Conical screw keeps coming loose on shift rod coupler

[NONO5.0]

Sorry if this has been covered, but I did a search and didn't find anything I have a '72 915 tranny out of a 911 that I installed in my 81 DeLorean (mated to a Chevy 4.3 vortec engine) back in 2003 and the tranny has been GREAT!!! No issues whatsoever! EXCEPT, that the conical screw keeps coming loose over a decent period of time and I have to keep re-tightening it. Is this a common problem? If so, can anyone recommend a fix? I was going to use some loc-tite (or somethin similar) on it to try and keep it in place, but was just wonderin what others may have done.

Thanks for any help!

[Oh Haha]

I replaced the conical screw with a standard 6 point version. I can get more torque on it than the socket style. I also drilled a relief in the coupler itself so the screw goes below the surface.

I have not had mine loosen up at all after this mod. You can always add a bit of Loc-tite blue for extra security.

[Scott R]

Pics?

[WilsonTC]

[Oh Haha]

I didn't take any pics at the time and I would have to remove my FE mount to get them today. (I 'm on Daddy duty so I can't do that right now. Sorry.)


Just mark the coupler/rod orientation, remove the set screw, go the the store and buy a short replacement with the same thread and install it. I would say the length can't be any more than 5mm or so. Measure the old one to be sure, though.

[Oh Haha]

Originally Posted by WilsonTC

Jeez, I thought that was nail polish!!!

[Scott R]

No pics of the Delorean

[WilsonTC]

Originally Posted by Oh Haha

Jeez, I thought that was nail polish!!!

It is nail polish...for men.

[Oh Haha]

Originally Posted by WilsonTC

It is nail polish...for men.

Touche, my friend.

[NONO5.0]

Wayne! Thanks for the tip! BTW, its been awhile since I've done research on the 915 tranny, however, my screw points straight down (ie if it came completely out, the conical screw would hit the ground) Is that the same way it is on the Porsche cars or is the conical screw installed from the top side? Just curious.

As far as the pics go, I do have TONS of pics of the car, and quite a few of the engine swap but not a whole lot on the tranny. I'll take some pics tonight while I'm workin on the conical screw and post them later

[Oh Haha]

Ours point "up" as it were but the concept will still apply. Use the Loctite for sure with the way yours ismounted.

[NONO5.0]

Originally Posted by Oh Haha

Ours point "up" as it were but the concept will still apply. Use the Loctite for sure with the way yours ismounted.

Thanks for the info! I've had it in the car since 03 and have had to tighten it about 4-5 times. AMAZINGLY enough, until the last time, I didn't even realize that there was a spot on the shift rod that it was supposed to be counter sunk into! I figured since I got it installed correctly last time, that it'd stay in place from then on. I am amazed though that you can STILL shift and that it doesn't come completely apart. I would have thought that once that conical screw comes loose, you couldn't shift it at all and it would just slide on the shaft. Thank God it doesn't Definitely can make finding gears interesting though

[RWebb]

yeh but I would not use 271 - aka Red

I'd use purple (low strength Loctite)

[WilsonTC]

Originally Posted by RWebb

yeh but I would not use 271 - aka Red

I'd use purple (low strength Loctite)

Why not permanent? That screw isn't something you remove regularly, is it? I always use permanent on stuff that isn't a regular maintenance item. (Note to others: DO NOT use 271 on screw-in wheel studs!).

[Scott R]

I'm with Randy on this, at some point that screw has to come out for doing maintenance. At least in the Porsche world, things like a partial drop and etc.

[WilsonTC]

Originally Posted by Scott R

I'm with Randy on this, at some point that screw has to come out for doing maintenance. At least in the Porsche world, things like a partial drop and etc.

The "permanent" isn't really permanent, unless you're dealing with large bolts...like wheel studs. Don't ask me how I know that. It is for bolts that aren't removed in the course of regular maintenance. I'm assuming we're talking about the shift-coupler bolt here, right?

[NONO5.0]

That's what I was thinkin too. Purple loctite or maybe just some black atv silicone. I've had it in there for 6 years now, and from what everyone has told me, I am EXTREMELY lucky with this transmission. (Knocking on wood that it keeps on holding up as well as it has) I remember when I first got it (bought it off this forum after posting that I was lookin for one) and a member here said he had one just sittin in his garage takin up space....$350 shipped!! ) That was PERFECT because I didn't even know if I could make it work in the DeLorean. I already had the Chevy engine mated to the stock DMC auto tranny, but the stock auto tranny lasted only 3 years....and with NO abuse what so ever! Even when the D was stock, the tranny only lasted me about 3-5 years ...which is why I did this swap. I was just lookin for a CHEAP tranny I could try. AMAZINGLY enough, the half shafts of the D mated RIGHT UP to the 915 tranny! When this trans does finally die, I will DEFINITELY look at rebuilding it.

[Jim Sims]

The thread locking patch on the screw is worn out (too many loosening and tightening cycles.) Spend $4 and get a new screw with a fresh locking patch.

[NONO5.0]

Welp, the conical screw turned out not to be the issue. The issue is a missing bushing on the side (if that's what it is) Here is a pic:





I'm assuming that just replacing the whole rod coupler is the way to go. Is this a common problem? Is there an updated fix over OEM? Granted, it can't be too bad of a part b/c it lasted this long, but if there's an updated fix, I'd rather go that way.

Thanks again guys!!

[Oh Haha]

Yep, that would be a problem.You CAN buy just bushings for it or go with an aftermarket coupler.
http://www.pelicanparts.com/catalog/shopcart/911M/POR_911M_Tshift_pg1.htm#item3
Check out WEVO for a better than OEM part. Pricey but worth it. http://www.pelicanparts.com/catalog/shopcart/911M/POR_911M_Tshift_pg2.htm