Swapping a 3 speed for a 5

After replacing the rear end with a stock V8 rear with 2.79 gears, the poor inline 6 engine just feels like a dog behind that 3 speed transmission. I worry if I have to start out on a hill, it won’t be able to go. That pushed me into using the 4 cylinder T5 transmission I have in the garage for this car. I am hoping that the gearing in this T5 means I wont have to replace the rear gears later as well. Gear math isn’t my thing, so I will just have to wait and see.

To do the conversion, I ordered a number of parts from Modern Driveline. The key part is a conversion plate to get the T5 bolted up to the original bell housing. I also need to replace the bearing on the engine for the smaller nose on the 4 cylinder T5. While I’m in there I will replace the clutch, though keep the Z-bar mechanical linkage.

First step is to remove the drive line. Easy enough since I just put it on a few weeks ago. I did a test fit to make sure it fits with the T5. I opted to not replace the yoke at this point. If it becomes an issue, that’s easy enough to replace later. I did get a new reverse pigtail though.

Removing the 3 speed was easy enough. I followed the directions in the shop manual which had me remove it from the bell housing and drop the shifter linkage. After that, removing the crossmemeber allowed it to basically fall right out. I did use my floor jack to support it as I wiggled it back out of the bell.

I had to take the starter out, then the bell came off. I had a hard time finding the 4th bolt, but once I did, it too fell right off. Evidently there are a number of different bell housings, but this is what mine looked like.

The adapter is basically a slab of aluminum milled to bolt between the original bellhousing and the T-5. The directions say to test fit it before doing anything else.

I had to drill a couple of holes in the bellhousing and bolt from the inside on those, plus counter sunk alan head screws on the outside. The housing itself is set. The clutch kit came with a new throw out bearing, so after installing that, this part is done. I would like to replace the rubber boot, but I don’t really want to stop everything for a week for that. The old one is rotted off, so I will probably remove the scraps and see if I can get the new one on later, without taking other things apart.

Day 2, I started early and took the clutch off. It had one of the 3 finger style, but other than that, it was very similar. It was obviously replaced not too long ago as it was still in really good shape. The pilot bearing just fell out too, so not sure if that was due to my wiggling the 3 speed out, or just not installed right. Either way, it saved me a trip to the auto parts store to rent the puller.

3 speed 9″ clutch and original bearing.

I had to replace the bearing for the smaller pilot shaft on the T5 or else I probably would have left the original clutch. This project is more towards the budget side, but not leaving broken or warn parts. I don’t want to drop the T5 for a clutch in the near future, so it’s worth the cost to avoid the extra work later.

New 9″ clutch and pilot bearing

The flywheel stayed in place. It was a little burned, but not scarred or warn.

Flywheel stayed

The new clutch went right back on. I had to hold the guide tool in place since only the very end was small enough to go into the new pilot bearing. Normally it would go into the pilot bearing about an inch, holding the clutch plate in place while bolting the clutch on. I guess they didn’t have the right tool for the smaller bearing. A little more hands on, but it worked.

New clutch mounted

With the prep work under the car done, I am ready to finish up the transmission and get it ready to install. I put the bellhousing back on since I thought it would make it easier to install the throwout bearing since the tolerance on it is pretty tight. Then I realized I don’t have enough height on the car to get the assembled unit under the car. I took the bellhousing off, moved things under the car, then put it back on.

Manual throwout bearing with the arm which attaches to the Z bar
Original bellhousing, adapter plate, and T5 ready to go

From here, I decided to get a new transmission jack from Harbor Freight to preserve marital bliss. Short detour later, and I managed to somehow get the T5 on the lift while under the car. Life got easier then and I was able to get it on level with the engine and start trying to convince it to line up and go into the pilot bearing. I got it within an inch, and put the rear cross-member transmission mount in. It has a bit more than an inch of slide built into it, so that made life easier. I really have to do this on a lift next time. I could probably do it in half the time. With the back supported, it took some work, but the front eventually lined up and seated, so I was able to bolt everything in place.

Putting things back together, the drive shaft went on easy and was a good fit. No length adjustments required. Starter went back on, and battery connected. I removed the wiring harness that went to the reverse light since I broke my new pigtail. I thought I would just unplug it from the firewall. Well, it turns out that the engine won’t turn over without that plugged in. So I zip tied it to the export brace until the new one comes in and I splice it into the old harness.

Once everything was bolted in, I went inside to check it out. The spacing looked just right. I was trying to avoid cutting the tunnel opening, which looks like I barely got away with not cutting it. Here is a shot with the Hurst shifter arm on the stock T5 shifter.

First gear. Just clears the stock cutout.

I still need to deal with the fit and finish parts of the shifter boot and fasteners. I think this kit also wants me to drill new holes, which I am not fond of. I will have to see what I can do to use this boot, but not drill new holes.

All that work for this. Worth it.

With the exhaust cut off just behind the back of the engine, I couldn’t give it a proper test drive. I will get an appointment at the local muffler shop and have them put something basic in. That also addresses the previous problem with the exhaust hitting the transmission cross-member and making all kinds of noise.

With this mod, I am feeling pretty good about the over all state of the car at this point. After a test drive, I am hoping it is ready for the trip across the country.

3 thoughts on “Swapping a 3 speed for a 5

  1. Evan Molnar

    Brad my name is Evan… I’m currently trying to do the exact same thing you are doing with my mustang and just have one simple question… How far does the tip of your pilot bearing shaft stick out past the mating surface of your bellhousing?


    1. Hey Evan, thanks for reading. I am not sure exactly. I don’t think I have any pictures from the side like that. Are you having trouble getting it in place? The last inch or so is pretty challenging to get seated as you have to get the transmission perfectly aligned since the bushing clearance is so tight.


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