Transmission trouble

[mikajo39]

So I've got a Th 400 tci streetfighter tranny and it leaks and the 1-2 shift slips, its pretty much new but It's past its return date. If I punch it the 1-2 shift is real solid and is a real tire chirper, its also ok at real light throttle but at part throttle it'll slip real bad. Anything I can do? I just got it and I'd really hate to throw away money through a bad product.

[chaosdsr]

Have you tried to call up the guys at TCI and see what they can do for you? I have delt with them many times in the past and they were pretty easy to do buisness with. If not where is the trans leaking from and how bad? 400 is a pretty simple trans I can probably help you through it if you want to fix it yourself.

[Longhorn Man]

does it have a high stall converter?

[highperf4x4]

I wish I had some definite advice for ya dude because I know that would suck to have problems with a new tranny. I have a rebuilt th400 that also has a soft 1-2 shift but a really firm 2-3 shift so I'm assuming it's in the bands. Longhorn might have a point with the stall but it would probably do it worse under light throttle. Where is the leak coming from? The pan gasket, cooling lines or a seal?

Have you checked the vacum modulator? I believe you can adjust it to firm up the shifts but I don't know about a tci tranny

[mikajo39]

Originally Posted by Longhorn Man

does it have a high stall converter?

Its not a very high stall just 1000 rpm above stock. But I hear that the stall speed has to do with your rear gear and load and the lower the gear (3.08s) the higher it will stall due to load. so maybe like a 2500rpm stall speed?

[mikajo39]

Originally Posted by chaosdsr

Have you tried to call up the guys at TCI and see what they can do for you? I have delt with them many times in the past and they were pretty easy to do buisness with. If not where is the trans leaking from and how bad? 400 is a pretty simple trans I can probably help you through it if you want to fix it yourself.

Thanks I'd appreciate your help, the truck doesn't get driven as much as i'd like , maybe once a week? So when I drive it I don't want it to be a weird shifting, leaking hunk of junk. It used to be pretty bad but I retightened the pan bolts and that stopped that, but it seems the gasket between the transmission and extension housing is saturated and leaks slowly, and my vacuum modulator also has a slow leak, its like they forgot to tighten things up? Its about time for its first filter change after 500 miles like TCI says. I have tried calling them but they're always closed weekends and I'm busy during the week, I'll try monday.

[mikajo39]

Originally Posted by highperf4x4

I wish I had some definite advice for ya dude because I know that would suck to have problems with a new tranny. I have a rebuilt th400 that also has a soft 1-2 shift but a really firm 2-3 shift so I'm assuming it's in the bands. Longhorn might have a point with the stall but it would probably do it worse under light throttle. Where is the leak coming from? The pan gasket, cooling lines or a seal?

Have you checked the vacum modulator? I believe you can adjust it to firm up the shifts but I don't know about a tci tranny

Thing is it shifts like a champ when it doesn't slip, when everything is cherry its "1-BAM-2 2-BAM-3" its the Streetfighter th400 with new valvebodies and all, so when its working right it shifts real nice.

[highperf4x4]

Originally Posted by mikajo39

Its not a very high stall just 1000 rpm above stock. But I hear that the stall speed has to do with your rear gear and load and the lower the gear (3.08s) the higher it will stall due to load. so maybe like a 2500rpm stall speed?

That is all out of whack!

Ok, 1000 above stock? What are you calling stock stall? Mine is pushing the truck at 800 rpm.

Stall is not weight dependent. It's rpm and that's it.

3.08 is not a low gear. It's a high gear or "tall" gear. If that's your gear and this is a daily driver then you don't want a stall.

If your torque converter really is 2500rpm stall then you're never going to get a firm part throttle shift. ESPECIALLY not with a 3.08 gear. Additionally, you're going to burn the bands up letting it shift that way. You better go ahead and put the throttle to it for shifts until you do something different.

[mikajo39]

Originally Posted by highperf4x4

That is all out of whack!

Ok, 1000 above stock? What are you calling stock stall? Mine is pushing the truck at 800 rpm.

Stall is not weight dependent. It's rpm and that's it.

3.08 is not a low gear. It's a high gear or "tall" gear. If that's your gear and this is a daily driver then you don't want a stall.

If your torque converter really is 2500rpm stall then you're never going to get a firm part throttle shift. ESPECIALLY not with a 3.08 gear. Additionally, you're going to burn the bands up letting it shift that way. You better go ahead and put the throttle to it for shifts until you do something different.

haha sorry My brain isn't quite on yet. My stock converter would push me along at about 950 rpm or so. and by low gear I just meant numerically not actually like 4.11's which some people would call a high gear. But it's not a soft shift it just feels like its slipping, and sometimes its a pretty bad slip.
Maybe I should wake up next time before typing on the forum

[highperf4x4]

Actually I'm looking at your sig dude and it says 2000rpm stall with a 3.08 gear. That isn't going to work. If you truly have a 3.08 gear and this is used for anything other than racing then you need to get that stall out of there or you're going to burn it up.

[highperf4x4]

Originally Posted by mikajo39

haha sorry My brain isn't quite on yet.

sounds like mornings around here too!

[mikajo39]

Maybe its time to swap out those 3.08s for some 3.73s hmmm

[highperf4x4]

Originally Posted by mikajo39

Maybe its time to swap out those 3.08s for some 3.73s hmmm

NOW YOU'RE SPEAKIN THE LANGUAGE!!

[mikajo39]

Originally Posted by highperf4x4

sounds like mornings around here too!

Well its a Tci saturday night special and I see tci stating that it's a 2000-2500rpm stall converter, maybe I should put that in my sig. haha
Yeah my rear gear is killing me, but hey I can still spin that right tire as long as I want if I punch it.

[highperf4x4]

Well if you switch to the 3.73 or lower you won't burn up the tranny and you'll probably want a limited slip or a posi to get some bite.

[Longhorn Man]

2500 stall and a 3.07 gear are a bad combination. When you are going down the freeway at 65 MPH which should be right at 2500 or so, you are finally starting to not slip. So ALL your normal in town driving will be under a slipping tranny. You may not feel it, but it is.
Also, the weight of a vehicle has a LOT to do with the stall of a converter. Engine output (torque and HP) rear gears, tire diameter and weight of the vehicle all effect the RPM in which a converter will stall at.
Get rid of the converter, or get rid of the freeway gears. If you keep it like it is, then you'll kill the tranny.
This is why whenever I see a thread asking for stall rate advice, I always say call the converter tech lines. Most of the converter shops (including TCI) have these tech lines. And in reality, if you gave TCI your (acurate) vehicle info, then some one there needs smacked for selling you that combo.

[highperf4x4]

Longhorn you're talking about the "selection" of the stall converter. I was referring to it's function after that has been determined. He has a particular setup already and the weight is not going to change. The converter will stall at the same rpm now.

Thank you for the clarification.

[mikajo39]

I'm pretty sure i'm swapping out to 3.73's as soon as I can it's gonna be a around town cruiser and I see no real reason to pull 80 on the freeway anyways. I just gotta find somewhere that will do it for me, diff's aint my specialty, maybe I could do in shop. I'd need a new carrier and stuff for the new gears,any idea where I could get everything to do a change over to posi 3.73s?

[highperf4x4]

I would hit the California section of the board and see if someone in your area already has a line on one you could get for a fair price.

The 3.73 will help but you might want to increase your shift points also. In other words, the tranny will hold a gear slightly longer before it shifts. I don't have all the knowledge on how to do it but I've heard adjusting the vacum modulator will affect it some. I'd like to check into it myself.

[mikajo39]

I would love if it held its shifts longer haha, slow roll out i can get into 3rd at 25 mph. You just turn the screw on the vacuum modulator by what I know. it'll raise it by a few hundred rpm. Looks like I get to save money and work now till I can save enough for 3.73s

[highperf4x4]

Wow 3rd at 25? I've never had a tci transmission but I would have thought the shift points were higher than that. Anyway, good luck locating a posi with the gears you want.

Until then, use the shifter to change your shift points!!

[Pont406]

mikajo39, try this. When cruising in drive about 35mph nail the gas pedal hard and watch your tach. It will jump to where the converter stalls. You might have to disconect kickdown switch for this test.
I also have 11" tci converter rated at 2500 stall but in my truck it stalls at 2900 rpm. Unless you have a custom made converter $$$$ use their ratings as a guide.

[chaosdsr]

Guys not to be an ass but one thing we are forgetting is what motor and cam is in this truck, and b a 2500 stall converter with a 3:08 will not tear the trans up unless the trans is getting extremly hot and there is no cooler on the truck. The slipping is done in the convertor not the trans and the only way he will tear up the trans is by overheating it. You need to contact TCI on this and make sure you have the specs on your cam handy and they will help you out a ton. I had a trans in a street car from them that had a bad sprag in it and grenaded. They made me send them my trans they tore it down and found the sprag faulty and sent me out a new trans.

If you have fixed the leaks have you made sure that the fluid is where it is supposed to be??? This is the first overlooked thing when a trans starts to slip. Start basic before you jump at things like gear ratio tire size and blah blah blah.

[chaosdsr]

Pont406 is also right on the stall test he is talking about flash stall of the convetor. You can also do this by getting on a road in first and letting the truck roll slow then WOT the truck and watch the tach jump to the stall speed. You shouldnt have to mess with the kickdown at all for this test.

[highperf4x4]

With a tranny cooler or not, it will burn up if it's continually stalling whether it's in the converter or slipping the tranny.

That's his motor in his signature. With those specs he doesn't really even need to be running a stall converter unless he likes to make a race or two. His mileage would improve without the 2500 stall.

However, he's not saying the tranny burned up or that he's going to change the stall. He's planning to drop his rear gear and keep his tranny like it is. So what point are you making? And I figure if a man knows he's got a fluid leak then he's probably checked it for the proper level.