Paging “John Walker” and other 915 trany experts! (long)

[Bill Oxley]

First, a quick comment to infamous “Randy” 915 thread. Learned a lot, great stuff! And John, your post there were inspirational! Tnx.

Ok, here’s the deal. I bought my 84 911 TL in late Dec. 04.

It’s a great car in every respect, runs like a dream, 96k miles, service stamps for the past 20+ years. This car has obviously been well cared for.

I’ve done some tweeks here and there cosmetically, but, for the most part, great car!

So here’s the deal. If there was ANYTHING where I thought the car had a shortcoming, it would be the 915 trany. Here’s the details:

It shifts quite smooth, in all gears. But, 1st to second occasionally shows some resistance if the speed of the shift is fairly fast. If I hesitate for just a moment in the neutral area, it’s goes into second just fine.

2nd to third is good, actually quite good, but occasionally, just occasionally, I hear and feel just a tad bit of “grind”. Not much, but noticeable for a gearhead like me.

4th and 5th are fine!

ANY attempt to downshift to 1st while still rolling, 5 mph or above, will show a definite grind. So I DON’T DO THAT!

So, here’s what I’m thinking. Fix the easy things first. I replaced all the shifter bushings. The coupler bushings were quite worn. The other two were not bad, but replaced them anyway, while I was there. Adjusted the linkage exactly per the Bentley shop manual. Shifting was improved noticeably. But, still not perfect.

So to the last “easy to fix items”. I’m not done here yet, but here is where my question is. I drained the fluid, it looked good coming out, not at all black. Quite clear actually.

But upon examining the drain plug, it has the normal steel hairs, from what I know, not too big of deal, but it did have ONE tooth stuck to the magnet plug. (My wife’s away on business with the digital camera, so don’t yet have a pic) The single piece looks like this:

http://www.luoxley.com/tooth.jpg

Seems like one tooth out of many, the shifting is good, not perfect, where do I go from here? I’ve got the Swepco 201 ready to go in, but advise is needed.

[john walker's workshop]

i drain a lot of swepco out of transmissions that are in for a rebuild. that seems to be the last try before giving up on them. one tooth, maybe, but there may be more that haven't made it to the magnet yet. all of a sudden one day, the rest will go, and you won't be able to get into gear. probably 1st, maybe 2nd. they both tend to shed teeth. so it's looking like you need to get in there.

[pwd72s]

Schwepco...it cures all gearbox problems...because Sweet Old Bruce said so.

[Zeke]

Well, it looks like ol' thread hijacker Zeke is here to tell you that I really do think some Swepco has quieted down a very whiney tranny that I KNOW has to be rebuilt. I'm getting some extra duty out of it before it comes out. I haven't found any teeth, though, but I do have a lot of slack in the ring and pinion.

Now back to your regularly scheduled thread: When I have had a tranny or tranfer case with a tooth or two missing, I could always hear the clicking. The 915 may or may not do this, I wouldn't know. But if a tooth goes thru the innards of a tranny, it can be nasty. I think I'd haul that thing out of there, pronto.

A suggestion: Locate a good used tranny from the Pelican, PCA, Rennlist or other classifieds and do a switch. You will have lots of time to work on your trans, or have it done, and still have your car. Or even raise money. When finished, you can sell either one depending on how good the one is in the car.

If you do the trans yourself, it doesn't cost too much. I'll tell you this, if you are any kind of mechanic, you can probably do a tranny. I did my first 2 years ago and it was easier than any engine rebuilding work. A few special tools are needed. About half of them can have a substitution. I bought a 32 (?) mm socket for 7.99 at AutoZone instead of the expensive *official* one. I used an old clutch disc in a vice for the input shaft holder. Ect., etc.

[Sonic dB]

To the original poster:

When I purchased my 86, in 2003 with 64K miles...it shifted EXACTLY as you described.

I did the bushing upgrades, new clutch cable, horseshoe spring (2)... Swepco... This helped a bit.

Now, 60K miles later (over 120K miles on the tranny) the car shifts...slightly better than when I bought it...but still EXACTLY as you describe.

Keep in mind that I drive in heavy LA stop and go, in and out traffic every day... this is a PITA, but the tranny responds fine if it is shifted correctly.

So...the moral of the story is that you may get many miles out of it yet.

[Bill Oxley]

Thanks for responses!

John, as always, I’m sure your guidance is correct.

This car runs so well, I will probably take the Sonic approach for right now. I have so much going right now on the retro issues, and 8 cars, I would hope this thing won’t explode on me any time soon.

However, I really enjoy working on these things, and so doing a 915 rebuild, possibly in fall or winter, really appeals to me. Fortunately, I have plenty of cars to drive in the meantime. I just hope no problems until then.

Pwd72, Man, I have no idea what you’re talking about. Who the hell is “Sweet Old Bruce”?

I guess your just “pulling my chain” to a 911 newbie. No problem, I can handle it.

[kenikh]

I believe this is the 'sweet old Bruce' being referred to:

Bruce Anderson

http://www.911handbook.com/

[arcsine]

"Sweet Old Bruce" = Bruce Anderson; Porsche mechanic to the stars, writer of Porsche tuning book, editor of the tech forum and keeper of used Porsche pricing in Excellence magazine. His is not word of God, but not to be dismissed either.

I found that following new bushings/adjustment/Swepco things were a little better. Much better after new engine/tranny mounts all around and off the charts once JW rebuilt it.

[cowtown]

Originally posted by Bill Oxley
This car runs so well, I will probably take the Sonic approach for right now.

It's your call, but I'd be really nervous about that tooth on the drian plug. There's really no way to know how many other teeth are circulating around, just waiting to do some damage when they feed between a gearset. I'm no expert, but I'd think about taking a look inside while it's still in relatively good shape.

[Grady Clay]

Another issue….

It is bad enough when something comes apart in a transmission. It gets much worse (progressively) when some hardened steel part(s) continue to circulate through the machinery. I have four large Alnico magnets inside the transmission to intercept such errant parts.

I think this might be a worthwhile addition near the shift pivot plate on a 915 or 930. The magnet could be outside the transmission with steel bolts carrying the magnetic field to the inside. Removing the shift plate at each lube change would allow inspection and cleaning.

Best,
Grady

[pwd72s]

Grady, that's brilliant! Heck, I think you came up with a good aftermarket product idea. Maybe even an electromagnet for more powerful force?

[Sonic dB]

Oh...I didnt read that he has a Tooth floating around in the tranny...

Mine hasnt had any broken tooth, just small amount of shavings on the plug which is normal...

Be careful with that man...if I had a tooth, Id rebuild immediately since its a daily driver