3 Spd Auto to 5 spd Manual Swap
The existing 3 speed automatic transaxle and 1.6 liter 4 cylinder engine yield little performance. Top gear is reached by 35 mph and acceleration is nearly
absent, which can create
real Pontiac excitement when merging into 70 mph freeway traffic at 35 mph.
While Pontiac originally offered a 5 speed manual F13 (RPO M79) transmission for the car, and I was able to locate one in a junk yard early on, the transmission
was damaged (as many are) by the yard handler's forklift. With only a very small number of junk vehicles within a day's drive, I opted to try to install a D16
transmission from a 2000 Daewoo Lanos S. Here is what I brought home:
- Lanos S D16 Transmission with switches and sensors
- Connector ends that mated to the switches and sensors
The D code indicates an hydraulic release transmission, while the original F coded transmission was a cable operated
assembly. Two options presented themselves:
1) install an hydraulic clutch assembly that includes the pedal, master cylinder, slave cylinder, and reservoir;
2) swap the hydraulic release fork for a cable fork and use the original LeMans cable operated manual transmission parts (pedal, cable).
After looking in vain for a donor LeMans with a manual transmission, from which to obtain the pedal, I started looking into the hydraulic setup. I pulled a
Lanos clutch pedal and quickly determined that it would be difficult to use the assembly. The pedal would need to be cut and rewelded to make it significantly
shorter, but more importantly, the pedal support from the Lanos was only lining up with a single bolt hole on the LeMans and the other holes would have needed to
be drilled through the pinch weld in the firewall. It would have been easier to weld it in. Additionally, the clutch master and reservoir would also need to be
mounted. At that point, I went back to looking for a donor LeMans, and several months later found one with the generous help of several fellow gearheads
(Chuck H, Joe G., John M., Vang Y.) who checked the transmissions on the few cars around the State.
After a 300 mile round-trip, I returned with a some LeMans parts:
- Clutch Pedal
- Clutch Pedal Spring (Green)
- Clutch Pedal Pivot Bolt
- Clutch Pedal Pivot Bolt Washer
- Clutch Pedal Pivot Bolt Nut
- Clutch Pedal Switch
- Clutch Cable Firewall Grommet
- Clutch Release Lever
clutch pedal (the pedal support is already present in AT cars), pivot bolt, spring, nut, washer, switch and
release lever. The release lever can only be removed by separating the transmission from the engine and then unbolting the release bearing from the post that is
attached to the lever. Alternatively, I could have made the (longer) cable-operated release lever with some metal stock and a welder. Thanks to John M. for
helping me to pull the engine and transmission so I could get this lever.
With the parts in hand, the clutch pedal bolted in to the existing support under the dash using a green spring, steel pin, washer, and nut. I had ordered a new
clutch cable assembly, but needed a rubber firewall bushing from the donor vehicle. I also grabbed the clutch pedal switch from the LeMans junker.
| Transmission Options |
| F10 | 3.55 | 1.96 | 1.3 | 0.89 | 0.71 | 3.31 | 4.18 |
| M79 | F13 | 3.55 | 2.390 | 1.3 | 0.89 | 0.73 | 3.31 | 4.18 |
| L73 | F16 | 3.545 | 1.952 | 1.276 | 0.892 | 0.707 | 3.333 | 3.94 | 4.176 |
| F16 Close Ratio | 3.55 | 2.16 | 1.48 | 1.13 | 0.89 | 3.33 | 3.55 |
| F18w | 3.58 | 1.87 | 1.23 | 0.92 | 0.74 | 3.33 | 3.55 |
| F18c | 3.58 | 2.14 | 1.48 | 1.12 | 0.89 | 3.33 | 3.55 |
| F20(3.55) | 3.55 | 2.16 | 1.48 | 1.13 | 0.89 | 3.33 | 3.55 |
| F20(3.72) | 3.55 | 2.16 | 1.48 | 1.13 | 0.89 | 3.33 | 3.72 |
| F23 | 3.58 | 2.02 | 1.35 | 0.98 | 0.81 | 3.31 | 3.84 |
| F25 | 3.38 | 1.76 | 1.12 | 0.89 | 0.77 | 3.17 | 3.82 |
| F28 | 3.57 | 2.16 | 1.45 | 1.1 | 0.89 | 0.74 | 3.32 | 3.72 |
| D20 | 3.54 | 2.15 | 1.47 | 1.12 | 0.88 | 3.33 | 3.50 |
The F16/D16/F18/F20/D20/F28-FWD all use the same differential (torque rating) aside from the different ratios
While some significantly stronger transmissions are available, some of them are also heavier and have less desirable ratios. The F16 CR would be the ideal
selection for my project, but I was unable to find one. It's worth noting that the Lanos uses an
incompatible flywheel and
clutch assembly, so the LeMans parts
must be reused. This led to a situation where I wasn't sure the throwout bearing would have sufficient throw to release the clutch. I developed a model in
Microsoft Visio to calculate how much throw was present. Here are a couple of links:
The end result was that I had about an inch of travel and that the bearing would be at the very end of it's travel, which is where it is weakest. It didn't seem
like a good situation. Shaving some metal from the bellhousing is probably a good plan, but I didn't do that. To check the release on the bench, I connected the
half shafts to the transmission and used a welding clamp to actuate the release lever. The clutch was released, so I moved on.
Pontiac LeMans Vehicle Speed Sensor (VSS)
After swapping the transmission, the speedometer was grossly inaccurate. I determined that the speedomater now reads in kilometers per hour, rather than miles per hour, which is something I can live with, although driving on the highway pins the needle against the stop.
Part Number for VSS:
GM 90149079
Daewoo Lanos S Speedometer Drive Gear: 3 teeth
Pontiac Lemans Vehicle Speed Sensor (VSS) driven teeth: 13
Speedomater Ratio: 4.33
3 Wire Sensor
Input Voltage: 12V
Ouput Voltage: 0-6V Square Wave
Hall-effect sensor
10 pulses per rotation
Typical mechanical speedo wants to see 1,000 revolutions per mile
Last update: Dec 7th, 2019
