PCM 40i to Velvet drive 10-17 swap

Hello all, I recently swapped out my PCM 40i for a Velvet Drive after getting frustrated with the PCM. The PCM had water in the trans fluid and warped the forward clutch plates. I took the trans apart and cleaned everything, put new clutches and seals in, and everything worked great until it warmed up. Once warm it would not engage forward unless the engine RPM were raised to 850-900 rpm.

Hoping to pull some information together for anyone looking to do this in the future. Keno and Duane in Indy were very helpful in this process.

The boat being worked on is a 1995 Supra Comp TS6M with a GT40 and PCM 40i 1:1. Using this thread: PCM 40 to velvet trans swap and lots of searching I was able to pull off the swap.

Here's how I did it:

- Drain trans fluid with fluid extractor.
- Unbolt prop shaft coupler.
- Remove cooling lines.
- Remove shift cable.
- Jack up engine with bottle jack and wood under the exhaust manifold.
- Unbolt transmission mounts from the trans and rotate out of the way.
- Remove qty. 4 bolts from the trans to bellhousing.
- Remove trans from boat and set aside.
- Unbolt starter.
- Unbolt ECM bracket at manifold and two bolts that also attach the bellhousing to the engine.
- Removed bolts from what looks like a fuel pump so it could be slid to the side.
- Remove remaining bellhousing bolts.
- Remove single 13mm bolt attaching the dust cover to the bellhousing near the engine oil pan.
- Remove bellhousing (it may be difficult to remove because it is on two dowels that are a very close fit.

I also removed the exhaust hoses to make the next steps easier. BTW, the PCM trans weighs ~50 lbs, don't trick yourself with the velvet drive, it's a tank (around 95 lbs).

I bought a new damper from ebay for the Velvet Drive, $65 with free shipping. Seller shipped it super fast. Same damper that ebasic sells.
Ebay damper

- Cut the damper to fit the Ford bellhousing.
- Installed damper with some loctite on the bolts.
- Install bellhousing.
- Bolt in ECM bracket.
- Bolt in cooler and reattach the fuel pump.
- The mounts of the B/W sit 7/8" further back than the PCM. There are two methods you could use, bolt the mounts to the trans and mark the holes then drill. Or transfer all the holes back 7/8" and drill then install the mounts and trans. I used the second because I was by myself, I would highly recommend the first if you can borrow a second person to help.
- Drill holes and install transmission mounts (same mounts as the PCM).
- The B/W Velvet drive uses all six bellhousing bolts. I only used two studs, the thread referenced used four.
- I bought two 7/16-14 6 inch studs from ace and cut them to 4 inches. Installed them in the lowest holes on the bellhousing with double nuts and blue loctite.
- Muscle trans into boat, slide onto lower studs and slide the input shaft into the damper plate.
- Install remaining transmission bolts (four).
- Install exhaust hoses and lower transmission so mounts line up.
- Bolt transmission mounts to transmission.
- Install cooler lines

KENO wrote: Roughly 13.25 inches on the feed hose and roughly 21.25 inches on the return hose. I could tell you I measured, but it was easy to check the Ski Dim and Nautiqueparts websites and they were the same on the numbers for both hoses. A little different on prices from one place to the other.

- Install starter.
- Make/change shift cable bracket to work. The ball mount from the PCM will work with the B/W, but the bracket needs to change slightly. I drilled new holes lower down on the PCM bracket and reinstalled it. If you get a longer bolt and use a spacer on that location, it will work out really nicely.
- Align prop shaft and bolt the trans coupler to prop shaft.
- Fill with fluid (approx 2 qts.) and check for leaks. Let trans warm up and check level, I had a second person shut the key off while I stood at the trans. Immediately pulled the dipstick, wiped off, reinserted and checked again.

I had no issues with the trans being 1/8" shorter overall but YMMV. Prop is an ACME 541.

I bought my transmission off of craigslist knowing it may need a rebuild, but the seller claimed it worked. It shifts great, no slipping, but the input seal was leaking. This transmission was sitting in his garage for a few years and it appears that the seal went bad. The pump had some fine scratches on it, but ended up putting it back in with a new seal and it seems good now.

I would recommend replacing the input seal (if the trans has been sitting) and checking the indexing of the pump before installing the transmission. Save yourself some headaches...although I can remove the trans in 30 minutes and install in about 45 now...

Here are a few pics. Ignore the trans fluid that got spilled in the bilge, that got cleaned up. I'll get some pictures of the boat once I wipe my greasy hand prints off the gunwhale.




And a picture of the pretty intake.

Good job and a good write up too

DW1 wrote: @2001Sunsport: Nice write up, I am looking to do the exact opposite swap install a 40i in place of the Velvet Drive. So I am in search of a 40i 1:1 box.

Just did this on an '81 SN last year. Very straightforward. The rear mounts were reused, with new holes drilled in the carriage. (slight difference). Also, the shift cable may need re-routing and/or a taller bracket on trans end. Works great. (so far)

As noted in a different thread, found one:-) Need some parts: output flange, damper plate, other misc stuff to bolt box to bellhousing & boat stringers, Current is VD71 coupled to Chevy SB. If you are clearing out your parts shelves, let me know.