[cahall]

Way to defend being wrong. Being a moderator DOES NOT give the right to post the wrong information. I was very polite in pointing out that you were wrong in your reply. You took it further by trying to prove me wrong. If you want to ban me, that's up to you, but as we can clearly see, that would only hurt the other members here. Are you more interested in having your members get the CORRECT information or flexing your computer muscles because you got your feelings hurt when you got proved wrong?
I stand by my statement...If you don't know enough about automatic transmissions to know that a torque converter WILL NOT cause a no 3-4 condition, then you shouldn't be building transmissions. The fact that this not only applies to 4L60es but it spplies to every automatic transmission is even more disturbing.

Frank

 

[93formulafirebird]

hey everyone,

I tried searching around the forums for my issue. The closest I found was not shifting at WOT. I figured I would ask just in case.

I have a 95 Z28 auto with about 125,000 miles on it. Out of no where the car shifts fine from 1st to 2nd, but does not go any higher than 2nd gear.

This is under normal driving conditions.

Would this be the 3/4 clutch going bad?? or speed sensor???

Thanks in adance!!

Jesse

Your 3/4 clutch isnt blown if it were you would loose all forward motion once it hit 3rd gear and just spin freely like your in neutral. shift solenoid or VSS is causing your problem. Speaking form someone who was once in this spot with a 94. First trans shop said, tranny rebuild second shop, popped the pan replaced the solenoid and sensor and i was on my marry way.

 

[Dynamic396]

Your 3/4 clutch isnt blown if it were you would loose all forward motion once it hit 3rd gear and just spin freely like your in neutral. shift solenoid or VSS is causing your problem. Speaking form someone who was once in this spot with a 94. First trans shop said, tranny rebuild second shop, popped the pan replaced the solenoid and sensor and i was on my marry way.

This topic seems to be a bit radioactive, but I'll comment again anyway as t this information is not correct either...

You don't lose all forward motion when it hits 3rd gear with a burned 3-4 clutch. You just won't have 3rd or 4th gears, as has been stated. It is not possible for it to "spin freely like it's in neutral" in this scenario.

A VSS cannot generate a signal enough for a 1-2 shift, and then no higher. It's impossible. It either works or it doesn't...

A bad shift solenoid will exhibit some weird gear patterns, but never a loss of 3rd and 4th. Once again...not possible.

As a guy who has built transmissions for 25 years now, and who builds 150-200 of these things every year, take it from me... You have a burned 3-4 clutch, just like every other 700R4/4L60E that has lost 3rd and 4th gear...

 

[thirdGEARchirp]

Thanks for all the comments guys.

Dynamic396, when having the trans rebuilt do you know what most shops will actually rebuild? Would they just replace the 3/4 clutch packs or would they replace majority of the internals? I am asking this because I received a quote of $900, $1000, and $1,200. All of them simply stating they would "rebuild" the trans but not get into specifics.
Is there a way to know for sure what they replaced?

I don't want to pay for a total rebuild and then they only replace one thing.

Thanks

 

[cocobolo95]

A honest shop when they rebuild a trans will install a master kit that includes gaskets, seals, sealing rings, clutch plates, & steels. Also many 4l60e master kits contain a new 3-4 piston.In addition; new filter, band, low roller clutch, forward sprag, needed bushings or all bushings, torringington bearings, rebuild the oil pump, upgrade to servo, and a few other items. Also many shops will install the beast sun shell which is stronger than the stock one. Valve body will be gone through and parts replaced or upgraded as needed.

They will inspect the other parts of trans and replace any not up to par. This usually adds to your bill as it's not included in the basic rebuild price.

Lastly, a new torque converter will be installed as a routine procedure to protect the rebuilt trans from damage. This too will usually bump up the price.

 

[Dynamic396]

There's absolutely no point in going into a situation like yours without performing a COMPLETE rebuild. There's just too much stuff that needs to be done to build a transmission that's going to live. First of all, ask them what they plan to do for your $$$. They are working for you! If any shop says that they're going to just replace the 3-4 clutch, turn and run...especially for those prices! I could, literally, replace your 3-4 clutch stack in about 15 minutes, but doing that would be pure lunacy!

As a 'for instance', in my shop, I would build you a 'Stage II' package, as I do for most F-bodies. The basic build is generally the same, but the specifics are always done on a case-by-case basis, depending what you, my customer, are looking for in a finished product.

My 'Stage II' package come in at around $1000 (bench build), without a converter. When I build ANY transmission, there are literally no two parts still assembled when it goes through the parts washer. EVERYTHING comes apart and is inspected - especially in a 4L60E! Every piece of the pump, every valve in the valve body, EVERYTHING!

I buy most of my parts in bulk, so a 'kit' does not really apply to my parts list, but a partial list would look like this:
Borg Warner frictions (7 disc high energy in the 3-4)
New OEM AC Delco 3-4 apply plate and backing plate
Kolene steels in forward and 3-4 clutches
Turbulator steels in reverse input and low/reverse
Bonded steel 3-4 clutch piston
Borg Warner low roller clutch
Borg Warner dual cage 29 element forward sprag
"Beast" sun shell
Wide forward and rear stator support and reaction sun gear bushings
Teflon pump bushing, babbit case bushing and most of the other bushings
Complete paper and rubber kit (obviously)
New shift solenoids, pressure switch manifold and 3-2 downshift solenoid
.500" boost valve
Yada, yada....

If you want a complete list, I can get you one, but my point is that there is absolutely no point in doing any kind of partial build on an automatic transmission. Also, notice that nowhere in my list did you see a Transgo "shift kit". Do yourself a favor and don't let anyone put any of that DIY-grade junk in your transmission. If the shop doesn't know how to modify your shift characteristics without a "kit", then walk away...

 

[93formulafirebird]

This topic seems to be a bit radioactive, but I'll comment again anyway as t this information is not correct either...

You don't lose all forward motion when it hits 3rd gear with a burned 3-4 clutch. You just won't have 3rd or 4th gears, as has been stated. It is not possible for it to "spin freely like it's in neutral" in this scenario.

Then you havent had the 3/4 piston split in half have you? i know thats what shutdown another 4L60E with no bite after 2nd. Granted i never really hear about those spliting in half either but it is a possibility.

 

[Dynamic396]

Then you havent had the 3/4 piston split in half have you? i know thats what shutdown another 4L60E with no bite after 2nd. Granted i never really hear about those spliting in half either but it is a possibility.

Yes, anything is possible. But, in 25 years of building transmissions for a living (including 12 years at a large Chevrolet dealership, and the rest working for myself, specializing in GM transmissions) I can honestly say that I have never seen a 700R4/4L60E 3-4 clutch piston split in half. I've seen a few cracked ones in the early years before GM went to bonded steel pistons in '97, but never one split in half. I guess I just haven't done enough of them yet...

But I would need someone to explain to me just how, even if the 3-4 piston was cracked, broken, split or missing altogether, it would do anything other than just not have 3rd or 4th gears. It cannot go into a false neutral. You're still in 2nd gear...! At no time does the forward clutch disengage and the servo can't build any pressure on the back side to unseat the band.

Can someone explain this to me? And, no, I won't accept a "...my cousin's friend Jimmy had this happen on his sister's Tahoe..." type of explanation. I can save you the trouble. It's not possible...

 

[kwacasey]

When i bought my 93 z28 it would not go into 3rd gear. Meaning that it would go from 1st to 2nd with no issues, then as it shifted out of second it just rev'd as if the trans was in neutral. If the car slowed enough it would catch second then once past a certain speed seem to slip into neutral again, where third should be. I tried manually shifting from 2nd to D, and allowing the trans to shift itself in D and OD, but same result each time.

I did end up rebuilding the trans myself, I do not claim to be an expert. The 3/4 clutch packs were toast. I did the master kit thing and on the advice of the guy at the trans parts store added a shift reprogramming kit from Superior Performance. Trans works well now.

Is it possible that when the clutch packs go they are slipping so much that the piston that controls the 3rd gear engage is engaging and the slipping is so much that it just seems like the trans is in neutral?

 

[93formulafirebird]

Yes, anything is possible. But, in 25 years of building transmissions for a living (including 12 years at a large Chevrolet dealership, and the rest working for myself, specializing in GM transmissions) I can honestly say that I have never seen a 700R4/4L60E 3-4 clutch piston split in half. I've seen a few cracked ones in the early years before GM went to bonded steel pistons in '97, but never one split in half. I guess I just haven't done enough of them yet...

But I would need someone to explain to me just how, even if the 3-4 piston was cracked, broken, split or missing altogether, it would do anything other than just not have 3rd or 4th gears. It cannot go into a false neutral. You're still in 2nd gear...! At no time does the forward clutch disengage and the servo can't build any pressure on the back side to unseat the band.

Can someone explain this to me? And, no, I won't accept a "...my cousin's friend Jimmy had this happen on his sister's Tahoe..." type of explanation. I can save you the trouble. It's not possible...

i held the piston in my hand, it was an old cast one being a 94. I had never seen one split that bad. then again with the driver being 17 and keeping his foot through the floor i should have known, the clutches were so warped that they had a convex shape to them. It would "engage" 3rd but just spin up till it fell back onto second. one of the strangest failures i had ever seen. either way though, the original poster needs a rebuild.

 

[Dynamic396]

That's why GM went to the bonded steel pistons. I have seen quite a few that were split and cracked, but never one split in half as you originally stated when you were trying to discredit my experience with these transmissions. And, yes, convex clutch plates are generally what you find in a burned up 3-4. Sometimes they can be quite difficult to get apart.

Kwacasey, what you'll typically feel, that may be construed as a false neutral, is that when you let up on the throttle, the engine will just fall back down to idle. This is because, in 2nd gear (in the "OD" position on the shifter), you're driving through the input sprag. Under normal circumstances, when you let up on the throttle in 2nd gear, the transmission would simply upshift into 3rd, and then ultimately into 4th if you have the road speed for it. When your 3-4 clutch is burned up, the PCM will command the 2-3 shift, but there's nothing there...so, rather than a direct drive through the geartrain in 3rd, the input sprag simply overruns and the engine falls to idle. When you get back on the throttle, the engine will spin up, like it's in neutral, until the input speed matches the speed of the geartrain and then it will begin driving through the sprag again. This whole scenario will feel very much like you have gone into neutral. If you were to pull it down into manual 2nd, the overrun clutch would engage and override the input sprag and it would feel more normal, albeit still stuck in 2nd gear.

 

[kwacasey]

Dynamic396, what you describe seems like what i was experiencing. Thanks for the detailed explination. I did actually slip the gear shift into 2nd gear and found that the trans would grab and as a result the engine rpm would incrase to match my speed. I also found this same issue in the drive position as well. I should probably also mention that my trans is the original 4l60 (non-E) also known as the 700r4. 1993 Z28 only year that uses this trans to my knowledge. However outside of the valve body i believe these two transmissions are similar if not the same.

For anyone that is reading this thread looking for a solution to their issue, i will mention that the rebuild was the fix for my individual case.

thx again dynamic396

 

[Dynamic396]

Any time, kwacasey...!

Yes, you are correct. The 4L60 (700R4) is essentially the same transmission as the 4L60E, except that, obviously, the 4L60E is electronically controlled.

One thing to note, just for the FWIW file, is that in the 700R4, when you select the "drive" (or D3) position, the overrun clutch will engage immediately upon selecting this position, beginning with first gear and it remains engaged as it shifts up through second and into third (assuming your 3-4 clutch isn't toast...). In the 4L60E, in the D3 position, the overrun clutch is not actually applied until a 2-3 shift is commanded and the 2-3 shift valve strokes in its bore, hydraulically completing the circuit to the overrun clutch.

Why did GM do this...? I'm not sure, to be honest, but that's the way it is. This operation can be changed to operate like the 700R4 with the careful application of some minor valve body trickery...

 

[kwacasey]

It may be as a result of some modifications that were made to my valve body, as suggested by the rebuild instruction that I used or the ones outlined in my shift reprogramming kit, my trans does not make use of the over run unless in the "OD" position. At that time the overrun works in all gears as you mentioned above. It should be mentioned that this could be a mistake that i made as a result of my modifications as well, always a possibility.

I thought this was strange but have not questioned it too much as the car seems to drive fine this way and seems to feel alot more powerful (as if i were manually shifting the car).

Any thoughts on this?

 

[kwacasey]

It may be as a result of some modifications that were made to my valve body, as suggested by the rebuild instruction that I used or the ones outlined in my shift reprogramming kit, my trans does not make use of the over run unless in the "OD" position. At that time the overrun works in all gears as you mentioned above. It should be mentioned that this could be a mistake that i made as a result of my modifications as well, always a possibility.

I thought this was strange but have not questioned it too much as the car seems to drive fine this way and seems to feel alot more powerful (as if i were manually shifting the car).

Any thoughts on this?

Turns out that i mixed up how the overrun clutches worked. I associated coasting to the over run clutches, which is wrong from what i found today. The over run clutch when applied locks the sprag causing engine braking. This is what i was describing above and from what i have now found this seems to be correct.

I have added the table below for refrerence in case anyone wants to look into this further.

 

[cahall]

23 years building transmissions for a living and specializing in perfprmance 4L60Es since 1993 and I've never seen a 3-4 piston break in half. Not even an aluminum one. On the other hand, I have seen many forward pistons crack.

Frank