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Is my transmission ok? Or is it my torque converter?

 
jagermarine
New User
Posts: 5
Joined: 05/12
Posted: 03/13/13 01:16 AM

I have a 1967 Ford Mustang. It was originally a 289 but swapped it with a 302 I had built, I underestimated the power it had and it burnt out the original C4 tranny that was in it, I recently installed a brand new C4 Streetfighter transmission from TCI along with a TCI Streetfighter torque converter/stall this time I am sure the Streetfighter tranny can handle the power my engine is putting out. My problem now is when I floor the accelerator peddle my rpms wont go past 3000-3500 and my mustang makes the sound as if its over-revving but if I press the accerlerator peddle 3/4 of the way down it still doesnt go past 3000-3500 rpms but it no longer makes the over-revving sound. Why wont it go past 3000-3500 rpms and why does it make that sound? A chevy buddy of mine says its the stall and Im just not use to it yet but im not too sure. If it helps my 302 is putting out 435 hp and 460 ft-lb of torque, TCI says the streetfighter transmission and torque converter/stall can handle 500 hp, I have a tranny/oil cooler installed and I put B&M Trick Shift transmission fluid in my transmission. Does anyone know what is wrong?  

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waynep71222
Enthusiast
Posts: 455
Joined: 04/12
Posted: 03/13/13 07:16 AM

is this 3000/3500 rpms limit... with your foot on the brake.. in drive or LOW range ?????

like you are have both staging lights on at the drag strip and are awaiting the tree to turn green.


factory stall speed in C4s.. is around 1100 or 1200 RPM.. that is in drive..  left foot hard on the brake.  right deep into the gas pedal..

now... if the engine won't rev past 3000/3500 RPMs while you are driving along...  then something else is wrong...

did you align the drain plug with the hole in the flex plate...

a HUGE TIP for installing C4 transmissions ...    set the torque converter drain plug to 6 o clock... turn the flywheel so the drain plug opening is at 6 o clock...  get in your tool box and find a 7/16" six point,  1/4 inch drive deep socket...  stick that on the torque converter drain plug   now when getting the transmission up or the engine in.. as you are lining up the engine dowel pins.. the socket will center the torque converter studs without needing help once you get the end of the socket thru the hole... this makes it so much easier to install the C4 and other fords with a torque converter drain plug..

look at what torque converter you ordered... find the listed stall speed...  you will probably find its in the 3000/3500 rpm listings..  

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jagermarine
New User
Posts: 5
Joined: 05/12
Posted: 03/13/13 01:29 PM

its in drive with no foot on brake, from a straight stop. The stall speed is 3000-3400. Drain plug is lined up.  

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waynep71222
Enthusiast
Posts: 455
Joined: 04/12
Posted: 03/13/13 07:47 PM

next question.. sounds like its going to go thru rear tires Smile  a LOT..  

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jlg2002
Guru
Posts: 1410
Joined: 03/08
Posted: 03/14/13 12:53 PM

While you will probably get differing opinions on this,
In my opinion, this is a drive-ability nightmare and  3500-stall converter has no place on a hi-way driven car. You need to have a conversation with TCI and let them recommend the right TC for your street driven car. I would expect you'll hear them say 2000-2500 stall speed is recommended. Most engines don't produce their peak HP and torque until well into the 4000 RPM range and I think your TC is not allowing your engine to "rev" correctly.  

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jagermarine
New User
Posts: 5
Joined: 05/12
Posted: 03/15/13 01:18 AM

I must agree with you Im sure i must get another torque  converter with a lower stall speed  

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waynep71222
Enthusiast
Posts: 455
Joined: 04/12
Posted: 03/15/13 07:57 PM

before swapping out the torque converter..

DO A PROPER converter stall speed test..


in a CLEAR AREA... without people or traffic... enough room to slow down if the car lunges forward...

engine at operating temp...  transmission also...

LEFT FOOT hard on the brake pedal...

transmission in LOW RANGE...    tachometer where you can see it...

verify no body is in front of you...

left foot still hard on the brake pedal..

mash gas pedal down to the floor while you are watching the tach... do not let the car move..

this test only requires 2 seconds of throttle...  not 20 seconds.. not 2 minutes..  2 seconds. perhaps 3...

how fast will the converter let the engine accelerate to without the rear wheels moving..


if you have a big cam... a big carb and a big intake... you might need this much converter.. so the engine is making the optimal power for take off..


you must have given the transmission supplier some data when you ordered the transmission...
cylinder head type and port size..
cam specs
intake and carb...
rear end gear ratio.
rear tire diameter..
engine horse power and  torque curve if the engine had been tuned on a dyno..
end usage... street only MPG build, street warm or hot... street strip... strip only...

ask some people with more experience in your area...
got any hot rod repair shops... performance repair shops...  any drag racers... any hot rodders..

you need to have somebody take a test drive with you..

warning.. way too many transmission shops... only KNOW OEM stall speeds.. anything else is just broken and needs replacing...

you want ESTIMATES ONLY...  no repairs..  second opinions...     additional warnings..

some shops will tell you drop it off .. we will take a look...  the employees may take your car out and abuse it... or worse... put it on the rack and remove the transmission.. tear it all the way down and  tell you that you need a compete overhaul..  then comeback.. oh... sorry.. its 500 bucks to put it all back together..  i have seen that happen to so many people.. even my former lawyer..

i set him up with a transmission shop that i trusted...  it was an 1800 buck transmission..  he called his local dealer... they said.. oh.. no.. bring it in.. we can fix that for 600 bucks...  they tore the transmission out and spread it across the work bench.. then told him that it is broken.. and that they don't rebuild transmissions.. they only install GM REMAN transmissions and that with installation.. it would be 3200 bucks..    they made the dealer buy the car.. at blue book value..  he was a lawyer.. his wife was one of the highest judges in the state of california..  they did not know who they were dealing with.  

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