 Lockout For 1 st Gear In A 901 Tranny, Anyone developed a simple lockout device |
|
|
|
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. |
|
|
  |
| 914forme |
 Oct 17 2006, 01:53 PM
Post
#21
|
|
Times a wastin', get wrenchin'!  Group: Members Posts: 3,896 Joined: 24-July 04 From: Dayton, Ohio Member No.: 2,388 Region Association: None 
 |
Attached image(s) 
|
   |
 
|
| Brad Roberts |
Oct 17 2006, 02:49 PM
Post
#22
|
|
914 Freak! Group: Members Posts: 19,148 Joined: 23-December 02 Member No.: 8 Region Association: None |
This is a store bought item tig welded to a block of aluminum and bolted to an existing threaded hole in the tub. It will also work with ANY shifter you install in the car.
B |
|
|
|
| drew365 |
Oct 17 2006, 06:44 PM
Post
#23
|
|
These are the good old days! Group: Members Posts: 2,004 Joined: 29-December 02 From: Sunny So. Cal. Member No.: 37 |
I like it. I'm going to build one, unless a couple guys want to negotiate a lower price for a few units I'm willing to go along. I damaged my trans last month at Laguna Seca doing the 5 - 4 - 3 downshift coming into two, I caught 1st for 1/2 second. It was enough to make my trans start acting weird. 1st and reverse work but I have to double clutch to get into 5th. It's the last time that's going to happen.
|
|
|
|
| Aaron Cox |
Oct 18 2006, 09:53 AM
Post
#24
|
|
Professional Lawn Dart Group: Retired Admin Posts: 24,541 Joined: 1-February 03 From: OC Member No.: 219 Region Association: Southern California |
QUOTE(drew365 @ Oct 17 2006, 05:44 PM)  I like it. I'm going to build one, unless a couple guys want to negotiate a lower price for a few units I'm willing to go along. I damaged my trans last month at Laguna Seca doing the 5 - 4 - 3 downshift coming into two, I caught 1st for 1/2 second. It was enough to make my trans start acting weird. 1st and reverse work but I have to double clutch to get into 5th. It's the last time that's going to happen. have a rennshift? ill even let you borrow mine if you want.... to check it out... i have only missed one shift on the rennshift..... |
|
|
|
| Brad Roberts |
Oct 18 2006, 10:31 AM
Post
#25
|
|
914 Freak! Group: Members Posts: 19,148 Joined: 23-December 02 Member No.: 8 Region Association: None |
The Rennshift doesnt solve it. I *thought* it did, but I experienced it myself a few events back in 914 2.0 car at an AutoX.
VERY fast right hand turn that I needed to upshift into third at the apex of the corner. I caught first. This may sound *crazy* but the actual weight of your arm may effect how much the shifter is going to move in a high G corner. You have your hand on the shift knob and your arm is trying to go across your body pulling on the shift lever. I was in a stock seat with the lower cushion out. B |
|
|
|
| GBallantine |
Oct 18 2006, 01:43 PM
Post
#26
|
|
Member Group: Members Posts: 74 Joined: 12-October 04 From: Toronto,Ont.Canada Member No.: 2,930 |
Brad,
I agree,the best and safest lockout seems to be the plunger style with the red ball. The Rennshift is defintely a quality product but it does not fully lockout 1 st gear, it uses spring tension to accoplish this. Others members using the Rennshift have commented that they are going to stiffer springs to safe guard this happening. I've tried to source this piece at local tool suppliers with no results. Where can it be found? Any leads? |
|
|
|
| brant |
Oct 18 2006, 01:46 PM
Post
#27
|
|
914 Wizard Group: Members Posts: 11,618 Joined: 30-December 02 From: Colorado Member No.: 47 Region Association: Rocky Mountains 
|
James will supply you with the correct stronger springs.
I guess I'm lucky... but I've never had a first gear situation on the track I don't autox though.... brant |
|
|
|
| Brad Roberts |
Oct 18 2006, 02:36 PM
Post
#28
|
|
914 Freak! Group: Members Posts: 19,148 Joined: 23-December 02 Member No.: 8 Region Association: None |
Brant,
I think he is referring to the lockout/red knob thingy above?? I would imagine this is a "McMaster Carr" item. Brant, you are also correct.. AutoX transitions are MUCH more harsh than road course transitions. I can easily see why this is an issue in AutoX but hasnt really been seen in road racing. B |
|
|
|
| brant |
Oct 18 2006, 02:45 PM
Post
#29
|
|
914 Wizard Group: Members Posts: 11,618 Joined: 30-December 02 From: Colorado Member No.: 47 Region Association: Rocky Mountains
|
oops..
I re-read the post. your right, he is asking about the custom lock out and not the springs. (regarding the rennshift... when I had one, I know James was kind enough to give me the stronger springs as they became available.) |
|
|
|
| 914forme |
Oct 18 2006, 05:05 PM
Post
#30
|
|
Times a wastin', get wrenchin'! Group: Members Posts: 3,896 Joined: 24-July 04 From: Dayton, Ohio Member No.: 2,388 Region Association: None
|
Brad good eye, yep McMaster Car.
Search Weld-in Pin not bad priced either. Might have to recess it a little, or extend the shaft 5/8th is not a lot to play with. They also have a T-handle model, which would be easier to grab with gloves on. Attached thumbnail(s) 
|
|
|
|
| Brad Roberts |
Oct 18 2006, 05:37 PM
Post
#31
|
|
914 Freak! Group: Members Posts: 19,148 Joined: 23-December 02 Member No.: 8 Region Association: None |
Beleive it or not.. I actually do get involved with race car builds..LOL I dont just talk about it (IMG:style_emoticons/default/smile.gif)
Based on his alum block.. they probably extended the shaft. The shift rod is VERY close to the tunnel right there.. maybe they didnt have to?? For that price, buy one and find out (IMG:style_emoticons/default/clap56.gif) B |
|
|
|
| drew365 |
Oct 18 2006, 06:29 PM
Post
#32
|
|
These are the good old days! Group: Members Posts: 2,004 Joined: 29-December 02 From: Sunny So. Cal. Member No.: 37 |
QUOTE(Aaron Cox @ Oct 18 2006, 08:53 AM) QUOTE(drew365 @ Oct 17 2006, 05:44 PM) I like it. I'm going to build one, unless a couple guys want to negotiate a lower price for a few units I'm willing to go along. I damaged my trans last month at Laguna Seca doing the 5 - 4 - 3 downshift coming into two, I caught 1st for 1/2 second. It was enough to make my trans start acting weird. 1st and reverse work but I have to double clutch to get into 5th. It's the last time that's going to happen. have a rennshift? ill even let you borrow mine if you want.... to check it out... i have only missed one shift on the rennshift..... Aaron; I have a Rennshift and I love it. I would never misshift on the street, I'm finding a small mistake on the track gets very expensive and I'd rather say I need some help than rebuild my gear box again. |
|
|
|
| JWest |
Oct 18 2006, 07:15 PM
Post
#33
|
|
Senior Member Group: Members Posts: 1,662 Joined: 6-January 03 From: Fort Worth, TX Member No.: 97 Region Association: None
|
All these items being discussed will do no good for shifting a car in a high lateral G situation.
The problem is that the trans is changing its location related to the shifter. Even if you had a robot shifting the exact same spot the shifter you would still miss, because the engagment slots in the trans have moved to a different spot than when the car is unloaded. This includes anything done in the cockpit of the car like the linkage blocking pin. The back part of the chassis twists and now 1st gear is in the position of 3rd as the linkage up forward sees it. The RennShift does all that can be done in addressing the issue up front - by having gate springs you allow the shifter to find the 3rd gear slot as you pass through neutral and do not put any side load on the shift knob. You can't do any better than this at the forward end of the linkage. I could easily build in a solid lockout device in place of the rev/1st spring in the RennShift, but it would be false security and would not solve the issue. The reverse lockout does work for upshifting, but that is a different dynamic situation. The only way to fix this situation is to stiffen the chassis (assuming the mounts have already been replaced with solid if you are experiencing this issue). You are only going to go so far with that, so eventually it becomes something you just have to drive or change gear ratios around. |
|
|
|
| Brad Roberts |
Oct 18 2006, 07:27 PM
Post
#34
|
|
914 Freak! Group: Members Posts: 19,148 Joined: 23-December 02 Member No.: 8 Region Association: None |
Roll cage
Solid engine mounts Solid tranny mounts And.. really light springs with a stock sway bar on not really sticky tires No rust chassis Still think this wont help? Two other cars with the same issue.. full cages.. solid mounts and tranny mounts tied into the cage. I beleive there is *some* movement, but come on ?? really ?? B |
|
|
|
| JWest |
Oct 18 2006, 07:32 PM
Post
#35
|
|
Senior Member Group: Members Posts: 1,662 Joined: 6-January 03 From: Fort Worth, TX Member No.: 97 Region Association: None
|
QUOTE(Brad Roberts @ Oct 18 2006, 08:27 PM) Roll cage Solid engine mounts Solid tranny mounts And.. really light springs with a stock sway bar on not really sticky tires No rust chassis Still think this wont help? Two other cars with the same issue.. full cages.. solid mounts and tranny mounts tied into the cage. I beleive there is *some* movement, but come on ?? really ?? B If it is stiff enough, then the RennShift or these lockouts will do the job. But a lot of the cars in this thread are going to encounter this issue even with the blocking pins installed. And, yes it does not take much twist to change the pattern, and produciton based racecars or not very torsionally stiff. |
|
|
|
| Brad Roberts |
Oct 18 2006, 07:36 PM
Post
#36
|
|
914 Freak! Group: Members Posts: 19,148 Joined: 23-December 02 Member No.: 8 Region Association: None |
Ha ha..
Half the cars have bad tranny mounts!!..LOL B |
|
|
|
| Randal |
Oct 18 2006, 07:37 PM
Post
#37
|
|
Advanced Member Group: Members Posts: 4,446 Joined: 29-May 03 From: Los Altos, CA Member No.: 750 |
QUOTE(Brad Roberts @ Oct 18 2006, 06:27 PM) Roll cage Solid engine mounts Solid tranny mounts And.. really light springs with a stock sway bar on not really sticky tires No rust chassis Still think this wont help? Two other cars with the same issue.. full cages.. solid mounts and tranny mounts tied into the cage. I beleive there is *some* movement, but come on ?? really ?? B With the ear bar (from the bulk head to the mounting point above the ear) you woudn't think you'd be getting much movement. Especially with solid mounts. But in any event we are building some special fixtures that should tie everything down so movement in the chassis is minimized. |
|
|
|
| 914forme |
Oct 19 2006, 09:29 AM
Post
#38
|
|
Times a wastin', get wrenchin'! Group: Members Posts: 3,896 Joined: 24-July 04 From: Dayton, Ohio Member No.: 2,388 Region Association: None
|
"If it is stiff enough, then the RennShift or these lockouts will do the job. But a lot of the cars in this thread are going to encounter this issue even with the blocking pins installed."
James, I got a solution, build a RennShift cable shifter for the 901. That takes the mechanical movement out of the picture. That is unless you mount the cable in a way that if causes stress and pulls the inner cable. I know there has been a couple of home grown version, but a good quality kit might sell, then again it might not recoup the investment in engineering time. Just Ideas. Ah crap I just came back to a Boxster Trannie installation. |
|
|
|
| JWest |
Oct 19 2006, 12:51 PM
Post
#39
|
|
Senior Member Group: Members Posts: 1,662 Joined: 6-January 03 From: Fort Worth, TX Member No.: 97 Region Association: None
|
QUOTE(914forme @ Oct 19 2006, 10:29 AM) James, I got a solution, build a RennShift cable shifter for the 901. That takes the mechanical movement out of the picture. That is unless you mount the cable in a way that if causes stress and pulls the inner cable. I know there has been a couple of home grown version, but a good quality kit might sell, then again it might not recoup the investment in engineering time. Just Ideas. Ah crap I just came back to a Boxster Trannie installation. Thanks for the input, but I don't like cable shifters with Porsche servo syncros. The Boxster tranny - that's certainly one I have thought about! |
|
|
|
|
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:
|
Lo-Fi Version | Time is now: 4th May 2024 - 05:07 AM |
Invision Power Board
v9.1.4 © 2024 IPS, Inc.