Well, the more I drive my teener... the more I realize... the gearing is less than "ideal" for my driving preference/style.

I've found, especially when driving around the twisties, I'm always right in the middle of second and third. As far as I know, I just have a STOCK 914 tranny.

Is there any alternatives for this? I'm sure I could use a tranny rebuild soon, as my first gear synchro is going anyway.

Trying to decide which way to go now...

You should have made the drive to the Dr. Evil Clinic

There were a couple of guys who re-geared.


T

Thanks, but that wasn't in the schedule for me. I'm in SOCAL.

C:>

Yep, I know just a

That said Rubber Boa did drive down from Oregon for the event. I am sure Dr. Evil will chime in here soon...

T

Chris was at the clinic and was talking about doing some gear changing. Something about flipping 3rd and 5th and swapping them. That would give you a lower 3rd and lower 5th. Not sure what he was doing for 4th. maybe he'll chime in when he gets back from the snow.

Either make more power or or flip a ZD 5th into 3rd spot.
I did both and it rocks.

Here is a gear chart for ya to consider. Let me know if I can help you with your tranny or rebuild it for ya.

Here are 2 graphs: Stock vs flipped ZD in 3rd. Flipping a ZD and adding it is cheap and easy and it puts your lower 3 gears closer together as demonstrated in the graph.

Thanks for the reply. Some good stuff in there. How's your 6 surgery coming along?

The 6 is still awaiting parts. I told Clayton (Twystd1) to enjoy his holiday season instead of locating me a part. He will likely look for the part this week and get beck to me. I have all the new seals and stuff and it is ready to go.

Good info above!

To help me assimilate and analyze all of the data I put this excel sheet together to help me "see" the shiftpoints and RPM/MPH range for each gear as compared to stock.

This model lets you build a 'virtual' gearbox with your tire diameter and your shift points to see if it meets what you are expecting (e.g. getting that 'right' gear in between your stock 2nd & 3rd)

Click to view attachment

Also, here's a short write-up on one way to approach a re-gearing project. Definitely not the only way.. and probably not the best way, but it's the way I did it.

Click to view attachment

I used this excel sheet and approach to build two 901 boxes, a Ka-Q-V and a M-S-X and got exactly what I expected from the model runs. No suprises! No 'do overs'!

Hope this info helps

easiest way to change your gearing is with tire sizes. In most instances, it is also the cheapest. Tearing into a 901 and regearing is nearly as costly as regearing a 915 box. Not to mention the cost of gears for 901 boxes... Porsche sells original gearstacks AFAIK with the stock drive ratio. As for the other gears, no clue.

Not necessarily, I sell ZD sets for $50 and can install them for far less than a new set of wheels ($150 if you send me the stack). If there is other work to be done in the box then the cost may increase, but it has nothing to do with the gear swap at that point. Carquest sells gears as well, but at a significant premium (especially compared to me).

I am thinking of doing a A F ZD S ZD in my box for AX. I want the other ZD for fifth because I drive to the event and don't want to burn out m transmission. How does this sound to you AX gearbox gurus? What would you do? I have all stock gears plus a S and M and X. If it sounds good or you disagree please tell me as I would love to know your thoughts before I do it. Oh, and I have five boxes to work with so I do have multiples of every gear.

Please let us all know how it goes I am always interested in hearing how different gearings work out.

Will do, but if anyone has any other gearing advise or something that may work better please let me know. Oh, and remember that there is a torque biased diff with this as well.

The simplest answer has been overlooked...Go Faster.

Wow, Greg, race914, just sent me a sheet on what it would look like if I were to do the gearing I would like. Looks good to me Thanks a lot Greg.

Glad to help!

Here are the charts generated by the gear ratio sheet available for download a few posts up

Click to view attachment

We AX gurus look at things a bit different.

Look at your most frequently run AX venue. What is the top course speed on average?
Does it (like many SCCA courses) have a slower starting section?
What do I need to cover this land with the least amount of shifting?
Can I shift my 901 down into 1st at any speed (no exceeding redline,eh)?
How many rpms can I turn with with my motor?

Now look at a gear chart........

I've got a gear stack ready to stuff in the back of my 914 with ZD flipped for 3rd gear and the V 4th gear flipped to make a R ratio gear.

Do you guys call the flipped ZD the "KA" gear?

I think the lower ratio 3rd will be cool to handle curves that would keep 2nd near redline. We'll see! I'll be sure to report back when it is working

Yes, the KA is the flipped ZD. I agree with you. I think it will be better to be in third also for the carbs. I hate going around some corners when you get hesitation because the carbs are fuel starved from the Gs.Keeping it al a lower RPM I would think would help eliminate that.

Chris,
that will add a few mod points

I spend 90% of my AX time in 2nd gear. Here's a short vid of the only 3rd gear blast I can remember. As you can see from the corner entry after the "straight", I'm not used to that. IIRC, this was before I did some gearing changes to first & second.

http://www.youtube.com/watch?v=DSZZ6LuN7fI#GU5U2spHI_4

Hey JP... You have to remember the whole HP thing too. I have much less than you do, and I have been in third a few times this last year. If the gears would have been the way the sheet shows my times would have been much better. I know on a few of the courses I lost at least a second if not two.

you can,t flip 4th gear V into 4th gear R,maybe i am building a box with AFIQX,i have to many projects

Here's the swaps you can do from 3rd gear ratios and 4th/5th gear ratios.

Click to view attachment