GT Performance Mods 2005+ Mustang GT Performance and Technical Information

TRANSMISSION PROBLEMS

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Old 12/20/06, 02:47 PM
  #21  
RPM
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No need to downshift to first at anything above 10-15 mph. Like posted above, double clutch if you need first at anything more than a dead stop. Reason the 2-1 is difficult is the HUGE ratio spread from 1st to 2nd. The synchro must accelerate the clutch disk in order to allow the slider to engage (speed matching). This takes energy that you feel in the shift linkage. Any kind is excessive use, powershifting, downshifting, etc. will cause premature blocker ring wear and another trip to the shop. These aren't racing transmissions and barely pass as hi-performance street trannys mostly because, IMHO, the type of blocker rings used.
Old 12/20/06, 06:12 PM
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I don't think I have ever down shifted from 2nd to 1st
Old 12/20/06, 09:52 PM
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Yeah, I don't see the need to at anything above 5-10mph... These engines have enough torque in them to move the car adequately in 2nd gear.
Old 12/21/06, 07:34 AM
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Originally Posted by RPM
No need to downshift to first at anything above 10-15 mph. Like posted above, double clutch if you need first at anything more than a dead stop. Reason the 2-1 is difficult is the HUGE ratio spread from 1st to 2nd. The synchro must accelerate the clutch disk in order to allow the slider to engage (speed matching). This takes energy that you feel in the shift linkage. Any kind is excessive use, powershifting, downshifting, etc. will cause premature blocker ring wear and another trip to the shop. These aren't racing transmissions and barely pass as hi-performance street trannys mostly because, IMHO, the type of blocker rings used.

Great explanation about the inner workings esp the difference in ratio ranges. I don't downshift into 1st at very high speeds - more like the 10-15 mph range. Sometimes when I come to a stop in 2nd gear it is still not easy to shift into 1st to start off again. In those cases I really have to concentrate to push the clutch all the way to the floor to get engagement.
Old 12/21/06, 09:16 AM
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I have an '07 GT convert with about 5000 miles and rarely downshift from 2 to 1, but when compared to my '03 GT, it is very smooth through all of the gears. My wife considered herself a bobblehead doll in the '03. No matter how hard I tried, it was very seldom smooth.
Old 12/21/06, 05:41 PM
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I never down shift any manual trans until at a stop or very close to it.
Old 12/21/06, 09:02 PM
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Originally Posted by metroplex
I am going to try double-clutching or rev-matching to see if it is just operator error or the gearbox.
I have a very hard time rev-matching my downshifts. I hope the BamaChips tune I ordered helps solve that problem. I don't downshift unless I am going into a curve or having fun, but I would say that overall my transmission is pretty smooth. You should drive a TKO equipped vehicle with a Pro 5.0 shifter, or a T5 with a Steeda Tri-AX. I really liked the notchy feel as I KNEW I was in gear. This stock setup is really a major improvement to me.
Old 12/22/06, 09:10 AM
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Originally Posted by ttbit
I have a very hard time rev-matching my downshifts. I hope the BamaChips tune I ordered helps solve that problem. I don't downshift unless I am going into a curve or having fun, but I would say that overall my transmission is pretty smooth. You should drive a TKO equipped vehicle with a Pro 5.0 shifter, or a T5 with a Steeda Tri-AX. I really liked the notchy feel as I KNEW I was in gear. This stock setup is really a major improvement to me.

I've always felt that gears were there to shift both up and down and I can't remember the last time I came to a stop in 5th gear. Gears are like having a second set of brakes plus you have instant control of engine power should you need quick acceleration if you get in a tight spot and need to vacate a situation that could suddenly become dangerous.
Old 12/22/06, 08:59 PM
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Originally Posted by RKNMACH
I've always felt that gears were there to shift both up and down and I can't remember the last time I came to a stop in 5th gear.
I guess there are other definitions of downshifting. We all have our style of driving and I have been driving a "stick" for over 20 years, so I don't really think about it. If you rev match and speed match your shifting properly, you barely need a clutch to change gears. I broke a clutch cable in a POS 80's Charger once and drove it over 40 miles home, going through the gears. Hardly a grind. It was bad starting in first though. Glad the starter had enough torque to move me and the car forward to get going.

If you are having a problem getting into 1st while the car is stopped, I would make sure you are not having a problem with the clutch dis-engaging completely. This would cause many issues.

Also, I very RARELY downshift to use the gears to slow down anymore, at least not during regular street driving. Brakes have improved so much...
Old 12/22/06, 09:21 PM
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I down shift when needed. Never 2nd to 1st unless at a stop or real close to it. I also do not use my engine and trans to slow me down to save my brakes. Does not make sence to add wear and tear to a engine and trans to save wear and tear to a 50.00 set of brake pads.
Old 12/27/06, 12:55 PM
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Originally Posted by Firedude
I down shift when needed. Never 2nd to 1st unless at a stop or real close to it. I also do not use my engine and trans to slow me down to save my brakes. Does not make sence to add wear and tear to a engine and trans to save wear and tear to a 50.00 set of brake pads.

It's not as much about using the engine as a "brake' as it is having control of the engine's torque/power so you have the ability to instantly react should an emergency situation develop requiring immediate action.
Old 12/27/06, 01:10 PM
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Originally Posted by dhof303
OK, I need to clarify the fluid flow thing. The 3650 in the 05 and newer cars is outfitted with a hydraulic clutch, all previous years 3650's that came in production Mustangs had a mechanical clutch. The timing issue comes from the movement of fluid or initial compression of fluid prior to it moving wheras the mechanincal clutch has no lag in movement unless it is out of adjustment or the cable is inadequate. Again I am not sure which part that TREMEC informed me would assist in solving the problem only that there is one if needed, call them if you are sceptical and ask the pro's.
Hmm, brakes are hydraulic, why don't we get brake lag?
Old 12/27/06, 05:42 PM
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I got an article directly from a TREMEC tech. It had to do with a GM application (Camaro drag car), but the same problem. Because of a fitting in the line, there is a restriction and theory is it causes a lag. What the GM guys have done is open that restriction a little and claim improved action. I am not sure I buy into it being a big lag, because the fluid is only slightly compressible. When you depress the pedal, you move a fixed amount of fluid almost instantly (but some is compressed due to the pressure and the flex hose swells slightly so all you loose is a tiny bit), and the clutch slave see's whats left just as quick.
Old 12/27/06, 06:11 PM
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Originally Posted by RPM
These aren't racing transmissions and barely pass as hi-performance street trannys mostly because, IMHO, the type of blocker rings used.
I am beginning to think the hi tech blocker rings TREMEC are using are most of the problem. The old ford top loaders were with basic brass blocker rings and no hi tech surface treatment or coating, and for me, never gave a second of problems up or down shifting. The blocker ring of any design is sensitive to the slickness of the trans fluid, and if its too slick, the blocker ring won't spool up or slow down the input shaft quick enough to ensure a smooth shift.
Old 12/27/06, 06:15 PM
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The clutch "lag" in our GTs is probably due to the weird clutch pedal travel. The friction point is close to the point where my foot leaves the pedal. From that point all the way to do the floorboard is practically dead travel time. However, I can hear the clutch engage the flywheel about 1/8 of the way from the floorboard (transmission begins making a buzzing noise). However, there's not enough contact for transmission of power into the gearbox until the friction point.
Old 12/27/06, 06:16 PM
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Originally Posted by RadBOSS
I am beginning to think the hi tech blocker rings TREMEC are using are most of the problem. The old ford top loaders were with basic brass blocker rings and no hi tech surface treatment or coating, and for me, never gave a second of problems up or down shifting. The blocker ring of any design is sensitive to the slickness of the trans fluid, and if its too slick, the blocker ring won't spool up or slow down the input shaft quick enough to ensure a smooth shift.
The synchros in my 3650 take a bit to actually synchronize for downshifts and I can hear it spooling up. Revmatching doesn't seem to work as well as double-clutching. I wonder if it is because of the ATF?
Old 12/27/06, 06:30 PM
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Originally Posted by RPM
No need to downshift to first at anything above 10-15 mph. Like posted above, double clutch if you need first at anything more than a dead stop. Reason the 2-1 is difficult is the HUGE ratio spread from 1st to 2nd. The synchro must accelerate the clutch disk in order to allow the slider to engage (speed matching). This takes energy that you feel in the shift linkage. Any kind is excessive use, powershifting, downshifting, etc. will cause premature blocker ring wear and another trip to the shop. These aren't racing transmissions and barely pass as hi-performance street trannys mostly because, IMHO, the type of blocker rings used.
Originally Posted by metroplex
The synchros in my 3650 take a bit to actually synchronize for downshifts and I can hear it spooling up. Revmatching doesn't seem to work as well as double-clutching. I wonder if it is because of the ATF?
Well ATF is loaded with friction modifiers to make it less slick so the clutches drenched in oil have grip, but not all ATF are the same. The guy I talked to at TREMEC swore by the Mercon that Ford specifies (they had a 05 Mustang mule to do all the transmission development on), warning that some of the other brands have additional additatives that are harmful to the coating on the blocker rings. So one should be careful what transmission fluid they decide to use if not Mercon. Whether some additional friction modifier in the Mercon would help I do not know.
Old 1/3/07, 08:27 AM
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These are slow shifting transmissions by design. The fact that the factory tune makes the rpm hang high between shifts only exacerbates this problem. The synchros in this tranny are getting a real beating by people who are trying to get into gear quickly. Synchros are fairly fragile in any tranny, and simply do not last when they have to put up with 2-1 downshifts at 25 mph, or power shifting. You will ruin them.

When I first bought this car, I thought it had a transmission problem because I could not shift it as quickly as a foreign transaxle- but there was no defect in the tranny, it is simply not designed to shift quickly. And forcing it damages it.

I have owned or driven more than 200 different performance cars, and on a scale of 1 - 10, this tranny gets a 4 from me. Just my .02
Old 1/3/07, 09:02 AM
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helicfii: Did you work as a valet? A few of my college buddies worked as valets in high profile clubs in the NYC area and frequently got to drive Porshes, Ferraris, etc...

So how would you recommend using the 3650? Granny shifts all the time? Double-clutching?
Old 1/3/07, 09:26 AM
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When I first bought this car, I thought it had a transmission problem because I could not shift it as quickly as a foreign transaxle- but there was no defect in the tranny, it is simply not designed to shift quickly. And forcing it damages it.

I have owned or driven more than 200 different performance cars, and on a scale of 1 - 10, this tranny gets a 4 from me. Just my .02
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I agree with your rating - it is not power shift friendly and I have not even tried one.


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