g-50 side cover seals

[kepperly]

Fellow members, I'm in the middle of wheel bearing and half shaft replacement on my 87 Carrera. I have also decided to replace the inner half shaft seals on the transaxel side covers. My next thought was, Can you just un bolt the side covers to take to my parts cleaner and really get them clean without anything in the transaxel falling out???

Thanks
Keith Epperly

[Eugene at Pelican Parts]

If you're not changing your tranny fluid, then leave the cover on. If you're gonna take the cover off, inspect the large O-ring that goes around it and replace it if it seems hard or inelastic.

[kepperly]

Eugene, thank you for the reply, have you seen one with the side covers removed? I spoke to a pelican employee at around 3:00pm your time and he said there was only one o-ring on the drivers side and no gasket for the side covers that house the stub axle seal. I ordered two stub axle seals and I guess take my chances and remove the side covers for cleaning "after I consult nmy PET disc". thanks and anyone else with any experience please chim in before I make a fatal error.

thanks
keith epperly 87 slant nos cabriolt slant nose turbo look

[dean]

I wouldn't take the cover off just to clean it. With the cover off the diff can come out. If it does fall out put it back in

[kepperly]

Is the side cover really the only thing that hold the ring gear in ?

[beepbeep]

Errr...pulling out side-cover "so you can clean it" when you are not expiriencing leaks sounds like really bad idea.

Apart from risking diff falling out (yes, it's only thing keeping diff from falling out), how do you plan to adjust backlash when you are done and want to put it back? It often takes special tools, lot's of expirience and loose gearbox on your table.

[Eugene at Pelican Parts]

Yes, popping off the side cover just to clean it seems a bit pointless, but if you're that curious to have a look-see, then go for it. If you're worried about the diff dropping out, then jack up the car up a few degrees higher on the driver's side and keep a bungee cord handy. As for backlash, that has already been set by the shim pack under the bearing retainer in the transaxle case. These shims adjust the depth of the pinion gear, as the differential is fixed at the center of the axle, um, holes.

[beepbeep]

Hmm...OK, i was under impression that backlash needs to be adjusted every time you pop the cover.

[wevoid]

Guys,

The backlash is set and adjusted by the shims between the taper roller bearing, inner race - and the differential unit.

The shim stack on the pinion bearing bulkhead is responsible for the pinion head depth, but once set (to the critical and marked dimension) the backlash is adjusted by the lateral position of the differential unit as set by the shims mentioned above.

Removing the side cover can not interfere with either of these settings.

If you have the inclination to remove it, do so and make a visual inspection of the parts inside. With the drive flanges removed, the differential can be taken straight out onto the bench, where you can make a visual inspection of the crown wheel teeth and the pinion teeth (still in the transmission). If nothing else you will satisfy some curiosity, it's nothing risky.

I always use Hylomar HPF on the large o-ring when re-installing the side cover.


Regards


Hayden

[beepbeep]

Hayden has talked!

If we knew this we wouldn't sell out gearbox as cheap (diff wasn't installed at the time). We were totally convinced that it needed costly backlash-ing

Hayden:
One more trick-question, do you know the ?-distance in picture (it's representing a flywheel and pilot bearing):



Thanx!

[wevoid]

Goran,

Here is a snip from one of our 930 flywheel drawings.

We eliminate the factory needle roler unit and use a sealed ball bearing. This is the same as the current factory race cars and others. The bearing is pressed into the flywheel in the 35(nom) bore.

Surface "B" is the crankshaft face

The ball bearing is SKF 6202 2Z or 6202 2RS

Regards

Hayden

[wevoid]

Goran,

I forgot you are not using a 911 motor.

The surface "B" is 8 mm in front of (beyond) the surface where the bellhousing is in contact with the crankcase.

Is this clear?

Regards

Hayden

[beepbeep]

Hayden , you rock!

Thanx a million!

Reason I'm asking this is beacuse we have to make our own flywheel. Unfortunately, we don't know the exakt position of 930 flywheel relative to surface where bellhousing contacts the crankcase. We are using 930/36 tranny (not G50!).

What we are planning to do is to turn our SAAB flywheel friction-surface untill it's at same distance from the surface where the bellhousing is in contact with the crankcase. That way, pressure-plate and clutch disk won't know that it's not boxer 6 turning it but two small gerbils in the cage.

Unfortunately, we have other crankshaft and adapter plate sandwiched between gerbils and transmission, so information about where B-surface is relative to tranny flange is of no use. What we need to know is distance from friction-surface to "the surface where the bellhousing is in contact with the crankcase" or "TSWTBIICWTC" from now on.

If our friction-surface is there, throwout-bearing won't notice any difference either.

I could backwards-measure the thickness of your flywheel in the picture to 25mm (using number of pixels and measurments to calculate proportions).

That means that friction surface of flywheel would end up 8 + 25 mm from "TSWTBIICWTC".

I posted this question earlier on 911 Turbo board...and got one of guys who had his 930 in pieces to go out and take a measurment. He said that flywheel friction surface was 13mm from "TSWTBIICWTC"???

Your info suddenly brings that to new light as it seems that OEM 930 flywheel should be much thicker than we earlier tought.

Is this flywheel of yours to be used with special pressure-plate and thus little thicker?

We are going to use OEM rubber-damped 930 clutch and pressure plate so it's imperative for us that throwout-bearing is on same place as originally planed.

Could you please enlighten me?

Should we turn our flywheel until friction-surface is 13mm or 33mm from "TSWTBIICWTC" in order to use OEM rubber clutch & throwout bearing?

Regards,
Goran

[beepbeep]

P.S.
Also, your drawing showa that TO-bearing entry-point should be approx. 10.5mm deeper into the engine relative to friction-surface.

I have to use friction-surface as a reference in our case beacuse nothing is similar to 911 beyond this point in our case

[beepbeep]

Here are some pics,

The flywheel wouldn't fit into 930 bellhousing at all:
http://project911.luminasweden.com/log_images/164_6495.JPG

So Mattias just turned away the ring gear as we'll be using 911 starter instead (with ring gear mounted on pressure plate). He also lightened the flywheel by removing the material from rear of the flywheel, as you can see in the picture:
http://project911.luminasweden.com/log_images/165_6521.JPG

[wevoid]

Goran,

You have three issues, which I hope you are considering in parallel.

1. pilot bearing engagment on input shaft
2. Friction surface location / Throw out bearing position
3. Starter ring gear location

The snip of our drawing is not for a O.E. clutch and the only value it has for you is to indicate dimension to satisfy #1. This is a function of the length of the input shaft, irrespective of you Saab motor, or any adaptors. With surface "B" 8mm ahead of the mount face for the bellhousing, you can ultimately calculate the correct position of pilot bearing relative to your Saab crankshaft.

I understand your need to locate the friction surface (#2) for the Throw Out Bearing (TOB - here after) to be correctly located. However, the TOB is quite insensetive to absolute positioning, within reason.

The location of the starter ring gear #3 is actually a function of the clutch friction surface position, as a result of the ring gear being mounted on the clutch cover. This is the key factor that will allow you to reverse engineer all the dimensions you require.

The gap between the ring gear and the closest engagment edge of the teeth on the starter pinion gear should be 1.5 / 2.0 mm in the static position. (as with the engine running)

If you inspect your clutch cover, with the starter ring gear mounted, then inspect the gap from the starter pinion to the face of the bellhousing, the difference between the two dimensions, minus 1.5 / 2.0 mm for the gap, will be the position for the clutch mount surface (friction surface) for the clutch you are using - from the mounting face of the bellhousing.

The starter ring gear position is far more critical than the location of the TOB mechansim. As listed above, #3 accurately drives both #2 and #1.

I hope this helps.

Good luck.

Regards

Hayden

[beepbeep]

Originally posted by wevoid
Goran,

You have three issues, which I hope you are considering in parallel.

1. pilot bearing engagment on input shaft
2. Friction surface location / Throw out bearing position
3. Starter ring gear location

Yupp!

The snip of our drawing is not for a O.E. clutch and the only value it has for you is to indicate dimension to satisfy #1. This is a function of the length of the input shaft, irrespective of you Saab motor, or any adaptors. With surface "B" 8mm ahead of the mount face for the bellhousing, you can ultimately calculate the correct position of pilot bearing relative to your Saab crankshaft.

...now i understand! I can reverse-engineer pilot-bearing entry point relative to "mount face for the bellhousing" (MFFTB) from your drawing. Tranny input-shaft is always on the same place relative to MFFTB, so i should discard friction surface as a reference in your drawing and just count from B-surface which is 8mm in front of MFFTB. Got it!

A little question:
In case we opt for SKF bearing (SKF is Swedish so it shouldn't be too hard finding right bearing) instead of needle-roller one (if it fits in our flywheel), how big hole should we drill? Your CAD-drawing says both 34.995 and 34.985 mm... i understand it's probably a crimp-fit so one of those dimensions (the smaller one?) should be for cold flywheel and other for heated-up, right?

I understand your need to locate the friction surface (#2) for the Throw Out Bearing (TOB - here after) to be correctly located. However, the TOB is quite insensetive to absolute positioning, within reason.

The location of the starter ring gear #3 is actually a function of the clutch friction surface position, as a result of the ring gear being mounted on the clutch cover. This is the key factor that will allow you to reverse engineer all the dimensions you require.

The gap between the ring gear and the closest engagment edge of the teeth on the starter pinion gear should be 1.5 / 2.0 mm in the static position. (as with the engine running)

If you inspect your clutch cover, with the starter ring gear mounted, then inspect the gap from the starter pinion to the face of the bellhousing, the difference between the two dimensions, minus 1.5 / 2.0 mm for the gap, will be the position for the clutch mount surface (friction surface) for the clutch you are using - from the mounting face of the bellhousing.

The starter ring gear position is far more critical than the location of the TOB mechansim. As listed above, #3 accurately drives both #2 and #1.

I hope this helps.

Good luck.

Regards

Hayden [/B]

Bingo! I get it now!
We just turn down our flywheel until ring-gear is in the correct position? That would assure that TO-bearing is in correct position too...

We'll do it that way then. We will first fix so ring-gear is in correct positon, then calculate friction-surface distance to MFFTB, then make sure our pilot-bearing (whichever it may be, SKF or OEM) is in right position.

*drumroll*

Ohh... there is slight posibility that our flywheel is a tad to thin. In that case i had this whacko idea of fabricating a spacer between flywheel and crank. We still don't know the dimensions of adapter plate so it's uncertain, but if spacer is needed at all it shouldn't be more than 8mm thick and we would use lenghtened high-tensile 12.9 bolts similar to OEM ones.

Is spacer a big no-no? (Theoretical question)


Once again, a thousand thanx! sorry for taking up your time...you already helped us a great deal!

Sincerly,
Goran

[wevoid]

Goran,

You obviously grasp the big picture now.

In answer to the bearing bore dimension, Yes, that is an interference fit to the ball bearing. The tolerance on the drawing is latitude to allow for manufacture. The tolerance is only 100th of a mm, per the drawing, but a number in this range will assure a good fit of the pilot bearing.

A spacer between the flywheel and crankshaft is quite unorthodox, but no more than the rest of your project.....
If you use 12.9 grade bolts in a longer length, to suit your spacer, that would be the best you can do. Also try to make the spacer hub-centric. This will ensure that it aligns concentric with the crankshaft and the flywheel. RPM's will be the greatest enemy of this composite assembly, as would inaccurate manufacture.

There will be a point where you might just decide to make a new flywheel,as it will be easier than making spacers, longer bolts, etc.

The flywheel you would require is a fairly simple piece, you can make it with the tools you have already displayed in the photos of your flywheel work.

No problems with the questions, I am as curious as many others to see your project come to completion.

Regards

Hayden

[beepbeep]

I just dug out this old thread to thank Hayden for his help and advice.

We have spent two days pulling and joining engine/tranny combo and doing R&D (click on pics to enlarge/play movie):


...and machining down original flywheel:


No spacer was needed behind and OEM SAAB flywheel was machined and drilled until it accepted 930 pressure plate with same sort of OEM 930 "lip". Surprizingly, it's center opening was exactly the size to accept standard (and cheap) SKF ball-bearing that Hayden mentioned, so there is no need for 60$ expensive and quite crappy OEM needle-style pilot bearing. (Input-shaft slid right into it too):


After that we used plasticine to find exact position of starter-pinion/ring gear combo:


After machining flywheel to correct thickness and size, whole clutch-package bolted like a charm (except hurting my finger!):


And whole kaboodle could be engaged with starter (and Timmy's stolen electric-wheelchair ):


flywheel now looks like more or less stock 930 item, except for another bolt-pattern.

So all in all, I believe we were quite lucky and solved this w/o use of spacers.

I know you guys don't like any other engines than Porsche boxer 6's but we succeded in mating two completly different engine/tranny's and are quite proud of it actually. If nothing else then for pure joy of problem-solving.