My '72 with a 2.7 six is back.

The engine is running great. However, the gear box is so shitty it's not even worth driving. I've owned a lot of 914's and never had a gearbox so bad. I tried to go for a drive today and made it about 2 miles before I gave up and headed home. I felt like leaving it on the side of the road for the trash collector. Seriously,it's that shitty.

The couple times I found second gear it wanted to crunch so I think I'm going to just rebuild it (of course all the shifter bushings and everything related to shifting will be gone through and updated).

So, I've looked at several threads and even found some charts of gear ratios/rpm/speeds.

For those with a 2.7 or 3.0, did you use the stock ratios? Are you happy with that? What would you change?

I'm thinking of changing fifth gear to cruise around 2800-3000 rpm at 70mph. Will that give me enough fan speed to keep the oil cool? I do NOT have an external oil cooler.

Tires size is 205/55-16

Any input is appreciated. Thank you

I had a 2.7 with webers and headers and I was happy with the stock gears. I also drove a stock 3.0 with stock injection and also thought the stock gears were fine. It wasn't until I upgraded to the 3.2, that I thought the stock gears were all wrong. I have since upgraded the stock trans with a late 915 gear box to better match my 3.2 motor. Couldn't be happier, but the 915 gear box does not shift as easy as a 901.

911 / 901 trans. ..AFMSX is a great choice - even in a 3.0

Thanks, Steve.

I think the 901 will be fine for the hp of the 2.7. I think a 915 would be overkill for my needs.

I do like the idea of dropping the RPM at highway speeds; albeit, not at the expense of oil cooling.

According to the RPM/MPH graphs in the back of my -6 owner manual, 70mph comes on right around 3000rpm, so a stock -6 trans should be fine.

Mine is geared with A,F, Flipped ZD, S, ZD. I had an HB in for fifth, which gave me 3K at 80MPH, but I found that for driving at 60 mph, 4th spun the motor too fast, and the temp started to climb, and 5th spun lugged the motor, and the temp started to climb. This is with a 2.4 S cammed motor.

I put the stock /4 ZD in for 5th, and I had no temp problems after that.

I have thought about using the stock /6 gear set I have, but I probably won't do that. I am trying to put a 3.6 in my car, and I am planning to use a Boxster 6 speed with it.

The /6 gear set is for sale.......

Clay...sent you a PM.


From research:
914-4 914-6
11:34 11:34 1st
18:34 18:32 2nd
23:29 23:28 3rd
27:25 27:25 4th
31:22 29:22 5th
ring and pinion gear: 7:32 (Same on both)


Rennlist 901 and 915 gear ratio tables


Based on the ratios given I listed above and the rennlist chart link shown, would a 6 gear stack be: A GA O V ZA ?

901/06 A HB S Z
901/07 A F M U ZD
901/75 B GA M T Y
901/76 AA E I M O
901/77 AA F J O S
901/78 C HA O T Y
901/79 B HA M R V
901/12 A HB S Z
901/13 A F M U ZD
901/80 B GA M T Y
901/81 AA E I M O
901/82 AA F J O S
901/83 C HA O T Y
901/84 B HA M R V

911/00 A HB S ZA
911/01 A GA O V ZA
911/80 B GA M T Y
911/81 AA E I M O
911/82 AA F J O S
911/83 C HA O T Y
911/84 B HA M R V

914/11 A F N V ZD
914/12 A F N V ZD

915/10 AZ HW OR SN
915/00 AZ HX NT QP TM
915/01 AZ HX NT QP TM
915/12 AZ HW OR SN
915/02 AZ HX NT QP TM
915/03 AZ HX NT QP TM
915/10 AZ HW OR SN
915/11 AZ HW OR SN
915/13 AZ HW OR SN
915/08 AZ HX NT RP TM

The factory 6 gear ratios are : A GA O V ZA

There's some good info here:

http://www.blueskymotorsports.com/index.ph...17&Itemid=6

I rebuilt my brothers and my trans with the following gear ratios : A, GA, O, X, flipped H. I came up with these ratios after talking with Mike , AKA Dr. Evil.
I took his recommendation on the ratios but have yet to drive the car.
My brothers car will run a hot 3.0 6 and my 6 will get a 2.7 RS spec engine.
If for whatever reason I don't like the ratios, I have a spare box with A, GA, O, V, ZA that I can install. I also have a few other gear ratios that I can swap around if need be. It all comes down to how you plan to use your car. I have a box set aside for Auto-x ( A, F, M, S, X ) so the above ratios will be a street box.

My 901 before the six was a an M/S - 3/4. Preserving the stock 5th gives you an overdrive gear. Though with all of the instrumentation I had it was alarming to watch the head temps rise when cruising in 5th. This was with a Type IV so not sure that would be a problem with a 6...

3.0 CIS. Stock gears make me happy.

I vote with Clay. I have a 3.2 with his gears and like him I tried a "tall" 5th gear, but returned to a stock Zd. There is no wrong choice.....if engine is ok.

I'll be trying A,F,O,X, HB (filpped) that is in trans#1.

Trans #2 is all stock 914/4 gearing and is my back-up.

I haven't tried it yet, but that is for a hot street carbed 3.0/6

Bill,

as you know, when we rebuild our transmissions for the IV's- 901 - at Evil's clinic at Scotty's a few years ago, I changed my 4 and 5 both, x & ha flipped I believe.
I like it for around here on the flat, and end up in 4th all the time when cruising between 55-60, 5th is nice on the interstate and I get great milage, but when up in the hills I don't like the increased gap between 3 and 4. If I lived up there I would probably drop back to a stock 4 and just a slight tick up on the 5th,. I think driving in to work today, at 70(in a 60 zone- that's with the flow of traffic) i'm well below the 3000rpm, I think that actually if I stay near the 60 mph my rpm in 4th is close to the 3000. (EDIT): just checked at lunch, 4th is 3200rpm at 60mph.-

don't know if that helps....

fyi - tire size, i'm running the 205/55 16" tires/rims and that's just a bit taller than stock. when I ran the smaller tires of course, rpms were lower, - I did also see those temps rise on the freeway with the lower rpms too, and will be putting a external oil cooler in before summer.

If you haven't already checked them, it could be something as simple as loose cone screws in the shift linkage.

what size tires are you running?

Unfortunately, it's not.

205/55-16

I'm buying a 6 gear set from Clay. Dr. Evil will build the box for me with new bearings...this should make me a happy camper

...sorry I was asking Clay

225/50/16 in the front.
245/45/16 in the rear.

rolling diameter of them matches 165SR15.