915 Gearbox 5th to Reverse? Is this possible?
 

I'm completely new to 911s. Just got my first one (76 Targa) after dreaming about a 911 for 20-plus years. So, I'm finally hitting the freeway running through the gears with no problems. While cruising in 5th, I'm having a hell of a time finding 4th. I'm a little freaked that I can accidentally hit reverse while downshifting. Is this possible?

I was knicking gears trying to find 4th without mistakenly hitting reverse. I'm apologizing profusely to my baby. I found 4th, but man it wasn't pretty (there must be shiny pieces floating in my gear oil now:mad:) and I was too freaked to go back to 5th:confused: The car runs through all of the other gears nice and crisp otherwise.

I know 915s are finicky, I just don't want to implode my gearbox by dropping it into reverse at 60 mph. Advice, pointers gladly appreciated. I'm really excited that the Pelican BBS is around! Seems like a great bunch of folks all obsessed like me.

A Sienes gate shift kit and Ivangene's coupler will keep this from happening.

But before that, be delibrate in your shifting, no speed shifts, clutch in, pause then shift. especiallly when shifting on turns

Where you located? it sounds like a coupler issue

I'm in Pittsburgh. I've been thinking about redoing the the coupler and bushings, etc. to make it a little more precise. When the car is cold I can nick second gear if I'm not super deliberate with my shifts. Once warm, I can go throughout the gears, except 5th to 4th!

Yeah, refreshing the bushings will help but you will see the most improvement with the coupler.

Also make certain the clutch is adjusted correctly, cold or hot you should not be struggling.

I would also consider new engine and trans mounts, at speed if the mounts are worn they will mis-align the gears. I went with Cabriolet mounts to lower the chance of flex.

The gate shift kit is extra insurance, it really should be called Mis-Shift Be Gone :D

Ask a Pitt Pelican with the setup to feel theirs, you will be amazed.

Awesome advice! I'll check the engine mounts. The clutch adjustment appears to be OK, as it has the right amount of forward play (little less the an inch). I'm going to look into the coupler you're talking about and that shift gate. I just ordered some Swepco 201. You don't think a 4 or 5 grinds threw too much shrapnel in my gear box?:confused:

Nah, you will be fine, just fix it before you make things worse.

Swepco? If I may suggest, when your car was built they did not have synthetic blends so I would consider conventional Valvoline or Kendal gear lube, 80W90.

Do you know if you have LSD Limited Slip Differential or Standard?

Raise the back end and in neutral, spin the driver side forward, if the passenger side rotates in the same direction, you have LSD, then get the gear lube with LSD additive.

Clutch:

Just checking, when cold or hot the clutch engages half way up or down right?

Really the measurements need to be checked below while a help depresses the clutch pedal for you. Making certain there is no play on the arm 25MM +/- .5MM difference at rest and depressed

Also, check the operation of the reverse lock-out cam on the top of the shift tower. On my car, the cam was a touch sticky and didn't always snap into place after moving the lever into fifth. I also found that if you have the factory short shifter installed, the coupler adjustment for fore-aft movement is much fussier. There is a much smaller window of proper adjustment—if you adjust the lever too far to the rear the lockout won't engage. Take your time and watch the operation of the lock-out before putting the shift boot back into place.

When I got my car it was doing exactly what yours is doing. No matter how carefully I shifted I could nick reverse coming out of 5th gear. There was no spring pressure at all when shifting into or out of 5th gear. I removed and inspected my shift tower only to find out that lock-out mechanism was completely useless. I obtained a stock replacement tower and shifter and installed it and I haven't had a problem since.

I believe the Swepco 201 isn't synthetic and seems to be the choice for 915 boxes? The 210 is synth and is cool for G50s. I definitely gotta see if I have the LSD!

My car shifted pretty poorly into second and third when I bought it. I got a WEVO shifter and shift coupler and it made a world of difference. The lockout for 5th is much better designed than the OEM lockout, plus it is spring loaded so that when the car is out of gear, it's always in the 3rd to 4th plane. Plus the WEVO shifter comes with new shifter bushings also.

Not to throw a wrench in your plans, but when purchased, my car had Swepco 201 in it. Last winter I switched to Kendall 80W-90 NS-MP Hypoid Gear Oil (sold by our host). It totally changed the shifting qualities of my gearbox. I would compare it's current cold oil temp shifting qualities to the way it used to shift when warm.

So you're a Pittsburgh Pelican? If you need help with anything, let me know.

a new set of bushings along with adjustments might work wonders for you. There is a pelicanite here who is currently machining coupler bushings out of Delrin(sp?) and seems to be a better option than stock 911 shift coupler bushings. I use 914 bushings. the 911 coupler bushings are somewhat oval compared to the round 914.

I had serious shifter issues when I bought my car. It was all related to bushings and a broken shifter shaft. I took the whole system apart, replaced all the bushings, lubed every thing up and reassembled it and now its great. The 5th to 4th takes some getting used to. The seine gate shifter is a great option, I dont have it but it is on my list of upgrades soon to come. The lack of the center (3rd,4th) shift plane can be an issue for some but take your time to shift slowly and you will get used to it. I would say take a month or two in this nice coming weather to drive the car alot, if you are still unhappy go for the seine gate mod. You should however replace all your bushings now.

If you do your own work its a quick maybe 3 hour job. Pick up the 101 projects for your 911 book written by our very own Wayne. its a great book and details how to do this very job. There are a few options in terms of couplers and bushings you can use. Check out the search function there are many threads that talk about this at length.

Regards
Dave

Arne and Kimo are right on the money. Yes, new shifter bushings will work wonders, as will Seine/Wevo and careful two-step shifting.

However, nicking reverse on the 5th-to-4th shift (assuming no major equipment failures) is primarily a fore-aft coupler adjustment issue. I think more than a few here have adjusted the coupler fore-aft to get the shift knob in a more comfortable position, only to create the same issue you're experiencing.

Search PP for coupler adjustment; you'll find plenty of tips on how to do it well/how to do it right the first time.

Good luck

this should help you learn the 915 shift pattern

(drawn to scale)

http://i15.photobucket.com/albums/a3...iftpattern.jpg

That's good advice right there. I had the same problem on my '79 racecar when I bought it. It already had a spring centering widget on there- the old Robotek. This was an older setup similar to Seine's better designed GateShift. But it still didn't shift right.

Turns out the cup bushing beneath the shifter lever was completely toast and crumbling to pieces. So my shift lever could move more freely than it should and the shift lever would miss the reverse lockout teardrop/pawl piece.

I had yet to use 5th gear until I got to Putnam Park. The car is not street legal so I hadn't ever cruised along in 5th or gone to a track fast enough to use 5th. Well I found out the reverse lockout problem at Putnam on the long front straight. Tried to downshift from 5th to 4th and had a horrible grinding noise a few times. I thought I was having trouble engaging 4th. It turns out I was leaning on reverse at about 80mph! :eek:

Nine ball's awesome map is making believe it's human error. Knowing fourth is that damn far away is quite telling! I was afraid of downshifting into second. I don't know if that's possible. I still want to do the bushings and possibly the seines gate... Thanks folks!!

You can try going from 5th up slightly into 3rd and then back down to 4th to make the 5-4 downshift.

Take him up on this, a reference point is invaluable, worth more than a thousand words :cool: Will Done Well Hung Sir :D This is what I love about our little village!

Yeah, I fiddled around with the shift coupler many times. Using both the Wayne's technique and the WEVO technique. If anything, having somebody experience the shift that isn't trying to sell you something (like a mechanic) might help.