TH400 issue

[AnaRamona]

Hi,

my transmission in my 1969 Riviera goes reverse and in first gear. 

It sometimes shifts to second if I step on the gas hard, and is often shifting  back to first when not necessary. There is no third. It's not missing fluid. Could anyone please make some suggestions of what it might be?

Thank you.

[1965rivgs]

2 hours ago, AnaRamona said:

Hi,

my transmission in my 1969 Riviera goes reverse and in first gear. 

It sometimes shifts to second if I step on the gas hard, and is often shifting  back to first when not necessary. There is no third. It's not missing fluid. Could anyone please make some suggestions of what it might be?

Thank you.

Modulator or its vacuum source

  Tom

[AnaRamona]

On 9/9/2017 at 1:11 PM, 1965rivgs said:

Modulator or its vacuum source

  Tom

Thanks Tom!

[Mr Riviera]

Check the line that goes down to the modulator  to see if it is plugged up as well  .

[AnaRamona]

On 9/9/2017 at 1:11 PM, 1965rivgs said:

Modulator or its vacuum source

  Tom

 

On 9/11/2017 at 3:50 AM, Mr Riviera said:

Check the line that goes down to the modulator  to see if it is plugged up as well  .

I have changed the vacuum modulator, and everything is plugged in. The liquid level is ok. Reverse works fine. When I put it in drive, it acts as if it's between gears, I have to step on the gas multiple times to get it going. I don't know what else to do.

[RivNut]

The vacuum modulator holds upshifts.  Sounds like it's time to visit your local transmission shop.  Just make sure the shop has someone old enough to have worked on TH400's 

[1965rivgs]

12 hours ago, AnaRamona said:

 

I have changed the vacuum modulator, and everything is plugged in. The liquid level is ok. Reverse works fine. When I put it in drive, it acts as if it's between gears, I have to step on the gas multiple times to get it going. I don't know what else to do.

Your symptoms now are different than your first post? Probably a good time to take the car to someone who is able to evaluate the symptoms like a trans shop. For what it`s worth, sounds like the pump,

  Tom

[KongaMan]

Concur with the pump possibly being at fault.  When my pump went out, it was like being in neutral until it eventually caught.  Right up until the point it failed completely.

[AnaRamona]

7 hours ago, 1965rivgs said:

Your symptoms now are different than your first post? Probably a good time to take the car to someone who is able to evaluate the symptoms like a trans shop. For what it`s worth, sounds like the pump,

  Tom

Yeah, it seems it's getting worse.

I'll order a new pump.

Finding a good mechanic that knows around american classics over here is no easy job.

Thank you for the reply

[AnaRamona]

I unscrewed the reverse oil line from oil cooler and I saw that the oil is coming out under pressure. That should mean that the pump is working?

 

[jsgun]

Yep, it'll still work. What happens is that the pump can still pump a volume of oil, but at a lower pressure. It's losing pressure because an internal seal most likely failed, and the pressurized oil is spraying out of those seal areas, instead of being directed out the pump and reaching the control valves. The way the pumps are designed, they never really fail completely, they'll keep pumping. It's the seals that give out. That's why it would engage when you floored it.... it was generating enough pressure at high RPM to switch the valves and engage bands.

 

For what it's worth, they're not that difficult to rebuild. My brother rebuilt his 64 Rambler's transmission (a Ford FMX of all things) in our driveway. You just have to be absolutely religious about keeping the internals clean, and making absolutely positive that you follow instructions. He laid his clutch packs out on a piece of plywood, and made sure to keep everything in order. I believe he did it in a half day, and that was taking his time.

[AnaRamona]

On 9/17/2017 at 6:47 PM, jsgun said:

Yep, it'll still work. What happens is that the pump can still pump a volume of oil, but at a lower pressure. It's losing pressure because an internal seal most likely failed, and the pressurized oil is spraying out of those seal areas, instead of being directed out the pump and reaching the control valves. The way the pumps are designed, they never really fail completely, they'll keep pumping. It's the seals that give out. That's why it would engage when you floored it.... it was generating enough pressure at high RPM to switch the valves and engage bands.

 

For what it's worth, they're not that difficult to rebuild. My brother rebuilt his 64 Rambler's transmission (a Ford FMX of all things) in our driveway. You just have to be absolutely religious about keeping the internals clean, and making absolutely positive that you follow instructions. He laid his clutch packs out on a piece of plywood, and made sure to keep everything in order. I believe he did it in a half day, and that was taking his time.

So, the guy installed all new traction plates, steel plates, direct clutch and clutch hub, because those were wasted as well. The transmission is back on the car. (the vacuum modulator was changed prior to the transmission rebuild) The filter and liquid is all new. Now, when I put it in drive, it starts going forward right away, when I put it in reverse, it goes reverse right away. But when I try going uphill, it seems as the gears slip, and the car starts going backwards. Is that a torque converter issue or what? My troubles are not ending yet.

[jsgun]

On ‎10‎/‎24‎/‎2017 at 7:17 AM, AnaRamona said:

So, the guy installed all new traction plates, steel plates, direct clutch and clutch hub, because those were wasted as well. The transmission is back on the car. (the vacuum modulator was changed prior to the transmission rebuild) The filter and liquid is all new. Now, when I put it in drive, it starts going forward right away, when I put it in reverse, it goes reverse right away. But when I try going uphill, it seems as the gears slip, and the car starts going backwards. Is that a torque converter issue or what? My troubles are not ending yet.

It sounds like the torque convertor. I'd confirm that the fluid level is ok. Going uphill effectively changes the fluid level because it some of it flows to the rear of the pan. Also, the transmission is now under heavy load, trying to push +4000lbs up a hill. 

 

If the torque convertor was drained, it has to be refilled, and it takes a lot of fluid. TH400's take about 6 quarts just in the convertor.

[AnaRamona]

4 hours ago, jsgun said:

It sounds like the torque convertor. I'd confirm that the fluid level is ok. Going uphill effectively changes the fluid level because it some of it flows to the rear of the pan. Also, the transmission is now under heavy load, trying to push +4000lbs up a hill. 

 

If the torque convertor was drained, it has to be refilled, and it takes a lot of fluid. TH400's take about 6 quarts just in the convertor.

Thanks for your reply.

The symptoms were just like before, at first it was somewhat going to first, but then gave up completely. We took the transmission off the car again. The fluid has gotten dark already and some plates were burnt. (just tested the car in front of my house) I have another torque converter, so I'll give it a try with that one, I'll put some new plates and fluid in and see what happens. 

[AnaRamona]

It seems that the valve body gasket was the issue, I put another torque converter from th350 in, looks the same and fits right. now it goes to first and second, but I can't get it to go into third.