I see your point Chris. With the orifice size I've been using, that problem has not come up. The area of the holes in the input shaft responsible for allowing fluid to exit the T/C are pretty large when compared to the feed orifice of 7/64". The more important thing to consider would be that the internal components in the torque converter don't present any flow restriction to any of the exit holes in the input shaft. Of course, grooving the front stator support bushing would be good insurance, but would still not make up for any blockage to flow by the internal components of the T/C.
TH400 build-pictures
- Thread starter 87buickracer
- Start date
I see your point Chris. With the orifice size I've been using, that problem has not come up. The area of the holes in the input shaft responsible for allowing fluid to exit the T/C are pretty large when compared to the feed orifice of 7/64". The more important thing to consider would be that the internal components in the torque converter don't present any flow restriction to any of the exit holes in the input shaft. Of course, grooving the front stator support bushing would be good insurance, but would still not make up for any blockage to flow by the internal components of the T/C.
No Don it was not.
lazaris. Between these tests, did you lower line pressure? Or was the orifice size the only change?
The more line pressure you demand from the transmission pump, the more hp you eat up. The more hp lost in the drivetrain, the lower the mph. Hmmm. I think I'm going to go back to my transmission and lower the line pressure a little.
:tongue:Only run enough line pressure to keep friction elements reasonably long lasting. Anything more is wasting horsepower. The needed line pressure will be significant to the application.
I have to tell you about a phone call I got last week at the shop. This fellow had just had a crank thrust failure with his newly built 383 SBC. He's using a 400. Recently built also, if I remember correctly. He was wise enough to check his cooler line pressure before driving around. He noted 80 psi at high load. He called his tranny guy who told him, don't worry, go ahead and drive it. Guess what happened. The crank thrust soon failed. This person was searching the internet high and low looking for an answer to his situation. When he came across the threads here, he had the sense to realize, like a hammer knocking him in the head, that this was the answer. He called me to gather information to help him talk his tranny guy into doing the mod, even after printing out the thread he found on this site and presenting it to him.
I really couldn't add anything to what was already addressed in the thread except some names to go along with an example I had given and the conviction in my voice. He was saddened that he couldn't convince this fellow to do the mod. I've heard the same story over and over. A tranny builder that was hesitant to restrict converter feed. The claims against it are torque converter cavitation, low lube flow, overheating, not the way the factory meant it to be. I finally had to convince the fellow to tell him to do the mod no matter how the builder felt about it. I just hope the trans builder doesn't think he knows better and tells the poor guy he did the mod, but, actually didn't.
I really couldn't add anything to what was already addressed in the thread except some names to go along with an example I had given and the conviction in my voice. He was saddened that he couldn't convince this fellow to do the mod. I've heard the same story over and over. A tranny builder that was hesitant to restrict converter feed. The claims against it are torque converter cavitation, low lube flow, overheating, not the way the factory meant it to be. I finally had to convince the fellow to tell him to do the mod no matter how the builder felt about it. I just hope the trans builder doesn't think he knows better and tells the poor guy he did the mod, but, actually didn't.
DonWG wrote:
The more line pressure you demand from the transmission pump, the more hp you eat up. The more hp lost in the drivetrain, the lower the mph. Hmmm. I think I'm going to go back to my transmission and lower the line pressure a little.
I've wondered about taking a 400 or 350 and removing most of the return springs in the intermediate & direct clutches, then using a weaker PR spring. This would reduce pump power loss; BUT, ONLY on straight 1/4 mile racing. The fewer return springs would lead to horrid overlap on the street during manual shifting (to say nothing of a killer reverse engagement), so no one try this there!
:biggrin:
Yes, converter ballooning goes down with lower pressure, as long as you have enough flow to prevent cavitation or lube starvation to the rest of the trans.
lazaris. Between these tests, did you lower line pressure? Or was the orifice size the only change?
The more line pressure you demand from the transmission pump, the more hp you eat up. The more hp lost in the drivetrain, the lower the mph. Hmmm. I think I'm going to go back to my transmission and lower the line pressure a little.
Only run enough line pressure to keep friction elements reasonably long lasting. Anything more is wasting horsepower. The needed line pressure will be significant to the application.
On that test the only change was the orifice size.
So you went from what orifice size and cooler line pressure... to what orifice size and cooler line pressure, and had a 1% increase in T/C efficiency?
What was the line pressure you were using with these tests?
3/32" to 9/64" 165psi main line for both.
Did you note what the cooler line pressures were with each of those sizes?
Any more T400 build pics ???
i agree
87buickracer
Member
- Joined
- Dec 2, 2004
I completed this mod and went with the .016 shim.
87buickracer
Member
- Joined
- Dec 2, 2004
th400 build
Chris I will be calling for one of those snap ring stabilizers and want to check availability of your 2004r manuals.I also changed wave plate for steel plate in intermediate power pack and will turn snap ring 180 degrees after getting stabilizer.I plan on running the transgo shift kit 400-1-2.If anyone know of a better shift kit,feel free to chime in.Thanks..
p.s-who has the best deal on deep pans with pick/up tube?
Chris I will be calling for one of those snap ring stabilizers and want to check availability of your 2004r manuals.I also changed wave plate for steel plate in intermediate power pack and will turn snap ring 180 degrees after getting stabilizer.I plan on running the transgo shift kit 400-1-2.If anyone know of a better shift kit,feel free to chime in.Thanks..
p.s-who has the best deal on deep pans with pick/up tube?
turbobitt
Well-Known Member
- Joined
- Feb 14, 2002
Trans-go just released a 400-pro kit you may want to check into.
General Motors Reprogramming Kits
I would buy at,
3L80 & 400 Valve body kits: Bulkpart transmission parts
General Motors Reprogramming Kits
I would buy at,
3L80 & 400 Valve body kits: Bulkpart transmission parts
turbobitt
Well-Known Member
- Joined
- Feb 14, 2002
Another cool little item . Will require a hardened yoke.
Attachments
That is a neat tailshaft.As for the shift kit there is no doubt the transgo kit will work for you.We sell a full bolt in valve body that has similar function as the tgo kit but has added features.It saves you the trouble of installing the kit in your original valve body for about the same price as the kit.It is a true manual automatic valve body.I would like to see the added mods the have for the pro kit.
blackplague
Are you watching Phil?
- Joined
- May 25, 2001
You'll laugh chris.
The only thing different from the -2 kit to the pro kit is the addition of the 200-4r low/rev cup seals at the center support area of the 400. It's no big revelation!!!:biggrin:
The only thing different from the -2 kit to the pro kit is the addition of the 200-4r low/rev cup seals at the center support area of the 400. It's no big revelation!!!:biggrin: