Here is the latest gearbox I am building for someone. It is an F-N-X-HBf box and I wanted to show how easy it is to lock out 1st in a 4 speed box. I have heard that there are people that charge a chunk of change to do the same thing....I think that is wrong as it is way easy. All you need is a rear gasket, tubing cutter and a section of 3/8" copper tubing (1/2" shown as I bought the wrong size).

Here is the FNXHBf stack (Ooo, purdy).
Click to view attachment

Here is the shift rod end for 1st that needs the sleeve to lock it out. I removed 1st gear completely other than the gear on the input shaft as you need it for reverse.
Click to view attachment

And here is the section of ~2" copper tubing. You need to keep the slider for revers. It looks like the sleeve will hit the slider, but it is just the angle of the pic. Click to view attachment

This could easily be done by anyone with limited experience.

Cool Evil...

I did the same thing to mine. Also installed an H gearset and fliped the others.
Very easy procedure. These are so easy to work on why would anyone pay someone to do it for them?

David

Is that the one we did at my place last month or another using the same method?

Cool stuff either way

T

Nope, this is a different box.

I agree ............Really no trouble at all to flip the gears and install a H gear. I didn't bother with blocking off the first gear,just don't use it for anything.

Bob

I was referring to the lockout modification as being easy and not worth paying big $$ for, I still understand when someone pays ME to do thier gearing and such.

When you guys say that you flipped other gears, what combo do you like best?

When Brad Mayeur did mine, he said it was no big deal, I can see why now.
I have the F- flipV-flipN-flipH setup, can't complain so far. Been running over 400 HP through for a while now. Nothing like hitting 100 in 2nd.

Mark

That seems like a tight grouping in the upper gears. Quite a bit of distance between 1 and 2 as well according to my chart.

What tire size are you using in your charts? 245/50?

Tire diameter of 25"

So based on this info, with a 26" tire, and a 7k rev limit... we could hit 60 in F gear? on a stock 901?

Dang, I am really short shifting.... Think of the 0-60 times... mid 3's!!

I think mine is a (1st gear delete) tight 1st, second, and third group. Then 4th is a big jump, a flipped H for freeway cruising.

Running errands has never been more fun.

Dr. Evil, I really like your ratio charts.

Is there a way to tell what gears I have by rotating the input shaft and counting rotations of the output shaft? or visa-versa? I'm curious what my 2 backup trans axles are running.

I would imagine so. The ratio of turns of the input shaft to turns of the output flange will give you a ball park of what you have. I have never tried it, but it may be quite accurate. Give it a shot and post your results and we can figure it out.

the chart that I am using is from Carquips web site. I down loaded it and then I plug in the gears and save the chart. Any combos you want ot see, just let me know and I will post it.

You like the short 1-2-3 and a long drop to 4th? I was under the impression that with the F-N-X-HBf that it would be smoother as the shifting is the same from gear to gear. If the preference is for the shorter 1-3 then I should let my customer know so I can see if he still wants to buy the X gear from me to make the pattern I felt was best.

25" wheels. With 26" wheels you will hit 70 faster, if you have the torque to pull it off.

More thoughts. It also depends on your power plant as you all know I am sure. All V8s are not the same. The engine I am building the box for is 200+ hp and peters out at 4200 rpm. So the shift points you get with my set up in this box are about:
-1st shift at 4K gets you to 35mph and 2nd at about 2.3k
-2nd at 4k gets you 63 mph and 3rd at 2.9k
-3rd at 4k gets you 85mph and 4th at 3K
-4th at 4k gets you 115mph with room to go to 183 mph (theoretically)

Looks good to me Mike....


thanks..


Michael

If we have the tq... is that a joke?

Hey Doc, are you still rebuilding 1st gear lock out 901s without the 1st gear installed? Have you encountered any issues with this method or is this your preferred way to setup a locked out 901?
I like this idea just installing the hunk of metal 1st gear spacer without the gear or needle bearing, but just want to make sure I'm not going to run into issues down the road.

. . . use one of these from a '65-'66 911/912 or a '67-'68 912 for your 4 speed modification . . . .

Click to view attachmentClick to view attachment

WANT

Never an issue. Toss 1st gear, keep the race as a spacer, and put a section of tube on the shaft so that 1st position is locked out. Easy

For those of us running a locked out first gear and taller gears: Is it easy to revert back to 5 speed and gear ratios for a turbo Suby?

Very easy. No special nothing needed.

Thats what I hoped, I'll give it a try. Thanks Doc.

BTW, anyone who doesn't own the Evil rebuild DVD is missing out big time. Didn't realize rebuilding a 901 would be so hilarious. Nice work

Thanks for the endorsement, Mark

who has best price on this knob???

found this...
http://www.autoatlanta.com/Porsche-Shift-K...0142401300.html

thanks
jim