

But in any case let me know, send your tune , No I do not think a low presure would cause such , But high presure surely might.
Could be worthwhile to put a guage on it .

Also if you do have HP or have a friend who does have them data log and send that to me showing this.

Anway whatever we need to do to get you to where you are pleased in a reasonable way.

I have really not had anyone have any complaints with shift feel issues . But I will work with you to try and solve it, Honestly I would have checked back in with you but assume was a solved issue when you I think posted about fliuld level and the lack of creeping in the previous post.

 

It for sure wasn’t me that sent one back to you. I don’t have the means to do so really. I’d have to pay a shop to remove it and I imagine a shop won’t let me leave it there very long with the trans out. So I’d have to rent a trailer or have a tow truck tow it home while waiting for the transmssion to come back. Then I’d have to tow it back up to the shop so they could reinstall the trans. I haven’t had that sort of money laying around. I bet I could drive it up to you from TX for about the same as a tow truck bill. 😂

The tune is stock and unfortunately I don’t have any tuning hardware or software.

Before I got the car it set neglected for I’m assuming a long time. It only had 27k miles on it and the transmission was already having issues. Not this issue though. The 1st-2nd was long and finally it started to slip. So I had it replaced. I wonder if maybe the cooler is clogged? It is still the original. What makes me think that it’s plausible is because when I first got the car the engine temps ran a little high, but after flushing the radiator w chemicals the temps came back down. Am I way off base thinkng that the clunking could be pressure related? Like is the cooler or lines weren’t letting enough fluid flow at low RPM, could that lead to a clunky shift?
What’s a better dice roll, a $130 radiator or a $1k tune?

 

Honestly for this and future , I would just buy the tuning softwage and MVP for your car. , HP TUNERS as while not required a 3200 stall and car could really benefit from some tuning with the trans for sure and you can do so much more
Radiator is not gonna change anything, I do wonder if they flushed the lines and such argh .
Have you had the pan off since it came ? Done the fliter change? I ask cause logic if not would be to do that first. If all looks good (normal to have some stuff in there and the black pan makes it look worse than reality)
Oh and peice of advice, older performance car, AAA its a life saver , its 12 a month for top tere and you get free towing up to 150 miles . They dont need to now why your towing ,
When My opti died 140 miles away at the air port in july they were a life saver, Towed car and me home 140 miles free . Then a couple year back when fuel pump died 25 miles home . when had dead battery pouring rain the came out , jumpp me off never had to leave the car.
Blew out front tire on my escort , no spare. towed it 50 miles home no charge .

Worth every dime, https://cluballiance.aaa.com/members...BoCBpMQAvD_BwE

 

I’m fairly certain that the cooler and lines weren’t flushed. Right after I got it home from the shop I checked the fluid and there was some clutch material left behind on the paper towel. I thought maybe the fluid was low since it banged real hard on the way home. The ride home from the shop is under five miles.

I was waiting until the 500 mile mark to change the filter but it’s had numerous drain and fills in between. The first time was to see if it would shift better with Dex III than it did with the Valvoline Maxlife that was originally put in it. It was drained again not long ago when I had it in a shop to get the tailshaft housing extension replaced. The shop that put in the trans messed up the original extension. The fluid looks clean on the dipstick but when you wipe it the paper towel has material left behind. I’ve finally reached the 500 mile mark so when I get a free weekend after the holidays I’m going to drop the pan and change the filter.

You don’t think that it’s a flow issue, hence the reason why a new radiator/ATF cooler wouldn't help?

 

Merry Christmas

 

No not a fow issue and the cooler lines and radiator are certainly flushed by now

Hey can you make a video with audio of the "bang " it could be helpful to hear/ visualize it .

 

I was kind of thinking that the cooler and lines might be permanently clooged with “stalactites”and “stalagmites” that built up from decades of siting. Kind of like gas will in a metal fuel tank.

I’ll try and make a video here soon.

 

It's not the cooler. After installing Frank's shift kit in my car, it does what sounds to be the same as you are describing.

Shifting at very low throttle at around 25mph into to 3rd gear can be very, very harsh and sounds like the diff is coming apart. You can drive around it by accelerating a little harder, so I haven't taken the time to see if razing the shift point would help. I am sure that it will help. Frank's kit shifts so fast into 3rd gear that at low throttle/low speed it feels as if there is some slack in the drive train and the shift just hammers the drive train. I feel as though it can be tuned out with HP Tuners or driven around. I agree it can be quite annoying, but there is almost always a trade off with high performance parts.

I discussed this with Frank awhile back and he suggested that having the 3-2 Down Shift and 3-2 control valves blocked in my valve body could be contributing to the problem. As of now I have not taken the time to unblock the valves to see how that would affect the shifts. This would not be the problem with OP's trans, as Frank doesn't block these valves.

I still would not hastate to install Frank's kit in other transmissions.

 

Mine does the same thing, I raised the 2-3 downshift and upshifts in my tune and dropped line pressure a bit. Im also using torque management and retarding by around 8 degrees on the shifts and those few things seemed to help a ton. It still shifts fairly hard but not clunky like it was before. 2-3 upshifts I have starting at 30 mph at 0% tps and downshift i have at 18mph at 0% tps. Line pressure originally was 30% duty cycle at -14map and I raised it to 36% mind you im turbo so my line pressure may be a little steeper then yours. I already have level 3 transmission with transbrake.

 

hmm . Maybe I have managed to make the 2-3 shift a little too good ? I used a .093 to. .100 feed here dependng on application. Perhaps I will lower the feed size a little. Maybe .083 to ,093 depending on application. I really perhaps didnt understand or know the low throttle 2-3 was a bit excessive. My main concernw is making it hold no matter what to be honest , But still with all these I have built otehr than this no ones really hollered at all except about the 3-2 bump.
The trans though as you mention are built more arround durability and performance than comfort in mind as that is what I market them as.
Though they also must be some variance to the cars also as My own car has the exact same set up wih .083 2nd feed and actualy .100 3-4 feed . it has notable bump but nothing I would see as excessive. Of course excssive is subjective. I have had guys say a 2800 stall slips horribly and a 4000 stall feels like stock so .
But as you mention the primary goal is performance- hold- durability and comfort is a back seat to that.
Ill gIve some thought to changing feeds a little.
Now of course smoothe shifting and performance 4l60e is an oxy moron . more like performance with a reasonable shift feel is the goal , But again subjective