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Started some work on the Dual Clutch Transmission.
Here's the DCT next to the 4L80E for a rough size comparison.
Started dissecting the Getrag V8 DCT.
FYI, I have a transmission work stand. There is a hole in the center of the stand so all the fluid that spills out goes down the hole into a bucket below.
The DCT has a very shallow pan on the bottom (it may be plastic). It also has a side cover that accesses the valve body and control computer. The connector goes up and leaves the top of the transmission. The cover appears to be resealable.
The other side of the valve body has hydraulic actuators that effectively do the shifting just like you would with a manual transmission, but the fluid for these actuators is controlled by the solenoids.
The actuators move the shift levers in the case.
The internals are pretty much like most manual transmissions with the syncros and all that except.... There are two sets of gears. One set if for the even gears and the other set is for the odd gears.
There are sensors that let the trans know the position of the gear shift levers and some other sensors I haven't figured out yet.
There is a parking pawl that can be engaged from outside the transmission.
The rear end of the DCT has a 3 eared output shaft that normally goes to a Guibo. There are companies out there that make adapters of various kinds. I might eventually go for one of these one everything is proved out and I decide what kind of adapter I want. I've heard good things about CV joint adapters.
For now I think I can get away with the same driveshaft already in the vette driven by the 4L80E It's a 1350, chromolly shaft. So I'm fabbing up my own temporary adapter from the DCT output shaft to my existing driveshaft. Keep in mind that the rear is a 4 link, so there has to be some spline interface that lets the driveshaft adjust for the changing length between the trans and the rear.
I had extra 4l80E parts laying around, so re-purposed the 4L80E output shaft to fit to DCT. I have one of those WWII lathes and like making this kind of stuff out of scrap I have laying around.
That's the 4l80e output shaft on the right and the DCT ouput flange on the left. First I machined a centering spacer out of brass.
Here's a mock up of how the two look together.
Then I machined a ford axle flange I had laying around to reinforce the 4L80E flange and welded the two together. Here;s the adapter.
Total rounout is 2 thousands.
I'm thinking that the DCT/output shaft combos is about an inch longer the the 4L80E shaft. There is a lot of spline there, so I don't think cutting about an inch off the splines and 1350 yoke should be a problem. I'll be able to better judge the length later, but I think it's close enough for now.
Then I'll try to fit this puppy into my C3 Vette. There are lots of threaded holes in the rear of the case for a trans mount. I'll fab up something to make it fit in the existing rubber trans support. I'd like to make this interchangeable between the DCT and 4L80E.
There are two trans cooler ports in the DCT that used to go to a tiny heat exchanger. I'm getting an adapter that lets these go to AN fittings. I'll connect these right to my existing trans cooler.
....Gettrag stock clutch DCTs can handle 600 ft/lbs of torque and with upgraded clutches or higher line pressures, way, way over that. Other than clutch wear, they just don't break.....
This is very misleading. Getrag DCT are a decent transmissions but they have plenty of problems. They also have really expensive parts, most clutch kits start at $2,500 and sometimes you need baskets/dampers. Sometimes internal (gears, shafts, forks) parts are not available for sale. Gears rarely break on them from power. Clutches fail very easily even from just sustained load or not enough cooling for trans fluid.
Line pressure does not solve issues with clutches or baskets but it does improve feedback and reduce amount of slippage. That in turn lets you change from harsh shifting to smooth unnoticeable gear changes.
I still think it's a great idea though for driveability. Do the aftermarket ecus have on-the-fly switching?
At first glance, the flex plate/starter ring appears to fit inside the adapter. I have a stock automatic flex plate and my old 5.3 block that I'll test fit shortly.
Based on initial measurements, looks like the stock 5.3 flex plate may fit. I also have a LS3 GM performance plate and they seem to be close to the same dimension.
But...... I'm not thrilled with the amount of spline engagement (only measured when parts were separate, so I'm not positive) between the DCT splines and the LS side splines. If the flex plate material would be thicker, then the engagement might be better. Gotta do some more checking. Unlike with a torque converter which balloons under high load, I don't see the need for space for stuff to "grow"
In hindsight, I thinking I should have asked for the longer spline adapter. From the photos, they had a long and a short version. Then I could machine off any excess length if needed.
Are all flex plates same thickness where they attach to the flywheel?
I'm going to grind the DCT case in the places I've marked with red marker to make it easier to bolt the adapter to the LS block. I think I could get by without grinding these by putting the mounting bolts in ahead of mounting the adapter ring to the transmission, but the grinding is minimal, should not weaken anything and will make it much easier to mount the adapter ring to the engine.
04-20-2020, 05:02 PM
