A guy in his garage attempts to rebuild a G50

[AlBackus36]

Part II: A guy in his garage attempts to install a LSD in an assembled G50 starts on page 6!

Hello Pelican, I am an average wrench and owner of an '87 911. I'm going to attempt to disassemble, inspect, and replace my 1/2 synchro rings and my 1-2 hub slider in my G50 transmission. I plan to document it all here on the forum to share with you all.

Why am I doing this?
The transmission isn't grinding currently, but it is difficult to shift into 1st when cold. It does loosen up a bit when warm, but is always tricky. To work around this I will double clutch or do the 2-1 shift to get it to drop into 1st. It sometimes still won't go easily.

So far I've:
1) Tried three different fluid changes including Mobil-1 and Swepco
2) Replaced the OE bushings in the OE shifter
3) Adjusted the OE shifter
4) Replaced the OE shifter with WEVO
5) Adjusted the WEVO shifter
6) Replaced clutch, slave, master, and pressure bled

No matter what I do, the symptoms seem the same and I expect them to get worse. The car has 150k on it. I'm sure it's been driven mostly lightly, but the clutch/slave/master had issues when I bought it 7 years ago, and it's not clear how long the issues were present. I'm certain the sychros have suffered over time because of this.

A new engine is going in the car and the trans is out. This is a great time to at least inspect.

How am I going to do this?
1) Well, I'm going to need help. Mostly from people like Dannobee, Matt Monson, and anyone else who has rebuilt a G50 and is willing to lead the blind. Anyone is welcome to contribute. I expect criticism

2) I have an engine stand and a yoke to mount the trans to. It feels pretty cantilevered on the case so I've propped in a 4x6 to support some of the weight. I've seen pro shops use similar setups so I 'think' I'm on right path. Things will get better as trans weight goes down. I'll get a furniture dolly as well as that seems to be a jig of choice to move parts around and rebuild this thing in a vertical orientation.

3) I'm going to use manuals and the forum to get through this. I have the commonly available G64 manual that someone is kind enough to host online and a 87-89 911 Bentley.

4) I have an assortment of tools, but I'm sure I'm going to need more. I'll share what I buy and where I get it as I go. I'll probably keep a tally of parts and tools along the way. I have a garage, own a welder, a press, a vise, and have space to do the work.

5) I have an OK background in cars and working with my hands. I'm not a professional wrench. I'm a mechanical engineer who has studied and approved aerospace repairs for the past 15 years. Before engineering I was in the autobody trade and have been trained in refinishing and structural repair. I've restored a few Ford Galaxies, and a modified a bunch of hobby cars along the way. I've been tinkering for my whole life from legos, lincoln logs, bikes, and now cars. I do most of the repair and maintenance on the home fleet.

OK with the background explained, let the pain begin.

My 1/4 drive 0-80in-lb deflected beam torque wrench is coming so I can measure pinion preload. My first step is to open up the G64 manual and the Bentley to see where to begin.

Onward!

Edit after completion of project;

Semi-Specific Tools Used:
1) Engine/trans yoke
2) Engine stand
3) Sturdy bench vice
4) Hydraulic press
5) Torch
6) Toaster or oven (capable of 120C/250F)
7) HF ICON master puller set
8) 41mm socket
9) 29mm socket
10) Torque wrenches capable of 0-120ft-lbs

[Tippy]

Subscribed.

I am in the "I aint scared" department, too.

Any time I hear, "you have to have a professional do it", that lights my DIY spirit.

Every expert was once a beginner, right?

[john walker's workshop]

One thing I will suggest is when you pull off the shift sleeve/hub assembly, DO NOT let the sleeve slide off the center of the hub, or all the springs and detents will pop out. Not that you can't reassemble it eventually, but it saves a hassle and you don't need to grow a third hand.

[gled49]

Hopefully your manuals have G50 info, the G64 info will leave u spinning.

[AlBackus36]

Excellent guys, I appreciate seeing some familiar names speaking up already

Tippy, I am scared. LOL, but I do agree with you. If a wrench can do this, then a competent person should be able to slowly perform the same tasks, when guided by the right people/docs.

John, I'll keep this in mind as I get in there. That's a great tip that will likely catch a newb off gaurd.

gled, the Bentley 'I believe' has a section for the G50. I haven't confirmed this. I have read through the G64 manual and agree it's a bit dizzying. You need to disregard the entire front of the G64 (output, center diff, clutches, etc) to get to the G50 bits.

First questions for the audience:

1) Pinion preload check is very first thing done or just done before removing diff?
2) Do you drain fluid before the pinion preload check? I guess 1st question will answer 2nd.

Family is in town starting tonight. Bear with me if there is a day between updates. This is happening though Weee

[dannobee]

2WD G64 manual will give you all you need. The 4WD G64? Yeah, don't even look at that part of the manual, it's nothing like a G50. And have the G50 parts catalog pages nearby for reference.

You'll need a basic puller set, with press plates and some all-thread to lengthen the reach. Or use a shop press if you have one available. Other than that, not much different than any other modern tranny. If you take the shifting mechanism apart, don't mix up the two springs; the workshop manual lists the lengths and gives you a warning.

At work I drilled a hole in the bench so that the input shaft had a place to go. And the bench tilted back and to the right, with a bucket attached to the bench to catch the fluid and keep it away from you, but certainly not required. You could also space the trans up with 2x4's. I always disassemble and build vertically, not horizontally, except for the differential/ring gear. Call it training, experience, stubbornness, whatever, but it works for me.

[88911coupe]

Looking forward to this, my G50 is on the floor for a complete clutch replacement. It was shifting fine but its out of the car so...
One thing I have read is there is some sort of highly specialized "puller" that is not something a DIY'er would have access to. Maybe I'm mis remembering? Matt Monson will be a world of help here I'm sure.

[mepstein]

G50 tools are different than 915 tools.

[3rd_gear_Ted]

What is the condition of the Ring & Pinion combo?
Having to exchange that will add to the skill set needed.
Its like the difference between a journeyman mechanic and a millwright.

[AlBackus36]

Dannobee, thanks for the tips on orientation. Figures I go rouge to set mine up horizontally and the experienced folks build vertically. When hot parts are involved, I can see the benefit of gravity when vertical.

I'll likely steal your idea of drilling a hole in the tabletop to put the trans up on the bench. I like that.

88911Coupe, I've heard similar. I'm going off the experience of Dannobee at the moment and will start the journey with a large puller and plates. I'm going to try and avoid the long finger pullers if I can, but we'll see when I get in there.

mepstein, gotcha. Won't plan on cross breeding tools here.

[gled49]

The thing about 5speed G50 that makes them tough, is all the coasting gear inner bearing races are a press fit. A variety of pullers to remove gears and bearing races and heat to install. GLWYB. good luck with your build.

[Matt Monson]

Originally Posted by gled49

The thing about 5speed G50 that makes them tough, is all the coasting gear inner bearing races are a press fit. A variety of pullers to remove gears and bearing races and heat to install. GLWYB. good luck with your build.

^This. But with patience and some ingenuity I’m sure it will get done.

[john walker's workshop]

And an electric frypan and a couple of quarts of oil for heat to reassemble. German soup.

[AlBackus36]

Thanks for the pic of the puller John, that's a big one.

I planned to use an electric hotplate with a lid, but I like the idea of heating it in oil to ensure a thorough soak. Delicious!

Sunday will be first big day of work on trans.

[AlBackus36]

Thanks for the pic of the puller John, that's a big one.

I planned to use an electric hotplate with a lid, but I like the idea of heating it in oil to ensure a thorough soak. Delicious!

Sunday will be first big day of work on trans.

Hopefully not a double post - seems to be major slowdown on technical forum today...

[AlBackus36]

Morning Pelican. Family was/is still here, but progress is finally starting! I've already found some WTF and have hit the first snag.

Expenditures:
Amazon engine stand $150
Engine yoke $250
M10x1.5x170mm bolts $20
4x6 lumbar free
Moroso engine bag $10






Does this all look normal? I'm seeing some damage on the gear teeth. No chunks in the bottom of the case. Drain plug looks normal.




Next steps will be tracking down a P9253 holder tool. This is the boomerang looking thing that locks the input shaft. Anyone in the Seattle WA area have an old G50 clutch they don't want or a tool I can borrow?

Locked in 5th and ready to take big nuts off.

[gled49]

Previous gearboxes could be locked in 2 gears, not the G50. Interlock system prevents 2 gears at once. Gear sets look ok so far.

[dannobee]

Take the bolt out for the 5-R shift fork and put the trans in 5th gear without moving the shift shaft, only the shift fork. Then use the shift shaft to put the rest of the trans in another gear. It'll lock in two gears at the same time.

Don't forget to take out the reverse switch and pin before you remove the intermediate housing.

[dannobee]

One more thing. In your second to last pic, it's in reverse, not 5th. And since the back cover is off, the R idler gear isn't there to lock anything down.

[AlBackus36]

Thanks gled49/dannobee. I used the fork to shift it into 5th. I'll try fiddling with the shift rod to see if I can get it in two gears at once to break the big nuts loose. I also found a used clutch online for 100 that I could make a tool from.

Gear questions:

In the first and second close up pics there is a smaller gear between the actual gear cog and the brass synchro. As you go around the circumference, the teeth change in height. It's most apparent if you look at the 12 o' clock tooth and compare it to the 3 o' clock tooth closest to the camera. This is the part that I'm most confused/concerned about. There is also some very small marks in the actual gear cog, but they're not sharp, shiny, nor was there any bits in the case when opened.

I didn't save my gear oil dangit.

More notes:

Bentley is useless for most of this project. The trans section that applies to dis/reassiembly is for the 915. You'll need the G64 manual floating around. Skip to the Carrera 2 section like someone else mentioned. It still leaves a bit to be desired from a newb, but has some good exploded views and notes on disassembly/re-assembly.

Onwards!