Maximum downshift point - 2nd to 1st
 

I have a recently acquired '85 911. The owner's manual says the maximum downshift point from 2nd to 1st is 39mph or 3750rpm. I say no way! There is no way I can get into 1st at anything over ~10mph and even that is pushing it. Sometimes at a full stop the only way into first is to press, release, and press the clutch again while in neutral in order to get it into the gear. Anyone else have this problem? What should I be looking at - synchros, bushings, ...?

Your syncros are probably shot. If you learn to double-clutch with some rev matching you should be able to downshift at a higher speed, but you don't necessarily need to...

The main reason the owner's manual specifies the max downshift point is to keep people from blowing up their engines.

Oh, BTW, I think, you've got a typo, I think that is 39 mph or 5750 rpm

Being an '85 you've got the notorious 915 tranny (probably shouldn't be that notorious). What's probably happened is that the previous owners have tried to pull the 1->2 shift like they were driving an old Chevelle, and the 915 just isn't designed to shift that fast.

Anyone else have this problem? That's funny ha ha--just everyone with a 915 transmission! There really is no reason to downshift to 1 except while stopped at a stoplight. Now there are a few tricks to get it into gear at that point--here are a few 1-while stopped and clutch depressed, move the shifter into 2nd then 1st. 2-blip the throttle slightly while clutch engaged and at the same time move shifter into 1st--this also helps if you are downshifting from 2nd to 1st and the car is moving (matches synchos to engine speed to make shift easy) and 3-jiggle the shifter a little while trying to engage 1st gear. I know this sounds like a PIA but these 915 transmissions can be tempermental. Some guys have had good luck replacing the bushings, installing a new gateshift kit from Seine or Robotek or Wevo and replacing the tranny fluid with Swepco. Lots of info on this board regarding this problem.

Thanks Steve.

No typo - here's the maximum downshifting points from the manual:

5th to 4th: 122mph or 5200rpm
4th to 3rd: 98 or 5200
3rd to 2nd: 67 or 4500
2nd to 1st: 39 or 3750

I wouldn't bother shifting into first untill you are at a dead stop. My syncros aren't shot & I still don't bother in order to try & perserve them. In fact my second gear syncros will need replacing before the first because I sometimes get too hastful trying to grab second. BTW don't push your odometer reset button while your moving or you may strip the nylon gear inside. Enjoy.

Hmm, weird, I think mine may be a tad different, but that wouldn't be surprising since mine's an '88 with a G50, no problem going into 1st there, but the 915 is a good box too when it's in good shape.

I would say the probability is that it's the syncros, but there is a possibility that replacing the bushings in the shifter, adjusting the coupler, replacing the clutch cable and making sure all of that stuff is working well could make a pretty big difference too. It may help or it may prolong how long it will be before you want to get a rebuild.

I'm betting everyone with a 915 tranny has the same issue, as did I.

I personally don't really see too much of a need to go from 2-1, by the time I get that slowed down, I'd rather just use the brakes.

As alluded to above, I DID have luck replacing the bushings, working on the linkage, although I haven't bumped to Swepco (yet...).

Try it out, what's to lose? The bushing kit is around 20-25 bucks, and the linkage adjustment just takes a little time to learn and make sure you know what your doing.

Do you have the mechanical history on the car? What's the mileage?You might be able to find some detail on whether or not the tranny/clutch/synchros have been worked on.

I had a lot of problems getting into first when stationary, even when using the neutral-2-1 trick. I replaced the bushings and got a new shift coupler, it made a huge improvement. My 915 still has "character", but it's now much more user friendly and I have no problems with first. Now of only I could persuade it to let me do fast changes…

PS.
Don't know if it would let me do a 2-1 while moving… I never use the gears to slow the car and don’t think there would be any point in going to 1st to accelerate… I can do a quick 2-1 if I've almost stopped and take off again straight away.

I bet it is 39 mph if you are coasting (clutch in), not actually "in" second gear.

All I know is that brake pads are a lot cheaper than synchros.

I am so glad you guys have problems too. I thought I was losing my mind when I was shifting - its just the 915 - I have to slid to 2nd sometimes and at a stop light - I have to cycle the gears to make 1st available - depends on how warm the engine is though - in the morning it can be real stubborn. I can't complain though the car is pushing 190,000 miles estimated - darn gear broke on the odometer when I pushed it when the car was moving - before I found Pelican.

replace motor $10,000
replace brake pads $100

Why would anyone use the motor to slow a car down? ;)

If my car is rolling at 10+mph, I take off in second. I don't like the sounds of metal on metal. Makes my teeth... and pocketbook hurt.

Your car should fall into first if you doubleclutch and slide it into first just before you come to a stop, 800 rpm or whatever your idle is should be about 3-5 mph, if you try to put the car into first at that speed the syncro's shouldn't be necessary, and then you won't have to worry about grinding into first while at a complete stop.

I have driven an '84 with a 915 that was buttery smooth, amazing really, and I have driven a 915 car that was really hurting for some work. You can double-clutch and rev match and get my car into first at 35 if you want (I don't generally want).

One of these days I want a 911 with a 901 tranny.

The lovely 2-1 shift. I agree with the rest, no reason to DS into first ESPECIALLY at 35mph. My mechanic told me not to ever shift into first, as the 915 just doesn't like it much. Why waste perfectly good syncro's. I recently changed out and rebuilt my shifter and bushing along with a new shift coupler. HUGE difference!! The coupler was a loose, floppy, mess. Swepco too. I usually only shift into first as I'm slowing to stop. I have found that if I shift into first and coast to a stop with the clutch pushed and then take it out of first once I've stopped, nine times out of ten picking up first gear is no problem. I do not sit with the clutch pushed in. Ruins the throwout bearing...

Another thing is once the clutch is pushed, give the trans time to do it's thing and line everything up, then it will go right into first. The 915 has a mind of it's own sometimes and they each have a specific personality... Get to know yours well and you'll love it.

PS: I was REALLY blown away at how much better my shifter felt after rebuilding it... I'm still thinking of doing a WEVO though...

I have learned to shift my 915 very smoothly and effectively. I know the proper shift points and never force it into gear, never grind.

Makes me wonder why my 915 has a little trouble from time to time in first or second gear. It is not due to any abuse from me....had to be one or more of the previous 6 owners.

With 88K miles on the car, the 915 is the only thing with any noticable wear and tear.

I wonder what the shifting would be like, had I been the only owner from day 1. Probably near perfect.

I have a rebuilt 915, factory ltd. slip in my car, and I can up/downshift into any gear from any gear between 0-6500 rpm w/o double clutching, putting it in another particular gear first, etc.....

I can downshift into 1st gear @ ~30 mph w/ no problem, but there is really no reason to w/ the torque available in 2nd @ that speed. The important thing is to have all of your gears available within their power range, shifting up or down. And only terrible drivers use a downshift in place of brakes; that is not even done on the track where it would upset the car completely. Brakes are for slowing/stopping, and the engine and trans are for going/accellerating. Never the other way around. :cool:

Speeder...

That is somewhat incorrect. Downshifting is nec coming into turns depending on the speed of the turn. F1 guys don't just brake (and slam three of four gears lower) they downshift all the way into the turn. It's a combination of the two. And of course the downshifting is only done coming in on a straight line into the corner in the break zones, not in the turn. If one downshifts in a turn... well say goodbye.

There shouldn't really be any brakeing in a turn anyway. There is a turn braking method which is combines acceleration and braking at the same to to maintain balance in the car. (I can't remember what it is called) It requires being able to brake with your left foot. Similar to heel/toe. In which case one would have downshifted to get in the proper gear to take the turn at full speed. Again, this is an F1 cornering strategy and works very well, but is difficult to learn.

Speeder is correct, the gears are not for slowing the car.

Sure on approach to a corner you down shift, but that's in order to be in the correct gear to accelerate out of the corner. On changing down you blip the throttle (heal and toe), consequently there is no engine braking as a result of the down change and the cars balance is not affected.

Left foot braking allows the transition from trail braking into the corner to accelerating out of the corner to be quick and smooth. You need a sequential transmission or to be able to shift without using the clutch.

Regards,
Andrew.

Keep downshifting into 1st and I'm sure you'll win the race to your mechanic.

There are a few things wrong with this statement on a number of levels as amk pointed out.
At rest your car has a 40/60 weight distribution. When braking you want to get the weight transferred quickly and smoothly to the front of the car so the weight distribution is stable. I would guess the split is about 60/40 depending on the grip of the tires/road cmbination and the skill of the driver. If it is exactly 60/40 then you want exactly 60% of the braking force on the front end and 40% on the rear. This will give maximum braking force. Any change to the split of force will reduce the total braking force.
Engine braking under these conditions will cause the rears to slip and tend to spin the car. Engine braking went away in every form of racing when the cars gained adequate brakes. Heel-toe braking is specifically used to keep the engine braking effect from upsetting the car (and make it easy on the syncros).
The F1 guys don’t engine brake - ever. If you watch them they tend to shift as fast as they can because there is so much braking force that they never spend much time on the brakes. On really fast straights you can see them start braking and at the end of the braking zone they do the flip,flip,flip... shifting bit.
Read Niki Lauda’s book from the 70’s; No engine braking.
Gas and brakes at the same time? A few reasons; -A tap to get the front of the car to bite without lifting on a full throttle corner. -If you want to grab the rears to loosen the car you can use gas and brake. Common in rally and very common (necessary!) in front wheel drive ice racing cars. -A really sharp driver can add some slight rear drag on a car that doesn’t have adjustable brake bias when a track has gone very slippery such as driving rain with a dry setup (tricky).

My advice on all of this is don’t do it. If you ever get to the point where you need this stuff then you will already have learned enough to ignore this thread and decide on your own.

Wayne

I sort of mis-stated what I was saying. I know that the downshift is not for braking, but it is necessary (as AMK stated) to be in the proper gear for the turn exit. (thanks AMK for refreshing my memory on TRAIL braking.) And I am aware of needing a sequential trans for that... I was using it as an illustration.

The post made it sound as if one were never to downshift at all.

And I don't ever downshift into first... :rolleyes:l

Since I wrote the post very late... maybe I'll just delete it...:D

Well, you can delete the post if you want, but it lives in infamy thanks to the "quote" button. :D

Once again, only terrible drivers use the engine and trans in place of brakes. (To slow down the car). The downshifting that you are hearing in a Formula 1 race is just rapid downshifting trying to keep pace w/ the incredible deceleration that the brakes accomplish on those cars. No way are they using the engine compression to brake the car, straight line or not. So what was your point? :)

I downshift my car on the track while braking hard before a corner at the end of a straight, my car will shift into any gear that I select, but obviously if a downshift causes over-revving it will blow my motor. Just use common sense, (and your tachometer), and these questions are irrelevent.

And like I said previously, there is no good reason to downshift into 1st above ~15 mph, but a good transmission will go into 1st easily much faster than that. Always match your engine/trans/wheel speeds when downshifting. :cool:

first gear is only designed to get you rolling from dead stop
so unless approaching a red light and you know you will have to come to zero mph : don't downshift.

yep , that's why every drivers instructor in Europe teach us stickshifters to use the engine while braking :rolleyes: to make sure everybody in Europe would be terrible or worse than terrible at driving...

Well to banter further... Maybe the ideal scenario is to not engine brake... Fine, I don't really do it, but it's fun to argue!!!

Anyway with the F1 cars... having seen them up close and in person both in practice and in race conditions, they do use that downshift for some slowing. Given the sequential transmissins... every time they pop a gear the car resoponds. Yes, it is true they are keeping up with brake forces, but the cars do spike the RPMs a bit in the downshift which indicates a slowing action taking place by the engine. Is it supposed to be that way... maybe not. But it does happen. When the cars come down the straight at indy they dump five gears into turn one. I must say it is wild seeing a car drop from 180 or so to 30 in about 200 ft... (if even that far!!)

Anyway, no big deal and I agree with everything said about 1st gear. From a shifting perspective, if your trans is good and you push in the clutch you should be able to "put the car into first" at just about any speed. Pop the clutch and watch it BLOW!:D

I put my car into first at a dead stop, or maybe if I'm rolling at 5mph...never higher. Never found a reason to. I'm not drag racing anybody, and it'll calmly pull in 2nd at low speed.

Wasn't the dogleg tranny made that way because 1st was only used to get out of the pits and never anywhere else?

Absolutly, love a bit of banter ;)

Is the spike in RPM you're hearing the throttle being blipped on the down change? In theory even with a sequential box and left foot braking you're still meant to blip the throttle on down change to avoid unbalancing the car (not that I've ever driven a sequential box on the track). Some sequential boxes blip the throttle for you, on others there's a gap between the gears being engaged, if you time it right you can blip the throttle between the change (apparently this is easier than it sounds).

AMK...

Perhaps... since I'm not going to be sitting this big ass into an real F1 anytime soon... I couldn't tell you for sure.
I just know the sound of deceleration along with backfire... which would suggest engine slowing to me.:D