Ford Muscle Cars Tech Forum banner

1 - 10 of 10 Posts

·
Registered
Joined
·
111 Posts
Discussion Starter · #1 ·
Hello,

I have a '68 429 in a '78 Bronco with a C6.

I recently put a new TCI converter in it, I believe it was stated as "3-400 RPM" over stock stall speed. I haven't yet figured out what exactly the stall speed is.

The trans also has a TCI valve body, B&M shift kit and a B&M light truck megashifter.

Oh and the 429 has a lopey cam with a .519 lift, so it's only got like 10"s of vaccuum.

So after the new converter, it shifts really soft. I can hardly feel it shift. A friend of mind said that's from the higher stall speed. Even when I shift it manually, it's barely felt.

Put a pressure gauge on it and the pressure is ok. Dad rode with me today for a test drive and gave me the "I don't think there's anything wrong with it." I dunno, I just find it hard to believe that this is normal.


Any thoughts from ya'll? Thanks in advance.
 

·
Registered
Joined
·
502 Posts
i wouldnt expect a converter 3-400 rpm over stock to soften shifts very much, if any. with a 2000 stall(more than yours probably), i could leave 10 feet of black on the 1-2 shift. with the 3200 converter all i get is a chirp.
 

·
Registered
Joined
·
111 Posts
Discussion Starter · #3 ·
I can definitely feel a change in the power. It's got oodles of power now. I left a nice set of posi marks in the driveway, and before I couldn't hardly get it to break lose - which has always been rather disappointing given the build of the 429. It'll grab and chirp going around turns too when taking off, but as far as traveling down the road you can't feel it shift. Even manually shifting it, it feels like a new car, not a built 429 with a shift kit.

It kicks down ok. Put it to the floor and it'll kick down to 2nd and then almost immediately back into third. The timing of the shifts have never been right because of that lack of vacuum. Even after adjusting the modulator I could never get the shift points decent, wouldn't gear down with slowing, had to come to a complete stop before it'd gear down.


The shift points I think are about the same, you just can't feel it it's sooo soft. My brother has a Dodge with a 727 that he's modded a little and that thing will jerk a knot in your neck when it shifts. He tried to talk me into adapting a 727 to put behind it.
 

·
Registered
Joined
·
1,950 Posts
My loose converter shifts 'soft' in traffic. At the track you barely notice a jerk during shifts but it shifts extremely fast so I don't care.
 

·
Premium Member
Joined
·
91 Posts
What type of oil are you using?............type F will make a noticeable differance over DEXTRON as far as firm shifts go.
 

·
Registered
Joined
·
4,003 Posts
Lets see, 10 inches of vacuum is all the modulator needs (on average) to be in the "low shift point" position, so that is normal. What B&M shift kit did you put in the tranny? Some shift kits are designed to make up for inadequacies the stock transmissions and not make them shift firm or particularly fast. A stall 2-400 above stock is in the range of 1400 - 1800 stall and it is easy to test. Apply the brakes with the engine running and in "D". Set the park brake with the engine at an idle. release and reapply the brakes with full body weight on the brake pedal. With the tranny still in "D" press down on the throttle smoothly until the RPM stops climbing with added throttle (making sure the wheel are not slipping (turning). That is your stall speed. Never hold the transmission in the stalled condition for more than 10 seconds and always cool the transmission after ward by placing the tranny in "P" or "N" and run the engine at 1200 RPM for a full minute. Then let it idle for another minute before doing it again. That will help dissipate the heat that is caused by stalling the converter. The stall RPM should be very consistant - you can test it a couple of times to be sure it is the same each time.
With all that out of the way the converter should not cause soft shifting as long as it is shifted at or higher than the stall speed. If the transmission is shifting before the tranny gets to stall speed then it will feel "mushy".
Which TCI valve body did you install and why did you put a shift kit in an after-market valve body. Was it authorized by TCI?
If you put an aftermarket valve body in a transmission and then modified it with a B&M shift kit you may have replaced components that TCI had there to make it work as designed - all bets are off when you install parts that are meant to improve a stock tranny into a modified part. If it was shifting better before you put the converter in and now it is softer then you have limited the causes to the converter. If it was ok before and now it isn't then the one part you modified or exchanged is the cause of your problem. If you changed more than one thing at a time then you will have to "undo" one change at a time until you find the one thing that made the change in performance.
Ford type "F" tranny fluid is the BEST fluid to run in any transmission (other than some of the very high end specialty fluids) because it is a lubricating limited slip fluid. It also tollerates heat better than any of the Dextron or Mercon fluids. If you are running any standard fluid other than type "F" I would advise you to change the fluid now.
You didn't say whether or not you had installed a cooler so I will advise you now to install a cooler with a towing rating of 24000 pounds right away. The high stall speed converter will generate more heat than the original and heat is the #1 worst enemy of the tranny.
To increase the shift point RPM you can install a modulator pin that is 1/16" longer than the stock pin or replace the governor with one that has a higher than stock RPM (there are three or four different governors available from Ford (or your local tranny shop) and with a little research you should be able to find which one shifts at the highest RPM.
Under mid throttle what RPM does your tranny shift at? At 3/4 throttle? at full throttle? Does it firm up under any of these conditions?

There are many things that can be done to make a tranny shift firmer and later but most of them require familiarity with the transmission hydraulics and modifications to stock valve body components. Without knowing what TCI did to the valve body that you have I would be nuts to offer any mods to that valve body. You can call them and ask what you can do to improve the shift - but you are going to have to let them know that you put that B&M shift kit in it.
Best of luck to you,
Paul
 

·
Registered
Joined
·
908 Posts
The modulator should be able to trim the shift points to help the shifting, if it is in fact shifting early/soft.

Simply pull off the vacuum hose at the modulator and using a small screwdriver, give the modulator a turn or two colckwise. It shouldn't take much to see a big difference if everything else is OK with the trans.

Plus, this little test is free, and it won't make a mess on the floor....lol...

Greg
 

·
Registered
Joined
·
111 Posts
Discussion Starter · #9 ·
On 2006-10-22 18:45, quickshift wrote:
What type of oil are you using?............type F will make a noticeable differance over DEXTRON as far as firm shifts go.
I used Dextron/Mercon.

On 2006-10-23 02:48, PaulS1950 wrote:
Lets see, 10 inches of vacuum is all the modulator needs (on average) to be in the "low shift point" position, so that is normal. What B&M shift kit did you put in the tranny?
I'm not sure. And after ya'll mentioned the B&M kit in the TCI valve body, I'm not sure it's still in there.

See, I had problems with the trans when we first got the swap running, almost 3 years ago. Seems like the old valve body had the shift kit, then he bought the TCI valve body. I forgot to ask him about it this evening, so I'm not sure the B&M kit is still in there.
On 2006-10-23 02:48, PaulS1950 wrote:
A stall 2-400 above stock is in the range of 1400 - 1800 stall and it is easy to test. Apply the brakes with the engine running and in "D". Set the park brake with the engine at an idle. release and reapply the brakes with full body weight on the brake pedal. With the tranny still in "D" press down on the throttle smoothly until the RPM stops climbing with added throttle (making sure the wheel are not slipping (turning). That is your stall speed.
Thanks, I'll try that tomorrow. I tried something similiar, just holding the brakes to see how high I could bring the RPMs before it really started to push thru the brakes and it seemed to be about 1800. *shrug*
On 2006-10-23 02:48, PaulS1950 wrote:
Which TCI valve body did you install and why did you put a shift kit in an after-market valve body. Was it authorized by TCI?
Like I said above, I'm not sure. That was 3 years ago. This wasn't something that was done recently.

Before the converter went south, it shifted ok. It just shifted way sooner than I felt it should, and it would never downshift when slowing to make a turn unless you came almost to a complete stop. That's why most of the time, I just shifted it manually, I had better control of keeping it in the powerband without it bogging down on me.

I always assumed it was due to a lack of vaccuum. A buddy of mine adjusted the modulator a few times, letting me drive it each time and that didn't make much difference - in the PAST. That was way before my current problem, just wanted to add that this transmission has never shifted right - in my opinion.
On 2006-10-23 02:48, PaulS1950 wrote:
If it was shifting better before you put the converter in and now it is softer then you have limited the causes to the converter. If it was ok before and now it isn't then the one part you modified or exchanged is the cause of your problem.
See, I agree with this, except my brother did some adjusting to a line on the carburetor that my dad said has something to do with how long it holds a gear. I can't tell you if this affected it before, because shortly after that is when the shaft sheared off the pump and the converter went south. So now I don't know if what he did to the carb has anything to do with this, or if it's something to do with the converter.
On 2006-10-23 02:48, PaulS1950 wrote:
If you are running any standard fluid other than type "F" I would advise you to change the fluid now.
You didn't say whether or not you had installed a cooler so I will advise you now to install a cooler with a towing rating of 24000 pounds right away. The high stall speed converter will generate more heat than the original and heat is the #1 worst enemy of the tranny.
I'll check into changing out the fluid. Dad said something about pulling the valve body again to have a look see, and I'll buy new fluid for it then.

And yes it does have a cooler. I may not know much about Autos, but I do know heat is the devil!
On 2006-10-23 02:48, PaulS1950 wrote:
Under mid throttle what RPM does your tranny shift at? At 3/4 throttle? at full throttle? Does it firm up under any of these conditions?
I'm not exactly sure at what RPM it shifts, but I do know it doesn't make a difference. It also doesn't make a difference if it's auto shifting or I do it manually. I put my foot in it and shifted manually really stringing it out before I shifted and it was almost the same, still pretty soft.
On 2006-10-23 02:48, PaulS1950 wrote:
Without knowing what TCI did to the valve body that you have I would be nuts to offer any mods to that valve body. You can call them and ask what you can do to improve the shift - but you are going to have to let them know that you put that B&M shift kit in it.
Best of luck to you,
Paul
Thanks for your reply, it gave me a lot to think about. I hope I wasn't too long winded, but I want to make sure everything is known about this issue.


On 2006-10-23 05:20, 393Clevor wrote:
tci valve body with b&m shift kit?????
didn't the tci VB come with a shift kit installed all ready?
Yeah, I know. I need to ask dad to clarify about this as I hadn't really given it much thought when he told me.


On 2006-10-23 06:49, GregP wrote:
The modulator should be able to trim the shift points to help the shifting, if it is in fact shifting early/soft.
Simply pull off the vacuum hose at the modulator and using a small screwdriver, give the modulator a turn or two colckwise. It shouldn't take much to see a big difference if everything else is OK
I've adjusted the modulator in the past - before this issue - and it never made a difference.



I've always been unhappy with this trans and the way it shifts. My dad is a MoPar man and can build the hell out of a 727, but he's not so good with the C6. Maybe next quarter when I take Auto Trans Rebuilding at school I'll rebuild it myself.
 

·
Registered
Joined
·
111 Posts
Discussion Starter · #10 ·
Ok, so it's just a TCI valve body with no shift kit. *rolls eyes*


I'm thinking about just replacin the modulator and see what that does. Couldn't hurt to try I guess. *shrug*

I'm gonna call TCI when I get a chance, too.

Went to move it the other day, pull it down in drive and nothing, brought the Rs up and it finally engaged the gear.

Oh and would going to a manual valve body be a good decision? I don't mind shiftin it manually, that B&M shifter makes shifting fun.
_________________
<font color="deeppink">-Melissa-</font>
1978 Bronco Ranger XLT "Brutus"
1989 Bronco XLT "Mad Bronco"
<font color="blue">Built Ford Tough!</font>

<font size=-1>[ This Message was edited by: Effie on 10/29/06 12:21pm ]</font>
 
1 - 10 of 10 Posts
Top