Husam

Is it normal for a 77 911 when down changing for it to not want to go into 1st gear. I'm finding it hard when slowing down, where I find I cant drop it into 1st unless I very gently and slowly ease it into first.
Is it a sign of the syncros being out?
Can this problem be fixed easily and cheaply?
<img src="graemlins/roflmao.gif" border="0" alt="[hiha]" />

ironspiderblair

i have an 85 targa, and my understanding is (as is with my 85 vw vanagon) that 1st cannot be shifted into AT ALL on the way down. I stop completely until i try. These are not hondas...

Elephant Chuck

First gear is supposed to be synchro meshed and down-shiftable just like the other gears. However it is a weak point in the 915 transmission and it is common to do bahave as you are experiencing. It indicates worn synchros.

The best medicine is prevention. You need to baby that first gear before the synchro wears if you don't want this probelem. Double clutch all downshifts, shift into 1st only after you come to a stop, and move the shifter slowly into gear. Also make sure the clutch is adjusted properly.

The cure for a worn synchro is a rebuild. Personnaly I wouldn't rebuild just for first gear. Using the techniques described above you should be able to drive just fine with a worn 1st gear synchro. And even if you do the rebuild you want to use the same techniques, so why rebuild.

Tom F

Just one more note on babying 915s. I believe that the key to long life on these synchros is to warm up the car thoroughly before trying spirited shifting. I believe that the key is getting the tranny oil warm and thin. I "short shift" when the car is cold, usually at around 2,000 rpm. I have an origal first gear synchro that works at 15 mph, maybe more.

cmoss

I agree! Warm up the tranny throughly. Your 915 tranny most likely has worn synchro's (first gear for sure...). Mine ('80 SC) was doing the same thing. I babied it as long as possible, then had 1, 2, 3 synchro's rebuilt ($$$).

Cheers,
Chris

nate

[quote] i have an 85 targa, and my understanding is (as is with my 85 vw vanagon) that 1st cannot be shifted into AT ALL on the way down. I stop completely until i try. These are not hondas... <hr></blockquote>

I second this. The 915 gear box was never designed to down shift into first. I would also question any gain that could be made by shifting into first while not at a complete stop.

CamB

Sometimes you gotta shift into first on the move - like the hill by my house with a "yield" sign (we call them a "give way" in NZ) - there is no way ANYTHING is pulling away from there in anything but first and I don't want to come to a stop, into first, handbrake hill start, blah blah blah.

So I double declutch. It sounds cool too

JonT.

how do you double clutch? I can do a double clutch dunk (not bad for a white boy) but not a double clutch shift....

Brian911

My 1980SC also has a problem of downshifting into first. However if you baby it, it can be done at about 10 mph. They need to develope a 1 1/2 gear. Also just wanted to second the notion of someone posting on how to properly double clutch/shift please.

craigg

I have an '84 Carrera - no 1st synchro for years and don't really mind.

To double declutch (or double clutch), watch Steve McQueen in Bullitt three times, then do the following:

As you are slowing down, and using the clutch, put into neutral, release clutch, then rev engine - more than a blip but not too much, around 2500 RPM or so should do it, while in neutral, then depress clutch quickly and insert into 1st gear. This is an art, not a science, but works for me every time. The faster you are going, the more you should rev. I tend to do it around 10mph or less. And usually for hill work or tricky traffic - but most times I come to a complete stop.

Von Kiser

Also...another thing that has helped mine is replacing all the fluid in it with Redline MTL...run it for about 3000 miles, then replace it again with new Redline MTL and you should see a difference...otherwise...rebuild.

my 1/50th of a dollar,
--Brian

pwd72s

The 915 was not designed for fast shifting. Porsche synchros do not work like those in a Muncie 4 speed, at least not in the 915. But to go to first? Learn the art of the double clutch, or the art of transmission rebuilding. Either one can serve you well...

pookee

I had the same problem with my 80SC I had the trans rebuilt and had a heavy duty 1st gear syncro installed. It's supposed to last longer than stock. I can easily go into first now even while going 25 MPH. (Not that I do that all the time, I just did a test to see if the new syncro was working).

Jdub

I would concentrate on the components around your 915 before anything else. Try this: car idling warm, disengage the clutch and push the shift over just above Reverse, then GENTLY push the shift into Reverse. Did it grind? If so, how long must you wait before this procedure does not cause grinding? Ideal is no more than 4 seconds I am told. This is a common PPI test for clutch drag and can tell you a lot about how your car is disengaging in preparation for the next gear.

So, I would first adjust your clutch cable so it is EXACTLY spot on. Then, I would make sure that the shift coupler bushing and the cup bushing at the end of the shift lever were replaced. Have the linkage adjusted by a pro (maybe the coupler at the same time) and then spin the car around to test the work.

Point is that you may be getting close to a rebuild. To stave off this expense, adjust and replace the surrounding, inexpensive bits prior to any other work. Only then if the shifting becomes impossible should you consider a trans rebuild (and new clutch as you see fit).

Overkill for your simple question, but I hope this helps you keep your trans out of the shop a bit longer!

Jw

911pcars

Here's a hint to save your synchros; don't overwork them in the first place. The function of the synchromesh is to bring both gears up to the same rotational speed before engagement. The more speed difference there is while changing gears, the harder the synchromesh has to work.

During upshifts, pause slightly before engaging the next gear to allow the engine speed to drop so the rotational speeds are closer.

When downshifting, the rotational speed for the desired gear must increase. The only way to achieve this is to rev the engine while in neutral (clutch engaged). You can't just blip it with the clutch pedal down). If the double-clutching rpm is done correctly, the shift will be effortless. The desired engine speed for double clutching = the engine rpm that would result if the trans. were already in this gear. In practice, rev it slightly higher as the revs will drop slightly as the shift is made.

Hope this helps,
Sherwood Lee
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