|
545RFE Automatic Transmission
The introduction of the completely redesigned 1999 WJ Grand Cherokee in June of 1998 was a much anticipated date for automotive enthusiasts. One of the major pieces of the redesign was the new five speed automatic transmission designated the 545RFE. This transmission was developed specifically with Jeeps in mind.
This transmission was available only on WJs with a 4.7L V8 engine; the 6 cylinder engine received the venerable 42RE. By design, the 545RFE is quite sophisticated. It employs multiple gear ranges controlled electronically to provide greater fuel economy as well as great responsiveness for passing and acceleration. Precision engineering and manufacturing methods also helped to reduce overall NVH (noise, vibration, harshness). It features five forward gear ratios with an alternative second gear ratio (2 Prime) for smoother 4th to 2nd kickdowns at high speeds to provide spectacular passing performance over a wider speed range. The addition of the fifth (overdrive) gear ratio is the primary cause of the lower NVH and better fuel economy (lower RPMs = less noise and fuel consumption).
It is electronically controlled by the TCM or Transmission Control Module. This module is the heart adaptive shifting programming. The TCM depends on data from several sensors and switches to determine driver demand and the Jeep's operating conditions. Controls are in place to protect the transmission from damage from high temperatures. The TCM protects the transmission by modifying shift schedules, line pressure and converter clutch control. These controls reduce the amount of heat that is created and increase cooling of the 545RFE. The 545RFE is contained by a one-piece die-cast aluminum case. To reduce NVH, integrated into the case are ribs to increase multi-angular torsional rigidity. There are dual lubricant filters in the 545RFE. First is the customary internal main sump pan filter; second is the external canister-type pump return filter.
545RFE Maintenance Recommendations
Fluid Capacity for Service fill (drop pan, change filters, refill): 6.2 Liters or 6.55 Quarts
Fluid Type: Mopar ATF +4, or any Dexron IV approved fluid (author uses Redline Oil Synthetic D4 ATF)
Torque specifications:
Oil pan bolts: 11.8Nm or 8.75 Ft Lbs
Primary fluid filter screw: 4.5Nm or 3.33 Ft Lbs
Gear Ratio
1st 3.00 : 1
2nd 1.67 : 1
2nd Prime 1.50 : 1
3rd 1.00 : 1
4th 0.75 : 1
5th 0.67 : 1
Reverse 3.00 : 1
Torque Converter Up to 2.40 : 1
More...Other source...
Chrysler's newest transmission in trucks is called either the 45RFE or 5-45RFE. RFE stands for rear wheel drive, fully electronic. These transmissions despite having different names are basically the same, except that the 5-45RFE has an extra overdrive ratio. the 5-45RFE does indeed use 5 ratios in its normal shift sequence. the 45RFE only uses 4 speeds in a normal shift sequence. BOTH trannies have alternate second gear ratios for kickdown. for instance when you floor the throttle at highway speeds the tranny will downshift to the taller numerical second gear ratio to help smooth out the downshift. Since the 5-45RFE goes through 5 ratios in a normal shift sequence, chrysler can call it a 5 speed automatic. Chrysler calls the 45RFE a multispeed tranny simply because of the two second gear ratios, but in a normal shift sequence it only uses 4 gears.
The 5-45RFE is supplanting the 45RFE in virtually all the trucks. Presumably that extra overdrive ratio in the 5-45RFE helps fuel mileage. Chrysler is able to "electronically" get another ratio out of the 45RFE planetary gearset. The extra ratio makes the tranny a 5-45RFE!
The 45RFE four speed plus kickdown automaticAn electronically-controlled transmission with five forward ratios including an alternate second gear ratio for improved performance for passing and better fuel economy was designed specifically for Jeeps (but was used later in Dodge trucks) starting with the 1999 Grand Cherokee V8.
The transmission features a tall, 3.00:1 first gear that gives the driver better initial acceleration. Real-time driver adaptive shifting fine-tunes the shift pattern to the driver, while an alternate second gear ratio gives the driver five forward ratios. During acceleration, second gear has a ratio of 1.67. Depending on speed and throttle position, both this gear and an alternate 1.50 second gear ratio are available for kick-down operation, making the down-shift smoother. Its reverse gear ratio is equal to the first gear ratio, to allow for heavier loads.
Other features include three planetary gear sets that combine the widest range of gear ratios available in any transmission in its class. Combined with precise step selections, this brings smooth shifts and maximum power and optimal fuel economy.
The transmission is built at the Indiana Transmission Plant in Kokomo, Indiana, in an all-new 1.2-million square-foot facility.
_________________
2006 CRD Sport,
Born on 5-20-2006 @ 7:20pm
Jeep Green, Oil drain valve
Tow Package, Transmission skid plate
EHM2, ORM,
Current mileage 79,000.
Past Jeeps: 63 CJ5,
1994, 1995, 2000 Cherokee,
1995, 1997, 2003 Wrangler
|
Login
Register
FAQ
Search
