4l80e moves forward in Neutral any help welcomed
09-20-2012, 02:35 PM
#1
4l80e moves forward in Neutral any help welcomed I got a 4l80e on trade and was told it was a new unit from a well known transmission builder with less than 100 miles on it. Well after getting the transmission in the car finally after doing a new turbo setup I took it out and it was slipping 3rd and 4th. I was told that the front pump seal was leaking and swapped it with the one that the owner provided in the trade. Well after no response or ownership from the original owner I took it to a shop around me that has built a few transmissions and I have never had a problem with them.
After I got the transmission up there I was told a few things that the front pump bushing had come out and the pump was trashed. I was also told that the 80e had a 10.25" intermediate shaft and it needed a 10-3/16's shaft and until he swapped that the end play would not come in and that was why. The old shaft was also rubbing on the end from being to long.
Well I got the transmission back and got it in the car. filled it and started the car. Ran it thru the gears on stands and noticed in Neutral the speedo got all the way up to 12MPH. I called the builder and asked about this and was reassured that this was normal. I put the car on the ground and took it out. Well the car still slips in 4th and if you put it in Neutral and give it gas the car moves forward in higher RPM's. I called the builder and he thinks it is in the valve-body as its a trans-brake unit. He assured that he put the check ***** in the proper place and built it to spec. .010" play in the front and .008" in the rear.
Now I am out a bunch of money and still can't drive my car. I am left with a few options.
1. return it to the original builder to get fixed for probably another 1000.
2. get a stock 4l80e and put a HD2 shift kit in it and enjoy the car
3. sell it all and go back to a th400
4. 5 gallons of gas and road flare
5. attempt it myself ( I am a helicopter mechanic so i am not incapable in mechanics)
What are your thoughts??????
After I got the transmission up there I was told a few things that the front pump bushing had come out and the pump was trashed. I was also told that the 80e had a 10.25" intermediate shaft and it needed a 10-3/16's shaft and until he swapped that the end play would not come in and that was why. The old shaft was also rubbing on the end from being to long.
Well I got the transmission back and got it in the car. filled it and started the car. Ran it thru the gears on stands and noticed in Neutral the speedo got all the way up to 12MPH. I called the builder and asked about this and was reassured that this was normal. I put the car on the ground and took it out. Well the car still slips in 4th and if you put it in Neutral and give it gas the car moves forward in higher RPM's. I called the builder and he thinks it is in the valve-body as its a trans-brake unit. He assured that he put the check ***** in the proper place and built it to spec. .010" play in the front and .008" in the rear.
Now I am out a bunch of money and still can't drive my car. I am left with a few options.
1. return it to the original builder to get fixed for probably another 1000.
2. get a stock 4l80e and put a HD2 shift kit in it and enjoy the car
3. sell it all and go back to a th400
4. 5 gallons of gas and road flare
5. attempt it myself ( I am a helicopter mechanic so i am not incapable in mechanics)
What are your thoughts??????
09-20-2012, 03:11 PM
#2
Movement forward in neutral with the car on the ground or on jackstands.
On jackstands, the movement would be normal, just residual drag from the fluid between the clutch plates, etc.
When you rev the engine, the residual fluid in the forward clutch pack between the apply piston and drum will be forced to the outside of the drum by centrifugal force. The fluid is exhausted in the center of the drum. If you rev it fast and hard enough you will partially apply the forward clutches and get a little movement.
If I know a customer is a "rev tuner" I will put a bleed in the forward drum to prevent issues.
The OD ciruit is pretty simple on a 4L80E. If you want to remove the valve body and send it to me, we'll check it out.
On jackstands, the movement would be normal, just residual drag from the fluid between the clutch plates, etc.
When you rev the engine, the residual fluid in the forward clutch pack between the apply piston and drum will be forced to the outside of the drum by centrifugal force. The fluid is exhausted in the center of the drum. If you rev it fast and hard enough you will partially apply the forward clutches and get a little movement.
If I know a customer is a "rev tuner" I will put a bleed in the forward drum to prevent issues.
The OD ciruit is pretty simple on a 4L80E. If you want to remove the valve body and send it to me, we'll check it out.
09-20-2012, 04:09 PM
#4
A pressure test would be a great help in diagnosis.
It depends on how much movement is happening in neutral... Is it on jackstands or the ground? How high/hard are you revving it?
09-20-2012, 04:20 PM
#5
On a 4L80E you could leave all the checkballs out and it would still function "OK". Very firm shifting and some issues with manual shifting timing, but it would work without slipping.
A pressure test would be a great help in diagnosis.
It depends on how much movement is happening in neutral... Is it on jackstands or the ground? How high/hard are you revving it?
A pressure test would be a great help in diagnosis.
It depends on how much movement is happening in neutral... Is it on jackstands or the ground? How high/hard are you revving it?
The slipping happens in 3rd gear also. It shifts into gear fine but then after in gear if you try to accelerate it just slips all the way to 5500+ and goes no where.
09-21-2012, 09:01 AM
#6
Ok update.
I can't get under the car to get a gauge on it but 1-3 work fine. 4th is what is slipping when I am commanding the gears in HP Tuners.
What will cause 4th gear to slip assuming the clutches are good?
Valvebody? checkballs in wrong spot?
I can't get under the car to get a gauge on it but 1-3 work fine. 4th is what is slipping when I am commanding the gears in HP Tuners.
What will cause 4th gear to slip assuming the clutches are good?
Valvebody? checkballs in wrong spot?
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09-22-2012, 01:44 AM
#10
Unfortunately it's impossible to diagnose these types of things without actually seeing the transmission.
We have to assume that other builders will do a proper rebuild, which would include looking for the root cause of a complaint or failure.
However we've seen this to not always or often be the case.
90% of the time when we send out a unit and there is an issue, either the customer or we find an issue with the tuning, wiring, install, etc. I recently had a customer have a 2nd band failure on a 200-4R. We dyno AND in car test these units and it was fine in the test car. Solid 2nd gear. I told the customer to check the fluid level and he discovered it was 3 qts low.
This last week we dyno'd approximately a dozen transmissions. Half of these were transbraked TH400's which are very simple hydraulically. No governor, modulator, or detent circuit to foul up, and typically no moving parts in the valve body.
One of our "tricks" to insure a quality product and repeatable pressures is that we use a new high quality boost valve in almost every unit we build. This adds $30 to the build cost but I do it to prevent issues and failures.
We have a TH400 using one of these valves that we discovered an issue with today after having it on the dyno a couple of times trying to find an issue.
We spend a CONSIDERABLE amount of time checking units on the dyno and making adjustments to nail a pressure we want for a given power level. It's really our biggest bottleneck to getting the transmissions shipped out.
It takes approx 12 hrs to build one of our 4L80E's from start to finish, but it may be on the dyno for 1 hr or 6 hrs, or in some cases we may have to pull it off the dyno to make adjustments or to move on to other units so we don't hold up everybody because of one unit.
We had another issue today with a 4L80E that we thought had no lube flow and after pulling it off the dyno and back on, we discovered the flowmeter was the actual problem.
We have to assume that other builders will do a proper rebuild, which would include looking for the root cause of a complaint or failure.
However we've seen this to not always or often be the case.
90% of the time when we send out a unit and there is an issue, either the customer or we find an issue with the tuning, wiring, install, etc. I recently had a customer have a 2nd band failure on a 200-4R. We dyno AND in car test these units and it was fine in the test car. Solid 2nd gear. I told the customer to check the fluid level and he discovered it was 3 qts low.
This last week we dyno'd approximately a dozen transmissions. Half of these were transbraked TH400's which are very simple hydraulically. No governor, modulator, or detent circuit to foul up, and typically no moving parts in the valve body.
One of our "tricks" to insure a quality product and repeatable pressures is that we use a new high quality boost valve in almost every unit we build. This adds $30 to the build cost but I do it to prevent issues and failures.
We have a TH400 using one of these valves that we discovered an issue with today after having it on the dyno a couple of times trying to find an issue.
We spend a CONSIDERABLE amount of time checking units on the dyno and making adjustments to nail a pressure we want for a given power level. It's really our biggest bottleneck to getting the transmissions shipped out.
It takes approx 12 hrs to build one of our 4L80E's from start to finish, but it may be on the dyno for 1 hr or 6 hrs, or in some cases we may have to pull it off the dyno to make adjustments or to move on to other units so we don't hold up everybody because of one unit.
We had another issue today with a 4L80E that we thought had no lube flow and after pulling it off the dyno and back on, we discovered the flowmeter was the actual problem.
09-22-2012, 01:59 PM
#12
I'll look at the VB no charge if you want to send it in. Maybe we can solve the problem without you pulling the transmission. However, if it slipped that hard in OD, the clutches are probably already cooked.
