I was wondering whether all 914's inherently are unable to shift from 1st to second without quickly--a slight hesitation has been my experience.
The bushing had been replaced, the shifter is a J West rennshift,tranny was rebuilt by Dr Evil, and it shifts fine from 2 to 3, and 4 to 5. Three to four takes a little work, but a lot less than 1 to 2
Any experience or suggestions here ?
Mine doesn't have a problem but I refreshed it at a DrEvil clinic last year!
Oh and I don't use 1st very often!
Does it grind if you shift quickly or do you mean it's difficult to find the gear?
Until my rebuild it would grind occasionally on a fast 1-2 shift, but now I can make the shift quickly without grinding or fighting to get it into gear. Mine is a factory setup though I'd like to upgrade to the J West shifter.
Guess: After watching the Doc rebuild video, I'm assuming your fist syncro is brand new and your others are left alone as "good". Sounds exactly like what it's supposed to do. Slight hesitation while the gears spool up.
Hesitation is normal but if its to much, it could be your gear lube, or your sliders and synchros for 2nd gear, which do wear out and fail.
If you are trying to race, 1st gear is good till about 13 mph.
Get out of it fast, use it in the pit and just for a few feet off the line, short shift to second, and with high hp motors, start in second, forget first.
Rich
I have the same exact issue. I was told my 2nd great synchro.
I mostly start with 2nd gear to avoid that. I guest that's the way they are?
Can more drivers comment on this.
I am going to bet the rennshift is not adjusted optimally. They are real hard to get right, it took me a while. You should not have hesitation, but Eric is correct that new bands can cause this until worn in. BUT, I rebuilt your trans in 2005. How many mile you have on it since?
My understanding is that hesitation is the end result of the original "Porsche-Type" syncromesh transmission design.
Could lube be the culprit? I know in my tranny, a modern lube prevented an easy shift into fist at a stop light as the "slippery'er'er'er" lube didn't allow the syncros to play with one another as they should.
Put some big, fat dyno lube in there if you haven't already and see if it makes a difference.
From the Wiki:
Synchromesh
Synchronizer rings
If the teeth, the so-called dog teeth, make contact with the gear, but the two parts are spinning at different speeds, the teeth will fail to engage and a loud grinding sound will be heard as they clatter together. For this reason, a modern dog clutch in an automobile has a synchronizer mechanism or synchromesh, which consists of a cone clutch and blocking ring. Before the teeth can engage, the cone clutch engages first, which brings the selector and gear to the same speed using friction. Moreover, until synchronization occurs, the teeth are prevented from making contact, because further motion of the selector is prevented by a blocker (or baulk) ring. When synchronization occurs, friction on the blocker ring is relieved and it twists slightly, bringing into alignment certain grooves and notches that allow further passage of the selector which brings the teeth together. Of course, the exact design of the synchronizer varies from manufacturer to manufacturer.
The synchronizer[3] has to overcome the momentum of the entire input shaft and clutch disk when it is changing shaft rpm to match the new gear ratio. It can be abused by exposure to the momentum and power of the engine itself, which is what happens when attempts are made to select a gear without fully disengaging the clutch. This causes extra wear on the rings and sleeves, reducing their service life. When an experimenting driver tries to "match the revs" on a synchronized transmission and force it into gear without using the clutch, the synchronizer will make up for any discrepancy in RPM. The success in engaging the gear without clutching can deceive the driver into thinking that the RPM of the layshaft and transmission were actually exactly matched. Nevertheless, approximate rev. matching with clutching can decrease the general change between layshaft and transmission and decrease synchro wear.
I believe 90w is spec.
GL5 dino oil.
Any synthetic is to slippery for the old style friction bands...they rely heavily upon friction to work right.
For Jim, if the bands are tight, and its notchy to get into 2nd, you may have a slider that it worn, or more likely the dog teeth were worn out in the first hundred thousand miles and may not have been replaced during the last build.
It could also have happened in the last 50 shifts...wearing out the tips of the dog teeth. They are hardened, so using a dremel or file to re-tip them is not really a long term solution.
rich
I change the tranny oil every 10K with 90 wt. About 40-50k miles ago,
Dr Evil replaced the gears that were worn.
The shift is not a serious problem; it cause a minor problem when starting off at a signal. By the time I'm going into second cars behind me are closing in on me because of the temporary acceleration.
I'll try shifting at a lower speed today. And thanks to all that have shared their knowledge
So, what he is saying is SLOW DOWN....
Its faster to start slow in first, then get into second and accelerate at that point, not before.
1st gear has the function of getting the car rolling, nothing more.
Short shift to second, unless you are on a hill,
You are driving a 40 year old classic car....let the people behind you wait a bit, you will get there to that next light with everyone else.
rich
I had a 930 with a G50 in it and same thing - it's tricky getting in to 2nd. You have to be a little patient. With the 914 ( and the G50) you have to find the sweet spot as Eric said and match the revs. Likw many of the others, for a lot of daily driving, especially downhill I use 2nd. for take off.
dont forget the 915 in the 911's seocnd sucks on those also
oh,
Our grandfather has the same issue.
356/beetle....same deal.
Went out to try shifting a lower speed/rpms. A little better.When pushing the shifter to 2nd it feels more like their is some sort of friction on the rod or something.
There is too much info here to clarify categorically, so I will just say that:
1) If it feels like friction going into a gear, it is in NO WAY bad teeth. Bad teeth GRIND. Friction is due to the synchro band, lube, slider. External things that change and can cause this are shifter bushings and improper clutch adjustment (drag from too tight).
2) The factory recommended changing oil every 10Kmi or yearly, so he is not crazy. The oil to use is 80w90 GL5 cheap dino. The more expensive the oil, the worse it will perform. Unless it is swepco, then it will perform well while it is polishing up all of your insides (not good)
3) 2nd is, by design, often a bitch to get into. But, this does not mean that it has to be. If this is a new thing, then start with bushings (you did this) and check the cable. The Rennshifter is either dead on, or it is off. There is no middle ground as it amplifies any imperfection. With a short shift you may be happier
"Mike has certainly seen his share of transmissions, but getting defensive is pointless.
Please take that the right way, a few of us have seen the inside of these boxes before, and broken a few of them in our day....."
Not defensive, although you did directly call into question my rebuild, you were just not correct
Using used parts has risk involved, nothing against you, but the parts are used.
Grinding dog teeth with a Drexel (never said you did that, or ever would, but I have seen the suggestion) is not going to be much more than a short term bandaid unless the new tooth profile is once again hardened.
I had my 1st gear blocked off when I had a taller road gear put in, and so I start off in 2nd. Sometimes it goes into gear like hot butter and sometimes, I find if I go from like 4th to 5th gear, and then I can go back over to 2nd and it will go in easier.
I'm wondering if the old stock shifter, when shifting, if a person leans the stick shift one way or another a bit too much, if that makes it go into gear harder as well??
It almost seems like before I shift, if I start putting pressure on the stick shift before I push in the clutch it goes into gear easier also?
I'm wondering if this would make the shifts, more spot on?
http://www.jwesteng.com/porsche/911/rennshift_911.htm
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