When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Hi Mike- Here's a shot of the dimension from the front face of the flare to the back face of the mounting flange- about 95-96 mm. I'm afraid I need to keep this wand for my spare G28.57 that I really should assemble...
Hi Rob, thanks for this measurement, I think I found a place that has the appropriate tooling to add the bubble flare and potentially replace the section of tubing that was cut.It appears to be just sweat soldered in place. having that measurement will be key. I'm headed over there this morning.
The flywheel material and the trigger ring are very, very different types of steel and take a special rod to weld together.
The welds are extremely prone to cracking.
I can't expand your picture, but the weld at 3 o'clock appears to have a line going through it.
I'd carefully inspect all of the welds for cracks.
Additionally, the welds were put exactly where the mounting bolt holes are. Note that this is also where the intermediate plate has to sit on the flywheel....perfectly flat.
If the welds are sticking up, even tiny amounts, the intermediate plate will not sit flat and the clutch will never be smooth.
Hopefully, you resurfaced that flywheel....it's got ugly hot spots.
And if it was surfaced, hopefully they surfaced out past the welds, so they are not "proud" of the flywheel surface.
That flywheel is from a model year that requires three dowels to keep the intermediate plate and flywheel centered. One of those dowels is larger on the flywheel side....it's a stepped dowel. In your picture, it is not present. Make sure that all three of the dowels are there and are in the flywheel, intermediate plate, and pressure plate, before tightening down the pressure plate bolts. Otherwise, the clutch will be out of balance and shake your fingernails off.
You're making great progress!
Originally Posted by GregBBRD
Why a dual disc clutch?
The flywheel material and the trigger ring are very, very different types of steel and take a special rod to weld together. The welds are extremely prone to cracking. I can't expand your picture, but the weld at 3 o'clock appears to have a line going through it. I'd carefully inspect all of the welds for cracks. Additionally, the welds were put exactly where the mounting bolt holes are. Note that this is also where the intermediate plate has to sit on the flywheel....perfectly flat. If the welds are sticking up, even tiny amounts, the intermediate plate will not sit flat and the clutch will never be smooth. Hopefully, you resurfaced that flywheel....it's got ugly hot spots. And if it was surfaced, hopefully they surfaced out past the welds, so they are not "proud" of the flywheel surface. That flywheel is from a model year that requires three dowels to keep the intermediate plate and flywheel centered. One of those dowels is larger on the flywheel side....it's a stepped dowel. In your picture, it is not present. Make sure that all three of the dowels are there and are in the flywheel, intermediate plate, and pressure plate, before tightening down the pressure plate bolts. Otherwise, the clutch will be out of balance and shake your fingernails off. You're making great progress!
Why the dual disk clutch? That is a reasonable question. I tried to do my due diligence research on which clutch to use. There seems to be a lot of support for the dual disk clutch as an alternative to the single disk clutch in the 928 community. The dual disk is significantly lighter and offers more clamping force suitable for higher torque HP situations. I understand the single disk clutch is sufficient for a stock GTS but not one that has been modified with cams, which is something that was planned at some point. My 88 5spd had the single disk clutch and all of the clutch engagement/diss-engagement was at the top of the pedal stroke (new disk). This always felt odd to me to have all the pedal travel for such a small engagement range. The dual disk setup clutch I drove on an 84 928 felt so much more linear with it's engagement. So. that is how I ended up choosing this path. Arguably, I made this more difficult on myself and there are plenty of folks out there who think this was unnecessary. So maybe this is an opportunity as a learning experience. I'm kinda committed to the dual disk at this point.
Hoping to get some help on filling the transmission and oil cooling circuit properly. The transmission was shipped back with oil in, however, an unknown volumne oil spilled out through the vent during shipping so I need to top it off. The filling capacity manual transmission for the GTS is listed as 4.8liters in the owners manual:
However the WSM generically states the filling capacity for any manual transmission is 3.8L, with no mention of a capacity change for the GTS
Given that the GTS transmission case is visually the same size and as the earlier boxes, can I conclude that the extra liter of capacity is in the oil cooling circuit?
My question is, how do I fill the system (transmission and cooler) to the correct level since I have an unknown volume in the box now? Do I leave the oil cooler dry and just fill the transmission to the oil filler opening? Or do I need to also pre-fill the oil cooler from the engine bay, and how will I prevent the oil in the cooler from just gravity draining into the trans?
Dunno if there's an official WSM procedure for this, my sense is that you put the car on a lift, put the car in 1st gear and let the pump on the rear diff cover prime the whole cooling loop, and then add more oil through the fill hole on the diff cover until it's up to the bottom of the fill hole.
On the feed lines to the cooler, there's a double loop of hose- I guess it's some sort of anti-siphon to prevent gravity-backfilling of the transmission (?) On the '93 it's just ziptied to itself, in '94s they made a bracket for it:
Dunno if there's an official WSM procedure for this, my sense is that you put the car on a lift, put the car in 1st gear and let the pump on the rear diff cover prime the whole cooling loop, and then add more oil through the fill hole on the diff cover until it's up to the bottom of the fill hole. On the feed lines to the cooler, there's a double loop of hose- I guess it's some sort of anti-siphon to prevent gravity-backfilling of the transmission (?) On the '93 it's just ziptied to itself, in '94s they made a bracket for it
Yea, I think that is the process I will follow as well. I was hoping I could do that before putting the exhaust on and blocking the fill port. But I think I can work with it.
That loop of hose on the supply side it very interesting in those two photos you shared. I wonder want the part numbers are? When I purchased the supply side hose, that loop is now omitted in the latest iteration of the part (928-307-039-01) and the flex line connects directly to the hardline feeding from the differential pump.
EZK and LH accommodations for automatic vs manual transmissions
@PorKen reminded me that both the EZK and the LH have subtle differences. Here is the information from the various manuals
LH Accommodations for automatic transmissions
Based on the info in the WSM, the same LH unit is used for all cars that the idle adjustment is controlled by a changing the coding plug (see below)
Here is the stock coding plug for the automatic
@PorKen was very generous and gave me the kit to build up my own coding plug for the manual (these are available new for about $18).
So I built my own.
EZK Accommodations for automatic transmissions
The EZK is a little more involved...
Undoing this was going to require a software change and once again @PorKen to the rescue! He was kind enough to provide me with a manual version of the EZK-s self tuning chip. Thanks so much Ken for this awesome product. I can't wait to give it a go in the GTS 5spd.
Transmission Cooling Lines
I found someone to put a flare fitting on the transmission oil spraying wand. You would not think it would be that difficult to find someone with a metric ISO (aka Bubble) flaring tool for 10mm. But sadly we still are intrenched in the imperial system.
The only problem is they had to take another 15mm of the end because the tube was not round. That made a shortened end even shorter
This compounded the already stretched flex line. I decided to have the flex line re-made about 3" longer to account for a more relaxed routing and account for chassis/drivetrain movement.
I expect to pick up the hose tomorrow sometime and then it's all about putting the finishing touches on. This is literally the last thing holding me up from wrapping up the job. If all goes well I can do some garage tests tomorrow, and then try some road tests and maybe get the alignment done before the weekend!
Based on the info in the WSM, the same LH unit is used for all cars that the idle adjustment is controlled by a changing the coding plug
The EZK is a little more involved...
The coding plug tells the EZK whether or not to pay attention to the shift pressure switch. Essentially it only stops the EZK from throwing a non-CEL code for a non-op transmission protection switch.
The LH is not coded for auto/manual but the wiring harness is different. The neutral safety switch (starter relay) input is set to ground on M481 (manual). If this input is open the LH will think the auto trans is in gear and the idle will be lower. (Already done above.)
I let the car idle in all the gears figuring that would circulate the oil through the transmission cooler circuit. I'll check the level once it cools down.
Problems noted so far
the PSD light is on when in gear. Is this a result of the car being on the lift?
The damn airbag light is on even though I did not remove the airbag plug. Did this get activated when I powered the car with the seats out? I am curious why this fault activated. Hopefully it will clear easily next time I get access to the durametric.
the reverse switch on the trans is bad now it’s stuck off. This was a brand new switch. How could it be
Next test will be on the ground and around the block
Last edited by Michael Benno; 08-11-2022 at 11:23 AM.
With some excellent help from my 14yr old neighbor we were able to get the car on the ground for some shake down drives. We did have to put it in the air again to bleed the clutch, again. Which is not surprising. But, after that we were able to get out for a more solid run through the gears.
The new transmission transforms the car. It's so much faster now. 1st and 2nd gear are a little tricky because it's so easy to break the tires free under full throttle (275/35 ZR18). I dont remember having 2nd gear wheel spin on the 4-spd auto. The rebuilt 5-speed feels great and the rebuilt PSD performs so much better than the one in the Auto which is likely worn and would cause some erratic hip movements that would cause one to let off the throttle. This PSD keeps the car going straight. Thanks to Greg and his team for the excellent work on the 5-speed.
So far the car and trans is awesome, but there are some additional bugs to work out. It will need an alignment (Wednesday) before I can put the car through the paces on the track. I am getting a lot more wheel spin and that could be the lower gear ratios, or the alignment, or aging rubber.
Still Sorting out Some Items
No Reverse lights - I had this working and then it just stopped. I can't figure out what cause the system to stop working. I'll post a follow up on my trouble shooting.
Clutch Rattle - Also, I am getting some odd rattling noise in the clutch when under low engine speed but high load like being over geared and accelerating. I have experienced this noise on my 88 5speed and other manual trans cars but far less frequently
Oil Ingestion into the intake - The other "new" issue caused by adding the 5-speed... Now I am spending a much more time in higher revs and that means a lot more oil breathing issues. The vacuum pump / Provent 200 breathing system is complete overwhelmed. I will need some re-working of the system or revert to a different breathing solution. After a few redline runs in the video, I sent a munch of oil vapor into the intake and blue smoke out the back because the Provent "bypassed" because of the over pressurization. The Provent 200 is rated at 200CFM which is barely not keeping up for low rpm causing but the pump flow rates increase a lot more as RMPS go up:
This a conversation for a different thread as there are a few of us using vacuum pumps and It doesn't seem like there is a great solution for dealing with high CFM outputs. Drag racers usually just push the output into a baffled catch can vented to atmosphere, which I'd like to avoid.
Last edited by Michael Benno; 08-16-2022 at 01:13 PM.
Great job Michael!!
The 5sp transforms the car into a totally different beast compared to the automatic. (I'm sure having a totally rebuilt one makes it even more special)
Add the GT cams and feel the adrenaline rush of living above 4k rpm
P.S. Now you've infected your neighbor so he'll want a 928 when he can drive too LOL
Clutch Rattle - Also, I am getting some odd rattling noise in the clutch when under low engine speed but high load like being over geared and accelerating. I have experienced this noise on my 88 5speed and other manual trans cars but far less frequently.
It's the sound of the splines twisting in the shaft coupler (with its 924 spec clamps). Moar torque = moar noise. Coulda put in a 968 coupler, but nooo...
Can make a 'PKalm' pretty easily. The shaft collars are a standard size - 35mm id - I had them plated but no need in the bell housing.
08-08-2022, 11:51 AM
