Printable Version of Topic

Posted by: porschechuck Apr 12 2007, 09:53 PM

Hi all,
Raced at road Atlanta last month came 4th against H.O. 2.2 sixes with my 2.0 4cyl. But trans issues, running a stock '73 box. On the back straight 4th pulled barely, and 5th was just blaaaah no increase in revs. I need help! We've tigged a diff to create a locker, Mid ohio teener club thanks, but what gears and where can i buy them. thanks for any thoughts and recommendations

Posted by: john rogers Apr 13 2007, 01:55 PM

When I had my four, both stock size and stroker I had "M - S - X" for the top three gears which allowed the engine to rev to top speed faster. Top speed is about 130 to 135 at a track such as Willow Springs or CA Speedway here on the west coast and with stock gearing I would never get out of 4th. When I went to a 2.2L six with less torque band and higher revs we had to go to "K - Q - V" which is lower geared but lets the revs work better. I would be concerned about running a locker diff when road racing as it you break an axle the car will usually turn the opposite side with little control. Most of the vintage racers out heer use either a Quaiff or GT limited slip. Good luck with the trans.

Posted by: race914 Apr 13 2007, 01:59 PM

Here is a previous thread with some good info on regearing a 901: http://www.914world.com/bbs2/index.php?act=ST&f=45&t=60883

In that thread I posted an excel spreadsheet that you might want to look at. You can do all sorts of "what if" gear combos. I have two gearboxes right now:

A-F-Ka-Q-V and A-F-M-S-X

The 1st box is getting a Ga second gear as my next improvement...

I got my gears at High Performance House 650 364-6234 Ask for Rich, he can help you select the right gear combos for your car/track.

Posted by: SirAndy Apr 13 2007, 10:37 PM

Posted by: bam914 Apr 15 2007, 07:57 AM

I have a 4.8 final drive for sale that might help your problem. Let me know

Posted by: Dan (Almaden Valley) Apr 15 2007, 10:17 AM

Greg, are you using a stock ring and pinion with stock final drive...?

I have been considering a A,F,Ka,R,Z box for my 2056 build.

Anyone out there done this one?

Ka is a stock ZD flipped
R is a stock V flipped
Z is a stock N flipped.

this way I would not need to buy any gear sets...just use what is already in the tranny.

New motor should be good for about 6K rpms. maybe 6200.

with this box there would only be about a .4 gear ratio drop from 2nd to 3rd and 3rd to 4th.

here is a sheet with the stock vs custom gearing


Attached File(s)
 gear_ratios_from_stock_gears.txt ( 618bytes ) Number of downloads: 139

Posted by: race914 Apr 15 2007, 08:59 PM

Hi Dan,

I'm using the stock ring & pinon. The Ka-Q-V works great for Laguna. The M-S-X works great for Thunderhill & Buttonwillow.

Your idea sounds interesting. Did you run those ratios through the gear spreadsheet?

I don't have it on this PC or I'd run your gears for you. I'll do it tomorrow morning if you don't have the sheet.

Greg

Posted by: race914 Apr 16 2007, 09:49 AM

Hi Dan,

Here are the gear sheets.

Your A-F-Ka-R-Z looks pretty good for not having to buy any gears!

 gearcalc_A_F_Ka_R_Z.xls ( 32.5k ) Number of downloads: 202


Here is my A-F-Ka-Q-V box that works fantastic at Laguna and you only need to buy a Q gear (Ka flipped 5th, Move V fourth to 5th) Downside of this box is 5th is too low for Thunderhill, Buttonwillow, etc. Your Z fifth would make is a good box for all tracks we run!

 gearcalc_A_F_Ka_Q_V.xls ( 32.5k ) Number of downloads: 211



Greg

Posted by: Dan (Almaden Valley) Apr 16 2007, 03:37 PM

thanks for that info Greg.

good all around box for the tracks GGR frequents.

this might help with the RPM drop from 2nd to 3rd and 4th to 5th, compared with stock gearing.

Posted by: Aaron Cox Apr 16 2007, 04:51 PM

I run a Ka S ZD box (kept stock ZD for overdrive and driveability. not a trailer queen yet)

flies on the street and pulls like a freight train to 90 in 4th, choose a shorter 5th gear to complement it

Posted by: stownsen914 Apr 17 2007, 09:44 AM

There's only one problem with flipping a stock V 4th/5th ratio to get an R ... you've now got an R 3rd gearset (not 4th). Flipping the ZD and N gearsets does work as you suggest.

Posted by: Aaron Cox Apr 17 2007, 11:53 AM

you can flip 3rds to 5th's and 2nd gears to 4th gears.... no intermingling allowed.

Posted by: porschechuck Apr 19 2007, 02:56 PM

Thanks to everyone for your help so far. Ok I've fliped and switched 3rd and 5th, but now when I tighten the nut and bolt on the pinion and input shafts it locks up. I kept all the parts with their respective shafts and everything goes on right. Any Ideas, has anyone actually got a box where they flipped fifth down to third and it works? I have had several folks say the took an extra third to create the "Z" but no one here on the left coast has done the flipped fifth. Thanks again for all your help
Chuckster
70 914-6
73 914 GT5 r/s
82 911SC euro

Posted by: Van914 Apr 20 2007, 06:25 AM

Chuckster,
I did mine last year. Flipped 5th and 3rd used a S for 4th. No problems and it really helps the revs at the track. Great at Mid-Ohio and Putnam.
Van914

Posted by: porschechuck Apr 20 2007, 03:38 PM

Hi everyone,
As homer says doh! I had one of the thrust washers in the wrong spot. WOrks fine now. Anone have an extra M or S gearset they want to sell Pm if you do. I'm going to run the A, F, KA, V, Z with the locker and see what that does
Thanks again for all the great advice!