coppercutlass

ok so over the winter i added a new tq converter and it flashes around 2800 rpm. When i drive the car it shifts well before the 2800 and it's soft. The only time i can get a good solid hard hitting shift is when im hammering on it. I havenever had a converter this loose i had 2100 rpm in it before. The car runs great now and will smoke the tires from a roll but my shift is soft. It ran fine last fall with the old converter the trans does not seem to slip ???? any ideas maybe new trans filter ? I also might add i manually shift it while hammering on it. if im just driving around town it stays in drive unless i need to down shift it had no switch.

ah64pilot

I have a 10" TCI 3000-3500 stall in mine and it is almost the same way...I say almost. I have a Trans-Go competition shift kit in it with the quasi-manual valve body. At part throttle it will shift quickly but depending on how much throttle I'm giving it is the difference of it shifting quickly or breaking the tires loose. I would say that your symptom is normal, especially if at full throttle it's still hitting hard.

Steve

coppercutlass

I remember it did the same thing last year but it went away after a few times driving it . i think i may also need a new filter but the trans does not even have 10k miles i just dont know the sypmtoms of a bad trans filter. Fluid is still cherry red and does not smell burnt. It's just the 1 to 2 shift is very light and then 3rd gear just eases in . I also forgot its a 10 in. 2600 to 2800 stall i got from a trans shop in the area. i think its closer to 2800-3000 rpm stall .

oldcutlass

At what mph is your trans shifting under light load. Perhaps a modulator adjustment may be in order?

coppercutlass

Its shifting at like 2k rpm . I knew you could adjust the modulator but I have never done it. This is actually the answer I was looking for I knew it came up on here once before.

455man

Could it be shifting softly because you are shifting under the 2800 lockup RPM? Under 2800 rpm wouldn't the stall still be slipping which would result in a soft shift? I've never had a high stall so I'm just askin.

coppercutlass

That's what I was thinking too.

droldsmorland

What trans, TH350 or TH400? Is it stock or have you beefed up the internals? Generally speaking soft shifts = low(er) line psi. Try turning up the modulator which is one way of increasing line pressure. Hopefully you have a TM50 adjustable modulator? And hopefully its hooked to manifold vacuum not carb.
Beware simply turning up the line pressure and adding a high stall converter to a otherwise stock trans without some key high perf mods will make quick work of eating a stock 350 or 400.

oldcutlass

What speed does the speedometer say when its shifting from 1-2, 2-3?

My T400 shifts very gently and very fast under light load with a 2600 stall. I adjusted my modulator for it to shift 1-2 at around 10 mph, 2-3 at around 23-25 mph at lite load. I have not gotten a tach installed yet.

coppercutlass

Speedometer is way off. And its a fully built th400 that was for a 10 second car and I picked it up cheap years ago. Has worked flawlessly for 4 years. 1-2 is around 15 mph I wanna say. 2-3 25-30 mph

4the1320

As A general rule of thumb,A stall converter will always "mild out" your shift.If you put a stock converter in that trans and go drive it you would say "xzxz!!!!"This thing is gonna break the trans case or something.It Does have to do with the line pressure during the shift,and of course while your still "in the stall" the line pressure is lower .
Another thing to note!The trans. is creating ALOT more heat during these soft shifts .So I hope you have a great Aftermarket trans cooler.Get the biggest you can find!

coppercutlass

I don't think its slipping because it will brake em loose from a dead stop and it holds the rpms good on the high end and keeps pulling. The shifts are what seems to puzzle me.

coppercutlass

I have a trans cooler in there along with the built in one ins my big beefey aluminum radiator I'm putting in a temp gauge soon.

droldsmorland

It sounds like you should have the necessary upgrades in the internals? Give the modulator adjustment a try. If it’s been "built" it should have an adjustable modulator. With a small screwdriver inserted into the modulator nipple turn it clock wise to increase the shift points/line psi. Couldn’t hurt to have a look in the pan either. Replace the filter while you’re in there, cheap insurance.
I have a rather stout TH400 under mine. I have the shift points turned up allow 1-2 at about 20-24MPH and 2-3 is about 30-32MPH. At "normal" throttle this provides a firm crisp up-shift. I get rubber in both 1-2 & 2-3 at moderate to WOT. I’m running a 2800 stall too and I do get a firm shift even at light throttle.
When I went through this trans I installed many upgrades & goodies. I use TCIs synthetic clear trans fluid...good stuff.
Make sure you feed the cooler correctly too. Route from the trans into the external cooler, then into the radiator then back into the trans. This applies to a street driven car. It’s important to maintain op temp. You don’t want it too cool. For a strictly strip car run only a larger external cooler, bypassing the internal radiator cooler.
Bottom line is if you can’t get the shifts to your liking with the modulator adjustment then you’re going to have to go into the trans starting with the valve body and separator plate and possibly re-calibrating the governor, all fairly easy mods. If that doesn’t make you happy then out it comes for internal mods. There is a multitude of upgrades, too many to list here.

coppercutlass

I think the modulator will do the trick. car drives fine and runs awesome at full throttle.

rkk69olds

Coppercutlass I have the same problem. I have a TH350 with a transgo shift kit. I had a B&M Tork Master 2400 converter in it and replaced it with a Coan 2800 this winter. First time I drove it I was worried about the soft shifts as well thinking I had a problem with the trans. It was very firm with the cheap converter. Car performs much better with the Coan so maybe I need to do some modulator adjusting. Please let me know what you end up doing.

Thanks

380 Racer

A higher stall converter will seem "mushy" at lower speeds. Apply more power and it gets firmer. First time for a serious converter in my car, I was driving thru the pits, shifted into second (manual VB) and it didn't feel like it was there. Going down the track it worked like it should. The trans isn't slipping, just the converter, which is also producing heat which can take the trans out. So yes a cooler is necessary.

coppercutlass

I added a cooler a trans temp gauge is next. Before I take it from the shop back home it's getting a gauge.

coppercutlass

How many turns do you think till i take notice. I turned it like 2 i think it felt a little diffrent seemed to shift really soon still ? I didint have enough time to mess with it as much as i wanted last weekend .

oldcutlass

Each turn is does not effect it much. I turned mine 2 turns at a time until i got it to shift at 20-25 mph for 2-3 shift under very light load. Anymore and it won't upshift in a school zone.

coppercutlass

ok i got the shifts to come up to around 3500 but still soft. My speedo bounces and is way off . Now here is a new twist. I finally took if for a nice long drive and i down shifted from 3rd to 2nd and the rpms stayed at 4000rpm it didnt free spin but it also felt like the cars wasnt pulling like it should at 4k rpm . Im starting to think this converter only flashes properly under w.o.t and is abit too loose for me. Under w.o.t it seems right from a dead stop but while driving w.o.t downshift it does not feel like it used to and by that time that converter should be fully engaged.

SBORule

I rebuilt and modified the Turbo 400 transmission in my car over 25 years ago and it doesn't have an external transmission cooler, just the one in the radiator and not only has the trans held up to racing down the track over 700 times it has over 60,000 street miles on it to boot. I use to pull my 18ft Skeeter bass boat behind my car for several years also, to area lakes, some more than 50 miles away, in the heat of summer months when temps reach 96 plus degrees every day.

The video of my car going down the track should prove the transmission still works pretty good without an external trans cooler.

SBORule

Does your car slow down when you down shift into second gear ?

If it doesn't, the front band in your transmission has failed.

That's if down shifting into 2nd from 3rd use to slow your car down before the convertor swap.

coppercutlass

It does not slow down . Rpms just seem to stay at 4k rpm and mph didnt drop car did not nose down i let off before really figureing it out . I know that at w.o.t it will just pull hard. I really need to take it to the track to figure out whats going on on my 60 ft. and mph. I assume if the converter is slipping too much mph will drop. If the converter is engaging right 60 ft will drop. I have never ran a converter this loose this is all new to me . I have a few th350 cores i want to re build one my self i have studied the repair manual and i think i can pull it off and i bet the th350 will gain me a few tenths . Its hard to do anything right now im closing on my house tuesday . Buying stuff isnt an option fixing stuff is .

oldcutlass

There is a pressure operated plunger in the T400 that will effect the 3-2 downshift at hi rpm. It is prone to breakage as the originals were plastic. There is an aluminum replacement available.

Also if your trans is not built for manual mode then it will not allow it to shift down above certain RPM's

coppercutlass

I guess i should start driving it again daily and see if it changes or i get used to it . At this point im gonna drop the pan and check the fluid even though it does not smell burnt or any signs of shavings when i swapped the converter . I also have to get it to the track if it works good there and improvements are made i wont mind the street performance. Before it would bearly spin the tires now it shreds them but now the car shifts soft and down shifting is not the gratest. The th350 is sounding more like a good i dea at this point to me .

ah64pilot

For lack of time I'll just ask, do you have a shift kit in your trans? What kind? What setting?

coppercutlass

yes it has a shift kit and has full manual control with drive. It hit hard with the old converter chirped em hard all the time.

380 Racer

It's time to take it to the shop you bought it from.....ask them about it or have them ride along to feel it. A good 2800 stall should not act like it is .

coppercutlass

it's probably my converter. That is the only thing i changed over the winter. It was a cheap one so im going to send it out loaclly to have it checked out and re flashed will still be under 400 bucks . Im gonna swap to the old converter again and see if it changes . My old one was a jegs brand and it worked good. I might add I just remember this ? how far in should the converter be into the splines . When i bolted it p i had to pull it back to tighten it up about a half inch.

380 Racer

A 1/2 inch is alot. I believe mine has about 3/16 inch maximum. They make thick washers to space the converter further back on the splines.

coppercutlass

Could this be my issue. Does this affect pressure in the trans. I was thinking back to it when i installed it and remember it having to get moved a bit froward to match up with the flex plate.

droldsmorland

X2 with 380 racer. You have a problem. Either the converter isnt what was advertised and or you have an internal problem. It shouldnt freewheel when manually down shifting.
Step one. Get it to someone who can read what the pressures are. Thats the first step before tearing into a trans is to read the pressures...after all its just a pump.

coppercutlass

im leaning towards converter. i think ill sawp the old one back in and if the problem does not go away then ill have it looked at. Like i said it seems to work at w.o.t . If i do a holeshot it will keep pulling and spining the tires right up to 6000 rpm . which is why im thinking converter .

SBORule

If your car would slow down, when you down shifted from 3rd to 2nd before you switched convertors, then the front intermediate band has failed, does this mean your transmission has suffered a catastrophic failure, not really.

There's alot more modifications to building a racing Turbo 400 than installing a shift kit or aftermarket valve body with a trans brake. There are many internal modifications that must be done to make the transmission capable of living in a racing environment. The reason I say if the front intermediate band has failed it isn't a catastrophic failure is because in a racing Turbo 400, it wouldn't even have been installed.

As long as your car still accelerates after downshifting into second gear, you are OK. Change the filter, add four quarts of tranny fluid and don't worry about it. You're probably going to find some grey matter stuck in the corners in the trans pan, that's the front band material.

Oh, sell the convertor on ebay and buy a PTC 10" 4000 stall convertor, it will be about the same $$$ as your are saying a local shop will charge you to do nothing.

coppercutlass

i wanna stay in the 2800 to 3000 rpm stall range. when i would down shift with the old convertor it would spin em and pull hard. Im gonna add a new pan which i have wanted for a while and change the filter . I think im gonna run this untill i can get it to the track and see what the numbers look like. I really dont wanna drop the trans again. I think im gonna build a th350 to shed a few tenths and put the th400 in my dads car which has a worn th350 . Probably gonna go with a converter from midwest converters here in rockford since they are close .

coppercutlass

ok guys i got an update. Today i dropped my trans pan and changed my filter. It seems to shift better it firmed up but still soft due to the converter but there was much improvement. When i punch it in drive it now gets up and goes alot better than before. When i down shift it moves better. I did see some flakes in there but not an alarming amount my local trans guy said put the new filter in drive it and change it again in 2000 miles or the end of the season to monitor the wear to see where it is really. I have had that trans in the car for almost 4 years and never did a filter he said most of that stuff is probably from when everything was still "breaking in" so to speak. Tommorow i finally get to bring it to my new house from the shop about 25 miles i shall see how it goes. Thanks for all the input guys if anything else pops i will re earth this thread.

coppercutlass

Ok guys here is an update. I got my car to my new house about 2 weeks ago. I take it out to run errands locally here just to keep things running good. Today i took it out and really got on it i might add the shifts firmed up at crusing speed and really hit hard now while shifting manually. My trans did this last year after sitting all winter maybe a ball check or valve or sumthing is gettinng gunked up . Is there anything i can run in it to de gunk it a bit. Anyone else have this happen. It also down shifts nice now everything is back to normal .