I have a 5 friction direct drum with an aluminum piston and a 34 element sprag. Can this drum/piston be machined to accept 6 frictions? Can you give me the dimensions on the machine work? Dave
I think this article has what you're looking for. http://www.bdub.net/tranny/TH400SuperBeefing-text.pdf
Some of the information in that article is outdated. The information to turn a 5 pack to a 6 pack is good.
Don, I'm confused......I have the .485 dimension that the article shows for a 6 disc drum. The drum only had 5 frictions upon disassembly. I am quite sure that it came from GM that way. The donor unit is a virgin 1968 Buick big block application. Correct me if I'm wrong, I'll need to machine the piston apply surface down to allow space for the extra friction and steel. This is all for a spare trans for myself. The trans includes a T-brake and fixed line pressure in the neighborhood of 190-200psi. My HP level is somewhere around 750-800. Not a ProMod by any means, but I want the unit to be strong and reliable. So I'm also interested in builder's opinions: I have read through the 12 page post on T-400's and plan on utilizing many of the suggested improvements . Selection of frictions and steels: Regular Raybestos or BW frictions and plain steels for the Forward Clutch.....or do I need Alto Reds in the Forward? Alto Powerpack for the Intermediate (with HD snap ring) Does anybody offer a waved steel for the Intermediate Clutch? 6 Alto frictions, one wave plate and .077 plain steels for the Direct Clutch What do you recommend for the band? Center Support Seals: 4L80E solid rings Case Saver: Adapt-A Case 34761 or John Kilgore case saver Intermediate Sprag retainer/snap ring: Spot braze (TIG) the stock snap ring to the drum in about 5 places. I pushed the 4L80E spiral retainer off the drum in my primary transmission last year. It made a mess out of the center support and the direct drum. Mike (Blackplague) gave me the idea to TIG braze the stocker in place. It can always be cut loose in a lathe if needed. Thanks in Advance, Dave
Only Cadillac came with the 6 pack, IIRC. Even trucks used 5 packs. That is correct. You will need to machine down the aluminum piston. Use high energy frictions all around. Koline steels in the direct. Intermediate steels can be normal or Koline. I just use normal in the intermediate. Waved plates are available for the intermediate. I don't use them, though. A good used rear band. You will not be using an intermediate band with the TB. Teflon rings on the pump also. You only need to tig braze in two spots, 180 degrees from each other. Ring gap between the two spots.
If it was me, I would invest in a super sprag at that power level for extra security. Also billet intermediate shaft. CK makes them both and prices them well. Both case savers will get the job done. The Alto frictions wouldn't be my first choice since most are smooth. I have a set of grooved ones in mine now but havn't had a chance to inspect them. Stay away from blue plates also. Seems like people like the stock High energy frictons and probably come in waffle cut. Allan G.
If your hp level of 750-800 is rwhp, then I would agree with Alan. Get the super sprag. I'm really impressed with the high energy frictions. They are holding up extremely well for me. They are smooth. I don't believe they are available waffled. The direct steels will hard hot spot in a high hp application. That is why I recommend the Koline steels in the direct. The Kolines don't seem to hard hot spot as easily, since the Koline process does pre-harden the surfaces of the steel plates.
I don't remember what the th400 thread said about the converter feed restriction but it needs to be small. I have mine at .113 and it looks like it could be smaller based on my charge flow data. It looks like it won't be enough but it is. Allan G.
I've always used no larger than 7/64" (.106") on the TC feed orifice. I know you can get away with smaller. I simply have never had the case where I needed to go any smaller than 7/64". As long as you can maintain a cooler flow of 1 quart in 20 seconds, you're good.
Yes. I'm referring to the later high energy frictions, like what comes in the 4L80E. I certainly am NOT referring to the old waffle style frictions from decades ago (1960s or 70s) that were also greenish in color.
Besides, with a waffle plate, a lot of surface contact area is lost in the making of the waffled grooving. A LOT.
TH400 build Info mentioned above. http://www.turbobuick.com/forums/threads/th400-build-pictures.255286/ Some good Tips/Pics here. > http://www.crankshaftcoalition.com/wiki/T-400_rebuild_tech Kilgore build. > http://www.kilgoretrans.com/html/kilgore.html TH400 Code List > http://www.teufert.net/trans/t-400.htm A few Makes aren't in this list. Checker codes start with N. Cadillac = A. Jeep = K & J. Olds = O.
Converter feed restriction and cooler flow measurement are definitely in the plan. Is the "super sprag" a drop in? or does it need a new direct drum? This is a 4T80E part, correct? Where can I source it?
The super sprag setup includes a modified direct drum, the sprag assembly, and a new intermediate clutch pack w/pressure plate. Several high performance transmission shops now offer the super sprag setup. I get them from Mike's Transmission in Lancaster, CA. Mike's drum comes assembled with the snap ring tig brazed in place.
Chris from CK performance makes them now to accept standard 400 clutches and is a supporting vendor. Allan G
Dont know. Maybe he can chime in. I see a while back he released this new arrangement with a new outer race to use standard clutches. Allan G.
Frankly, I prefer to have the races of the sprag, inner and outer, as beefy as can be gotten away with. Much less chance of deflection with the thicker race.
