Manual Transmission Rebuilding 5 Speed
Hi Guys, David Haydon does not claim to be a mechanic but he did a great overall job. We have attempted to clean up things a bit but an overall KUDOS to David Haydon for his efforts here. Thanks for sharing the info with us! Here are his Comments:
(I am not a mechanic and these pages do not represent official workshop procedures in any way.
They are purely a record of what I did when replacing my 2nd gear Syncro on my gearbox and are posted here for information purposes. Do not attempt this yourself unless you are competent to do so. I accept no responsibility for any damage or injury caused by following the information provided on these pages.)
This information is NOT intended to be the PERFECT rebuild info but it will really help out those attempting this Job. Some of the procedures for the earlier model 5 speed transmissions will be different but the overall setup is the same.
(http://homepage.ntlworld.com/home01/index.html is Davids Homepage)
Here's the gearbox out of the car ready to start (You can remove the gearbox by taking out all the bolts from around the transmission bell housing, supporting the engine and removing the driver side sub frame to access everything. Removing the battery is not necessary but could give a bit more room.
Remove the 5th gear housing and gasket by removing the bolts around the outside of the 5th gear housing cover
Drive out the shift fork pin with a dowel or similar tool.
Remove the input shaft circlip with a pair of cir-clip pliers or a small flat blade screwdriver.
Lift of 5th gear shift fork and Syncro sleeve by gently prying up on the shifter fork.
Use a puller to remove 5th gear and the Syncro assembly from the input shaft. Be careful here not to use too much force to remove the gear with as you WILL break the edges of the teeth here. Be sure to insert the puller arms far enough beneath the gear lip.
Lift off the Hub and Syncro ring.
and 5th gear. You can pry up from the bottom as well but you WILL BREAK THE TEETH if not careful!
Remove the needle bearing that the gear rides on.
Bend-out the locking indentations in the output shaft lock nut. In most cases you can use and impact wrench to remove the nut with out any issues and without prying on the gear to release the indentions.
Remove the locking nut - I couldn't figure out how to lock the shaft in place, so used an air wrench which worked great. (I was expecting to be able to lock the shafts by selecting reverse and then pushing down on the 5th shift fork. I couldn't do this, but thinking about it now, removing the shift fork and pushing down on the Syncro may well do the job.) You actually can lock the gearing by remove the 12 mm reverse lock in the trans and manually selecting the gear in reverse and another gear. (in most cases you are better off remove the reverse shaft support bolt (see below) before splitting the two halves)
use a puller to lift 5th off the output shaft
Recover the gear but be careful when prying on the bottom of the teeth!
remove the 4 bolts securing the input shaft bearing cover (note: you do not need to remove this to remove the gearbox housing - I didn't know this until too late) 3 of the 4 bolts were so tight the heads rounded off (you can tap them with the ball of a ball peen hammer to get the to break loose), so shown here are bolts I welded in place to get them out - a neat trick I had to learn especially to get them out! (another trick here is to grind a straight groove in them which allows them to be removed using a Flat screwdriver)
Lift off the bearing cover and shims
Remove the inner companion flange bolts and take out the companion flange unit (note: you do not need to remove this to remove the gearbox housing - again I didn't know this until too late) (In this situation you may want to get in the habit of placing a screwdriver down in the hole so that the spider gears won't turn once both drivers are out)
Remove the reverse light switch, drive out the two bush/pins (arrowed) and remove all of the gearbox housing to bell housing bolts
...including the reverse shaft support bolt (in most cases you are better off remove this bolt before splitting the two halves)
Remove the retaining ring (note: you do not need to remove this to remove the gearbox housing, but this time it does need to be removed before subsequent bearings and gears will come off)
Now for the fun part. use a puller to lift the gearbox housing from the bell housing (complete with the output shaft bearing) Use a rubber, or other soft-faced, mallet to help break the seal between the housings. This can be very difficult to do but don't be a bull in a china shop! Take your time and carefully tap over and over and over until everything frees up!
and all is revealed....Be careful here as you don't want the Syncro springs to fly apart. Caution is the best remedy here!
Remove 4th gear from the output shaft (A word of advice here is to remove the gears one at a time and place them on a piece of cloth in the order they are removed. The old saying (a picture is worth a thousand words applies here. Take digital photos along the disassembly procedure)
...and the spacer sleeves
Use a puller to remove the input shaft bearing my puller wouldn't go completely underneath the bearing and as you can see the puller actually needs to fit completely underneath in-order to remove the bearing without damaging it. If you are replacing the bearing it won't be an issue though. During installation of the bearing you can use heat (ie.. heat gun/hairdryers to heat the bearing before install but be careful during the installation to drop it on the correct way).
...so I had to trash it to get it off
Remove 4th gear from the input shaft
and the needle bearings
Remove the Syncro hub circlip (you will need a pair of good quality circlip pliers - unlike mine)
Drive out the pin from the 3rd-4th shifter fork and check for wear on the fork by checking to see if the mating surface where the fork meets the hubs are sharp. If they are sharp then replacement of the forks it necessary.
and remove the fork and Syncro hub assembly
Remove 3rd gear from the output shaft
Then remove 2nd gear and a couple of the Syncro rings
Remove the last of the 2nd gear Syncro rings
Now remove the steel ring from the 2nd gear (you may just about see the wear and heat marks on the three teeth)
take off the brass ring from 2nd gear (the brass rings were in really good condition - only the steel ring was showing signs of wear)
and now it's time to put it all back together.... (yep that's me)
Put the brass Syncro ring onto 2nd gear
Then the steel Syncro ring (note how the ring should look)
Fit the other brass rings into the Syncro hub assembly
Then reinstall 2nd gear and the new rings
Next put 3rd gear back onto the output shaft
Then the spacer-sleeves and make sure you use a new collapsible sleeve. The spacer sleeve on the output shaft should always be replaced with a new one, it is a collapsible unit designed so that the bearings can be preloaded. 2nd mistake is that I didn't check or adjust the bearing end float. This requires a dial gauge and will result in premature bearing failure if not done correctly. This is the same type of sleeve that Saab has used for years. The reality of it is that many techs DO NOT replace the sleeve because they feel that the primitive way of checking the preload will always take you to the same place during the compression of the spacer. Truth is we have checked old ones that come out of different trannies and they are all extremely close. Saab recommends replacement so lets try and do it right!
Reinstall the 3rd-4th Syncro hub assembly and shifter fork and drive in the locating pin
Install a new circlip (although most techs use the old ones) and make sure the bearings and springs are correctly seated as in this picture
Reinstall 4th gear and Syncro rings
Reinstall the 3 leaf springs (on the earlier trannies Saab used Springs and Balls, OH BOY!)
Drive home a new input shaft bearing or heat it up and drop it on. Many schools of thought regarding the heat up method but I know techs who have done this for 20 years without an issue.
Apply plenty of flange sealant (Anaerobic sealer is recommended something like gasket eliminator by Loctite, If the memory serves me correctly it is Loctite 510, check to be sure though)
And locate the housing (be sure to carefully clean the housings before reassembly as dirt can be a main contributor to trans bearing failure)
Reinsert the reverse shaft support bolt then all of the housing securing bolts and the two locating bushes
Insert the bearing shims
And the companion flange assembly
Replace the companion flange bolts
Now drive the output shaft bearing into place
Re-install the input shaft bearing cover and shims
And replace the bolts
Install a new input shaft bearing clip
Reinstall the needle bearings
and the 5th gear assembly
Reinstall the 5th gear Syncro assembly and shift fork (note the teeth on the Syncro hub and sleeve are slightly keyed - make sure they line up correctly)
Drive 5th gear onto the output shaft
Install the output shaft lock nut
|Make sure that the spacer sleeve on the output shaft should is replaced with a new one, it is a collapsible unit designed so that the bearings can be preloaded. You will also need to check the end float here and adjust the bearing end float. This requires a dial gauge (and in some case a degree socket from Saab) and will result in premature bearing failure if not done correctly. |
Now install the 5th gear shift fork
replace the shift fork locating pin (at this point I managed to pull the shift rod up too far resulting in the rod coming out of the shifter assembly. The ball bearings, springs, etc. all ended up in the bottom of the gearbox and I had to take the whole lot apart again. Then I had to get the shift rod components back together and start again!)
Drive the 5th gear Syncro hub into place (I did this bit out of order 1st attempt - hence no gear on the output shaft in this picture)
Install a new circlip
Create locking tabs on the output shaft lock nut in line with the indentations in the gear
Install a new gasket and replace the 5th gear cover and bolts all that is left to do now is to fill the gearbox with oil and put it back into the car
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