Converting a 901 side shift to a 4 speed. |
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Converting a 901 side shift to a 4 speed. |
9144me2enjoy |
Nov 26 2019, 06:35 PM
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#1
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Member Group: Members Posts: 310 Joined: 19-June 18 From: Oregon Member No.: 22,240 Region Association: Pacific Northwest |
I have a 74-914 with a 4 cyl Raby engine 2270cc. It has the 901 side shift trans. Tired of the dog bone pattern. What would it cost to go to a 4 speed, 1st to 2nd position and make the smaller gear integral with the main shaft and possibly replace 4th gear with a lower highway ratio gear for mileage. I know this is common with V8 conversions etc. What is your thoughts. Thanks
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mepstein |
Nov 26 2019, 07:15 PM
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#2
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914-6 GT in waiting Group: Members Posts: 19,258 Joined: 19-September 09 From: Landenberg, PA/Wilmington, DE Member No.: 10,825 Region Association: MidAtlantic Region |
It’s pretty expensive to do since our trans have a non removable 2nd gear. You need to buy a 904 mainshaft and gear. Runs about $1,500-2k.
The other method is something my friend used to call a baby turbo box. He would take a 4 speed 911/912 box and switch the end with a 914 tail piece. He felt it worked well. Personally, I don’t mind the dog bone. An early 914 was my first car so everything feels normal to me. Even the vague shifting and reaching to the dash to turn on the wipers. I think what is common in V8 Chevy conversions is to start out in second using the torque of the engine and just use first for creeping along at slow speed. |
sixnotfour |
Nov 26 2019, 07:18 PM
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#3
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914 Wizard Group: Members Posts: 10,428 Joined: 12-September 04 From: Life Elevated..planet UT. Member No.: 2,744 Region Association: Rocky Mountains |
901 4sp flip the ring gear done..how many ..4 speads you want ??
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9144me2enjoy |
Nov 26 2019, 07:21 PM
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#4
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Member Group: Members Posts: 310 Joined: 19-June 18 From: Oregon Member No.: 22,240 Region Association: Pacific Northwest |
Sounds like 1) leave things alone if it isn’t broken and just start off in 2nd or 2) flip the Ring gear. Thanks again!
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theer |
Nov 26 2019, 08:13 PM
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#5
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Senior Member Group: Members Posts: 676 Joined: 31-July 15 From: Dover, MA Member No.: 19,014 Region Association: North East States |
As Mark says, the V8 guys will lock out first and just use 2-5 in the H-pattern
And... uh... isn’t a dog-leg pattern? |
9144me2enjoy |
Nov 27 2019, 10:39 AM
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#6
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Member Group: Members Posts: 310 Joined: 19-June 18 From: Oregon Member No.: 22,240 Region Association: Pacific Northwest |
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mepstein |
Nov 27 2019, 10:47 AM
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#7
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914-6 GT in waiting Group: Members Posts: 19,258 Joined: 19-September 09 From: Landenberg, PA/Wilmington, DE Member No.: 10,825 Region Association: MidAtlantic Region |
I'm not sure what flipping the ring gear will do unless you use a 914 tail cone.
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thelogo |
Nov 27 2019, 10:54 AM
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#8
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Senior Member Group: Retired Members Posts: 1,510 Joined: 6-April 10 Member No.: 11,572 Region Association: None |
Its already a 4 speed
Just block off 1st gear ...ye old (Mental block ) (IMG:style_emoticons/default/screwy.gif) How hard is that ? But i dont have a raby engine so i guess you have cash to burn ? Lugging a higher highway gear ..not good for the engine imho or mpg or any temp etc with this engine Ask jake ? My 2332 /4. Is on the stock 901 I guess highway gearing 5th is a little short But keeps me from getting arrested Shout out to the cheap sob And happy Thanksgiving to all you other Just : sob Its raining so that canceled my plans To take out my 914 and go 91mph down the 91 freeway with a hot number in the other seat . a drink in my hand and a big cigar . But maybe next Thanksgiving |
Superhawk996 |
Nov 27 2019, 01:21 PM
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#9
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914 Guru Group: Members Posts: 5,784 Joined: 25-August 18 From: Woods of N. Idaho Member No.: 22,428 Region Association: Galt's Gulch |
Not trying to be quite as outspoken as Thelogo but . . . .
The dog leg transmission was a defining characteristic of the early 911's and it carried into the 914 via the 901 transmission. Why would you want to change it? It is part of what makes a 914 different from most other vehicles on the road. Remember that in 1970 a Porsche 914 had a 5 speed transmission at a time when most domestic OE's had a 3 on the tree . . . or maybe a floor mounted 4 speed if it was "fancy" for crying out loud. The main idea of the dog leg transmission is that competition oriented vehicles had a transmission that only used 1st gear to launch the car at the starting line. The rest of the racing was done in 2-5 gears. Don't get me started on how Porsche came to forget their own roots . . . I've already made an ass of myself engouh over on the other thread. (IMG:style_emoticons/default/happy11.gif) Think a 914 is a PITA to shift? By all means don't buy a Ferrari with a gated dog leg transmission shifter. (IMG:style_emoticons/default/lol-2.gif) Per Thelogo's and Mepstein's posts; Just don't use 1st gear if you have enough torque to launch in 2nd. Still don't like it? I guess you go find and old Hewland, Muncie, or ZF transmission and do a swap? |
Mark Henry |
Nov 27 2019, 09:40 PM
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#10
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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 |
... and possibly replace 4th gear with a lower highway ratio gear for mileage. I know this is common with V8 conversions etc. What is your thoughts. Thanks You have to remember that the T4 doesn't like to be lugged and you have run about 3000 rpm + to get proper cooling from the fan. With a performance T4 engine on the street you have to keep this in mind because you will be tempted to run at 2k to 2800rpm. The oil temps will look good but even the slightest incline will send head temps soaring if you're lugging the engine. V8 engines are WC and can handle low rpm cruising. |
gms |
Nov 27 2019, 10:22 PM
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#11
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Advanced Member Group: Members Posts: 2,695 Joined: 12-March 04 From: Chicagoland Member No.: 1,785 Region Association: Upper MidWest |
I built a 4-speed for my race car, just block out first gear and add appropriate gear ratios for the rest.
I used A-H-P-X |
ClayPerrine |
Nov 27 2019, 11:28 PM
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#12
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Life's been good to me so far..... Group: Admin Posts: 15,443 Joined: 11-September 03 From: Hurst, TX. Member No.: 1,143 Region Association: NineFourteenerVille |
(IMG:style_emoticons/default/agree.gif)
Porsche actually made a 4 speed version of the 901 for some early 911s. Not a big deal to do, just a different main shaft with a fixed A gear, and a special replacement for the old 1st gear with just the reverse slider. I have the pieces in one of my boxes of trans parts. |
Mark Henry |
Nov 28 2019, 10:47 AM
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#13
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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 |
My 914/6 3.0 conversion is custom geared A, F, O, X, HB (flipped).
I can easily use it as a 4 speed for jack rabbit starts, but having the granny gear 1st comes in very handy for stop and go traffic, line ups, starting on grades, parking, etc. The flipped HB is one tooth shorter than the H that V8 guys use, following the aircooled 3K rpm rule and stock height tires I can only use it at 90 mph and over. For street use with an aircooled engine would make an H gear all but useless. |
ClayPerrine |
Nov 28 2019, 10:58 AM
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#14
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Life's been good to me so far..... Group: Admin Posts: 15,443 Joined: 11-September 03 From: Hurst, TX. Member No.: 1,143 Region Association: NineFourteenerVille |
My 914/6 3.0 conversion is custom geared A, F, O, X, HB (flipped). I can easily use it as a 4 speed for jack rabbit starts, but having the granny gear 1st comes in very handy for stop and go traffic, line ups, starting on grades, parking, etc. The flipped HB is one tooth shorter than the H that V8 guys use, following the aircooled 3K rpm rule and stock height tires I can only use it at 90 mph and over. For street use with an aircooled engine would make an H gear all but useless. My 2.4 has a custom geared 901, A, GA, Fiipped ZD, S, ZD. I found the HB I had in 5th kept me from running 60 mph. I could run over 60, or below 60 but not at 60. It would overheat. Fan was turning too slow in 5th, and too fast in 4th. Changed 5th for the ZD, and it was fine. |
sixnotfour |
Nov 28 2019, 11:24 AM
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#15
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914 Wizard Group: Members Posts: 10,428 Joined: 12-September 04 From: Life Elevated..planet UT. Member No.: 2,744 Region Association: Rocky Mountains |
(IMG:style_emoticons/default/agree.gif) Porsche actually made a 4 speed version of the 901 for some early 911s. Not a big deal to do, just a different main shaft with a fixed A gear, and a special replacement for the old 1st gear with just the reverse slider. I have the pieces in one of my boxes of trans parts. 70-71 mag case, pull clutch 911/00 4 7:31 A HB S ZA 1969 912 mag case push clutch 902/04 902.300/14 4 7:31 A H Q X Attached image(s) |
9144me2enjoy |
Nov 28 2019, 12:14 PM
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#16
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Member Group: Members Posts: 310 Joined: 19-June 18 From: Oregon Member No.: 22,240 Region Association: Pacific Northwest |
Great feedback, thanks........we will see. I think for now I will leave the 901 like it is, make sure all the shaft connections are in good shape and see how it lugs and pulls using 2-5th. Watching head temps. I have a message off to Raby on his suggestion, will see.
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Mark Henry |
Nov 28 2019, 01:17 PM
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#17
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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 |
For a T4, stock or performance the stock 914 gearing is pretty damn good, IMHO not worth messing with it if you're using about stock tire height and mostly for the street.
I have a T4 2600cc in my '67 bug with a 911 (901) 5 speed trans, 195/65-15 tires and I built it with all stock 914 gear ratios. |
9144me2enjoy |
Nov 28 2019, 09:09 PM
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#18
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Member Group: Members Posts: 310 Joined: 19-June 18 From: Oregon Member No.: 22,240 Region Association: Pacific Northwest |
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