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JET951 03-20-2012 07:25 AM

944 Transmission Walkthrough (image heavy)
 
27 Attachment(s)
Well i have been meaning to put this together for some time. Here is a general walk through of our 944 Transmissions. This one in Particular is a 944 turbo trans, We are setting it up to receive a 944 S2 crown wheel and pinion and an aftermarket Modena LSD. Obviously without the right tools its going to make things a bit difficult, but not impossible.

So we step into the tear down

Step 1.
set the Gearbox up so that it can be worked on
Attachment 1208268
Step 2
Lock the CV flange with a screw driver and remove the 6mm allen bolts
Attachment 1208269
Step 3
With a screw driver puncture the rear seal and pry it out
Attachment 1208270
Step 4
Remove the 17mm gear selector detent
Attachment 1208271
Step 5
Remove the 3 10mm socket bolts, remove the gear selector plate
Attachment 1208272
http://i718.photobucket.com/albums/w...%20trans/5.jpg
Step 6.Lock the input shaft and select a gear. THis will help lock the Pinion so that you can remove the triple square bolt Behind the Rear seal. Remove the triple square bolt.
Attachment 1208273
http://i718.photobucket.com/albums/w...anslock001.jpg
Attachment 1208274
Step 7
Now remove all the 6mm allen bolts holding on the rear housing. then tap the rear housing off with a drift. alternate sides with the drift until the housing is removed
http://i718.photobucket.com/albums/w...%20trans/6.jpg
Step 8
Remove the 17mm bolt on 5th gear
Attachment 1208275
Step 9
Use a puller to remove the rear bearing race and part of the 5th gear assembly.
http://i718.photobucket.com/albums/w...%20trans/9.jpg
Step 10
Remove the circlip in the 5th gear assembly
Attachment 1208276
Step 11.
Next remove the 5th gear selector fork dowel with a punch.
http://i718.photobucket.com/albums/w...20trans/11.jpg
Step 12.
With a bit of coercing you can now remove 5th gear.
Attachment 1208277
Step 13.
Use a 2 arm puller to remove the matched 5th gear. It is easier if you heat the gear up with hot air guns before removal
Attachment 1208278
Step 14
Remove the shim for 5th gear. you can see it below sitting atop the main shaft bearing.
Step 15
Remove the 2 6mm stop bolts and the 17mm stop bolts and detents on the main carrier case
Attachment 1208279
step 16
Now remove all of the 13mm bolts holding the main carrier to the diff carrier. Use a drift and tap both sides of the main carrier until it is loose from the diff housing. you can now remove the main carrier with the gearset.
Attachment 1208280
Step 17
with a punch remove the dowel for 1st/2nd and for 3rd/4th.
http://i718.photobucket.com/albums/w...20trans/18.jpg
Step 18
you can now remove 3rd/4th selector Rod. be careful though as there is a small locking detent which lives in the 3rd/4th selector Rod. when removing you will most likely hear it fall into the main carrier case. you will also find a detent and spring beneath the 3rd/4th selector rod
Attachment 1208281
Attachment 1208282
Attachment 1208283
Step 19
Remove selector Rod Locks with a magnet
Attachment 1208284
Attachment 1208285
Step 20
You can now move the pinion forward with 1st/2nd selector rod and now remove the input shaft
Attachment 1208286
Attachment 1208287
Attachment 1208288
step 21
With the pinion removed you can now disassemble it if needed. You will need a press for this. you can see where the circlips are.
Attachment 1208289
Step 22
Here is the Pinion assembled with new bearings ready to have the pinion preload set. Every time the bearings are replaced the preload will need to be rechecked and modified if necessary. Next photo is of the tools needed to assemble the 944 trans and set pinion preload, pinion depth and diff backlash
Attachment 1208290
http://i718.photobucket.com/albums/w...20trans/37.jpg
Step 23.
Setting preload. We use the original shims behind the bearing shells to first check pinion preload. remove old bearing shells and replace with the new ones.
Attachment 1208291
Attachment 1208292
Step 24
With the Pinion in place and main carrier torqued to the diff case(all bolts) you can now check Pinion preload with a torque gauge as shown. you turn the torque gauge until the Pinion is turning and then take the reading. We use 2.5NM as a good preload. Assemble the shims so that 2.5nm is reached. This may take a few attempts with different shims
http://i718.photobucket.com/albums/w...20trans/38.jpg
Attachment 1208293
Attachment 1208294

JET951 03-20-2012 07:25 AM

38 Attachment(s)
Step 25
Next up is pinion depth.
The RO distance for the 944 S2 crownwheel and pinion is 59.65mm. to this we add the "quite running" number on the new crown wheel. In our case you can see here is 0.36mm.
Attachment 1208230
Step 26
Here you can see us setting the pinion depth tool to our desired level. In our case the number was 60.01mm. We set the dial gauge at 2.5mm depth with the micrometer attached
Attachment 1208231
Step 27
The pinion is in place and torqued. The Pinion also has a special tool(flat magnet) attached to it. This is so we can use the pinion depth tool against it and get an accurate reading.
The tool in placed where the diff would be placed and the diff case torque down. We now turn the tool until we read a maximum depth. We are trying to get as close to Zero as possible on the gauge.(which is our original 60.01 reading) Usually we get it within .01 of our desired quiet running distance. Remember when obtaining the Quiet running distance you will be moving the pinion forward or backwards. Considering the pinion preload is already set you need to remember if you remove shims from one side of the pinion to move it in a certain direction you must then add the exact same thickness shim(s) to the other side to keep your preload correct. Attachment 1208232
Attachment 1208233
Step 28
Assemble the diff with new bearings.(and in our case a new crown wheel and pinion, always use new crown wheel bolts) Its best to heat the Bearing with heat guns to aid in installation.
Attachment 1208234
Step 29
Setting diff preload
you can now remove the Pinion again. And set the preload as you did with the Pinion. Using shims behind the new diff side shells Install the Diff and you can now set the diff preload to 2.5NM.
Attachment 1208235
Step 30
Setting Diff backlash.
When setting diff backlash we are looking to obtain .10mm of movement on our dial gauge. this is a very small amount of movement so a dial gauge is needed. This is done with the Pinion torqued onto the diff housing with the main case(but without the gearset). The backlash tool is moved side to side to see the freeplay on the dial gauge. this will take some trial and error to get right.
Attachment 1208236
Step 31
Time to re assessable the transmission. basic reverse of our disassemble. but a few things to look out for.
Make sure the pin(short arrow) is in the slot (big arrow) for reverse gear. other wise you will have problems.
Attachment 1208237
Step 32
assemble Pinion with 1st/2nd selector shaft.
Attachment 1208238
Step 33
Place locks in place and detent underneath 3rd/4th selector rod. Make sure the small lock is in place before 3rd/4th selector rod is installed. i use grease to hold it in place
Attachment 1208239
Attachment 1208240
Attachment 1208241
Attachment 1208242
Attachment 1208243
Step 34
install Dowel for 1st/2nd and 3rd/4th selector Rods
Attachment 1208244
Step 35
install stop bolts
Attachment 1208245
Step 36
Put shims back on before 5th gear install
Attachment 1208246
Attachment 1208247
Step 37
Heat 5th gear and install.(it needs to be hot)
Attachment 1208248
Attachment 1208249
Step 38
Install 5th gear set assembly, install dowel, install circlip
Attachment 1208250
Attachment 1208251
Attachment 1208252
Step 39
Heat 5th gear syncromesh ring and install, then heat inner bearing race and install
Attachment 1208253
Attachment 1208254
Attachment 1208255
Step 40
Torque up 5th gear bolt to 70NM
Attachment 1208256
Step 41
assemble with transmission sealant on gasket and torque together
Attachment 1208257
http://i718.photobucket.com/albums/w...0trans/765.jpg
Attachment 1208258
Step 42
Heat up outer bearing race and install
Attachment 1208259
Step 43
Remove input seal from diff case
Apply transmission sealant to between main case and diff case and torque down.
Attachment 1208260
Attachment 1208261
Step 44
install reverse switch
Attachment 1208262
Step 45
install selector, install selector plate, install top detent
http://i718.photobucket.com/albums/w...20trans/81.jpg
Attachment 1208263
Attachment 1208264
Step 46
Install Rear seal, front seal and torque side flanges
http://i718.photobucket.com/albums/w...20trans/84.jpg
Attachment 1208265
Attachment 1208266
Trans build now complete
Attachment 1208267

regards
Sean

Thom 03-20-2012 07:42 AM

Excellent. Thanks much for that.

Paulyy 03-20-2012 08:04 AM

nice write up! :thumbup:

Adonay 03-20-2012 08:37 AM

Thank you so much. Have been thinking about doing a aftermarket diff in my gear box, and this has given me a better understanding how the gearbox is put together and if i want to do it my self.

67King 03-20-2012 08:56 AM

Great write-up! Thanks much for posting that. A few questions for you.
1. The factory manual states 0.30mm should be added to the pinion shim thickness for pre-load, and 0.50mm should be added for carrier shim thickness for pre-load. My experience shows these numbers to be too thick by about 0.15 and 0.10mm, respecitvely. Curious as to your experience?
2. Of the three transaxles I have, one of them (came from an S2) has a shim/plate between the gear housing and rear housing that is probably 8mm thick. I have never seen any references to it elsewhere. I'm curious to know if you've seen this, and if so, any info as to whey itis there? FWIW, the rear housing on that transaxle is shorter by that much. The one that has it is the only one wihtout a cooling loop.
3. Any secrets for removing the triple-square bolt from the back of the input shaft? I eventually got them, but they are bears!

cwigg66 03-20-2012 09:05 AM

Amazing writeup. What a valuable resource for everyone. THANKS!

JohnKoaWood 03-20-2012 09:40 AM

Most excellent write up Sean!

I have been back and forth with buying a used LSD box, or installing the LSD I have on hand to my gearbox... Guess I need to start searching for the special tools... as I am sure I will use them more than once!


Originally Posted by 67King (Post 9376231)
Great write-up! Thanks much for posting that. A few questions for you.
1. The factory manual states 0.30mm should be added to the pinion shim thickness for pre-load, and 0.50mm should be added for carrier shim thickness for pre-load. My experience shows these numbers to be too thick by about 0.15 and 0.10mm, respecitvely. Curious as to your experience?
2. Of the three transaxles I have, one of them (came from an S2) has a shim/plate between the gear housing and rear housing that is probably 8mm thick. I have never seen any references to it elsewhere. I'm curious to know if you've seen this, and if so, any info as to whey itis there? FWIW, the rear housing on that transaxle is shorter by that much. The one that has it is the only one wihtout a cooling loop.
3. Any secrets for removing the triple-square bolt from the back of the input shaft? I eventually got them, but they are bears!

the tans reinforcing plate is available, my understanding is it is used to stabilize the rear of the housing when horsepower is stepped up (V8 swaps, and GT40 replica builds)..

Here is just one source I have found over the years for them.. there are others!
http://www.texasperformanceconcepts....sionparts.html

reno808 03-20-2012 10:27 AM

The fact you made it look that easy shows how hard it is

CyCloNe! 03-20-2012 10:32 AM

Excellent Write Up, I honestly Learned a great deal!

67King 03-20-2012 10:51 AM


Originally Posted by JohnKoaWood (Post 9376319)
the tans reinforcing plate is available, my understanding is it is used to stabilize the rear of the housing when horsepower is stepped up (V8 swaps, and GT40 replica builds)..

Thanks, John! Had never seen that before. Probably won't need it for my mild SP3 car, but at least I know what it is.

Tom M'Guinn 03-20-2012 11:11 AM

Post of the year! Thank you!

95ONE 03-20-2012 11:14 AM

Fantastic. Excellent write up. Thank you for your time to do this.

Could an admin please make this a sticky of sort?

reno808 03-20-2012 12:02 PM


Originally Posted by 95ONE (Post 9376564)
Fantastic. Excellent write up. Thank you for your time to do this.

Could an admin please make this a sticky of sort?

2 things
1. we need a section for this on the 951 section
2. where is testarosa badge

944V8inDFW 03-20-2012 01:26 PM

Very nice pictures and writeup


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