Regearing for a longer 5th gear, is it a reasonable thing to do? |
|
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG.
This site is not affiliated with Porsche in any way. Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners. |
|
Regearing for a longer 5th gear, is it a reasonable thing to do? |
SGB |
Nov 28 2006, 08:14 PM
Post
#1
|
just visiting Group: Members Posts: 4,086 Joined: 8-March 03 From: Huntsville, AL Member No.: 404 Region Association: South East States |
(IMG:style_emoticons/default/piratenanner.gif)
I'm getting a tranny for christmas! (IMG:style_emoticons/default/chair.gif) (IMG:style_emoticons/default/chairfall.gif) no really, DR EVIL is rebuilding the ol' 901 for me, and I've been thinking (IMG:style_emoticons/default/bootyshake.gif) with my brain that a longer 5th gear would be really nice. (IMG:style_emoticons/default/driving.gif) With a speed limit of 70 (usually traveled by EVERYONE at 80), my car gets pretty buzzy after a while. I know it can be done, and if I ever was going to do it.... A flipped 904 "I" 5th gear might work.... of course I've already been advised that cubic dollars are needed AND another mainshaft. I'm just dreamin'... Somebody slap me with a reality stick. What else would be involved in this? Who has details? Or better, who has a 904 5th gear lying around needing a home? |
Aaron Cox |
Nov 28 2006, 08:15 PM
Post
#2
|
Professional Lawn Dart Group: Retired Admin Posts: 24,541 Joined: 1-February 03 From: OC Member No.: 219 Region Association: Southern California |
with at type 4 bad idea...
what size tires? ZD with short tires should keep you in the 3000 rpm range at 70... bad idea |
Aaron Cox |
Nov 28 2006, 08:16 PM
Post
#3
|
Professional Lawn Dart Group: Retired Admin Posts: 24,541 Joined: 1-February 03 From: OC Member No.: 219 Region Association: Southern California |
BTW - you flip a second gear from a 4 speed 901/902 to get a taller 5th
2nd in a 4 spd... is the same position as third in a 5 speed... THUS the flipped 5th into 3rd for a short third (i love it) what size tires? are you gonna make me post my chart again? you wont cool well enough at high speeds without some rpm to turn the fan..... |
SGB |
Nov 28 2006, 08:17 PM
Post
#4
|
just visiting Group: Members Posts: 4,086 Joined: 8-March 03 From: Huntsville, AL Member No.: 404 Region Association: South East States |
They are 50 series tires. Is ZD what is in there now?
|
Aaron Cox |
Nov 28 2006, 08:19 PM
Post
#5
|
Professional Lawn Dart Group: Retired Admin Posts: 24,541 Joined: 1-February 03 From: OC Member No.: 219 Region Association: Southern California |
ya made me do it!
here is the chart i config'd for my motor/gears/tire size grey shading is stock gears.... A F N V ZD ill try and find the one with the flipped H,HA, and HB gears.... Attached thumbnail(s) |
SGB |
Nov 28 2006, 08:19 PM
Post
#6
|
just visiting Group: Members Posts: 4,086 Joined: 8-March 03 From: Huntsville, AL Member No.: 404 Region Association: South East States |
I've alway had fine cooling, and could compensate with bigger main jets in the webers.I wanna see that chart? Is it big and UGLY? WIll it shut me up?
|
SGB |
Nov 28 2006, 08:20 PM
Post
#7
|
just visiting Group: Members Posts: 4,086 Joined: 8-March 03 From: Huntsville, AL Member No.: 404 Region Association: South East States |
AAAARGGHH!!!
|
SGB |
Nov 28 2006, 08:21 PM
Post
#8
|
just visiting Group: Members Posts: 4,086 Joined: 8-March 03 From: Huntsville, AL Member No.: 404 Region Association: South East States |
but its kinda COOL. |
Aaron Cox |
Nov 28 2006, 08:22 PM
Post
#9
|
Professional Lawn Dart Group: Retired Admin Posts: 24,541 Joined: 1-February 03 From: OC Member No.: 219 Region Association: Southern California |
your head temps will go up with less RPM turning the COOLING fan (IMG:style_emoticons/default/smile.gif)
|
Dr Evil |
Nov 28 2006, 08:27 PM
Post
#10
|
Send me your transmission! Group: Members Posts: 23,032 Joined: 21-November 03 From: Loveland, OH 45140 Member No.: 1,372 Region Association: MidAtlantic Region |
ZD is what is in there now. I do not see how smaller tires will cause lower RPMs, Aaron (IMG:style_emoticons/default/huh.gif) If you put larger profile tires on your car you will lower your RPMs, not the other way around. Like a said before, you should be at 4000rpm at 89MPH in stock form. the 50 series tires should only bump the RPMs up a bit. Our engines are not like the water cooled type. Air flow is life, thus higher RPM under load at fast speeds = better cooling and less fatigue on your engine. This is why long hills on hot days are particularly bad for our cars (more so than many other scenarios). Lots of demand, hard to keep up RPMs AND speed. If you want to know what it will be like to drive with a taller fifth gear just go for a long drive up a steep hill (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/wink.gif)
<:edited because Aaron posted the damn chart first (IMG:style_emoticons/default/rolleyes.gif) :> |
Aaron Cox |
Nov 28 2006, 08:29 PM
Post
#11
|
Professional Lawn Dart Group: Retired Admin Posts: 24,541 Joined: 1-February 03 From: OC Member No.: 219 Region Association: Southern California |
ZD is what is in there now. I do not see how smaller tires will cause lower RPMs, Aaron (IMG:style_emoticons/default/huh.gif) If you put larger profile tires on your car you will lower your RPMs, not the other way around. Like a said before, you should be at 4000rpm at 89MPH in stock form. the 50 series tires should only bump the RPMs up a bit. Our engines are not like the water cooled type. Air flow is life, thus higher RPM under load at fast speeds = better cooling and less fatigue on your engine. This is why long hills on hot days are particularly bad for our cars (more so than many other scenarios). Lots of demand, hard to keep up RPMs AND speed. If you want to know what it will be like to drive with a taller fifth gear just go for a long drive up a steep hill (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/wink.gif) Here is Aarons chart for those of you watching at home and wandering where we pull these numbers from (IMG:style_emoticons/default/biggrin.gif) taller gear = less rpm. less rpm = less cooling. shorter tire = MORE rpm i dont think i said that mike.... |
SGB |
Nov 28 2006, 08:32 PM
Post
#12
|
just visiting Group: Members Posts: 4,086 Joined: 8-March 03 From: Huntsville, AL Member No.: 404 Region Association: South East States |
I'm trying to grasp this with my little tuna-like brain and I gotta ask- the colored bands- yellow is 50 series? At 5K? OK, the flipped 904 2nd gives a 0.61 in place of 0.71 for the ZD. That doesn't seem too drastic...
(I'm a stubborn ol' fishhead) |
Dr Evil |
Nov 28 2006, 08:33 PM
Post
#13
|
Send me your transmission! Group: Members Posts: 23,032 Joined: 21-November 03 From: Loveland, OH 45140 Member No.: 1,372 Region Association: MidAtlantic Region |
Now now Aaron, dont get testy (IMG:style_emoticons/default/wink.gif) I reread your post and relized what you were saying with the 3K at 70mph and 50 series tires.
|
Aaron Cox |
Nov 28 2006, 08:34 PM
Post
#14
|
Professional Lawn Dart Group: Retired Admin Posts: 24,541 Joined: 1-February 03 From: OC Member No.: 219 Region Association: Southern California |
click the picture... it gets bigger...
if you look at the top.. you can see it is setup for a 23.59" tire.... (225/50/15) and a 205 50 is slightly smaller 23.0" so the rpms will be SLIGHTLY more than what is pictured.... |
SGB |
Nov 28 2006, 08:45 PM
Post
#15
|
just visiting Group: Members Posts: 4,086 Joined: 8-March 03 From: Huntsville, AL Member No.: 404 Region Association: South East States |
Of course I realize you know what you are talking about (both of ya). It is just a pipe dream (IMG:style_emoticons/default/smile.gif)
The 50 tires cretainly seemed to make a profund impact on the admitidly already innacurate speedo readings- |
Aaron Cox |
Nov 28 2006, 09:10 PM
Post
#16
|
Professional Lawn Dart Group: Retired Admin Posts: 24,541 Joined: 1-February 03 From: OC Member No.: 219 Region Association: Southern California |
Of course I realize you know what you are talking about (both of ya). It is just a pipe dream (IMG:style_emoticons/default/smile.gif) The 50 tires cretainly seemed to make a profund impact on the admitidly already innacurate speedo readings- 9% shorter than stock.... the MPH's on the chart are ACTUAL speed... not indicated your speeds will be 1-2% lower than the chart.. (same as saying your RPM's will be a few% higher at the same speed) |
jwalters |
Nov 28 2006, 09:15 PM
Post
#17
|
Sooo Close....... Group: Members Posts: 1,677 Joined: 14-May 04 From: Huntsville, AL Member No.: 2,068 Region Association: Europe |
|
Aaron Cox |
Nov 28 2006, 09:18 PM
Post
#18
|
Professional Lawn Dart Group: Retired Admin Posts: 24,541 Joined: 1-February 03 From: OC Member No.: 219 Region Association: Southern California |
no bozo (IMG:style_emoticons/default/smile.gif)
you have a few choices for first gears A AA B C D A is stock on most 911's and all 914's AA harder to find... a few hundred bucks... B/C/D hens teeth. good luck with that. |
Dr Evil |
Nov 28 2006, 09:18 PM
Post
#19
|
Send me your transmission! Group: Members Posts: 23,032 Joined: 21-November 03 From: Loveland, OH 45140 Member No.: 1,372 Region Association: MidAtlantic Region |
Nope. I was wondering the same thing once, but you would have to machine it and I do not think that there would be enough meat.
|
jwalters |
Nov 28 2006, 09:18 PM
Post
#20
|
Sooo Close....... Group: Members Posts: 1,677 Joined: 14-May 04 From: Huntsville, AL Member No.: 2,068 Region Association: Europe |
I clicked the picture - it got smaller.
Couldn't read it anymore. Even with my coke bottle glasses and nose plastered on the screen. I really gotta learn 'puters. So, how again do you get a taller fifth? You guys lost me - |
Lo-Fi Version | Time is now: 27th September 2024 - 05:33 PM |
All rights reserved 914World.com © since 2002 |
914World.com is the fastest growing online 914 community! We have it all, classifieds, events, forums, vendors, parts, autocross, racing, technical articles, events calendar, newsletter, restoration, gallery, archives, history and more for your Porsche 914 ... |