Brutal trans O.D. shift with Suncoast convertor

[SKari]

I am experiencing very hard O/D shifts with a newly installed Suncoast torque converter and valve body. Before I do anything drastic, is there anyone out there in TDR land experiencing the same problem? I have had numerous trans guys call it very hard lock up, but I am worried about internal trans part failure with such hard shifts (especially when pulling a 15K fifth wheel). I was thinking maybe it is a bad marriage with the cummins exhaust brake. Suncoast has suggested a switch back to a single disk converter.



06 4X4 Megacab with smarty SW #3, stock exhaust break (cummins), open exhaust, 285 tires. No other engine mods.

 

[cerberusiam]

Eithet that or adjust the line pressures downward. The OD shift on a built trans is a problem, and, yes it will destroy internal parts if they are not billet. It is possible to use a triple disk and get a good shift but the VB MUST be setup correctly. If you are towing heavy fix the VB, the triple disk will do you much better than a single.

 

[Allnew2Me]

I had the same issue with mine a while ago. I had the 48RE VB in my truck and it was almost perfect, except for the fact that it would not manually go into second gear unless under around 25 MPH. I sent it back and they sent me a new one that shifted great into second but about knocked my teeth out when going into OD. I talked to Ernie at length about it and he insisted that it was normal. I disagreed with him. I ended up sending the "new" VB back and they fixed the second gear problem with the first one and all has been well. Since then they have a fix for the hard OD shift so call and talk to Ernie about it. They were great about doing what they could to make it right. I never did find out if it was a pressure issue or a valving or clearance issue.

 

[SKari]

VB=valve body?

I talked with Ernie and he was most helpful. Said he would be glad to build a new VB, but did not think that would work and suggested a single disk (which I cringed at). Is there another system I should go with, especially if a new converter/trans is in order. If I were to spend the $ on all billet internal parts and still have a bad shift I wouldn't be ahead. Can't even soft pedal it when I am towing.

 

[SKari]

Suncoast converter

Sounds like I need to get a new VB

 

[MountainMan1]

I've had the same hard shift since day one of the install. When I was near Sun Coast I stopped in... they took a ride with me while towing. Result was no problem it is shifting normally. But if I wanted a softer shift they would make some spring adjustments. I opted not to do this.



I have the billet input shaft and their flex plate. The transmission was installed in Dec 2005 with 90,000 miles on my 2005. Today I have 417,000 miles and it still shifts the same as the day I installed it! However, I replace at least the very rear U-joint about every 100,000 miles. I think you guys have a 2 year warranty, mine is a 3 year warranty unlimited mileage. If I recall correctly it is warranted to 1000 HP and 1800 foot pounds of torque. I still have some 5 months and probably another 50,000 miles left on this old warranty.



I am extremely pleased with the Sun Coast.



So I say your transmission is performing as designed.



Peter

 

[cerberusiam]

So I say your transmission is performing as designed.

Maybe as designed but not correctly. The trans DOES NOT NEED a violent OD shift/lockup like this. You have pieces to support it and the OP doesn't. You are twisting the input and intermediate slightly every time it hammers in and eventually they will give up and you will be unhappy.

Good luck on getting it warrantied when it breaks, you will be told it "works as designed" and get to pay for new parts and a rebuild.



Bottom line is, a violent shift is not needed and can be changed. It is NOT a normal condition and does not need to be tolerated.

 

[MountainMan1]

Maybe as designed but not correctly. The trans DOES NOT NEED a violent OD shift/lockup like this. You have pieces to support it and the OP doesn't. You are twisting the input and intermediate slightly every time it hammers in and eventually they will give up and you will be unhappy.

Good luck on getting it warrantied when it breaks, you will be told it "works as designed" and get to pay for new parts and a rebuild.



Bottom line is, a violent shift is not needed and can be changed. It is NOT a normal condition and does not need to be tolerated.

Perhaps your violent is not the same as my violent... . and as I said it is adjustable as South Coast offered and I declined.

 

[SKari]

Someone alluded to a teeth jarring shift which is a pretty accurate description, especially when towing. Agree with you that if that kind of shift is "normal" and to be expected, the upgrade is not a good one. I don't have a billet input shaft, now I am worried and afraid to upgrade if the shift still remains unchanged. BTW, it recently threw a code suggesting the O/D solanoid was bad. My understanding is Suncoast uses OEM solanoids-maybe mine is bad.