gear ratios for race

I know that most panteras have a 4.22 ring and pinion. My Bora has a 3.77. IMO the 4.22 is too slow for street use thereby requiring the engine to turn at approximately 3,200 RPM at 80. It would be nice to have it under 3,000 at 80. A 5.25 would be fun until you go on a long trip on the highway.

For racing that's a different story. Each track would have its own gearing ideally.

My opinion is that for a street driven car, the -2 stock ratios are fine.

The 5.25:1 rear is usefull if you are going to drag race the car and use it as a 4 speed.

Gary Hall put one in his GTS and had Mike Cook drive the car into the 9's in the 1/4.



The ratios in the -1 I think are better street ratios simply because there is a better 1st gear ratio at 2.41, I believe.

The 3.77's that came up "recently" were from a batch of GT40 sets that were in storage from the 60s.

This is not a 200mph+ vehicle. There is no point to me in using them. It will kill the first gear launch.



Considering that Botfoy gets $4,000 for a new ring and pinion set, an RBT 6 speed would be a better approach BUT that essentially is just adding a low first gear and maintaining the top gear as overdrive of .7:1.

Then you can have t10 type close ratio spacings, a 3.27 first gear for nose pulling launches AND a high speed over drive gear.

For a high performance vehicle in reality, not talk, you want a first gear and final drive ratio to produce a number around 11 to 1 when you multiply the two. Depending on the weight of the vehicle the "generality" is a number of at least 10.



If you look at the Ford Mustang with a 289HP engine, look at the 2.32 first gear, the 3.89 final drive, the product of those two numbers is 9.02.

I think the Pantera's design acceleration is modeled after the 289HP Mustang. It is NOT fast. It is a 15 second 1/4 mile car.

The Pantera is 9.284 with a -2, 10.170 with a -1 ZF.



This is Ford Engineering's involvement in the Pantera. They were afraid putting the potential for acceleration in the hands of the public, so they neutered the car somewhat with a BAD first gear ratio.

What "you" want is probably a 2.80 to 3.25 first gear, a product of about 11 when multiplied by the final drive would be a great launch ratio.

You work the ratios of the gear box with this all in mind. If you want to plan for 200mph at top speed then at what rpm, I suggest 6,800 rpm, and calculate the overdrive that way.

For me 5 forward gears are enough. 6 I have very little use for.



If you want a nice low level hum so you can sleep when you are travelling, put in an electric power train with automatic sensors for everything. Better yet, get a limo with a Chauffer and sleep in the back or watch tv?

I think it is a nice setup for hillclimb race..

The standart 4.22 ratios are not to bad- yes.
But when I compare it with a Bmw Z4 gr3. Car,
the 1st gear is about 75mph. the 6th gear about 290 km/h .
This is a perfect setup at nearly any track we have here in Europe .

It doesn't matter how fast mph it goes in first gear, it's how HARD it pulls in first gear, 60ft times is what you are working for.

You are talking to a Yank though. We have just a little different criteria?

Only on a few occasions have our race cars been set up to where they pull like crap off the line.

One of those instances was the 427 GT40 cars at LeManns. Euro race stuff. Ford was SO concerned that the 427's wouldn't last the full 24 hours that they limited the rpms of the cars on the track.

They did this in two ways, 1) they set a 6000 rpm upper engine limit 2) they made special final drive ratios of 2:1.

That enabled the cars to go over 200 (220) but they were so weak in first gear that the mechanics had to give them a push start like a bobsled team to get them rolling.

So all of this is relative. You are the only one who can define what the car needs to do. Then you gear it accordingly.



Personally I say, "if you talk the talk, you had better walk the walk". If it is supposedly a kick ass car, it had better produce big time or don't show up. That's just me.

Even a 2v station wagon can pull hard if geared right. There are some drag racers and former drag racers here. You need to know gearing otherwise it can be a waste of time.

"YOU", some will may need the windshield wipers to clean MY rubber off of their windshield and there will could be plenty of it, I don't drive well? Oh and from the Webers too. They make a terrible slimy exhaust mess. Very distasteful and crude.

I don't need the wipers and I don't need no stinkin' rear view mirrors. The Ferrari guys hate me for it. It makes their Gucci loafers smell of tire rubber and this foul smelling, oily/fuel mess all over the windshield makes them run right to the car wash! I can't blame that for that? Yuck!




Oh forget all that, lol, just gear the car to pull hard in every gear.

IF you are building your own ZF and selecting gears for it, I would look at this article.

http://www.5speedtransmissions.../5sp_comparison.html

I personally like the gearing in the Richmond 5 speed but it makes no provisions for the overdrive 5th like in the ZF.

It is in my GT350 and it copies gear spacing as used in high performance T10's. It pulls hard in every gear.

I would use it as a model for gearing the ZF if I had this type of choice.

With it I can only adjust for the final drive in fifth by changing the rear gear ratios.

The -2 ZF has an effective final drive in 5th gear of 2.95:1.

An RBT 6 speed MIGHT be an alternative?



I would think that the 4.22 rear is going to be the easiest and therefore the least expensive ratio to come up with.

The last time I was involved with Pro Stock racing at all was about 1990. At that time there was a dyno computer program where the engine could be run on the dyno, through the 1/4 and the best combination of gears ratios, engine rpm and shift points could be determined for the best ET.

It's an extensive amount of work to determine the best results and combinations but actually to answer your question scientifically would probably be necessary. It produces reams of data that may or may not be useful to you at all?

What software is being run now I don't know. Certainly the BIG F1 teams have been running their engines like this for quite some time.

Exactly how an individual can do this now WITHOUT software is not clear to me. The entire procedure is mind boggling.


The only way I COULD do it now is to make a spread sheet. You are going to need a completely linear induction system though for one thing. Engines tend not to be linear in performance. How much time do you want to invest in this?

Personally I have never seen the point in the RBT 6 speed; It is a couple inches longer than the stock 5 speed, so requires some minor mods to fit, which may not be as big a challenge with a race car and no A/C.

The tall 5th I have in my road going ZF is the same tallest gear available in the 6 speed, but if you look at the ratios and shift points and rpm drop the 5 speed ratios are well spread, the 6 speed just closes them up and adds another shift.

quote:

Originally posted by PanteraDoug:

... The 3.77's that came up "recently" were from a batch of GT40 sets that were in storage from the 60s ...

*** Actually the 3:77 has been available for the dash 2 box forever. The ones for the Ford GT 40 program ( -0 box) is physically a different part not compatible in a dash 1 or 2 box because it is a different length and originally put into the dash "0" ZF from the very first GT 40 cars before going to the dash 1 box. It is shorter therefore the -0 GT 40 part is useless to us. When the dash I box came down the pipe THEN the 3:77 ratio was made in the longer piece that fits dash 1 & 2 ZF's*****