Ok. My turbo 400 (orig 70) has failed twice now for the same reason. It was rebuilt by JW in like 1995 or 1996, leaked so bad I had to have it rebuilt by a local reputable tranny shop in I think 1998 or 1999, in the summer of 2002 it got a bunch of metal in the filter, lost line pressure to the clutches, and fried the tranny. I had it rebuilt while the car was getting its cam swap. Toward the end of the summer, right before I was putting the car away because I was moving, I took it out for a ride. Safe to say it is toast again. Metal flakes in the pan and filter, clutch material, exactly the same as before, but fluid looks OK.
I think I might have a lemon TH400 that just can't deal with higher HP. it does fine just driving.. or with gradual throttle application.
But if you just lift you foot up and wail the gas, the trans just slips straight to the rev limiter. I had incorrectly-- for number of months-- blamed this phenomena on a tranny governor that could not handle the higher hp/higher RPM shifts I had recalibrated the governor for when using it at the track, so I ran around with the kickdown disconnecting thinking my modded governor confused the kickdown too much because it was dealing with kickdowns that would bring the enging back up to 6700+rpm in an extremely short period of time, I figured it was just too much.
So, I disconnect the blades on the kickdown. Now usually (99% of the time) I don't just lift the throttle and pound on it, one, it draws attention, 2, I don't need the attention, and 3) the tires usually blow into smoke.
But, I figured, heck, its the last day out, so I am doing about 55 and just lift my foot up and *mash* the gas..
bzzzzzzzz right to the 6800 chip on the MSD box.
Just like I thought was "wrong" with the kickdown because of the modded governor.
Well, I pulled the pan, and my prelim inspection says its fried, but I probably couldn't tell a good trans from a bad one, but the filter seemed clogged and there seemed to be crud in the pan.
I have spent $500 (rebuild 1995?), $550 rebuild 1999(?) and $550 rebuild whatever it was last winter or summer or two ago..
I am starting to think this trans has some sort of internal tolerance issue that is frying parts. It might also explain why I have consistently over the years run a bit slower than I should, given all the cams and converters I've tried.
Anyway.
I talked to my cam guy about seeing who he could talk to about getting me a trans.
I wanted to fish the question out to you guys. All those jegs/b&m/tci whatever TH400's in the catalogs only say they are good for 400hp, I am pushing 565hp w/ alternator, water pump and my entire exhaust on the car, so peg it somewhere at like 580.. or whatever.. Its more than 400.
I am looking for a TH400 for a reasonable price that can take 7000rpm 650ft-lbs/650tq (incase I ever do some mods) and do it for a good long while.
I also need the trans to use the same driveshaft as mine and accept the gear vendors unit that replaces the little tail housing at the end of the trans (not sure if this matters). My current trans is the orig 1970 TH400 out of an LS5 (canadian built, not sure if that matters).

I just wanted to field this out.. I can't work on the car right now for a number of reasons, but I am ready to research and maybe buy just so I have it a transmission.
I already have a new dynamic converter in the car that only got one run at the strip where I encountered transmission problems and had to leave early.
So.. seeing as I already have a (actually more than one, I still have my other 9.5" converter sitting around), who should I go to or talk to about a new/rebuilt/whatever you would call it TH400?

Sorry for the bible here folks.

I have been very busy, been away, and am frustrated with this transmission.

I want to get this resolved.

also, i wanted to toss this out:
the guys at gear vendors claim their unit costs like 1hp per 100 when its being used, but whatever, 5hp, I am not going to bend over backwards for, I gained 5hp with a spacer I just don't run it because I'd have to buy a new air filter. Should I ditch the gear vendors, ditch the 3.90s, put my old 3.31s back in, or perhaps 3.42s?
I will be upgrading hopefully next summer my 26" ET Streets to 28" ET Streets, so I am a bit worried about trap rpm, but as long as it is near 6000, I am ok, my motor builds until 6200, then is flat to 6500, and then dies off quick past that.
Or since i already have it, just keep it and keep going? I'd have to buy a new driveshaft in that case, which wouldn't thrill me..

again..
if you read this, thanks..

Matt

Trans Specialty's charges $350 for a freshen up.

Thats part of the problem though..I have had new clutches, sprags, governors, sleals, whatever, the whole works, done in the trans numerous times, and it keeps dying for the same reason.
I think the trans is a lemon for higher HP. At this point I think it should be replaced, plus, I can keep my # matching TH400 in a safe spot in my locked garage..

Matt

Why not call Dynamic?

i would check with someone on this bullitin board. www.quikstreet.com (http://www.quikstreet.com) mike

Originally posted by mr 4 speed:
Why not call Dynamic? graemlins/clonk.gif I didn't even think of that.
I don't want to go full manual valve body, so I want to say away from the "hardcore" racer tranny guys. Maybe dynamic can put something more normal together for me.

Thanks...

matt

Mad Marv, it sounds like we have the same problem,I punish a th350 for over 4 years and it does a fine job,worked great when I took it out last november,swapped in a th400 and cooked the clutches in 2nd and 3rd gear, gettin ready to load up and race yesterday,check oil and trans fluid,trans fluid smells burnt but made it thru race day yesterday,gonna change the fluid today,hope it can make at least one more points race, I'm going back to a TH350...heck with it.

I am likely going to have Steve, the guy who builds Racer1320's transmission do mine as I sit here with 2 broken TH400's :( :( :(

Matt,Dynamic will build you anything you want.

my family and i self own a tranny shop. the th400 is a very good tranny, i wonder if the guy's who have built the tranny know what there doing.most th400 only need slight mods to be very tough!

i've built alot of racing th400 for customers and friends and our own race cars, we had a 66 chevelle that weighed 3000 lbs with driver that ran 9.40's with a stock th400 except for the transbrake and 5500 stall!

there alot of little mods that can be done,but th400 doesnt need alot of money spent on it other than transbrakes and converters!

thanks! chris

Good points Chris - you guys - what are you DOING with those things? You aren't starting burnouts in 1st gear or coming out of the burnout box under power are you? Is your linkage set up perfectly? What exactly are you breaking??

I am making well over 1000 rwhp and I often pedal my car three of four times hammering it with nitrous.

I have almost all stock parts - the only upgrades PERIOD are the better sprague and a transbrake - we put a couple of extra clutches in the direct drum, and mine live.

Don't waste money on a whiz-bang tranny out of a magazine - I know someone here who spend several thousand on a "special" mail order shop for an "ultimate 400" and it broke - took it apart and found out they were missing some parts and assembled it carelessly.

My buddy disected this whizzy 2000hp capable monster 400 that was behind all of 900hp and found out that there were not as many "tricks" as he thought - he can easily replicate it - most of the cost are the vasco-jet or 300M hard parts which we haven't needed yet. We are going to test one of ours in 2005 with as much as 1600hp so we will find the weak link.

Find someone local who can build a tranny and follow instructions and you will have zero problems. I have a buddy who builds them for all of us in his garage and other than the odd burnt clutch from being on the transbrake WAY too long, nobody has hurt one. Not a single broken hard part, and there are 5 of them between us that see more than 1000HP regularly. He assembles them on about 3 feet x 2 feet of counter space with hand tools and they seem to live. :D

I'm no tranny expert - but I bet if you went with a manual valvebody a lot of your problems would go away. If you are burning clutches you either have not enough line pressure or a leak somewhere - go manual and have full line pressure. I don't know why people are afraid of rowing their own gears - on the street you can drive around in 2nd gear most of the time anyways. If you can street drive a 9.5" converter you can put up with a manual valvebody! LOL

I agree totally. There are few parts needed to be changed in them. I will make sure to use the 34 element sprag and drum setup, along with a Torrington bearing for the rear thrust. The bearing is the same as the one from the drum in a TH350, and then you just add shims to set the rear endplay before installing the center support for good. Use Teflon rings on the pump and center support to avoid wear. If using a transbrake install heavier springs in the direct clutch as well as a 3/32 bleed hole in the direct drum under the piston, and pay close attention to the condition of the reaction carrier surface and band. You need to often work over the rear servo apply pin to correct the band clearance if you replace the OEM band. I am not a fan of the aluminum manual valve bodies like the old B&Ms as they flex too much to retain a good seal at the valve body to case mating surface. Use 180 in lbs of torque on the 5/16 valve body bolts and 108 in lbs on the 1/4 ones to help seal things up. The motor home cases were beefier too. If you want to have longer trans life and do not mind spending a bit then look to the aluminum drums as they save a lot of wear with less weight to stop and start. A steel hub is not a bad idea either, and you can rob some parts from the later 4L trannies that drop right into the 400.

First Trans was a Hughes bought right from Summit - lasted 3 1/2 seasons. Intermediate sprag is what I believe went bad. RPM's went to the rev limiter when I hit second gear, trans still worked with normal driving, but at WOT and hit 2nd gear it would just completely "slip".

Second Trans, ATI, 10 weeks old and 45 or so passes, chattered and bound up when in first gear and eventually lost first gear completely on my ride home.

66 283 - please describe your burnout procedure when you get the chance.

Tom,

I am just plain abusive to my TH400 - I leave wide open with more than 400hp on the fogger as soon as I let go of the button. I actually gave my TH400 to a friend who was having trouble with C6's behind a 600 inch 14-71 blown intercooled street car - he was in a pinch so he cut my bellhousing off and put an ultrabel on it. It survived his combination - he makes over 950ftlbs at 2800 RPM and it just goes up from there. His horsepower and torque both peak above 1100. He needs to find me a core so that we can replace mine this winter.

I don't have much of a burnout procedure - I start in third, half throttle, ease off the throttle as it comes out.

I have been told by my tranny-buddy to never start a burnout in 1st - start in 2nd and as soon as they start spinning put it in third. He said the sprague will fail if you do 1-2 shift in the burnout box - not sure about that - I do 1-2-3 shifts spinning/smoking on the street all the time.

How have you been doing it?

Call Carl Rossler he builds the best turbo 400 anywhere and stands behind it 100%%%%%
330-530-5000 sean

With the Hughes I was starting in first and it would go to third pretty quickly..it lasted 3 1/2 years.

With the ATI I was starting in first and going to third rather quickly...I would try and let out before it grabbed out of the box, but many times it would grab before I let off.

Never shipped a trans before...Any recommendations ???

Sudden traction while still in second gear will generally break the sprague in any Turbo 350 or 400. Go 1-2-3 to get the wheel speed up then get your foot OFF the gas and come out of the burnout box. Coming out of the burnout in second gear and your foot in the throttle is the fastest way to kill your Turbo 350 or 400. My son's broken three of them. He's much more careful about the burnout now.

I would say that the burnouts are killing it - start in second and let off early coming out. And triple check that the linkage is perfectly lined up with the gears - that will kill clutches if the valve isn't quite in position.

if you need any tips you can call at my tranny shop and i'll try to help you out?i've built a ton of these th400 and th350 and powerglide tranny's for drag racing.if your not making 800-900 horsrpower, you dont need alot of trick parts for a th400 other than a good shift kit or brake and good converter and a few other small mods!!

you can call me at 559-733-2434 pacific time. this is oue tranny shop # and ask for chris!


i hope i help you out! chris

Never shipped a trans before...Any recommendations ???

Call BAX Global they have good rates use them all the time. Sean

Hello Merv I would be glad to build you a THM 400 just let me know.Email me for details and phone number.