Torque Converter woes

[Dogface]

I have a 95 dually which has had Banks and injectors added. Current HP is about 325. Auto trans was rebuilt (seal failure) 18 mos ago. TC was made by Precision Industries in Oakland Tn and Transgo shift kit. I do have stock transmission cooler. The TC failed in early Sept after only 15K miles or so. I do tow a fiver... about 11K but stay aware of boost and transmission temp. TC rebuilt just three weeks ago and failed on the test drive with no trailer !! New TC was put in last week... PDQ out of Sac and said to be very heavy duty. It lasted three days. transmission did heat up towing slowly this time to about 200 but towed well on the hwy. Failed the next day just driving to town w/o trailer, etc. . All failures show up as coming out of lock up in third and/or OD. Clutch material all over the pan and filter.



My transmission shop, I think, is stumpped. Is there something we're missing about why these things fail so quickly? What are the possibilties. All this is being done on warranty from the shop... very stand up guys (Monroe's in Newcastle Ca) Do I need now to spring for a BD and valve body? Need despartely to know what to do next.



Thanks for input...

 

[Strick-9]

I don't have a transmission shop, but maybe I can help a little.



Your shop seems to really stand behind their work as they keep trying to help you and haven't given up.



The fact that they are throwing a variety of different TC's at the problem leads me to believe they don't have much experience with high performance diesels.



First have them install a pressure gauge and monitor line pressure.



What pressures are you seeing while in lockup?

To give you a reference point, with my truck at 350 hp, I had my valvebody setup for 130-140 psi while in 4th or lockup.



I've also had an OD piston seal fail and lose pressure which caused a loss of TC lockup. Again, a pressure gauge would show this.



If you are finding clutch material in the pan then it's obvious you are slipping your TC clutch. Can you not feel it slipping or see it on your tach?



No TC on the market will live behind a 320+ HP cummins if the driver doesn't understand the limitations and drive accordingly.



What do you mean when you say you stay aware of boost? When the truck goes into lock up don't exceed 1 psi of boost for every hundred RPM. And don't pull below 1900 RPM.



Another trick is to install a TC UNlock switch and don't allow the TC to lockup until you are at cruising speeds. Then allow the TC to lockup to cool the transmission fluid and maintain speed. The TC clutch was designed to reduce cruising engine RPM for economy reasons. It wasn't designed to accelerate with. You can read this on most any service book about the transmission and it's design or repair.



You could install a hobbs pressure switch to automatically unlock your TC at 20 psi of boost.



-Chris

 

[Joe G.]

Dogface,



I see in your signature that you have a BD Torquelock. Those things are TCC killers!!! The first thing you want to do is throw that thing away. Then get hold of Bill K. at http://www.dieseltrans.com/DTTech/index.sht and get the right stuff to handle your engine power. It appears that what is happening is that your TCC is locked and you have enuff torque to just tear the thing out. Search the archives on this site for some of Bill's remarks concerning BD products and business practices. With that kind of power and towing you need the best and that's DTT. Anything else is a waste of money.

 

[Bill Kondolay]

Dogface,



I realize that there are a lot of companies who advertise that their companies can handle 500+ hp, i read their adds too, i must admit they are very impressive. So do their converters that are lined up on my shop floor, most of the did not survive 300 hp.



As Joe G. says, take the torque loc and throw it in the garbage where it belongs.



This is a double edged sword for me, as i make a good living from guys running the torque loc, 20% of my business comes from guys running the torque loc or mystery switches(loc up switches)without understanding the concquences of these type of devices.



The best way i can explain the torque loc to you is this,



If you owned a 5 speed transmission for example, and as soon as you hit 30 mph you shifted into gear and left it there, no matter what the driving conditions. It doesnt matter whether you are driving uphill, towing, you leave it in 5th. What would happen to the clutch in your 5 speed?



Gear selection is important not only for standard guys it is also critical for the automatics. Dont be afraid to lock it out of od,



Having said all this, i dont think this is your only problem this time going by what you are saying.



Have the transmission shop check your input shaft for nics, cuts,

there is a seal inside the tc than can be damaged if there is any kind of rough surface on your input shaft.



Also have them check the pump assembly, the pump bushing , the stator bushing, also the vb could have a problem.



There is one part in the vb that has been known to cause repeated tc failure, unfortunately i cannot list it on a public forum, if you wish , have your transmission call me and i will give him a hand if he wishes.



PLEASE throw that torque loc in the garbage you are not only hurting your truck but the transmission shop's business also.

If they had any idea of what that torque loc's function was they would understand whats going on .

 

[Dogface]

Thanks for the input. When I say that "I stay aware of the boost" what I mean is that I try not to over torque things. It was my understanding that the boost gauge will give you some reference to amout of torque your applying with the peddle... . probably wrong about that but that's how I was told to drive it. I have not changed my driving habits or practices yet the frist TC lasted 15K miles and the next two lasted only a few days. I do have the BD torque lock but really never use it. I leave it generally in the off position (all the way down) and only occasionally use it when going down steep grades to provide some engine braking and only when I tow. That's what I was told it was for...



I spent two hours last nite cruising the archives of this forum and read a lot praise about DTT so I may call them today and see what they have to say.



Mark... aka Dogface