 Need a new transmission...so, what gear ratios?, 2.7L |
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| billh1963 |
 Nov 28 2015, 05:40 PM
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#1
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Car Hoarder!  Group: Members Posts: 3,402 Joined: 28-March 11 From: South Carolina Member No.: 12,871 Region Association: South East States  |
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 |
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| Steve |
Nov 28 2015, 06:40 PM
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#2
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914 Guru Group: Members Posts: 5,569 Joined: 14-June 03 From: Orange County, CA Member No.: 822 Region Association: Southern California 
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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.
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| 0396 |
Nov 28 2015, 06:47 PM
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#3
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Advanced Member Group: Members Posts: 2,046 Joined: 13-October 03 From: L.A. Calif Member No.: 1,245 Region Association: Southern California |
911 / 901 trans. ..AFMSX is a great choice - even in a 3.0
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| billh1963 |
Nov 28 2015, 06:48 PM
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#4
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Car Hoarder! Group: Members Posts: 3,402 Joined: 28-March 11 From: South Carolina Member No.: 12,871 Region Association: South East States |
QUOTE(Steve @ Nov 28 2015, 07:40 PM)  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. 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. |
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| fixer34 |
Nov 28 2015, 07:31 PM
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#5
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Senior Member Group: Members Posts: 1,075 Joined: 16-September 14 From: Chicago area Member No.: 17,908 Region Association: Upper MidWest
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QUOTE(billh1963 @ Nov 28 2015, 05:40 PM) 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 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. |
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| ClayPerrine |
Nov 28 2015, 10:03 PM
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#6
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Life's been good to me so far..... Group: Admin Posts: 15,410 Joined: 11-September 03 From: Hurst, TX. Member No.: 1,143 Region Association: NineFourteenerVille
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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....... |
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| billh1963 |
Nov 29 2015, 06:54 AM
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#7
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Car Hoarder! Group: Members Posts: 3,402 Joined: 28-March 11 From: South Carolina Member No.: 12,871 Region Association: South East States |
QUOTE(ClayPerrine @ Nov 28 2015, 11:03 PM) 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 |
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| Luke M |
Nov 29 2015, 08:03 AM
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#8
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Senior Member Group: Members Posts: 1,369 Joined: 8-February 05 From: WNY Member No.: 3,574 Region Association: North East States
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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. |
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| ConeDodger |
Nov 29 2015, 11:48 AM
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#9
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Apex killer! Group: Members Posts: 23,558 Joined: 31-December 04 From: Tahoe Area Member No.: 3,380 Region Association: Northern California
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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...
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| VegasRacer |
Nov 29 2015, 01:26 PM
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#10
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ELVIRA Group: Benefactors Posts: 8,478 Joined: 27-March 03 From: Between Scylla and Charybdis Member No.: 481 Region Association: None 
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QUOTE(billh1963 @ Nov 28 2015, 03:40 PM) For those with a 3.0, did you use the stock ratios? Are you happy with that? Any input is appreciated. Thank you 3.0 CIS. Stock gears make me happy. (IMG:style_emoticons/default/piratenanner.gif) |
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| old914dog |
Nov 29 2015, 01:30 PM
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#11
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Member Group: Members Posts: 72 Joined: 28-August 04 From: dallas,tx Member No.: 2,643 Region Association: None
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QUOTE(VegasRacer @ Nov 29 2015, 11:26 AM) QUOTE(billh1963 @ Nov 28 2015, 03:40 PM) For those with a 3.0, did you use the stock ratios? Are you happy with that? Any input is appreciated. Thank you 3.0 CIS. Stock gears make me happy. (IMG:style_emoticons/default/piratenanner.gif) 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. |
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| Mark Henry |
Nov 29 2015, 04:06 PM
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#12
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that's what I do! Group: Members Posts: 20,065 Joined: 27-December 02 From: Port Hope, Ontario Member No.: 26 Region Association: Canada |
QUOTE(Luke M @ Nov 29 2015, 09:03 AM) 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. 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 |
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| DRPHIL914 |
Nov 30 2015, 07:20 AM
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#13
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Dr. Phil Group: Members Posts: 5,758 Joined: 9-December 09 From: Bluffton, SC Member No.: 11,106 Region Association: South East States
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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. |
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| Elliot Cannon |
Nov 30 2015, 11:52 AM
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#14
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914 Guru Group: Retired Members Posts: 8,487 Joined: 29-December 06 From: Paso Robles Ca. (Central coast) Member No.: 7,407 Region Association: None
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If you haven't already checked them, it could be something as simple as loose cone screws in the shift linkage.
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| Mark Henry |
Nov 30 2015, 02:48 PM
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#15
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that's what I do! Group: Members Posts: 20,065 Joined: 27-December 02 From: Port Hope, Ontario Member No.: 26 Region Association: Canada |
QUOTE(ClayPerrine @ Nov 28 2015, 11:03 PM) 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....... what size tires are you running? |
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| billh1963 |
Nov 30 2015, 05:50 PM
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#16
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Car Hoarder! Group: Members Posts: 3,402 Joined: 28-March 11 From: South Carolina Member No.: 12,871 Region Association: South East States |
QUOTE(Elliot Cannon @ Nov 30 2015, 12:52 PM) If you haven't already checked them, it could be something as simple as loose cone screws in the shift linkage. Unfortunately, it's not. |
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| billh1963 |
Nov 30 2015, 05:50 PM
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#17
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Car Hoarder! Group: Members Posts: 3,402 Joined: 28-March 11 From: South Carolina Member No.: 12,871 Region Association: South East States |
QUOTE(Mark Henry @ Nov 30 2015, 03:48 PM) QUOTE(ClayPerrine @ Nov 28 2015, 11:03 PM) 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....... what size tires are you running? 205/55-16 |
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| billh1963 |
Nov 30 2015, 05:52 PM
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#18
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Car Hoarder! Group: Members Posts: 3,402 Joined: 28-March 11 From: South Carolina Member No.: 12,871 Region Association: South East States |
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 (IMG:style_emoticons/default/smile.gif)
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| Mark Henry |
Dec 1 2015, 03:24 PM
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#19
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that's what I do! Group: Members Posts: 20,065 Joined: 27-December 02 From: Port Hope, Ontario Member No.: 26 Region Association: Canada |
QUOTE(billh1963 @ Nov 30 2015, 06:50 PM) QUOTE(Mark Henry @ Nov 30 2015, 03:48 PM) QUOTE(ClayPerrine @ Nov 28 2015, 11:03 PM) 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....... what size tires are you running? 205/55-16 (IMG:style_emoticons/default/biggrin.gif) ...sorry I was asking Clay (IMG:style_emoticons/default/wink.gif) |
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| ClayPerrine |
Dec 1 2015, 04:50 PM
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#20
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Life's been good to me so far..... Group: Admin Posts: 15,410 Joined: 11-September 03 From: Hurst, TX. Member No.: 1,143 Region Association: NineFourteenerVille
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QUOTE(Mark Henry @ Dec 1 2015, 03:24 PM) QUOTE(billh1963 @ Nov 30 2015, 06:50 PM) QUOTE(Mark Henry @ Nov 30 2015, 03:48 PM) QUOTE(ClayPerrine @ Nov 28 2015, 11:03 PM) 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....... what size tires are you running? 205/55-16 (IMG:style_emoticons/default/biggrin.gif) ...sorry I was asking Clay (IMG:style_emoticons/default/wink.gif) 225/50/16 in the front. 245/45/16 in the rear. rolling diameter of them matches 165SR15. |
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