F40 Drop Gears?

I drive the F40 on public roads all the time without getting into trouble. If you don't get the revs up, and therefore keep the turbos out of the mix, the car drives like a very stiff 308. Very pleasant and very predictable. I like the tranny and clutch in my F40 - it's relatively easy to modulate and the car is quite happy burbling around in traffic at suburban speeds. I wouldn't mess with the factory gears myself, but if it will give you more reason to get the F40 out and about, go for it.

 

The 9% reduction is a big difference. I never had any problems with GTO or F40 transmission (basically the same gearbox) with excessive noise, so I'm not sure where that comment is coming from. I tend to leave well enough alone. But, I have driven both a GTO and F40 with the drop down gear and they rocket through the gears. As if one needs to accelerate much faster than a stock car.

Steve

 

How much top speed do you lose? I know some tests had the F40 at over 200 MPH. With a 9% reduction in gearing, it must fall to about 185ish?

 

Personally, I wouldn't mess with the gears but then again, I got a speeding ticket in the F40 for 140+...

At any rate, here's why I wouldn't. When you get on the power in 2nd, the back tires break loose. When you get on it in 3rd, they're barely holding on and I know that if I'm hitting freeway expansion joints that are slightly unweighting the rear intermittently, I can feel the tires slipping under full boost as the rear gets unweighted. And these are at 85mph to 110 ish. With drop gears, that gets even nuttier. Hitting full boost under full throttle in third is already a dicy proposition with stock gearing, what's it going to be like with drop gears.

Tim, I know that you're a great driver and I don't think that you'll get into trouble but one of the real parts of enjoying the F40 is when I push that throttle down all the way in 2nd and 3rd and feel the boost hit and managing the car as I shift through the gears. As you shift up, you can already the drop in the boost and surge as it hits hard again. With drop gears, are you going to have to be even more careful with the throttle as you shift up and the boost dies then comes back? With stock gears, I can do it under full throttle and manage the wheel spin. I don't know if I would be able to go full throttle from 2nd to 3rd with drop gears.

I've never seen higher than 170mph so for me, any loss in top speed is really a moot point. My bigger concern is driveability.

Just my $0.02.

 

I've been curious about these "drop gears" and the 9% reduction. Do they merely change the final drive? Although I can't see how that would cause a "straight cut" whine? Maybe the whole gear set is revised? But surely not for $720?

Interestingly, in the factory parts manual Non-Cat cars show to have a 11/30 final drive while Cat cars had 10/29. Assuming the gear sets are the same, the Cat cars would already have about a 6% "drop" compared to the Non-Cat cars.

I also love shifting; and for me, the F40 is geared about right. I find it much better for streetplay than a FordGT, or even a 996GT3. Both of which, I think would be a lot more fun on the street with a "drop".

Mark

 

Ok, my thoughts....

My F40 had (has) straight cut drop gears. It would be one of the first things I would do to my next F40.

It is not just about speed. Its about drivability and torque.

Wes, who has my F40 now will tell you, you put two F40's side by side, the drop gear car will out accelerate it till about 175....

They drive better, they are quicker, (not faster) and much more useable on the street and on the track. I suspect very few F40 owners actually drive the car very hard, but I did and the factory gearing is almost unusable on anything other than Road America. (with stock brakes the cars are unsuable on the track anyway)

The gear noise, is fantastic, IMHO.

If you drive a F40 with the drop gears, you will not want the factory gearing. The side benefit is the 9% drop in ratio is percieved as a 9% increase in torque so the car just launches when you are in the throttle.

Don't knock it if you have not tried it!

Chris

 

Word!

 

Chris and Wes, what's hte verdict on the noise?

 

Sorry, but I don't notice any noise.

Even if it was there it would just be part of the fun.

Chris is right, the car out pulls it's brethren all day long....

 

LOL... I might be showing my ignorance here but I really don't know what the difference between "drop" gears and regular gears should sound like but Wes' F40 sounds like pure nirvana! It sounds awesome and I wouldn't change a thing if it were mine.
I don't have a video clip that's small enough to post but I'm going to try to get a sound clip of it soon.

 

Please do!

 

There is a difference in the gear noise. The drop gears are
"straight cut" so the way the gears connect it creates a high pitch whine (almost like a supercharger whine), a sound that I personally love! If you go to a race track and you are around any true race cars you will recognize the "whine". The main benefit to a straight cut gear is strength, they are significantly stronger than a traditional gear.

 

I thought that sound was from the turbos. Wes' 40 is the first turbo car I have ever been in.

 

Contrary to poplular belief, straight cut gears are not stronger that helical cut gears. Helical cut gears have more gear tooth width and therefore can take more force. The downside of the extra width, is that the absorb more power, reducing the efficiency. A slight benefit of straight cut, is they eradicate the side loading on the gearshaft, but the g/b bearings will already be designed to cope with that. In short, these drop gears referred to in the thread, will reduce the ratio between crank speed and gearbox output speed in all gears and allow more power to be transmitted to the wheels due to less transmission losses - as noise is not an issue in race cars but power is, straight cut gears are used. There are reasons other than this, but those are the main ones.

 

There is a definite change in gear noise, but it doesn't bother me a bit. I highly recommend the drop gears.