6 bolt Torque converter for TH400 Tranny

[Herm]

TH400 Transmission got overheated along with the engine. The old tranny had a 6 bolt Torque Converter. The replacement came with a 3 bolt so the mechanic changed the flywheel. From What I've gleaned the 6 bolt is Heavy Duty to help keep tranny temps cooler. I think My Mechanic made a mistake.
Anyone got any advice on this?

[bkahler]

I agree, your mechanic made a mistake. The extra 3 bolts make a big difference in strength. Manufacturers don't add extra bolts for no reason. It's not just a cooling issue, it's a performance issue.

I'd seriously consider getting the correct 6 bolt torque converter and re-installing your original flywheel.

[cmadmaxman]

Brad is spot on. I installed a Hughes Performance XTM Heavy-Duty Towing.
6 bolt and very heavy duty. Also your transmission us a 475. Heavier duty planetary gears, straight cut, not helical like the 400, and more clutches and such. Yes it's a TH400 case.

[Herm]

Did my 1990 Land Yacht originally come with the 475 tranny or the 400? I thought it was the 400 and trusted the mechanic to know the difference and I didn't know where to find the ID, the little plate on the side which I thought was the ID tag was wiped out.

[bkahler]

Originally Posted by Herm

Did my 1990 Land Yacht originally come with the 475 tranny or the 400? I thought it was the 400 and trusted the mechanic to know the difference and I didn't know where to find the ID, the little plate on the side which I thought was the ID tag was wiped out.

Your coach has the 475. The 400 was used in pickups and similar lighter vehicles. As cmadmaxman described, the 475 is an improved version with straight cut gears for more strength. The 475 looks just like the 400, all of the differences are on the inside. Your mechanic should have looked at the application, noticed the 6 bolt mounting and purchased a torque converter accordingly. In my mind this mistake is all on the mechanic and he should make it right.

[Herm]

Yes, My Transmission was a 475. Had it rebuilt. Mechanic made a bad judgement call and didn't notify me. Swapped the 400 for my rebuilt 475 at no labor charge, only the cost difference of the transmission.



Problem now is not down shifting on the steeper inclines. Seems pretty smooth upshifting. I'm gonna check vacuum lines, TB sensor and connections. Mechanic siad my TBI runs rich. I thought that too when I pulled the plugs after the engine blow. Carbon coating.
Any suggestions for adjusting Richness?
Also, does anyone have experience with installing Temperature gauges for the transmission and engine? The original temperature gauge was replaced by the previous owner with one that inserts into the drivers side Head. I've seen reports of other places. The mechanic suggested the water pump but the sensor on the gauge appears too long.

[bkahler]

Originally Posted by Herm

Yes, My Transmission was a 475. Had it rebuilt. Mechanic made a bad judgement call and didn't notify me. Swapped the 400 for my rebuilt 475 at no labor charge, only the cost difference of the transmission.

I'm a little confused. You state your 475 was rebuilt and then you state that the mechanic swapped a 400 for the 475. Did your original 475 get rebuilt and then it failed again and he swapped in a 400?

Regardless of which it is the mechanic in my opinion really screwed you. I think he owes you a good rebuilt 475 to put back in your coach.

Problem now is not down shifting on the steeper inclines. Seems pretty smooth upshifting. I'm gonna check vacuum lines, TB sensor and connections. Mechanic siad my TBI runs rich. I thought that too when I pulled the plugs after the engine blow. Carbon coating.
Any suggestions for adjusting Richness?
Also, does anyone have experience with installing Temperature gauges for the transmission and engine? The original temperature gauge was replaced by the previous owner with one that inserts into the drivers side Head. I've seen reports of other places. The mechanic suggested the water pump but the sensor on the gauge appears too long.

I suppose there are several possibilities for the down shifting problem. I could be wrong but I think the 400 version used vacuum for shifting and the 475 used on these coaches had a throttle position cable for shifting. Like I said I could be wrong and it's been a long time since I've looked at either of those transmissions. Hopefully someone with more knowledge on the 400/475 transmissions will chime in and set me straight.

If your coach came with TBI then the coolant sensor should be in the front left of the intake manifold.

There are three locations I know of where you can install temperature probes for a gauge. The left head, the right head, and the intake manifold near where the large radiator hose connects. I've not see one in the water pump and I'm not sure that would be the best place for one.

On the transmission I added a gauge to mine although my transmission cooling setup is totally custom. You can see how I did it here..

Brad

[cmadmaxman]

The 400/475 uses an switch for the down shift. On my 82 the switch is at the gas pedal. Should be the same for your 90. Earlier years in different cars and trucks, the switch was located at the carburetor. Idea is at full throttle it would down shift and increase pressure to the clutches. I chose to down shift myself!
My transmission temperature sending unit is mounted in the aluminum fin deep pan. I also have one to turn on the fan for the secondary cooler, inline before it goes into the radiator. On at 180 and off at 160. I have a light to tell me when it triggers the relay for the fan.

[uraljohn]

Originally Posted by Herm

Did my 1990 Land Yacht originally come with the 475 tranny or the 400? I thought it was the 400 and trusted the mechanic to know the difference and I didn't know where to find the ID, the little plate on the side which I thought was the ID tag was wiped out.

Go directly to the shop that did the work and get all of your old parts back. Everything! Tranny, 6 bolt torque convertor, and flex plate. Find a reputable shop that knows the difference between a 400 and 475 THM. Have them rebuild and reinstall a correct 475 tranny with a correct flex plate and torque convertor. Get your money back from the first incompetent rebuilder.

Your old parts have to be returned to you if you request them. Hopefully the incompetent shop has them. The 400 will not live long in your application.

Good luck. Keep us posted.

[bkahler]

Originally Posted by cmadmaxman

The 400/475 uses an switch for the down shift. On my 82 the switch is at the gas pedal. Should be the same for your 90. Earlier years in different cars and trucks, the switch was located at the carburetor. Idea is at full throttle it would down shift and increase pressure to the clutches. I chose to down shift myself!
My transmission temperature sending unit is mounted in the aluminum fin deep pan. I also have one to turn on the fan for the secondary cooler, inline before it goes into the radiator. On at 180 and off at 160. I have a light to tell me when it triggers the relay for the fan.

Chris, thanks for clearing up the shifting arrangement.

[Herm]

The latest thing I noticed is it seems like the transmission is controlling the speed. When it is engaged in 3rd gear on a level road, slight incline and decline I can take my foot off the pedal and it maintains speed. If I put it in neutral the engine quiets right down instantly. The other thing that was happening almost seemed like a 4th gear, when after a high RPM sound/whine after shifting into 3rd it for a while it would finally settle down and quietly run. A friend said that is when the torque converter locks in.


it's been 2 days since the mechanic was asked to drains some Tranny fluid and test drive it. Still hasn't done that.


I also get a check engine light after driving for a while and then climbing a steep hill. Code #43, engine knock sensor/low or no voltage reading

[bkahler]

Originally Posted by Herm

The latest thing I noticed is it seems like the transmission is controlling the speed. When it is engaged in 3rd gear on a level road, slight incline and decline I can take my foot off the pedal and it maintains speed. If I put it in neutral the engine quiets right down instantly. The other thing that was happening almost seemed like a 4th gear, when after a high RPM sound/whine after shifting into 3rd it for a while it would finally settle down and quietly run. A friend said that is when the torque converter locks in.


it's been 2 days since the mechanic was asked to drains some Tranny fluid and test drive it. Still hasn't done that.


I also get a check engine light after driving for a while and then climbing a steep hill. Code #43, engine knock sensor/low or no voltage reading

I would be surprised if a 400 has a torque converter that can lock up. I think you have to get to a 4L60e, 4L80e, or possibly a 700R4 type to get a 4th gear lock up.