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Posted by: Dr Evil Feb 25 2008, 05:53 PM

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).


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.


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.

Posted by: Dr Evil Feb 25 2008, 05:54 PM

This could easily be done by anyone with limited experience.

Posted by: So.Cal.914 Feb 25 2008, 06:00 PM

Cool Evil...

Posted by: dwillouby Feb 25 2008, 06:11 PM

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

Posted by: Trevorg7 Feb 25 2008, 06:12 PM

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

Cool stuff either way

T

Posted by: Dr Evil Feb 25 2008, 06:23 PM

Nope, this is a different box.

Posted by: BIGKAT_83 Feb 25 2008, 06:30 PM

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

Posted by: Dr Evil Feb 25 2008, 06:43 PM

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.

Posted by: Dr Evil Feb 25 2008, 06:44 PM

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

Posted by: marks914 Feb 25 2008, 07:35 PM

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


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Posted by: Dr Evil Feb 25 2008, 08:09 PM

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.


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Posted by: rick 918-S Feb 25 2008, 09:22 PM

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

Posted by: Dr Evil Feb 25 2008, 09:29 PM

Tire diameter of 25"

Posted by: Andyrew Feb 26 2008, 12:37 AM

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!!

Posted by: Dr. Roger Feb 26 2008, 02:38 AM

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.

Posted by: Dr Evil Feb 26 2008, 08:23 AM

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.

Posted by: Dr Evil Feb 26 2008, 08:24 AM

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

Posted by: Dr Evil Feb 26 2008, 08:47 AM

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)

Posted by: michaelt55 Feb 26 2008, 09:04 AM

Looks good to me Mike....


thanks..


Michael

Posted by: Andyrew Feb 26 2008, 07:53 PM

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

Posted by: slothness Feb 27 2012, 02:52 PM

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.

Posted by: type47fan Feb 27 2012, 03:21 PM

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

Posted by: slothness Feb 27 2012, 03:22 PM

WANT

Posted by: Dr Evil Feb 27 2012, 03:42 PM

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

Posted by: matthepcat Feb 27 2012, 03:48 PM

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?

Posted by: Dr Evil Feb 27 2012, 03:57 PM

Very easy. No special nothing needed.

Posted by: slothness Feb 27 2012, 05:36 PM

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

Posted by: Dr Evil Feb 27 2012, 09:05 PM

Thanks for the endorsement, Mark

Posted by: jimkelly Sep 25 2015, 01:10 PM

who has best price on this knob???

found this...
http://www.autoatlanta.com/Porsche-Shift-Knob-Push-On-Type-Fits-1967-1971-4-Speed-Parts-PN-B90142401300.html

thanks
jim