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New Trans coming for my '78 5 Speed...

 
Old 04-14-2019, 09:23 AM
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78Silver928
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Default New Trans coming for my '78 5 Speed...

So I finally dropped some money to have a professionally rebuilt and warranted 5 speed transaxle sent to me. The remove/ replace doesn't look too bad (watched a youtube vid on it), but what I'm wondering is: what else should I be replacing while I have it apart? I'm looking forward to cleaning the castings and the body while it's out but should I be replacing torque tube bearings or the clutch? The car has 82K miles, clutch seems pretty strong. How hard is it to replace? Not sure how to check TT bearings to see if they're OK. I've already replaced both rear calipers and brake lines. Did all of the shift bushings and front nylon cup last year (nightmare, would've been easy with the TT out) Any thoughts?
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Old 04-14-2019, 09:57 AM
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hlee96
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If the TT bearings are original since '78 and the front/rear shifter plastic pieces, then it is definitely worth having them replaced. They have a shelf life due to their plastics (very brittle) and the heat/cold cycles.

If TT bearings are intimidating (to me at least), I would ship them out for rebuilt.

FWIW, once the exhaust shielding is down, along with TT, the front/rear plastic parts are easily replaced. Don't forget the rear shifter boot. They often gets torn when removing/checking.
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Old 04-14-2019, 10:07 AM
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78Silver928
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I already replaced all of the plastic shifter parts... they had turned to dust. New shift coupler and front cup.
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Old 04-15-2019, 09:25 AM
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Clutch comes out pretty easily once the slave cylinder and starter are taken loose from the lower bell housing. Two clamp bolts on the clutch shaft to torque tube coupler, install some shims under the T springs to keep the pressure plate from fully relaxing so it's easier to put back together, pop the lever off the ball, remove the 6 bolts that hold the clutch pack to the flywheel (you'll need to be able to rotate the assembly to do this either from the engine crankshaft bolt or from the rear wheels when jacked up), then the whole clutch pack drops out. Depending on your exhaust setup, some of that may need to come off for the lower bell housing to be removable.

Since it's easy to do, you can do it now or do it later after a failure.

This is the later dual disc clutch with intermediate plate that my '79 has been upgraded to, but I believe the process is the same for the earlier single disc clutch too.





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Old 04-15-2019, 10:56 AM
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Excellent pics!
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Old 04-16-2019, 06:45 AM
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drooman
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Originally Posted by 78Silver928 View Post
So I finally dropped some money to have a professionally rebuilt and warranted 5 speed transaxle sent to me. The remove/ replace doesn't look too bad (watched a youtube vid on it), but what I'm wondering is: what else should I be replacing while I have it apart? I'm looking forward to cleaning the castings and the body while it's out but should I be replacing torque tube bearings or the clutch? The car has 82K miles, clutch seems pretty strong. How hard is it to replace? Not sure how to check TT bearings to see if they're OK. I've already replaced both rear calipers and brake lines. Did all of the shift bushings and front nylon cup last year (nightmare, would've been easy with the TT out) Any thoughts?
From where did you source this transmission?
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Old 04-18-2019, 06:10 PM
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78Silver928
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Originally Posted by drooman View Post
From where did you source this transmission?
On it's way from a place called Cogs Cogs in Cleveland Georgia that only rebuilds Porsche transmissions. Decent price and a 2 year warranty with reasonable shipping.
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Old 04-19-2019, 04:25 PM
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OK that would be Joe Cogbill...... owner of several different Porsche businesses over many years which got serially closed. You might do a bit of searching on the internet it gets very interesting, very quickly. Highly recommend you pay with your Amex card so you have leverage should you need it. The 2 year warranty presumes that Cogs Cogs will be in business for two years.....
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Old 04-19-2019, 06:10 PM
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78Silver928
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Oh man... I don't see any negative threads from recent years, but wow. Doesn't sound encouraging.
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Old 04-19-2019, 07:11 PM
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Randy V
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Originally Posted by 78Silver928 View Post
On it's way from a place called Cogs Cogs in Cleveland Georgia that only rebuilds Porsche transmissions. Decent price and a 2 year warranty with reasonable shipping.
Except our cars use a Mercedes transmission.

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Old 04-20-2019, 12:25 AM
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Originally Posted by Randy V View Post
Except our cars use a Mercedes transmission.

Except when you have a manual.
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Old 04-21-2019, 09:30 AM
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Petza914 -- Does the whole clutch assembly drop out the bottom of the bellhousing once the bottom cover is removed? Did you make the little shims that hold the pressure on the pressure plate? I notice that full clutch kits are $800+ which is about 6 times more than any clutch I have ever bought.... is it common to just replace the discs and keep the pressure plate? Mine has no chatter, takeup is very smooth but I sense it is nearing the end of its life.
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Old 04-21-2019, 09:50 AM
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Originally Posted by 78Silver928 View Post
Petza914 -- Does the whole clutch assembly drop out the bottom of the bellhousing once the bottom cover is removed? Did you make the little shims that hold the pressure on the pressure plate? I notice that full clutch kits are $800+ which is about 6 times more than any clutch I have ever bought.... is it common to just replace the discs and keep the pressure plate? Mine has no chatter, takeup is very smooth but I sense it is nearing the end of its life.
Yes.

My shims came from Carl at 928MS but I think they're thicker than they need to be. I took them over to my grinder and tapered the points so I could get them started and then tapped them in with a hammer - no way they were going in any other way.

Once you've installed the shims and loosened the 2 pinch bolts you can slide the coupler back toward the torque tube. Then push on the yoke to pop it off the ball up top. Then once you remove the 6 bolts that hold the clutch assembly to the flywheel it should come out with the splines shaft still run through the center of the assembly.

Mine didn't just fall out like I've heard they can. I had to slide the coupler back over the splined shaft and rotate the assembly using the rear wheel jacked up, and then once it rotated about 100 degrees, it freed itself and separated. Sliding the coupler back again then let me remove the whole assembly.

Hope that helps.
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Old 04-21-2019, 07:21 PM
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The friction discs on a dual disk clutch are somewhere in the $550 range. TOB (just the bearing) is $150. Pilot bearing is cheap, maybe $10.

Parts for these cars are not cheap.

I kept my flywheel, intermediate plate & pressure plate. If they are still in good shape, they should be reusable.

WSM has good info on all of this. Including the shims. I just used some thick aluminum wire I have. You just need a 'U" shape. The pics in Petza914's thread show them in place very nicely.
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