930 4 Speed Pops Out Of 1st and 2nd

blainemeyer · 12-06-2007, 08:58 AM

Looking for some help on this trans problem. I am including emails I have been exchanging with Wayne Dempsey.

From: Blaine Meyer [mailto:blainemeyer@hotmail.com]
Sent: Sunday, December 02, 2007 2:04 PM
To: Wayne at Pelican Parts
Subject: Transmission shifting problem

Wayne,

I recently replaced some transmission parts on my 1977 930 Turbo's 4-speed to fix a second gear grinding. The parts went in and the transmission assembly went smooth. After putting the engine/trans back into the car, when shifted into 1st or 2nd, the trans pops out of gea when the clutch is let out. Other gears, 3rd, 4th and reverse are fine. I tried several shift coulper adjustments but tahta did not fix the problerm. Here are the parts that were replaced :

1. 1st/2nd Shifting sleeve - 930-302-411-01
2. Syncro ring - 930-302-301-00 ( both 1st and 2nd replaced)
3. 2nd gear synchro hub - 910836( probably not the porsche part number, but look to be correct)

I still have the parts I replace and visually the all look to be correct. These parts were simply replaced and I did not change anything else such as the shift fork adjustment.

I suspected that I installed the shift sleeve in wrong since this seemed to be the part that affects shifting the most. The 930 Turbo shop manual states 'the asymetrical profile teeth must face 1st gear'. There doesn't seem to be any clear info or photo as to which side of the shift sleeve is the asymetrical side but I took it to be the side where the gear teeth point to 1 side and are not centered. The side with the gear theeth which have centered points is not the asymetrical side and should face 2nd gear. If this is the correct direction for the teeth then this is how I had it installed and yet the shifting problem.

I thought I simply installed the shift sleeve backwards but that doesn't seem to be the problem. The other parts that were replaced seemed to be installed correctly. Would you have any information and/or ideas that may help? is there a way to chcek that the transmission is shifting correctly before putting it back into the car ?? Any info would be greatly appreciated. If pictures help and anc sent them if needed.

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Subject: RE: Transmission shifting problem
Date: Sun, 2 Dec 2007 22:31:08 -0800
From: wayne@pelicanparts.com
To: blainemeyer@hotmail.com
CC: scott@pelicanparts.com

Yup, send me some pics. I know how these are put together, but I wouldn't necessarily call me a super-expert. The asym assembly you have done here seems correct - you are right that the first gear asym is the short/long triangle, and the other side is the equal-length triangle. That's pretty basic.

The synchro rings work to both spin the transmission shafts up to the speed of the engine, and to also hold the current gear in place (spring loaded). There are several anchor blocks and thrust pieces that must be assembled properly in order to have this function correctly. I suspect that you made a mistake on assembling the anchor blocks - I have done this previously with a 914 transmission.

This is an article I wrote about eight years ago on the 914 repair:

http://www.pelicanparts.com/techarticles/914_tranny_repair/914_tranny_repair.htm

Picture 5 shows the proper orientation of the first gear assembly, this is what is easy to mess up:

http://www.pelicanparts.com/techarticles/914_tranny_repair/914_tranny_repair_pic5_big.jpg

Not the same as the 930, but the concept is very similar. If the anchor block and upper circular ring (brake band) is not installed properly, then the spring tension won't be enough, and it will probably slip out of gear, as you are experiencing. Again, this is just a guess based upon my experience with the 901 / 914 - I haven't rebuilt a 930 just yet, although we did take one apart at Jerry Woods' class and the construction / design was similar to the 901.

http://www.pelicanparts.com/PartsLookup/HTML/911T_USA_KATALOG/303-05-Frame4.htm

???

-Wayne

Wayne R. Dempsey
CEO, Pelican Parts Inc.

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From: Blaine Meyer
Sent: Tuesday, December 04, 2007 6:01 PM
To: Wayne at Pelican Parts
Subject: RE: Transmission shifting problem

Wayne,

Checked out the assembly based on your pictures and pictures in the shop manual( its amazing what you can find if you read the manual) and from what I can tell the synchos are assembled correctly. Attached are pictures of each assembly. Picture quality isn't great but I think you can see everthing. Maybe you will see something I can't. I also attached a picture of the new shift sleeve where the equal-length triangle is facing up and this side should face 2nd gear, asking and not telling.

If everything looks to be assembled correctly what would be your suggestion as to a next step ??? I am obviously trying to avoid the re-install/test/remove cycle if I can.

The shift coupler bushings were not in the greatest shape when I first put the motor/trans back in the 1st time but I didn't thing they were bad enough to cause this problem. I have new bushings and they will get replaced before the I re-install. One last fact, the clutch if failry new( less than 1,000 miles) and I don't it was adjusted incorrectly and contributing to the problem.

Again any advice, help or infomation would be appreciated.

Thanks.

Subject: RE: Transmission shifting problem
Date: Tue, 4 Dec 2007 22:29:15 -0800
From: wayne@pelicanparts.com
To: blainemeyer@hotmail.com

Okay, I don't have my 930 manuals here, so I can't really check your synchro, but I'll take your word for it that it is *exactly* like the factory manuals say. You might also want to put this info up on the forums: http://forums.pelicanparts.com

"After putting the engine/trans back into the car, when shifted into 1st or 2nd, the trans pops out of gear when the clutch is let out. "

Can you give me more information on this? Let out, do you mean engaged? Do you mean the peddle pushed into the floor? Does the gearshift lever move and pop out? What if you hold it in place? Do you have a "before" photo of the synch assembly (always wise to do this). How does the shift sleeve (slider) compare with the old one?

-Wayne

Wayne R. Dempsey
CEO, Pelican Parts Inc.

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From: Blaine Meyer
Sent: Wednesday, December 05, 2007 7:41 PM
To: Wayne at Pelican Parts
Subject: RE: Transmission shifting problem

Wayne,

The trans pops out of gear like this :

1. push the clutch in and shift into first gear.
2. let the clutch out normally and the car starts to move forward.
3. almost immediately after the clutch is release all the way the shift lever moves and the trans pops out of gear.

I did notice that when trying to shift into first or second from a stand still it didn't feel like it was completely in gear. I did try to hold the shift lever in place as I let out the clutch and the car moved forward but it still popped out. I only tried this a couple of times and was afraid of trying to force it into gear, wasn't sure if this could have broken anything.

I re-checked each assembly compared to the pictures in the 930 shop manual and the before photos I did take and I am confident that they are both assembled correctly. On the 930 assemblies the stop ring and the stop block can only go in one way and the their positioning on the ring doesn't allow the ring to be swapped between gears.

I measured the installed diameter of the synchro rings on each and they are both within the allowable diameter stated in the shop manual just in case there was some difference between the old and the new.

Check the new shift sleeve and it is exactly the same as the old one. I also took some basic measurements with a caliper to compare the 2, such as their widths.

While I had the assemblies on the bench I was able to put the shift sleeve over the assembly and using some downward hand pressure push the sleeve over the syncho ring and fully engae it onto the syncho gear teeth. I know this isn't a great test but I guess it at least shows that the parts fit together.

I did adjust the position of the shift sleeve as it was not centered when the I installed the shift rod jig. I also checked that all of the shift lever notches on the shift rods are all lined up.

So at this point I am not sure if there is anything else I can check or adjust. I am going to put a post on the forum and see if there is and other suggestions or ideas but at this point I think it may be ok to put the rest of the trans back together. Is there anything else that would suggest I do ??? Do you know of any bench test that can be done that will better indicate that everything is working properly ???

RE: Transmission shifting problem?
From: Wayne at Pelican Parts
Sent: Thu 12/06/07 12:14 AM
To: Blaine Meyer

There's something wrong, and it's probably obvious, but I don't rebuild transmissions on a daily basis. I seem to remember a problem just like this being caused by something, but I can't for the life of me remember.

Point me to the thread pls?

-Wayne

Wayne R. Dempsey
CEO, Pelican Parts Inc.

john walker's workshop · 12-06-2007, 09:07 AM

unusual to have both 1 and 2 pop out. excessive shaft end play could cause that, due to a worn 4 point bearing tensioner plate. shift sleeve adjustment off-center would tend to affect the gear that it was farthest away from. worn shift coupling bushings or a wasted bushing on the end of the shift handle could result in the gears not being fully engaged, so check that first.

Wayne 962 · Wayne 962's Garage

John, how about if the shift sleeve was turned around, so that the asymetric part was facing the wrong direction? I seem to remember something that Jerry Woods mentioned with respect to the 930 popping out of gear, but I can't recall...

-Wayne

blainemeyer · 12-06-2007, 12:11 PM

John,

All of the shift lever and trans tunnel bushings are bran new and the trans shifted ok before the work was done. I just replaced the shift coupler bushings last night but haven't put the trans back in to test it.

blainemeyer · 12-06-2007, 12:25 PM

John,

How do I test for excessive shaft end play ???

john walker's workshop · 12-06-2007, 12:28 PM

a reversed 1 and 2 shift sleeve won't feel quite right when shifting, and i suppose it could cause popping out of gear occasionally, but i've seen several of them installed wrong when a trans was opened up for a rebuild, but no complaint of it popping out of gear, so it's a big maybe. he did say he paid attention to that on assembly. sounds like it needs to come apart again anyhow, so we'll see.

john walker's workshop · 12-06-2007, 12:32 PM

Quote:

Originally Posted by blainemeyer

John,

How do I test for excessive shaft end play ???

that's done when it's all apart and you're checking how the lips of the 4 point ball bearings on both shafts and how they fit into the recess cut into the tensioning plate. they need to be at least flush with the surface and preferably, slightly proud by a few thousandths. the bearings wear also. should be pretty obvious to cause popping out of gear. end play in the pinion shaft is accompanied by ring and pinion noise.

blainemeyer · 12-06-2007, 12:42 PM

Is up and down movement of the pinion shaft a sign that is is worn ?? I notice this type of play when I was adjusting the shift sleeve last night. If it is worn wouldn't there have been shifting problems before I replace the parts ???? BTW the trans is out right now but I only have the cover off...

blainemeyer · 12-06-2007, 12:58 PM

John,

Just to check again, when installing the asymetrical shift sleeve the side with the unequal length triangular poit need to face 1st gear ???

john walker's workshop · 01:44 PM

yes, 1st syncro hub on the gear is angled and the angled side of the shift sleeve needs to face it. when the center housing is off, the ends of the shafts are not supported by bearings, so there will be some up and down movement. does the shift sleeve appear centered? did you center it with the nuts on the ends of the shafts snugged up. that's important as it pulls the gear stack into proper position.

blainemeyer · 12-06-2007, 05:38 PM

John,

The shift hub was installed correctly then. I adjusted the shift sleeve with the nuts pretty snug but not torqued to spec and a shift fork jig in place for alignment. If was off center towards first gear and had to be moved about .88 mm toward second. Is it there anything tricky to removing the tensioning plate to ckeck the 4-point bearing and the end play ???

john walker's workshop · 12-06-2007, 07:13 PM

wrench tight/snug should be sufficient for setting up the forks/slider. just pull and push hard on the shafts and see if there's noticable end play. there would have to be quite a bit to pop out of gears. the shafts are also adjustable, but in a circular direction. turn them lock to lock and split the difference before tightening the fork bolt. that centers the detents in the shaft lockout notches.

blainemeyer · 12-07-2007, 05:21 AM

John,

Thanks for all of the info and advice, I will be chceking all of this out this weehend and I will let you know how I make out.

hobieboy · 12-07-2007, 08:13 AM

I have the exact same problem in my recent tranny rebuild - but only on 1st gear.

It turned out that I/my mechanic installed the shift sleeve (or the gear itself - sorry, can't remember now) in the reversed direction.

We found out after we re-opened the tranny - when you try to engage 1st (in my case), you'll see that the gear is not fully engaged (by ~1-2mm) hence it will pop right out as soon as you apply torque (i.e. release the clutch).

Maybe your situation is different but worth checking...

blainemeyer · 12-11-2007, 05:01 PM

John and others,

I wanted to be able to becnc test the trans to see what was going on and to test it before I put it back into the car. The first 2 pictures shows how I was able to build a "frame" that would allow the trans cover to be bolted on along with the shift lever fork assemble so the trans could be manually shifted while out of the car. Maybe this idea can help other who want to test their transmissions.

With this setup I was able to see the gears and synchos working and with some adjustment of the 1/2 shift fork( i think it need an up/down adjustment more that a back/form adjustment) it now appears to be working. Second gear engages fully as can be seen in the pictures, but I am not sure about first gear. The picture with the white arrow shows a gap between the shift sleeve and 1st gear and it is about 1.88 mm. Is this o.k ??? I tried to re-adjust the shift fork but it doesn't want to move any further towards first gear. I tried tapping it with a block of wood and a hammer but it doesn't seem to move. I was sure if it had a limited amount of travel and don't want to damage it.

blainemeyer · 12-11-2007, 05:05 PM

The shift sleeve has been checked and is installed in correct direction, that asymetrical thing....

john walker's workshop · 05:18 PM

something's wrong there. that slider needs to be up flush to the gear. disassemble and pop the slider onto the gear by itself. looking at the top pic, is the slider contacting the gear on the mainshaft before it's all the way into 1st? that "jig" doesn't support the shift shafts like the proper jig would.

MBEngineering · 12-12-2007, 07:16 AM

HI John & blainemeyer
1st gear fixed gear is the wrong way round on the input shaft, as it has a shoulder on it and should go the other way round to clear the slider.

regards mike

hobieboy · 12-12-2007, 09:15 AM

Looking at your pictures, I had the same issue when I put mine back together earlier in the Fall. And as Mike said, the gear was installed in the wrong direction. So I also think this might be your issue here.

blainemeyer · 12-13-2007, 09:11 AM

John and Mike and hobieboy,

The jig I build is obviously not super accurate but it served its purpose and allow me to see how thing were woking or in this case not working. I did have the proper jig in place( you can see in the background) but removed just to take the pictures. Will check the gear installation as it appear I did install it wrong. Thanks everyone for youtr commenst and help. Wil post back if it fixes the problem.