Dec 30, 2011 Speed Sensor The Getrag F23 uses the newer 24,000 ppm magnetic hall effect sensor, which can be found in other newer GM four cylinder transmissions. To correctly configure this input for the Fiero's 4000 ppm speedometer, a PCM which can filter the 24,000 ppm signal must be used to interface the signal along with the infamous conversion circuit.
Transmission Speed Sensor Replacement Service
What is the Transmission Speed Sensor all about?
Because both the engine and the transmission can rotate at different speeds, it’s vital that the vehicle’s computer is able to calculate the speed of the transmission’s torque converter or input shaft. The transmission speed sensor is a magnetic sensor that provides this information, allowing the transmission to shift smoothly. The sensor counts the internal number of revolutions of the transmission and transmits that information to the transmission control unit, where the data is used to determine the rotational speed. If the speed is too great, the gears need to be changed – it’s the same principle as watching the tachometer and shifting before the RPMs get too high while driving a vehicle with a manual transmission.
Keep in mind:
- On some makes, one of the engine mounts may need to be removed to access the failed part.
- Transmission speed sensors cannot be repaired, only replaced.
- While transmission speed sensor failure is not uncommon, many other problems can present similar systems such as ABS sensor failures. A full professional inspection will be needed to determine the actual cause of the problem.
How it's done:
- The transmission speed sensor is verified that it needs to be replaced. The vehicle is lifted and supported on jack stands as required.
- The transmission speed sensor is located in the transmission housing and removed.
- The new transmission speed sensor is installed into the transmission housing.
- The transmission speed sensor is connected. The vehicle is removed from the jack stands.
- The vehicle is road tested and scanned for proper operation of the transmission speed sensor.
Our recommendation:
The transmission speed sensor isn’t a part that can be inspected during normal maintenance, nor does it have a specific service interval for replacement. If you notice abnormal shifting or speedometer readings, have one of our expert mechanics diagnose the sensor.
What common symptoms indicate you may need to replace the Transmission Speed Sensor?
- Transmission shifts roughly
- Transmission doesn’t shift into higher gears
- Speedometer and/or odometer doesn’t work
- Cruise control is inoperative
How important is this service?
With a defective transmission speed sensor, the transmission control unit will be unable to determine the actual speed, which can make shifting gears difficult or even impossible. This will render the car unusable, so it is very important to have the sensor replaced as soon as it is determined to be faulty.
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(Redirected from F35 (MU3) transmission)
The F35 is a Saab-designed five-speed manual transmission built in Saab’s Gothenburg, Sweden, powertrain plant. This extensively tested manual transmission was originally introduced in the 1984 Saab 9000, and today it is used in the Saab 9-3 and 9-5, Saturn Ion Redline, Chevrolet Cobalt SS, Chevrolet HHR SS and various GM/Opeltransverse engine front-wheel drive applications.
- 1Design
Design[edit]
The F35 features a two-axis conventional transverse layout, with fully synchronized gears, and compact packaging. It features a higher torque carrying capacity than most manual transmission currently in use by competing North American small cars.
Design was updated 1994 with synchronized reverse, triple-cone synchronizers on 1st and 2nd gears, and single-cone synchronizers for 3rd, 4th, 5th and reverse gears.
Specifications[edit]
It weighs approximately 99 lb/45 kg and uses 2 quarts/1,9 l of GM 88862472 gear oil. This gear oil is identified in GM documentation as a synthetic 75W-85 GL-4, Castrol Burmah (BOT 0063) manual transmission fluid, and is validated as 'fill-for-life'. No maintenance is required for normal operation. The gearbox is rated for 260 ft-lb (353 Nm) of engine torque.
The GM transmissions are usually numerically designated in newton metres that means F35 is rated at 350 Nm, the weaker rod shifted SAAB version of the F35, the F25, at 250 Nm, F40 at 400 Nm, M32 at 320 Nm, and so on.
Differential[edit]
A limited-slip differential is available for high-output applications. GM has sourced Quaife's automatic torque biasing (ATB) torque-sensing (Torsen-style) differential, which is an all-mechanical geared unit that uses no clutch packs or preloading to transfer torque from one axle to the other. The torque transfer occurs automatically and gradually when one wheel loses traction. This type of differential can severely reduce the effects of torque-steer.
Performance[edit]
The gearbox has shown to hold more power than the factory stated quite reliably. That being said, a lower geared final drive helps eliminate excessive stress on the gears; thus the 3.82 FD (final drive) is weaker than the 4.05 and the now hard to source 4.45 gearset is the strongest. The transmission can still break, especially with a fast spooling turbo to create a low end boost spike. The most common gear to break is third, and commonly a boost ramp is tuned in to help prolong the stock transmission. In general, the transmission will hold up better if the boost comes in later so it is not a sudden surge of power. Wheel hop is a killer of transmissions and axles, creating excessive stress as the wheels load and unload.
3.61 final drive is used on Saab 9000 2,3l engines with turbocharger, other final drive rations used on early cars is 4,21, 4,05, 3,82 and 4,45 (non turbo).
Versions[edit]
Different versions of the transaxle are available depending upon the application. Both cable and rod shift mechanisms are available, as well as application-specific clutch housings. The MU3 and MC2 are differentiated by ratios, with the MC2 available with a lower top-gear ratio.
MC2 gear ratios:
Final Drive | 1 | 2 | 3 | 4 | 5 | R |
---|---|---|---|---|---|---|
3.82 | 3.38 | 1.76 | 1.18 | 0.89 | 0.70 | 3.17 |
MU3 gear ratios:
Final Drive | 1 | 2 | 3 | 4 | 5 | R |
---|---|---|---|---|---|---|
4.05 | 3.38 | 1.76 | 1.18 | 0.89 | 0.70 | 3.17 |
Applications[edit]
- 1985-1998 Saab 9000 (F25)
- 2004-2007 Saturn ION Red Line (MU3)
- 2005-2007 Chevrolet Cobalt SS Supercharged (MU3)
- 2008-2010 Chevrolet Cobalt SS Turbocharged (MC2)
- 2008-2010 Chevrolet HHR SS Turbocharged (MC2)
- 1994-1998 Saab 900 (F25)
- 1998-2003 Saab 9-3 (F25, Viggen with F35 differential)
- 1998-2010 Saab 9-5 (F25, with F35 differential)
- 2013-present Senova D Series (F25, with F35 differential)
![M86 transmission speed sensor M86 transmission speed sensor](/uploads/1/2/4/9/124990971/163084385.jpg)
References[edit]
- www.opel-infos.de Reliable source for specifications of European produced GM transmissions, including the F35.
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