2nd gear grind on upshift

[Redlineshftr]

When I first drove the car I fugured it was a bad synchro but It never grinds on downshift. Could there be a linkage problem or is it a synchro?

[Oh Haha]

Adjust the linkage first, then consider worn snychros. Fine tuning the linkage can do wonders. Try doing a search here for more info than you can take in about this very problem.

[Redlineshftr]

I adjusted the linkage this afternoon and its better but not totally gone. Now it just grinds and higher rpm's. Im going to replace trans fluid tomorrow and see if that helps. What should I put in there?

Mike

[Oh Haha]

SWEPCO is the choice of demanding Pelicanites. I have been using it since I had my trans rebuilt two years ago. I don't know if it made a difference because all the parts were new anyway. I still nick second every now and then on fast upshifts. Tuning the linkage can get a bit tedious after a few hours.

[mayfiebl]

I too am having a trans issue, My 77 shifts hard going into first, hit her 2-3 times at a stop and it seems better, Then drives fine till the car is brought up to a fast pace, I then get a faulse neutral and I cannot get it in gear. If I back down it shifts again.....If driven in a regular street mode only first will bind and that is off and on...No I have not gone down and checked the level(Yep I know) I'm getting all sorts of don't go synthetic and others are saying put a additive in it.....My friend just asked a shop and they say sycros and if I pull it its $1000.00......Hmm then again I read here a linkage problem. Its done this for some time and yes I have yet to check the oil as the car is rarely pushed. What ideas can you hit me with? And the best oil?

[Redlineshftr]

I wish my garage looked like that....

[mayfiebl]

Thanks it could I'm going to have to sell the 914 cheap

[Rick V]

I was having the same trouble with the 915 in my 82 SC. I replaced all the bushings and spent what seemed like 9.5 weeks adjusting the coupling and got it as good as it gets. I then changed the fluid to the sexy-smurf-blue swepco201. My trans now behaves nicley. The only time she gives me the scond shift issue is if I pull it out of first before the clutch is on the floor. I would recomend the fluid change and the adjustment trick. Also make sure all of the bushings are up to speed.

[911pcars]

Your upshift symptoms lead me to believe it's an adjustment issue, or as Rick V suggests, perhaps a difference in fluid.

Synchros work during upshifts and downshifts, but the natural tendency for engine speed to decrease while upshifting automatically ensures gear speeds will coincide at some point resulting in much less chance of teeth clashing. This is opposed to downshifting where one either relies on the synchro to match speeds or to doubleclutch. If the gearbox downshifts easier than it upshifts, I'd suspect some adjustment or wear issue.

As Rick V says, try replacing all the bushings and replace the fluid with Swepco, then let us know.

Sherwood
http://members.rennlist.org/911pcars

[mayfiebl]

Thank you guys this weekend will be the test, I will order the fluid tonight, any tricks to getting the old stuff out?

[c911s]

I have an old 901/911 trans, it will not take a fast shift from first to second. Local PCA member with a 993 turbo also has the same problem. Try starting in 2nd - avoid the problem : )

[klaucke]

My trans is quite behaved on proper downshifts into 2nd.... but always a bear on upshifts into 2nd. I know the syncro is bad but I am just double clutching to put it off for a little while longer. Still, my point is that it can behave worse on upshifts than downshifts, despite the logic behind Sherwood's statement (with which I agree).

[dfink]

Join the I rebuilt my tranny club. I went through the whole adjusting thing new fluid all the trys and it still grinds on second hard shifts. I have now replaced everything associated with second gear and hope that takes care of it. Second gear is on the same shaft set as first so I don't see how adjustments are going to help much as it is a straight pull from 1st to 2nd. Down shift worked fine in mine also but for reasons previously given downshifts are naturally going to work better. I think you have two choices 1.) drive nice and make sure you shift before 3000 or rebuild. From what I understand you are still never going to be able to power shift a 915.

[mayfiebl]

My car shifts fine except a slight grind into 3rd but if shifted with care it is very smooth, If I push the car and shift a grand or two below redline, its fine for about 10 min or so then it will refuse to go in a gear unless I back off then it seems to go in 4th no problem....but when that warm and the prior just happened I have a bear of a time finding first, No grinding but just can't find it....I have driven Porsches on and off for years and I have 2 911's a 944 and a914 current....so I have to assume its not me.I'm getting the oil right now

[Redlineshftr]

I just bought some fluid for my tranny, going to replace it tomorrow. How much does a 901 hold?

[911pcars]

Less than a gallon. The excess is for unintended spillage.

Next, how to get the lube from container A to gearbox B without endangering the habitat. The archives suggest several methods to accomplish this task. BTW, make sure you can remove the fill plug before you remove the drain plug.

Sherwood

[Rick V]

the process of empting the fluiid bottle into the trans is simple. Just get a suction gun. They are cheap and have all kinds os uses.

[Geronimo '74]

I had a grinding noise going from second to third too, asked my mechanic to open up the tranny and check, synchros were replaced.
I sure hope it has been resolved.

[drsimonwong]

On my car I found that 1-2 upshifts at 3k are always smooth and trouble free but redline shifts always baulky (but no grind). When I double declutch the story changes and the lever is almost sucked into 2nd.

Now I started to pay attention to the exact rpm at which 2nd engaged best and it seemed to favour 2-3k.

Not ideal for fast shifts of course as you loose some 3-4k in rpm!

Now I came across the factory power chart for my car and noticed at 3000rpm in first the corresponding 2nd gear rpm is 1800rpm at 30km/hr.

At 6000rpm in 1st the 2nd gear rpm is 3500rpm at just under 60km/hr.

Is this just coincidence or relevant to the easiest on the synchro shifting points?

The ratios appear more closely stacked up the box. with 2000rpm drop 2-3, 1200rpm drop 3-4 and 4-5 is less again.

Simon

[Oh Haha]

I think we need to add a better first gear to these boxes! From what info I gathered when I ran into this problem BEFORE having my gearbox rebuilt, first gear in a 911 is only for getting out of the pits. Think about it, in a race situation you hardly ever use first gear once rolling. I made the mistake of shifting mine like my 94 Z28. Uh yeah, that'll be $2000.00 please. DOH!!!!!!