[DeTomaso] optimum ZF ratios

[Julian Kift]

IMO the stock 1st through 4th, with a tall (0.642) 5th will provide what you stated and has a good gear to gear ratio. Changing at 6500 and dropping to around 4300 in the low gears and to 5000 in the higher gears. 

 

Ring and Pinion is your preference and doesn't make any difference to the rpm shift between changes, just the speed you'll be going. If a good top end speed (200 mph) is important then you probably want a 3.77 R&P, on the other hand if exiting out the corners or away from the lights is top priority then the 4.22 may be the best choice. Either way you'll have more than enough torque to sit you back in the seat. I'd be nore interested in asking Llloyd at RBT what he recommends doing to ensure the ZF can handle your intended 600 ft/lbs based on what your intended use is (i.e. street, track, race).

 

Good luck,

Julian
 
> From: MikeLDrew at aol.com
> Date: Mon, 11 Jan 2010 21:55:46 -0500
> To: dgordon100 at cox.net; detomaso at realbig.com
> Subject: Re: [DeTomaso] optimum ZF ratios
> 
> 
> In a message dated 1/11/10 18 40 43, dgordon100 at cox.net writes:
> 
> 
> > If buying a new ZF from RBT, what would be the optimal ratios for each
> > gear and final drive given a max torque of approx 600+ ft/lbs at 4250
> > and max horsepower of approximately 700 horsepower at 6500 rpm both
> > measured at the wheels? I would thing that after each gear change it
> > would be desirable to not drop below the peak torque rpm providing I
> > shift at 6500 rpm.
> > 
> 
> It's a highly academic question, because you'll have enough power and 
> torque to alter the rotation of the earth anyway. Most likely, the limiting 
> factor will be tire traction.
> 
> That said, there's a wonderful ZF gear calculator on Mike Dailey's website:
> 
> http://www.panteraplace.com/page32.htm
> 
> If you click on that link, it will download an Excel file to your hard 
> drive. Open it, and you'll find a program that tells you exactly what you need 
> to know. It's pre-loaded with standard ZF gearing (plus an optional sixth 
> gear), but you can change the values for tire diameter, rear-end ratio, and 
> each gear ratio.
> 
> I just recently figured out that there are tabs at the bottom; if you click 
> on the other tab, it presents the data in a graphical format.
> 
> Unfortunately the cells aren't formatted very nicely; I fixed it on my 
> personal copy, and will e-mail that to you directly.
> 
> Mike
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