Torque Converter Question

[Don Schmidt]

Was reading a post a while back that said if your T/C was working good your RPM's would only drop about 150 when the T/C locked up. When my truck locks up the RPM's drop by 400. I have been thinking about getting the 230/605 TST plate but I don't know if my ole transmission is up for it. Anyone have any suggestions???

------------------
1994 4X4 2500 Auto.
1998 Harley FXDS
1998 Harley Sportster 1200

 

[Strick-9]

Your torque convertor is operating normally. If you increase the power of your engine, the rpm drop going into lockup will be more. The next generation of torque convertors that DTT sells, and a few other companies are just coming out with, have much better fluid coupling, and the rpm drop is less.

I just had to rebuild my transmission because I thought I could add some engine power before I upgraded my transmission. Since you have a '94 like I do, my suggestion to you is to get your transmission pressure checked by a good transmission shop to find out what kind of condition it is in. Then add a valve body or some sort of shift kit to increase the internal pressures.

-Chris

'94 2500 4x4 auto DTT TC/VB Diamond B 370's custom fuel plate, hi-flo delivery valves, AFC spring kit, governor springs, 4" exhaust

 

[John_P]

Don:

I just went through the same thing
as "Strick-9. " I had a "TransGo"
Shift Kit put in my truck along with
a TST #6 Plate at about 22,000 miles.
That "stock" transmission lasted until
98,000 miles! As he said, the pressure
checks are important. If you have alot
of miles and the pressures aren't "good"
I recommend doing a "complete" rebuild.

Don't do what I did. I had the new TC
and VB installed and about 10,000 miles
later, the seals and front clutch packs
went bad and the transmission began
"revving" up during the 2nd to 3rd gear
shift! So... ... the transmission had to
come back out! My fault, I should have
done it "all at once!"

---------------
John_P

------------------
Red '96 4x4 2500 Auto 3. 54, TST #5, Major Pump Mods(By "Scheid Diesel") 370 Diamond B Injectors, Gov. Spring kit, AFC Spring kit, Banks Exhaust, Prime Loc, Cummins Chrome Kit,Psychotty Air Filter, Pro-Torque Converter, BD Valve Body, BD Pressure Loc, Isspro Gauges, Sendel 16" Alum Wheels w/ 33" BFGs

 

[Bill Kondolay]

Don,

Chris and John are giving you good advice
Do not install a vb or tc on a high mileage truck. Sometimes adding vb's or shift kits can actually actually shorten whats left of the life on the trans if it has high mileage or is being used for heavy use.

On the average if you are doing a tc it takes an additional 3-5 hours to do the basic seal change on the front half on the transmission.

It is our policy to not sell vb's or tc's to guys with high mileage unless the transmission has been checked for internal leaks and wear on clutch pacs.

For emample, if you have a high mileage vehicle that is slipping in gear, it is good practice to simply have your transmission rebuilt rather than waiting until you have added the components and then have the trans fail, because when the transmission does fail, it will contaminate the new vb and tc, forcing you to start all over again.

Bill
Diesel Transmission Technology

 

[Don Schmidt]

Sounds like I should wait a few more miles. The truck has about 92,000 miles on it and the transmission has not given me any trouble at all,(knock on wood)!! What is involved in getting the pressure checked and what pressure would be acceptable to go ahead with a new T/C and a shift kit without doing a complete rebuild??

------------------
1994 4X4 2500 Auto.
1998 Harley FXDS
1998 Harley Sportster 1200

 

[Joseph Donnelly]

The 230 hp TST kit is designed to work OK with the stock transmission. It may speed its demise if it is in trouble already and/or you use the extra torque a lot. The torque converer has slip to allow the engine to run up to its horsepower range more easily so it can pull better. As you increase power, you want less slip to use the new power at lower rpm.

Here is another test for efficiency that will eliminate the variable of lockup efficiency (dynamic coefficient of friction): try a 1-2 and a 2-3 shift with the converter locked up vs. unlocked at full power. This will tell you how efficient the entire fluid coupling system is, vs. the mechanical lockup system, which should be 100% if line pressure is adequate and the clutch is in good shape and of adequate size.