Morphing a 1980 Broomhandle into a Short Throw Short Shifter
11-28-2004, 05:26 PM
#1
Burning Brakes
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Morphing a 1980 Broomhandle into a Short Throw Short Shifter
I bought Jim Doerr's "broomhandle" off of Ebay (thanks Jim!) and thought I would try this little experiment to see what I could get.
Pic 1: The upper shifter is out of an 80' and the lower is out of my 86'. I had previously shortened the 86' by 1 1/4 inches and liked the boot height, so I wanted to keep the height the same or even a tad bit shorter. Notice the distance between the shift coupler bushings on the 80' (35mm) and the 86' (25mm), which affects the shifting geometry. Also, notice how much higher the shift boot shoulder-stop is on the 80' (where the shifter boot slides down and stops). I realized that although I cut my 86' shifter shorter, the shift boot would only go down as far as the shoulder-stop would let it.
Pic 2: I cut the broomhandle down and ground the shoulder-stop down to be even with my 86' shifter. The 80' shifter is made of a harder metal than the 86'.
After this pic was taken, I ended up grinding the shoulder-stop down about a 1/4 inch farther. The top of the shortened broomhandle now goes all the way up into the shifter boot and the overall installed height is about a 1/4 shorter than what it was with the 86' shortened shifter; because of the lower shoulder-stop. Make sense?
Pic 3: Short Throw Short Shifter installed. Unfortunately, I am waiting on clutch parts so I haven't been able to go for a test drive. Also, I had a terrible time trying to get the shifter springs back in and after thinking about it, I came to the conclusion that they were pretty much useless anyways. The shifter has no side to side play without the springs and I don't think the springs are used in the aftermarket shifters either.
I'll post an update soon. I can already tell that the shift pattern feels tighter
. The other threads and comments that I have read about the aftermarket short throw shifters seem to all be positive.
Pic 1: The upper shifter is out of an 80' and the lower is out of my 86'. I had previously shortened the 86' by 1 1/4 inches and liked the boot height, so I wanted to keep the height the same or even a tad bit shorter. Notice the distance between the shift coupler bushings on the 80' (35mm) and the 86' (25mm), which affects the shifting geometry. Also, notice how much higher the shift boot shoulder-stop is on the 80' (where the shifter boot slides down and stops). I realized that although I cut my 86' shifter shorter, the shift boot would only go down as far as the shoulder-stop would let it.
Pic 2: I cut the broomhandle down and ground the shoulder-stop down to be even with my 86' shifter. The 80' shifter is made of a harder metal than the 86'.
After this pic was taken, I ended up grinding the shoulder-stop down about a 1/4 inch farther. The top of the shortened broomhandle now goes all the way up into the shifter boot and the overall installed height is about a 1/4 shorter than what it was with the 86' shortened shifter; because of the lower shoulder-stop. Make sense?
Pic 3: Short Throw Short Shifter installed. Unfortunately, I am waiting on clutch parts so I haven't been able to go for a test drive. Also, I had a terrible time trying to get the shifter springs back in and after thinking about it, I came to the conclusion that they were pretty much useless anyways. The shifter has no side to side play without the springs and I don't think the springs are used in the aftermarket shifters either.
I'll post an update soon. I can already tell that the shift pattern feels tighter
. The other threads and comments that I have read about the aftermarket short throw shifters seem to all be positive.
Last edited by JKelly; 11-28-2004 at 10:32 PM.
11-28-2004, 05:43 PM
#2
Developer
Nice job John, and nice pics.
Shortening the shifter lever makes a significant improbvement, but, although it shortens the shift throws, it does not make it a "short throw shifter"
The Short Throw Shifters, in addition to being shorter in length, also have the linkage attachment points further apart so that a shorter motion of your hand translates into a longer throw of the shift lkinkage. Plus, their tolerenceas are tighter to eliminate wasted motion, and they eliminate the "slop springs" entirely.
The differance, over even a shifter that has been shortened, is signifiacant.
Shortening the shifter lever makes a significant improbvement, but, although it shortens the shift throws, it does not make it a "short throw shifter"
The Short Throw Shifters, in addition to being shorter in length, also have the linkage attachment points further apart so that a shorter motion of your hand translates into a longer throw of the shift lkinkage. Plus, their tolerenceas are tighter to eliminate wasted motion, and they eliminate the "slop springs" entirely.
The differance, over even a shifter that has been shortened, is signifiacant.
11-28-2004, 06:08 PM
#3
I think the best solution is a pillow joint at each end, getting rid of the rubber support on the TT behind t he shifter, and short throw shifter. That should be tight and short.
11-28-2004, 07:18 PM
#5
Rennlist Member
Originally Posted by Quick Carl
Nice job John, and nice pics.
Shortening the shifter lever makes a significant improbvement, but, although it shortens the shift throws, it does not make it a "short throw shifter"
The Short Throw Shifters, in addition to being shorter in length, also have the linkage attachment points further apart so that a shorter motion of your hand translates into a longer throw of the shift lkinkage. Plus, their tolerenceas are tighter to eliminate wasted motion, and they eliminate the "slop springs" entirely.
The differance, over even a shifter that has been shortened, is signifiacant.
Shortening the shifter lever makes a significant improbvement, but, although it shortens the shift throws, it does not make it a "short throw shifter"
The Short Throw Shifters, in addition to being shorter in length, also have the linkage attachment points further apart so that a shorter motion of your hand translates into a longer throw of the shift lkinkage. Plus, their tolerenceas are tighter to eliminate wasted motion, and they eliminate the "slop springs" entirely.
The differance, over even a shifter that has been shortened, is signifiacant.
John, I'm curious as to how the shifter will be without the springs: I reinstalled mine after chopping with the "vise compress/piano wire" trick - and tricky it was.
11-28-2004, 07:55 PM
#6
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Originally Posted by BrendanC
I think the best solution is a pillow joint at each end, getting rid of the rubber support on the TT behind t he shifter, and short throw shifter. That should be tight and short.
I don't track my car at all, but I like to have things tight and accurate. I've noticed quite a few cushy things that Porsche has put into this car that could be done away with, without losing any real luxury. Actually, I think many of the luxury items end up causing big headaches.
11-28-2004, 08:15 PM
#7
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Originally Posted by Garth S
That would be correct - if the 'short shifter' pivot points are seperated by more than 35mm ( as we are talking about chopping a 16v broomhandle); however, I do not know that data. The elimination of the springs is definitely an installation plus with the aftermarket short shifter.
John, I'm curious as to how the shifter will be without the springs: I reinstalled mine after chopping with the "vise compress/piano wire" trick - and tricky it was.
John, I'm curious as to how the shifter will be without the springs: I reinstalled mine after chopping with the "vise compress/piano wire" trick - and tricky it was.
As I understand it, the 35mm broomhandle IS a short shifter compared to the 25mm shifter. I'm not sure exactly what the aftermarket shifters are (also 35mm?). In my 86', if the linkage attachment points were 40mm or longer, center to center, I don't know if it would fit without modifying the thick sound deadening material in there. The 80' shifter came with a different type of clip than the 86'. I used the 86' washer and "C" clip instead of the 80' clip (see first pic) and there isn't even a 1/4 of a millimeter of side to side play; it fits perfect. If I had used the 80' clips, I would have had to put a washer in there or something.
Edit: I am still using the 4 small white bushings. I eliminated the larger two holed bushing and the two springs.
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11-28-2004, 08:18 PM
#8
I'll call it a universal joint that looks like it has a pillow over the joint.
http://www.summitracing.com/catalogs...vdec/204f.html
The joint in the lowerish right corner, with the red silicon cover.
These can be used at the back - NO MORE PLAY. The front can be even more rigid, as in a rose joint or something.
The "loop carrier" behind your hand and closer to your right thigh attached to the TT would be removed and replaced with a simple aluminum carrier for no movement.
The REAR coupler is WAY to loose, even NEW. Those bushings are asking to be pushed out under hardish shifts.
http://www.summitracing.com/catalogs...vdec/204f.html
The joint in the lowerish right corner, with the red silicon cover.
These can be used at the back - NO MORE PLAY. The front can be even more rigid, as in a rose joint or something.
The "loop carrier" behind your hand and closer to your right thigh attached to the TT would be removed and replaced with a simple aluminum carrier for no movement.
The REAR coupler is WAY to loose, even NEW. Those bushings are asking to be pushed out under hardish shifts.
11-28-2004, 11:40 PM
#9
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I've searched on web sites, on here, and in catalogs, and it seems like there are two versions of an aftermarket short throw kit. I have seen a few were the linkage attachment points are the same spacing as the 1980 broomhandle (maybe for later cars?) and ones that appear to have the linkage attachment points a little further than the 1980 broomhandle (maybe for earlier cars?). I can't find any specs on any of the Big Three shifters. Out of curiosity, and to clarify things, it would be nice to know some details and measurements. 
11-29-2004, 05:43 AM
#10
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Originally Posted by JKelly
I've searched on web sites, on here, and in catalogs, and it seems like there are two versions of an aftermarket short throw kit. I have seen a few were the linkage attachment points are the same spacing as the 1980 broomhandle (maybe for later cars?) and ones that appear to have the linkage attachment points a little further than the 1980 broomhandle (maybe for earlier cars?). I can't find any specs on any of the Big Three shifters. Out of curiosity, and to clarify things, it would be nice to know some details and measurements.
No one has yet coughed up the details, so I will happily assume we each have a 'short shifter' due to the 35mm pivot axis; see https://rennlist.com/forums/showthre...=short+shifter for some more laughs.
Anyway, keep this to yourself - or there may be a midnight run on OB 'broomhandle' shifters
11-29-2004, 10:26 AM
#11
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Garth,
If the shifter in your 80' is cut the same length as the GT shifter, does your shift boot slide all the way on? I had to grind down the shoulder-stops on the 80' shifter to get the boot to slide down farther (compare pic 1 & pic 2). A bench grinder took care of it pretty quick, but the gold metal (grade 8?) of the 80' shifter is definitely harder than the metal of the 86' (cheap stuff?).
...Which makes me think....From looking at pictures of the aftermarket short throw shifter, they appear to be reinforced (thicker) between the linkage points, which makes sense if they are made out of aluminum; therefore you can't use springs with them either. Being aluminum, maybe that is one reason why they aren't made any taller, too soft? If they were, the customer would have the option of trimming them to a desired height instead of settling for super short.
Just an observation, as the shifter grows shorter, the metal grows softer:
1st generation = The Gold Broomhandle: very tall shifter, shorter throw, grade 8 hardened metal?
2nd generation = The Black shifter: shorter shifter, longer throw, softer mild metal
Aftermarket = Red or Blue shifter: very short shifter, shorter throw, softest metal (aluminum)
If the shifter in your 80' is cut the same length as the GT shifter, does your shift boot slide all the way on? I had to grind down the shoulder-stops on the 80' shifter to get the boot to slide down farther (compare pic 1 & pic 2). A bench grinder took care of it pretty quick, but the gold metal (grade 8?) of the 80' shifter is definitely harder than the metal of the 86' (cheap stuff?).
...Which makes me think....From looking at pictures of the aftermarket short throw shifter, they appear to be reinforced (thicker) between the linkage points, which makes sense if they are made out of aluminum; therefore you can't use springs with them either. Being aluminum, maybe that is one reason why they aren't made any taller, too soft? If they were, the customer would have the option of trimming them to a desired height instead of settling for super short.
Just an observation, as the shifter grows shorter, the metal grows softer:
1st generation = The Gold Broomhandle: very tall shifter, shorter throw, grade 8 hardened metal?
2nd generation = The Black shifter: shorter shifter, longer throw, softer mild metal
Aftermarket = Red or Blue shifter: very short shifter, shorter throw, softest metal (aluminum)
11-29-2004, 10:48 AM
#12
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It might not be a good idea to tighten the shift linkage too much...
The plastic bushings in the rear coupling are deliberately designed with some slop. Ever wonder why Porsche did that?
If you gently press on the shift lever while driving, you can often feel the shift forks in the transmission rubbing on the collars. If you tighten the linkage so much that there is no free play at all, the forks will continually rub the collars, and cause excessive wear.
The linkage design allows the transmission detents to hold the forks and collars in the proper position. If you change to all Heim joints and metal-to-metal linkage, you could very well change all of that, with potentially expensive results, not to mention the probability of increased noise and vibration.
The plastic bushings in the rear coupling are deliberately designed with some slop. Ever wonder why Porsche did that?
If you gently press on the shift lever while driving, you can often feel the shift forks in the transmission rubbing on the collars. If you tighten the linkage so much that there is no free play at all, the forks will continually rub the collars, and cause excessive wear.
The linkage design allows the transmission detents to hold the forks and collars in the proper position. If you change to all Heim joints and metal-to-metal linkage, you could very well change all of that, with potentially expensive results, not to mention the probability of increased noise and vibration.
11-29-2004, 11:17 AM
#14
Developer
Yes, there are two models of the billet short-throw shifter.
78-84 is Type 1 and 85-95 is type 2
There are also two types- DEVEK has its own and 928 Intl, 928 Motorsports, and 928 Specialists have the other style.
I cannot speak to the DEVEK one.
I have installed both early and late models. Again, the geometry of the linkage attachment points is better on the aftermarket ones, and that improves the shifts in addition to being shorter as well.
78-84 is Type 1 and 85-95 is type 2
There are also two types- DEVEK has its own and 928 Intl, 928 Motorsports, and 928 Specialists have the other style.
I cannot speak to the DEVEK one.
I have installed both early and late models. Again, the geometry of the linkage attachment points is better on the aftermarket ones, and that improves the shifts in addition to being shorter as well.
