Sunbeam Alpine V6 Restomod: Internal Throwout Bearing Woes

The car was now tuned and running great. The car moved through traffic incredibly well. The gearing and RPMs of the engine were perfectly suited for zooming around town. Even in the higher speed range around freeway speeds, the RPM of the engine didn’t go higher than 3,000 RPM. The engine loves 3,000 RPM and from what I’ve heard from a couple of gray hairs, that is when the engine really comes alive. There was one complaint about the drive train. In 5th gear, there was a whine. It wasn’t a significant concern because the car was still getting power and the sounds didn’t sound catastrophic. In order to rectify the issue, we decided to have the transmission completely gone through since we wanted peace of mind and we really didn’t know how much life was left in the unknown transmission. So out came the transmission. 

Since we had decided to get the transmission removed, we called up our local transmission shop who we have used in the past and they said to bring it on down for a refresh. It’s funny how time can blur your memory and how much you can forget over the course of a few years. The first error we made was forgetting that the engine had to be removed in order to remove the transmission but it all wouldn’t matter after this short trip. Luckily for us, when my dad dropped the car off, the guy was miraculously missing. It was during the holidays so we cut the guy some slack but it was the return trip that proved quite eventful. 

On the return trip from the transmission shop about halfway home, my dad lost the clutch pedal. It dropped right to the floor. My dad could really only shift when the car was stopped. He eventually nursed the car home on the backroads using 1st and 2nd gear. Once home, we evaluated what went wrong. The clutch reservoir was bone dry and there was a puddle of brake fluid on the floor. It was abundantly clear that this was a clutch issue. We tried refilling the reservoir and retesting the clutch. The clutch worked but it was confirmed, the hydraulic throw-out bearing was kaput.

After having the car towed over to my house, I took it upon myself to remove the transmission not realizing I needed to remove the engine as well. After removing the exhaust and drive shaft, I barely was able to remove the transmission. To say it was a fight was an understatement. Once the transmission was out, we inspected the hydraulic throw-out bearing and found one of the rubber seals had ruptured. We didn’t want to run into this problem again and after some deep thought, we both decided it would be a good idea to install a more conventional external slave cylinder setup on the car. We had the bracket and all of the hardware, but we were still missing a few components. 

Mustang II Bellhouse PN# D4ZA 6394 CC
Bellhousing Missing Clutch Arm Bushings

The bell housing we had was the correct type but we were missing the internal guts of the bell housing. The part number of the bell housing is D4ZA 6394 CC. The first thing we noticed was the bushings were missing for the internal throw-out arm. These are bronze bushings that are pressed into the bell housing. We would have to get this machined at a shop. The second thing we realized we were missing was the actual throw-out bearing arm. We also realized how difficult this part would actually be to purchase let alone find. 

Mustang II Clutch Arm Bracket in Original Ford Box
Mustang II New Old Stock Clutch Arm PN# D4ZZ-7515-C

During my exhaustive search for the clutch arm, I discovered the part number to be D4ZZ-7515-C. What happened next, I still don’t believe to this day. A simple google search showed a new old stock (NOS) clutch arm matching the same part number and vehicle model. It was even in the original Ford box. We could not believe our luck. I immediately purchased the part off eBay and a couple of days later the part showed up on my doorstep. What unbelievable luck stemming from an unlucky chain of events.     

Outer Diameter of the Clutch Arm Rod is .75 Inches
Outer Diameter of the Bearing Seat is .924"

When I measured the shaft and the opening in the bell housing, we needed a bronze bushing approximately 1/8″ thick. After finding a machine shop that was recommended, I dropped the bell housing and the arm off at Rohm Machine and Welding in Orange, CA. I explained to the shop foreman what I needed and he recommended a bronze bushing. I have a tendency to over-explain things to people and he stopped me by saying, I know exactly what you need. A few days later and I picked it up and they had done the job perfectly. There was the perfect amount of clearance between the arm and the bushing and the arm moved flawlessly. I would recommend Rohm Machine and Welding to anyone. They really know their stuff. 

Partially Installed Clutch Arm in the Bellhousing

After testing the fit of the arm, I had to fully assemble the arm with the throw-out bearing. The arm is secured to a rod via two press-in pins. I originally wanted to replace the pins with bolts but there was too much slop in the holes where the bolts sat. I pressed in the pins with a hammer and the installation was complete. I started to have second thoughts about the press-in pins and decided to take them out but after unsuccessfully trying to remove them, I realized they weren’t coming out. This gave me a ton of peace of mind because after all if those pins come out, the whole car doesn’t work and I have to repeat the whole process all over again. 

Bearing Retainer was trimmed to a distance of 4.5"
Ground Down Bellhousing

There was some concern about the distance the throw-out bearing need to travel on the transmission. Recommendations for trimming the bearing retainer ranged from 4″ to 4.5″. We opted to go with the longer distance of 4.5″. This is a necessary modification when marrying the transmission to this bell housing and engine. One of the last things to do to the bell housing was to trim off the unused mounting points on the starter side of the bell housing. This must be done to make room for the external throw-out slave cylinder which actuates the clutch arm. A trip to the hardware store to buy a die grinder and about 15 minutes of grinding later and the bell housing was complete. 

Pilot Bearing Adapter made by Jeff Kelley

Before we fully married the transmission to the engine, we received some advice on extending the pilot bearing to the T5 input shaft. The T5 input shaft is not quite long enough to fully seat into the pilot bearing. It only seats around 1/4″. I was referred to Jeff Kelley of Kelley Precision Products in Washington who makes an adapter that bolts to the flywheel and essentially extends the pilot bearing. After a quick conversation, Kelley sent over the adapter. He know exactly what we were doing and what we needed. 

Although an unfortunate series of events, the road was well traveled and we received some solid advice on how to get the car up and running. With some luck and solid knowledge on our side, we were ready to remove the engine and finally marry the transmission to the modified bell housing and transmission. The next post will deal with a quick radiator project recommended by a forum member. Motor on.