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Originally Posted by Mike Drew  I had lunch with Lloyd Butfoy last week. We were literally laughing at the Superformance guys who are specifying ridiculous gear ratios like this for their gearboxes. Lloyd doesn't care personally--he will build a gearbox with whatever ratios the customer wants. But he would prefer that his customers were happy with the final result, and to that end he has tried to convince people that they are making a mistake by specifying such tall gears, but most people just won't hear it.
The reality of the situation is that nobody, and I mean NOBODY who buys one of these cars will ever drive it at 200 mph on the road, yet most customers are making HUGE sacrifices in day-to-day, real-world performance in order to have bragging rights that they have a "200 mph car".
The ratios on this dataplate indicate the maximum lunacy. Yes, with a 26.5 inch tire, the combination of the .642 fifth gear (normal is .705) and the 3.77 ring and pinion (normal is 4.22) will yield 195 mph at 6000 rpm. But again, what is the likelihood that any of us will ever have the opportunity or desire to achieve that?
With the 'normal' gearing (that is, 'normal' until some early Superformance customer convinced everybody else to go off into the wilderness with their gear ratios), 6000 rpm will deliver 160 mph. Arguably that should be fast enough; few race tracks in the USA are long enough to even allow shifting into 5th gear anyway. But having 'low' gearing like this will radically increase REAL performance, i.e. acceleration.
About the only people who would have a 'need' for taller gearing would be those who plan to run their cars in open road races, i.e. the Silver State race in Nevada, etc. Perhaps if somebody was planning on doing a lot of long-distance driving (and who buys a GT40 for *that*?), the .642 fifth gear combined with the standard 4.22 ring and pinion would be a reasonable compromise.
As another datapoint, Lloyd pointed out that the great delays in ZF delivery have been largely due to the specification of this lunatic gearing (delays in getting 3.77 ring and pinions made); he told me he can deliver gearboxes with 'normal' gearing in much less time.
Remember, you don't need 200 mph gears to brag to your buddies that you have a 200 mph car! Everybody knows that GT40s will go 200 mph, so you might as well TELL them that, regardless of what gears are in the gearbox. But when you then spank them coming out of the corners because you have proper (i.e. lower) gears, you will be all smiles. Having somebody in a Ferrari 360 ACTUALLY eat your lunch at a track day because you can THEORETICALLY go faster than he can is no fun at all.
As an aside, the demand/supply curves for ZF gearboxes are getting closer together; Lloyd told me that the turnaround time from order acceptance to gearbox completion is now in the three-month timeframe (for orders accepted today, with a 3.77 ratio) and potentially less for a 4.22 ratio (since he has those ring and pinions on the shelf, apparently). His facility in Texas is completing and shipping about one brand new ZF per day, and Lloyd himself is reconditioning and shipping about four used gearboxes per week.
As another aside, if somebody wants to go completely the other direction, I will have access to a lightly used 3.20 ring and pinion soon. This was purchased from Lloyd by a Pantera buddy in the UK who insisted he wanted to go 200 mph in his Pantera, equipped with 24-inch tall tires. He has since discovered that he literally can't drive the car in 5th gear most of the time because the gearing is simply too tall, and he is driving everywhere in 3rd and 4th gear; meanwhile his acceleration is severely blunted, even though he has a 550 hp Windsor stroker. I will be getting him a 3.77 from Lloyd pretty soon (the existing batch is already spoken for by Superformance customers!), which actually is the perfect ratio for his car, since he has 345/35-15 rear tires that are only 24 inches tall. That will leave his 3.20 surplus to the cause, and it could be had fairly reasonably if somebody had Bonneville aspirations for their GT40.... |
Here are the gear ratio of some other performance cars…
Ford GT- 6th .625 with a final drive ratio of 3.36 (265 mph)
Dodge Viper. 6th .50 with a 3.07 final drive (318 mph)
Chevy Corvette 6th .57 with a 3.42 final drive (244mph)
None of those cars will ever be able to reach the speeds that the gearbox ratio is capable of. So why did Ford, Dodge and Chevy waste time and money setting them up to run that way?
Why don’t you go and get a job at one of the big three? It seems you know a lot more then their engineers do. At least you should give them a call and tell them how much you and Lloyd are laughing at how stupid they are, maybe then they will fix their flawed gear ratios.
Or maybe you don’t really have a clue after all. Did it ever occur to you that large V8s (and V10) don’t like high rpms? Did it ever occur to you that cruising on the highway at over 3000 rpm is not very desirable for v8s? Apparently it occurred to Ford, Dodge, and Chevy, but I guess that fact is still eluding you, which is why you’re not working for them.
Just out of curiosity what trans and ring and pinion are you running in the cobra in your sig? Hopefully it’s not one of the Tremecs with that big overdrive 5th (or 6th) otherwise you might get labeled as a hypocrite.
Just so you know if you cant tell by the tone of my post I think your post was a little rude to Spyder Mike…