915 Transmission removal WITHOUT dropping motor

[Montreal Tom]

Ok, so I know most people remove motor and trans in order to rebuild the trans but this simply was not an option for me, mainly because where it is parked the landlord would have a cow if I started to disconnect fuel lines, oil lines, remove motor. Not to mention the motor would have to basically sit around loose in a parking garage until it was put back in the car. I did end up removing transmission only. The only thing that was hindering me was the tunnel passage/ hole for the shift rod, so I cut a slit, bent it out of the way and dropped the trans. Its all back together as of last week, and I simply bent the piece back painted the bare metal edges and sealed it with automotive seam sealer.

Car is an 86 carrera with 199,000 km (136,000 miles i think)
fist time I ever took a trans apart. Have changed clutches on cars and motorcycles before.

Things I replaced in trans:
-Dog teeth/engagement teeth for 1st gear (this was reason for rebuild, syncro gone on 1st and metal grinding tooth contact when engaging 1st gear and could only be engaged at dead stop and even then with some grinding.
-Syncro rings for gears 1, 2, 3, and 4.
-brake bands gears 1 and 2
-needle bearings an gears 1 through 5.
-clutch kit
-gaskets
-gear oil: Kendal I found a local Canadian sell for this if anyone wants to know

Cost of all parts; about $1700 Canadian with shipping and taxes, including oil and gaskets.


Things I did differently than what I've read on the web:
-removed transmission only
-Cut dog teeth off with dremel (2 hrs) rotary tool after failed attempt to make/weld an extraction jig and use a puller.
-removed all gears from shaft by using inertia method (hitting shaft against floor)
-reused the big main and pinion shaft nuts.
-Used 20$ needle bearings from Honda manual transmission as opposed to $100+ for porsche part. This saved me about $500.
-reused pressure plate bolts.

[Jerome74911S]

Wow, that's a pretty gutsy project. I am unable to predict how the substitute parts and methodologies will work in the long run, but I applaud your willingness to think 'outside the box' to try something that's a bit experimental - at least it's not the same approach that is official around here, meaning on this forum.

I suspect that like me, you will not have your car on the road for a while until the world thaws out, but be sure to report back with details on how it works when you get to actually drive it. Maybe we'll see each other on the road.

[Montreal Tom]

Some other notes or issues that crept up during this work:

-Old pressure plate was aluminum, new one is all cast iron

-When removing the starter an a 3.2 carrera, a regular L shaped 10mm alan key and box wrench for added torque worked better than any type of socket or adapter

-I over torqued one of the 2 shift detente retaining bolts and partially stripped the thread in the aluminum housing. decided to use a dab of JB weld on the threads. We will see how this worked out if i ever need to remove this bolt...worst case scenario, dill out and re-tap for slightly bigger bolt

- I used a big 15" adjustable crescent wrench to remove the nut on the main shaft (the long one) I used the old clutch disc in a vise to hold the shaft.

-when pressing on the dog teeth, they went on slightly crooked and only straightened out when fully pressed in, this caused some metal shavings that had to be cleaned out. I decided to ignore any kind of reservations that I had about this and pretend it didn't happen.

-When re installing the axle flanges, I noticed that if you over tighten the bolt, the diff gets tight and almost locks up. the bolts for the axle flanges only require about 32 ft-lbs,which seems too little but apparently is not. hopefully initial over tightening didnt damage anything.

-the throw out bearing guide tube has some wear on one side, so i flipped it over, doesnt seem to be an issue, it works very smoothly.

-used cell phone camera to take pic of TOB through the little viewing cut-out in bell housing to confirm proper clutch fork engagement. A friend had to help me under the car to re-mate the trans and motor. All other work was done solo. wait, my brother helped me hold the trans while I torqued the main shaft and pinion shaft bolts.

-After trans was in it seemed that the clutch was STUCK, i could not disengage it using the lever and a 2 foot long pipe. This is because the clutch pedal assembly and linkage actually end up multiplying your foot force several times, once I connected the cable, it disengaged smoothly when pressing the pedal, but was impossible to budge from under the car using a pipe on the little lever.

- following the Pelican Technical article about adjusting the shifter linkages was key, this procedure yielded best results the first time I tried it. I tried a whole bunch of futile crap for about 30 minutes before I went upstairs got my laptop and re-read the procedure, which I had used a year ago after changing all bushings in the shifter system.

-I initially forgot to put the ground strap back, so when I put the key in the acc position, the AC blower kicked in and would not turn off, car would also not start. Weird voodo, hopefully nothing is permanently fried.

-I bought a transmission jack adapter but even with my jack fully lowered, the whole assembly was about a foot tall and would not allow me to drop the transmission enough or roll it out from under the car. My car was already lifted to the max that my 6 ton jack stands would permit. So I simply did not use it!

-My old jack does NOT have a spring loaded handle. I had to buy a new, bigger, jack to complete this job that DID have a spring loaded handle. When lowering car at end of job i let go of handle to adjust something and it sprung up under the motor. THE CAR THEN DROPPED A BIT AND THE MOTOR IMPALED ITSELF
ON THIS GODDAMED SPRING LOADED JACK HANDLE. good news: only an oil return tube got damaged. Bad news, I nearly had a heart attack when it happened and oil started to gush out of the motor. Why do some jacks have a spring loaded handle? Bastards.

New oil return tube should be in this week and I will be able to test how the trans shifts/ goes into gear. i have about 50' of parking garage to test this in. There is too much snow and ice outside and until I can actually see the pavement again, I will not attempt to drive the car out of the parking garage ramp. I can only wish for the type of weather they had last week in Georgia. For me, and SOME other Canadians, that would be a welcome break from snow that apears in november, hides everything on your lawn that is less that 2' tall, and only melts in march or April. Here the snow plows do not even bother leaving the garage unless about 2 inches fall. Snow is only a problem when the snow is scraping against the floor pan of your car and causing you to slow down or not make it up a hill if you loose momentum.

[pors1968]

Wish you well .Good luck ...

[Montreal Tom]

Thanks for the comments. Yes time will tell! As for using the Honda needle bearings, I read that someone did this and it was all good thousands of kilometers later. I measured the bearings and they were IDENTICAL in all dimensions to the Porsche part. Also, considering they were designed for a front wheel drive Honda transmission/motor I imagine they have equal (if not better) resistance to heat and wear. After I replaced the bearings I noticed slightly less play in the "loose" gears.
I will consider myself a guinea pig for the benefit of all budget minded 911 owners! Worst case scenario, I take it out next winter and fix it again!

[Montreal Tom]

As it is I can barely afford a Porsche 911. I scoured the internet to find the best prices for parts. I admit I bought none from Pelican, but only because their shipping to Canada seemed too expensive for me. anyways, the Pelican forum has been a big help over the last year so even though I didnt buy parts from them I hope my posts will encourage other to try some repairs and buy their parts here. I paid 1700$ for parts alone, imagine the repair bill had i taken it to a shop. $4000? $6000?

The Wikidiot porsche transmission tutorial was also very helpful, although that dude has better tools than me. and better lighting in his workshop.

Below are some more pics:
-useless transmission adaptor
-sacrilegious made in Japan needle bearing packaging
-press i made from pallet racking while waiting for parts to come in
-dirty transmisison after it came out of car
-parts laid out IN ORDER/ SEQUENCE
-Shafts back in place just before putting the case back on and sealing it.

[Montreal Tom]

Notice the Honda part starts with "911" ??? Is this a sign from the almighty??
Maybe his plan is for my transmission to fail and thereby save my life by rendering impossible any high speed shenanigans or fast lane changes that are so fun with a 911?

Another note about clutches:
(for 915 type transmissions)
I read that a new one is 10mm thick and should be changed when it is 8.5mm thick.
Mine was 6.5mm thick!

[Jerome74911S]

Originally Posted by Montreal Tom

Notice the Honda part starts with "911" ??? Is this a sign from the almighty??
Maybe his plan is for my transmission to fail and thereby save my life by rendering impossible any high speed shenanigans or fast lane changes that are so fun with a 911?

Another note about clutches:
(for 915 type transmissions)
I read that a new one is 10mm thick and should be changed when it is 8.5mm thick.
Mine was 6.5mm thick!

If I'm not mistaken, the thickness of a new cutch disk for your car is 8.1mm. Again, if I'm not too far off, 9.8mm is the thickness of a clutch for a 930.

In any case, 6.5mm is still OK.

If I'm wrong somebody will point this out, but you have it back together anyway . . .


Edit: I did some more checking. 6.5mm is close to the limit. There are a couple ways to measure this, but overall thickness of ~6.3 means replace. Clutch disks wear more slowly later in their lives, but all of this is moot if the trans is back in the car.

[Montreal Tom]

I typically scour the internet to get multiple sources of info and 9.8mm is what I remember coming up most often for the 3.2 Motor. At 6.5mm a few of the rivets on the used clutch disc were starting to touch/get polished so it was an easy decision. I thought I measured the new one at around 10mm out of the box, but this last bit I am now uncertain about.

Is it possible that there is a difference in the SC and 3.2 Carreras AND the 930 turbos?
There was also some flex/compression to the disc, my measurements were un-compressed.


And yes, its back together so what is done is done!

I read part of your blog briefly and agree that doing it yourself, right or wrong, is the best way. It certainly is better than paying beacucoup dollars to an 'expert' who ends up making the same mistakes or worse. If it goes south, at least I have an idea where I went wrong and the endeavor to correct it will be faster and less painful than the first time around.

6 weeks ago the 915 transmission was a pseudo-magical box to me. Breaking just one apart made virtually all of the mystery disappear. Even reading detailed posts by known experts did not give me the knowledge or confidence that came after taking mine apart. Baptism by fire?

In any case I'll let my technical knowledge and skills get taught a lesson rather than my wallet take a beating and learn nothing from it.

[Jerome74911S]

Originally Posted by Montreal Tom

Is it possible that there is a difference in the [clutch disks for] SC and 3.2 Carreras AND the 930 turbos?

I wouldn't be surprised.

There was also some flex/compression to the disc, my measurements were un-compressed.

And yes, its back together so what is done is done!

I read part of your blog briefly and agree that doing it yourself, right or wrong, is the best way. It certainly is better than paying beacucoup dollars to an 'expert' who ends up making the same mistakes or worse. If it goes south, at least I have an idea where I went wrong and the endeavor to correct it will be faster and less painful than the first time around.

6 weeks ago the 915 transmission was a pseudo-magical box to me. Breaking just one apart made virtually all of the mystery disappear. Even reading detailed posts by known experts did not give me the knowledge or confidence that came after taking mine apart. Baptism by fire?

In any case I'll let my technical knowledge and skills get taught a lesson rather than my wallet take a beating and learn nothing from it.

Anyway, you are to be congratulated for your bravery, jumping into this. Keep up the good work and report back - I'll be interested to learn if your baptism by fire burned you, or not. Good work, and best of luck.

[tazzieman]

Bravo Tom! Well done!

[Pierre911SC]

Good to you Tom, my hat off to you.
As they say "no guts no glory".
All the best to you.

Regards

[Flojo]

Uh, crazy, cutting the body.
How odacious.
But okay, the way is the goal.

[Reiver]

I'm with Flojo...I appreciate getting 'it' done but if you do that again you'll probably break that piece off by over flexing/weakening the metal.
It is a minor modification but cutting the tub only weakens it. Re weld it and drop it properly next time I'd suggest.
Nice tranny work tho.

[pors1968]

I read somewhere some race car had the same cut to change trans faster.

[Bob Kontak]

Originally Posted by Montreal Tom

In any case I'll let my technical knowledge and skills get taught a lesson rather than my wallet take a beating and learn nothing from it.

Now THAT is beautiful.

We need more lateral thinkers here. Please stick around.

[Nuen Werke]

I made that same cut only wider and symmetrical in my 930 and almost all 911's I have ever owned..with one caveat, I made a new cover , flanged, with rubber seal and bolted in. looks factory and is a legit mod done correctly. Nice work Tom.

[Montreal Tom]

I thought about the cut for a while and considered the following:

-Will there be weakening of the structure... I arbitrarily decided "no" based on eyeballing the surrounding construction. The "box" for the shifter coupler already adds strength to the floorplan area and there was already a hole there anyway. As a stand alone piece of sheetmetal, yes, seam sealer is weaker and should be welded, in the greater scheme, meh....
-I did tell myself that I would check up and If I see the seam sealer coming apart this means that the flex in the metal is greater than the flex in the sealer and its separating, at that point I would weld it, but

-So many 911's have crazy rust and still stay together nicely, what are 2x 3" cuts in comparison
- 911's are some type of unholy unibody construction with rocker covers, inner rockers, and innner-inner rockers, with an additional brace, and a sub brace etc etc. I exaggerate but they're built wicked strong.
-Ive seen so many different modifications on these, especially track cars that I doubt my small mod will have any effect. I mean simply removing the passenger seat "weakens" the car, as do cut out/bolt on plastic fenders or lightweight windshields. I imagine putting a plastic post 1989 bumper system is also "weaker" than the metal ones!
- I could weld the part as I have a MIG welder, and agree 100% that this is the most solid method, but I opted to paint and seal with a seam sealer for easier future access if required.

Because of this and also based on comments from Nuen Werke and pors1968 I conclude, arbitrarily, that there is little if no harm in this and in fact I feel the benefit outweighs any perceived disadvantages.
And if I'm wrong then time will tell, but I doubt it.
I accept that my method is not the norm and don't preach one or the other, this is simply how I did it!!

[Montreal Tom]

Originally Posted by Nuen Werke

I made that same cut only wider and symmetrical in my 930 and almost all 911's I have ever owned..with one caveat, I made a new cover , flanged, with rubber seal and bolted in. looks factory and is a legit mod done correctly. Nice work Tom.

Hey are you saying mine is not symmetrical!! lol

I like your idea, do you have a picture of the cover you made? I have been known to cobble and mig weld things together that could be interpreted as body work so I may give this a try down the line.

[yelcab1]

My hat is off to the hackiness of this job. You are second in line to the title the Hack mechanic from Rob Siegel.