Shift linkage 'feel' question
01-17-2007, 12:48 PM
#1
Seared
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Shift linkage 'feel' question
While working on Steve's C4S yesterday, I noticed that his shifter felt somewhat different from mine. Where mine clicks from gear to gear rather solidly, his mechanism felt more 'mechanical'. Is there a difference between the C4 and Carrera shift linkages? The only obvious differences are that I have the RS shift boot/****, and he now has the MY02 **** - which is a very solid piece.
Moving my shifter feels 'muted', while his has a nice 'clack' going into gear. I have 43,000 miles on the car, and I think Steve may have 70,000+. Any thoughts?
Andreas
Moving my shifter feels 'muted', while his has a nice 'clack' going into gear. I have 43,000 miles on the car, and I think Steve may have 70,000+. Any thoughts?
Andreas
01-17-2007, 12:54 PM
#2
Three Wheelin'
Does it also depend on the type and age of gear lube you are using? My shifter felt different when I switched to MTL-R from Mobil1. Of course Im talking syncro engagement and not the linkage so sorry if this is not applicable....
01-17-2007, 01:03 PM
#3
Seared
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I switched to Mobilube SHC last year and noticed a much smoother gear engagement over what the factory fill provided. But the 'action' of the linkage did not change with the fluid replacement.
Maybe Steve has the RS shift rod and does not know it?
Andreas
Maybe Steve has the RS shift rod and does not know it?
Andreas
01-17-2007, 01:37 PM
#5
Rennlist Member
There is a difference in the shift rod coupler to the trans between the C2:C4 versions, pics here ; however, that may translate into no meaningful difference in 'feel'.
The next time under the car, you might try the "10 min, 10 cent" mod done with a couple of hose washers: That may firm things up .... and if not, no harm done.
The next time under the car, you might try the "10 min, 10 cent" mod done with a couple of hose washers: That may firm things up .... and if not, no harm done.
01-17-2007, 01:40 PM
#6
Seared
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Mark,
I wondered that as well. I'll have the 993 on jack stands soon and will take a look at the rubber isolator again. I may need to requisition one of my wife's Delrin cutting boards and make a test piece
Andreas
I wondered that as well. I'll have the 993 on jack stands soon and will take a look at the rubber isolator again. I may need to requisition one of my wife's Delrin cutting boards and make a test piece
Andreas
01-17-2007, 02:35 PM
#7
Rennlist Member
Originally Posted by Garth S
There is a difference in the shift rod coupler to the trans between the C2:C4 versions, pics here ; however, that may translate into no meaningful difference in 'feel'.
The next time under the car, you might try the "10 min, 10 cent" mod done with a couple of hose washers: That may firm things up .... and if not, no harm done.
The next time under the car, you might try the "10 min, 10 cent" mod done with a couple of hose washers: That may firm things up .... and if not, no harm done.
I had thought about doing something like what Andreas is thinking... a firmer/harder piece in place of that rubber "buffer". Not sure what Delrin is but it sure sounds cool
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01-17-2007, 03:59 PM
#8
Rennlist Member
Mark,
The two 'bolts' that secure the shift rod to the coupler are not yer average bolts . The fastener is of two diameters, and the threads are cut on a small diameter portion of the total length that permits the the shift rod flange and rubber piece to be tightly forced together - even if the rest of the coupler was cut away.
The lower length of this bolt is a larger diameter that is a loose fit in the coupler flange itself ... AND is ~3mm longer than the thickness of the coupler. Ergo, when the shift rod is bolted on, there is some side to side 'wiggle' room plus the 3mm fore/aft travel. The thick rubber absorbs torsion and compression to dampen vibrations - as does the black rubber disc vulcanized to the contact face of the 'bolt'. I'm sure the latter is done more to suppress noise.
While 3mm may not sound like much, the distance of travel from 1,3,5 to 2,4,6 gates is 30mm .... so that is a nice 10% max slop! As the shift lever moves 5" (127mm) between the same gates, that translates as a max 1/2" of mush between hand input and shifter fork movement.
[BTW, the reverse of that indicates that the compound leverage of the shifter is 127:30, or 4.2:1 ... which drops to 3.3:1 with the short shifter .... phew ...]
The spacer I inserted effectively takes up this 3mm while leaving the rubber in the train to quench vibration - the spacer would have an identical effect inserted between the rubber and the coupler flange as it would on the side shown.
If I'm not too lazy later, I'll get a pic .... but it's -18 today, so chances are poor
PS Delrin is a hard, machinable teflon like material - nylatron is very similar, but is better at self lubricating if movement is required.
The two 'bolts' that secure the shift rod to the coupler are not yer average bolts
. The fastener is of two diameters, and the threads are cut on a small diameter portion of the total length that permits the the shift rod flange and rubber piece to be tightly forced together - even if the rest of the coupler was cut away.The lower length of this bolt is a larger diameter that is a loose fit in the coupler flange itself ... AND is ~3mm longer than the thickness of the coupler. Ergo, when the shift rod is bolted on, there is some side to side 'wiggle' room plus the 3mm fore/aft travel. The thick rubber absorbs torsion and compression to dampen vibrations - as does the black rubber disc vulcanized to the contact face of the 'bolt'. I'm sure the latter is done more to suppress noise.
While 3mm may not sound like much, the distance of travel from 1,3,5 to 2,4,6 gates is 30mm .... so that is a nice 10% max slop! As the shift lever moves 5" (127mm) between the same gates, that translates as a max 1/2" of mush between hand input and shifter fork movement.
[BTW, the reverse of that indicates that the compound leverage of the shifter is 127:30, or 4.2:1 ... which drops to 3.3:1 with the short shifter .... phew ...]
The spacer I inserted effectively takes up this 3mm while leaving the rubber in the train to quench vibration - the spacer would have an identical effect inserted between the rubber and the coupler flange as it would on the side shown.
If I'm not too lazy later, I'll get a pic .... but it's -18 today, so chances are poor
PS Delrin is a hard, machinable teflon like material - nylatron is very similar, but is better at self lubricating if movement is required.
01-17-2007, 04:04 PM
#9
Rennlist Member
Ah, these are shoulder bolts! I get it now. Thanks Garth.
You'd think I would have remembered that since I just put all of this back together a few weeks ago after doing the clutch job. I'm getting old and senile.
Think I may give that a try.
BTW, in my book, -18 is really really cold. Sounds painfully cold. Yikes.
You'd think I would have remembered that since I just put all of this back together a few weeks ago after doing the clutch job. I'm getting old and senile.
Think I may give that a try.
BTW, in my book, -18 is really really cold. Sounds painfully cold. Yikes.