Installing a T5 in a +S
Posted: Tue Sep 06, 2016 1:46 am
Thought I would pass on my experience with installing a T5 transmission in my +2S. I had read all of the existing posts on install 5 speeds. Being in the US I decided the T5 was the best option.
I found a S10 T5 for $100.00 and a Mustang unit for $75.00. I bought both off of Graig's list. Prices are all over the place but with a little patience you can find units at a decent price. The Mustang unit I have has ratios of 3.35, 1.93. 1.29, 1.00, 0.68. While these ratios, except the od are acceptable there is a T5 that was used in the 50. Mustang that has a little better ratio set. However, as fewer of them were made they are harder to find and tend to be quite a bit higher in price. As far as the 5th gear ratio it is easy enough to buy a set of overdrive gears and change that to something in the 0.80-0.85 range
After I got both of the units the first thing I did was to fit the S10 tailshaft to the Mustang box to move the shifter into a more acceptable location. Then I spent quite a bit of time measuring and playing with bellhousings and various fittings. I determined that the Mustang box input shaft was approximately 3/4" longer than the Lotus unit from the transmission face to the tip than the Lotus box. I decided that if I made an adapter plate to fit between the bell housing and the transmission that was the proper thickness I could use the original Lotus bell housing. This meant I would have fewer problems with frame clearance and could use the standard Lotus starter. For mockup I cut off the back of a Mustang bellhousing, machined it to the proper thickness and drilled holes to fit the Lotus bellhousing. While this adapter worked for mockup purposes I will have a proper adapter machined before final fitting.
Because of the input shaft differences three possible issues arise. I will probably not be able to use the original Lotus throwout bearing. This is a minor issue as there are several concentric throwout bearing that are designed for the Mustang box. Second is the fact that the pilot bearing diameter is different. Again this is a minor issue since you can easily machine a pilot bearing to the proper diameter. Finally I will have to find a Mustang disc with the proper diameter to fit the Lotus pressure plate.
There were a couple of areas in the frame that had to be cut but nothing major. I also cut a hole in the frame and body so that I could access the transmission filler plug.
The box had several fittings on it that were used as mounts in various cars. As none of these met my needs I cut all of them off. This made for better clearance when installing. For the rear mount I bought several low profile mounts from Summit. I found one that fit and machined a bracket to fit it to the transmission.
Next up was the shifter. I bought a short throw adapter for a Mustang that has a stub handle to attach a shift lever to. Since the tailshaft housing cutout is different for the S10 I had to modify the baseplate of the adapter to fit the different bolt pattern. I put the Lotus transmission in the frame and made a template that showed me the exact location including angle and height of the original Lotus shifter. Then I took my Lotus shifter and cut off the portion that holds the anti-sizzle bushing and the lever. I then made an adapter that fit the stub on the short throw adapter that I could weld the piece I cut off of the original Lotus shifter. By using the template I ended up with the shift lever located within 1/8? of the original including height and angle and I was able to retain the anti-sizzle bushing.
For the shift boot I was able to retain the original to mount on the console. For the external boot I found one from Summit that fit the short throw adapter.
The S10 unit that I bought had an electronic speedometer output. I am able to mount the reducter ring to the Mustang output shaft. There are several units available that can take the electrical signal and convert it to a cable drive. In this manner I will be able to use the original speedometer. I am also looking into the possibility of getting a GPS enabled unit that will drive a cable output.
I have talked to a driveshaft shop in the area and they can shorten my shaft and fit the proper u-joint at the front. They say that there is no problem with having different joints at the front and rear as long as they are aligned and balanced properly.
While time consuming I found that this swap in not nearly as hard as I was lead to believe after reading the existing posts. Also, since I have a milling machine, lathe and MIG welder I was able to do all of the work to this point myself. For the final installation I will have a machine shop make a more accurate adapter and machine the pilot bearing. While I have probably spent 25-30 hours on this I could do another in less than half the time, now that I know exactly what is necessary. I estimate the total cost will be about $750 unless I find a 5.0 box at a decent price and purchase it. Although the car is still a long way from being on the road I am very pleased with this part.
I found a S10 T5 for $100.00 and a Mustang unit for $75.00. I bought both off of Graig's list. Prices are all over the place but with a little patience you can find units at a decent price. The Mustang unit I have has ratios of 3.35, 1.93. 1.29, 1.00, 0.68. While these ratios, except the od are acceptable there is a T5 that was used in the 50. Mustang that has a little better ratio set. However, as fewer of them were made they are harder to find and tend to be quite a bit higher in price. As far as the 5th gear ratio it is easy enough to buy a set of overdrive gears and change that to something in the 0.80-0.85 range
After I got both of the units the first thing I did was to fit the S10 tailshaft to the Mustang box to move the shifter into a more acceptable location. Then I spent quite a bit of time measuring and playing with bellhousings and various fittings. I determined that the Mustang box input shaft was approximately 3/4" longer than the Lotus unit from the transmission face to the tip than the Lotus box. I decided that if I made an adapter plate to fit between the bell housing and the transmission that was the proper thickness I could use the original Lotus bell housing. This meant I would have fewer problems with frame clearance and could use the standard Lotus starter. For mockup I cut off the back of a Mustang bellhousing, machined it to the proper thickness and drilled holes to fit the Lotus bellhousing. While this adapter worked for mockup purposes I will have a proper adapter machined before final fitting.
Because of the input shaft differences three possible issues arise. I will probably not be able to use the original Lotus throwout bearing. This is a minor issue as there are several concentric throwout bearing that are designed for the Mustang box. Second is the fact that the pilot bearing diameter is different. Again this is a minor issue since you can easily machine a pilot bearing to the proper diameter. Finally I will have to find a Mustang disc with the proper diameter to fit the Lotus pressure plate.
There were a couple of areas in the frame that had to be cut but nothing major. I also cut a hole in the frame and body so that I could access the transmission filler plug.
The box had several fittings on it that were used as mounts in various cars. As none of these met my needs I cut all of them off. This made for better clearance when installing. For the rear mount I bought several low profile mounts from Summit. I found one that fit and machined a bracket to fit it to the transmission.
Next up was the shifter. I bought a short throw adapter for a Mustang that has a stub handle to attach a shift lever to. Since the tailshaft housing cutout is different for the S10 I had to modify the baseplate of the adapter to fit the different bolt pattern. I put the Lotus transmission in the frame and made a template that showed me the exact location including angle and height of the original Lotus shifter. Then I took my Lotus shifter and cut off the portion that holds the anti-sizzle bushing and the lever. I then made an adapter that fit the stub on the short throw adapter that I could weld the piece I cut off of the original Lotus shifter. By using the template I ended up with the shift lever located within 1/8? of the original including height and angle and I was able to retain the anti-sizzle bushing.
For the shift boot I was able to retain the original to mount on the console. For the external boot I found one from Summit that fit the short throw adapter.
The S10 unit that I bought had an electronic speedometer output. I am able to mount the reducter ring to the Mustang output shaft. There are several units available that can take the electrical signal and convert it to a cable drive. In this manner I will be able to use the original speedometer. I am also looking into the possibility of getting a GPS enabled unit that will drive a cable output.
I have talked to a driveshaft shop in the area and they can shorten my shaft and fit the proper u-joint at the front. They say that there is no problem with having different joints at the front and rear as long as they are aligned and balanced properly.
While time consuming I found that this swap in not nearly as hard as I was lead to believe after reading the existing posts. Also, since I have a milling machine, lathe and MIG welder I was able to do all of the work to this point myself. For the final installation I will have a machine shop make a more accurate adapter and machine the pilot bearing. While I have probably spent 25-30 hours on this I could do another in less than half the time, now that I know exactly what is necessary. I estimate the total cost will be about $750 unless I find a 5.0 box at a decent price and purchase it. Although the car is still a long way from being on the road I am very pleased with this part.