Shifter question, Going from 1st to 2nd... Options

[jim_hoyland]

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 ? (IMG:style_emoticons/default/smile.gif)

[Jeffs9146]

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!

[somd914]

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.

[jim_hoyland]

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.

No grinding, just a little difficult to make the shift quickly

[Eric_Shea]

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.

[jim_hoyland]

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.

I was thinking the same thing; however, I can't remember having this problem when driving other 914s...and it is better described as a hesitation.

[r_towle]

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

[914itis]

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? (IMG:style_emoticons/default/confused24.gif)

Can more drivers comment on this.

[Dr Evil]

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?

[worn]

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?

Shifting a 914 always reminds me of the book "Dune". In the book they fight with knives because shields prevent attack by swift motion. My little British cars shift with a quick snik. My Porsches, even after listening to the Dr, shift with the "wierding way" you need to be just patient enough. If you we're supposed to be in control, you wouldn't have a Porsche.

[Eric_Shea]

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.

[worn]

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.

I was surprised how difficult it was to get the synchros to shift when new. So how fat should the dinosaur be? i.e. any oil recommendations?

as per my other posts I am planning to use roofing tar as motor oil to get the pressure up, but that may not be quite the thing for the transmission.

[Eric_Shea]

I believe 90w is spec. (IMG:style_emoticons/default/confused24.gif)

[r_towle]

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

[jim_hoyland]

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

[Eric_Shea]

I change the tranny oil every 10K with 90 wt. About 40-50k miles ago

(IMG:style_emoticons/default/screwy.gif) (IMG:style_emoticons/default/biggrin.gif)

[Eric_Shea]

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

On a more serious note... if you're accelerating through 1st fairly quickly, you may have passed the "sweet spot" for a "quick" shift into second. You can actually shift without the clutch if you know where those "sweet spots" are. Anything above that will cause the syncro to work harder to spool up second to match your rpm's.

[r_towle]

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

[porschefile2010]

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.

[r_towle]

dont forget the 915 in the 911's seocnd sucks on those also (IMG:style_emoticons/default/smile.gif)