I fixed the throttle lag with my 07 GT, but it still has a bit of throttle dead space and extremely high clutch take up. My foot is almost off the clutch pedal before the clutch engages with the flywheel and it has been this way since day one.

This makes for very clunky shifts if I let off the clutch pedal abruptly. So I'm wondering, how do you properly shift for WOT acceleration with the 05-09 S197 GT?

I thought it was my technique at first, but I have my 09 Cobalt SS/TC and the clutch and stock short-throw shifter work well together. It is a much smoother ride with the same person behind the wheel.

For the GT, do you release the clutch a bit slower while engaging the throttle or do you just dump the clutch and immediately get on the throttle? I always hear a lot of clunking in the driveline and rear end if I try to drive the GT like I drive the SS/TC. With all of the stupid construction going on around SE MI, it is getting to the point that I want to fix the problem or figure out why it is such a PITA to drive.

 

I have throttle lag with my automatic GT - drives me crazy. New tune hasn't helped. Thought about getting a new accelerator pedal to see if that would help.

 

I have a new throttle pedal but it still has the dead space issue. Lag is solved, but there's a slight amount of initial travel that doesn't do anything.

I test drove a bunch of manual cars with DBW throttles and none of them exhibited throttle lag:
Subaru WRX
Mazdaspeed3
Cobalt SS/TC
automatic Mazda3

It is really easy to drive the SS/TC smoothly. There's no lag and the clutch take up is much much lighter/shorter.

 

I think part of the problem is also the driveline slack, and I think most of it is caused by the two piece driveshaft. Others have noted here that the herky/jerky motion of their cars improved quite a bit after swapping to a one-piece. It also might be some of the rear axle/suspension design problems with the single upper link. I'd imagine that hard mounting everything would solve that, but lots more NVH with that.

Just bought an Audi S4 six speed, and its engine decels so quickly when the clutch is in, I have a hard time shifting fast enough to clutch-out before the revs are too low. I think I'm just used to the laggy Mustang. Wonder if the flywheel plays a role here, too?

 

Man this is the 4th time this week this false rumor about the 2 piece causing clunk has come up. Ya'll work for Dynotech or something?
Ford engineers will disagree with you, and a 1 piece counteracts important design features:

Excerpts:

***
Clunk is driven by total driveline lash, dominated by the gear sets and clutch tuning/capability. The 3.73 amplifies this a bit compared to the 3.31 and 3.55 axles. The 2-piece driveshaft is not the cause of the clunk noise. The Bullitt will have higher levels of clunk compared to the base GT. The base GT throttle response is a bit softer than the Bullitt's. The increased throttle response makes the clunk a bit easier to get. It is a trade-off - improved performance feel vs clunk.


***
The post mentions high speed and 160mph - The Mustang (as it leaves AAI) is speed limited well below that for a reason. Like I said before, I do not know specifics about the dynotech piece, what it does or does not do. I do know about the 2-piece in the factory car. It is a fairly robust piece. Vibration is not an issue unless the centerbearing shims are not installed properly, the shaft has a balance issue or the pinion angle is off. These would be quality issues (that I'm not aware of having in production), not design. The 2-pc has no roll in whether or not you have a random vibration. U-joint angles, run-out (flange or shaft), balance and system modal (resonance) response govern vibration.


*** 2 piece drive shaft

The 2-piece driveshaft is required to meet internal engineering requirements for safe operation at max vehicle speed. Basically, it is designed to provide a driveline system resonance well above what the speed limiter will allow you to operate at. If you put your driveline into resonance, bad things may happen! I've seen what it does to a car and it isn't pretty.

The driveshaft CV joints are required components on this type of driveshaft when combined with a live axle. If the rear suspension were IRS, simple flex couplings would be used (look at the new Camaro, Challenger, etc...) and would make for a lighter driveshaft.

The driveshaft also has an internal torsional damper (ITD) which is soley there to attenuate axle whine. If package allowed, the ITD would be mounted on the exterior of the driveshaft as a much lighter ring design. Since the equivalent inertia is required out of the smaller diameter part when installed inside the driveshaft, the mass has to increase. So, you get a heavier ITD vs a lightweight ETD.

A single piece steel or aluminum 1-piece would have to be larger in diameter than the current package allows. Basically, you would have contact with the fuel tank at full rear suspension jounce. 1-piece carbon fiber was explored at one time...

Hope this helps.


I would not assume an aftermarket piece "solves" a problem. Yes, you can stuff a massive driveshaft into the tunnel but it will not meet standard vehicle engineering requirements. Our requirements take many factors into account, with the biggest one being your personal safety under a wide variety of operating conditions. Our parts are engineered to work in one big system. Aftermarket parts are generally not engineered. By this, I mean that they are designed to fit properly (usually) and improve one or two attributes specific to your application.

For example, if you want a lighter weight driveshaft that gives you less rotating inertia, you can buy this aluminum 1-pc driveshaft. But, that's all you get - lighter weight. Not proven durability, safety (how does the driveshaft react in a rear impact?, clearance to other parts like the fuel tank?), NVH, ride (driveshaft plunge force actually affects your ride quality), etc...

But that's the great part about it being your car. You get to decide what you want your Mustang to be. Just be cautious and think about how these parts may affect the rest of your driving experience, safety and wallet if it breaks or breaks something else in the car.

I've been in your shoes (which is why I became an engineer and worked my way onto the Mustang team!) and know exactly where you are coming from, though. I don't know specifics about the d/s you are referring to but I'm just giving you some things to think about and consider.

Thanks for buying a Bullitt!


*** lower control arm bracket axle masses
They are there to attenuate axle whine. If you currently notice axle whine in your car in the 45-65mph range, it may increase a bit if you remove the masses. They are one part of a fairly extensive package engineered to address axle whine on the s197 platform.

 

C,

Just my 2 cents here, but I can say that the point where my clutch grabs on my '08 is about right. My '99 Stang's clutch catches really high, but not my '08. So, hopefully someone will have some more insights into how to adjust this, but just thought I'd note that I don't see that with my '08.

BTW....I feel your pain with the roads here. Ugh! Good ole orange barrel season.

 

I'm pretty sure Ford chose the 2 piece steel driveshaft for cost reasons. A carbon fiber driveshaft is the best way to go due to the reduced mass and increased strength. Ford used to provide an aluminum metal matrix composite driveshaft on the 99-00 Crown Vic Police Interceptors with 3.55s due to the driveline vibrations above 120 MPH and because the CVPIs were speed limited to 130-132 MPH. Ford stopped doing this and just set the speed limiter to about 120 MPH because the AMMX shafts were too expensive.

I can see that the slop in each part of the driveshaft adding up to excessive slop (spline meshing, u-joints, ring and pinion gears, etc...) versus a FWD transaxle which has tighter clearances and less components.

 

Years ago, when I was working at the Ford dealer I was surprised at the variation between vehicles.
Many seemed very high, and at first I thought that was the Ford way.
Then I drove others that seemed just fine.
My 2006 seems just right.

 

One thing is for sure....too high is easier to drive than too low....so if it is going to be off one way or the other, I would prefer it to be too high. Obviously, somewhere in the middle would be ideal.

 

Too high isn't good IMHO because you either engage it properly or you let off too quickly and stall or stumble. With my Cobalt, it is more to the middle/low and you have a LOT more leeway in engaging the flywheel - which is perfect.

I let my dad drive the Mustang, and he's driven stick all his life. The first thing he said to me was that the clutch sucked a$$ in the Mustang - he said it didn't feel right.

I never used a short throw before, but my SS/TC came from the factory with a short throw and it is significantly faster to row from 1-5 than it is in my Mustang, and it isn't because of resistance in the gates.

As for variation, I test drove two Mazdaspeed3's from different MYs and a 2010 Mazda3. All of them had consistent build quality and the throttle lag was non-existent. Torque steer was present in all of the Mazdaspeed3s and was still noticeable in the Mazda3. I test drove 2 different Cobalt SS/TC's and the one I ended up buying (3 different ones) and all of them drove the same and did not have throttle lag. I didn't get a chance to test drive other Mustangs but it sounds like none of the S197 productions were consistent.

 

Hey C, I didn't mean to imply that it being too high was OK, so hope it didn't sound that way. I had driven a friends Celica years ago and the clutch grabbed so low that it was difficult to make sure it was fully disengaged, which was a nightmare to drive. So, that's what I meant when saying high was better than low. My SN95 is high, but the travel is much longer too, so it's not ideal, but works. Hopefully, you'll find a solution to get it in the location that is best for you.

 

Umich97, yep I hear ya!

 

The S197 is clunky as hell, I'd like to think it can be cleaned up but when I think back to my 4x4 B4000 with two piece rear driveshaft, plus the extra gearing of a transfer case and it was no where near as sloppy.

I don't mind my clutch grab point though, it's 2/3 up... I drove valet years ago, trust me there are MUCH worse out there... Ford's in general (theres always exceptions) tend to grab high.

 

I don't doubt it! I usually never use valet parking because it is above my pay grade, but I had to use valet (valet-only at the hotel) during TDY and I always chatted up the drivers to get their impressions of cars. They all hated the Camaro and Challenger due to poor visibility.

I tried something different today and tried increasing my shift time. It seems like most of the clunkiness can go away with a short-throw shifter because I am wasting a few milliseconds with the long-throw rowboat shifter. I don't feel like messing with the shifter though, there aren't many aftermarket designs that seem OEM-grade/foolproof.

 

C, if you do decide to add a short-throw shifter, Hurst and MGW both tend to be fairly popular options (there are others as well). They definitely shorten the throws a lot. I have the Hurst in mine and it is a little "notchy", but I don't mind the feel. I've heard the MGW is not, but do not have any experience with one, so cannot say first hand. I can say that I rarely if ever hear anyone say anything but good things about the MGW in particular.

 

I had the same issues with my '06 stick. I found that letting off the gas earlier really helped. Let off gas then push in clutch. It totally changes the way it re-engages. My upshifts got almost perfect, but I still could not match shift well on downshifting in turns. It was the only real complaint I had about the car. I bought a Steeda Tri Ax shifter and it made the car a little noisy. I would probably try MGW if I had to do it again. I had a Bama tune and he tweaked the throttle response for me to my liking, which really helped also.