by Orest Lazarowich (August 1994 and May 1995), for Skinned Knuckles
The Chrysler designed and built A-520, A-525, and A-555 fully-synchronized, 5-speed manual transaxles combine transmission and differential functions in one unit housed in a die-cast aluminum case. You can service the selector shaft housing, all synchronizers, intermediate shaft speed gears, fifth speed gears, input shaft, reverse idler gear and shaft, shift forks and pads, shift fork rails, and speedometer pinion with the transaxle in the vehicle.
The clutches used on all models are a single, dry disc type with no adjustment for wear being provided in the clutch itself. If you find it difficult to shift gears and if there is gear clash when the shift lever is moved to reverse, this can be a clutch problem and not the transaxle. With the engine running and transaxle in neutral, depress the clutch pedal to the floor and hold. After five seconds, shift to reverse; if clash is evident, the clutch is the problem. This can be caused by dry rust on the input shaft spline or damaged clutch disc hub splines. Either way the transaxle has to be removed to get at the clutch assembly.
If the clutch chatters during engagement, check to see that the clutch cable routing is correct and operates freely. Check for loose, misaligned, or broken engine and transmission mounts. Correct this problem and test the vehicle again. If the chatter persists, the disc assembly is worn or has oil on the facings. If the clutch slips, the linings on the clutch disc are burned, worn, or oil soaked. If the clutch is noisy, the release bearing, the clutch disc, or the pressure assembly need replacing. The transaxle has to be removed to service the clutch assembly. If the transaxle is difficult to shift, but there is no gear clash, you may be able to solve the problem by adjusting the gearshift linkage.
Drape a fender cover over the left front fender and remove the lock pin from the transaxle selector shaft housing. Reverse the lock pin (long end down) and insert into the same threaded hole while pushing the selector shaft into the selector housing. A hole in the selector shaft will align with the lock pin, allowing the lock pin to be screwed into the housing. This locks the selector shaft in the 1-2 neutral position. Raise the vehicle and support it safely. Loosen the clamp bolt that secures the gearshift tube to the gearshift connector. Check to see that the gearshift connector slides freely in the gearshift tube.
Position the shifter mechanism connector assembly so that the isolator is contacting the upstanding flange and the rib on the isolator is aligned fore-and-aft with the hole in the block-out bracket. Hold the connector isolator in this position while tightening the clamp bolt on the gearshift tube 19 Nm (170 in.-lbs.). Do not exert any significant force on the linkage during this operation. Lower the vehicle. Remove the lock pin from the selector shaft housing and reinstall lock pin with the long end up; torque 12 Nm (105 in.-lbs.). Check for shift into first and reverse and for block-out into reverse.
If this linkage causes hard shifting and you suspect the cables may be the cause, disconnect both cables at the transaxle. Then, from the driver’s seat, manually operate the gearshift lever through all the ranges. If the gearshift lever moves smoothly, the cable(s) should NOT be replaced. Drape.a fender cover over the left front fender and remove the lock pin from the transaxle selector shaft housing. Reverse the lock pin with the long end down and insert it into the same threaded hole while pushing the selector shaft into the selector housing. A hole in the selector shaft will align with the lock pin, allowing the lock pin to be screwed into the housing. This operation locks the selector shaft in the 1-2 neutral position.
Remove the gearshift knob and pull the boot over the pull-up ring. A squirt of liquid dishwashing soap will help. Remove the screws that hold the console in place, disconnect the wiring connectors, and remove the console. For body models H, K, and P, you will need a set of cable adjusting pins as shown on previous page. (The five-inch long adjusting pins are 5/32” diameter on H bodies and 3/16” diameter on K and P bodies.) On body models G and J, there is an adjusting screw tool and spacer block which is taped to the shifter support bracket. When finished with the adjustments, retape the tool to the shifter support bracket. Replace the console and boot and connect the wiring. Remove the lock pin from the selector shaft housing and reinstall with long end up; torque 12 Nm (105 in.-lbs.). Check for shift into first and reverse and for block-out into reverse.
Road test the vehicle on a smooth level road. If the linkage adjustment did not correct the shift difficulties, then the problems are either in the clutch or the transaxle. If gear clash is still the problem, the clutch will have to be serviced. If the transaxle slips out of gear, the shift forks and rails may need service. If you are troubleshooting a noise problem, note the speed at which the noise occurs and which gear the transaxle is in at the time. A transaxle which is noisy in all gears may have damaged or worn bearings or a damaged input gear. Remember that all gear trains will have some operating noise. Check the lubricant level as a noisy transaxle in all gears can be caused by insufficient lubrication.
Fabricate an engine support fixture and use the No. 4 cylinder exhaust manifold bolt as the balancing point. Disconnect the negative battery terminal, and loosen hub nut and wheel nuts while the vehicle is on the floor. Raise the vehicle to a suitable working height and set on safety stands. Remove both front wheel assemblies, hub nut and washer, and left front splash shield. Disconnect gearshift linkage.
The driveshafts are held in the side gears by a constant spring force provided by a spring contained within the inboard constant velocity joints. Remove the speedometer pinion before removing the right driveshaft. Wrap the constant velocity joints with an old inner tube to provide support to the joint and prevent damage to the boots when removing the driveshafts. Remove clamp bolt securing ball joint stud into steering knuckle, and separate ball joint stud from steering knuckle by prying against knuckle leg and control arm. Separate outer constant velocity joint from hub. Remove driveshaft from transaxle. Separate left-hand driveshaft in a similar manner and remove. If the boots are torn, they should be replaced while the driveshafts are out.
Remove left engine mount from transaxle, then remove the starter. Remove anti-hop dampener from crossmember bracket. DO NOT remove bracket from transaxle. Remove the clutch lower cover, then disconnect clutch cable from release lever. Position a transmission jack to the transaxle and chain the transaxle to the supporting plate. Remove the upper bell housing bolts and pry and pull the transaxle away from the engine. DO NOT let the weight of the transaxle hang on the input shaft. Lower the transmission jack and pull the transaxle out. If the transaxle needs internal work and you are not comfortable doing it yourself, have it done at the service shop.
If the transaxle has been losing oil, check the driveshaft seals, selector shaft seal, and input shaft seal. If they show signs of leakage, replace them while you have the transaxle out. The drain hole on the input shaft seal retainer must face downward on reassembly. Have the seals replaced at a service center, if you wish.
Check the input shaft spline and release bearing for dry rust. If you find evidence of some, the clutch disc has not been releasing properly and gear clash has been the result. Clean the splines and apply a very light coat of grease. Check the clutch disc hub splines for damage and replace the disc if necessary. If the clutch has been slipping, remove and inspect the disc and pressure plate. Mark the relative position of the clutch cover and flywheel to aid in reassembly of the present parts. New or rebuilt assemblies will have a balance mark to match with the flywheel. Loosen the clutch cover attaching bolts a few turns at a time in a criss-cross pattern to avoid bending the cover flange.
Remove the clutch pressure plate assembly and clutch disc from the flywheel. This is a heavy piece — DO NOT let it fall on you. Replace disc if the facings show signs of grease or oil soakage or wear to within less than .015” of the rivet heads. If the rear engine seal is leaking, replace it at this time; if you don’t, oil soaks into the new linings and the disc starts to slip and you are going to do this job over. Check the flywheel and pressure plate for burned areas, small cracks, deep grooves, or ridges. Have the flywheel resurfaced if required. If clutch chatter was a problem, check the flywheel for runout (.003” max). Check for uneven wear on the clutch fingers and bent drive straps on the pressure plate; replace if necessary. The bearing is pre-lubricated and should not be washed in solvent. It should turn smoothly under a light thrust load. If the bearing is noisy, rough, or dry, it should be replaced. Usually the clutch disc, pressure plate, and clutch release bearing are replaced as an assembly.
Reinstall clutch disc and pressure plate. Handle the clutch disc without touching the facings. Match the balance marks. If you do not have a clutch disc aligning tool, use any round stock that will fit into the crankshaft and then “eyeball” an even distance around the clutch disc and pressure plate. The closer the alignment, the easier the transaxle will slide into place. Use a criss-cross tightening sequence a few turns at a time until all the bolts are seated; torque 28 Nm (21 ft.-lbs.). Remove the aligning tool.
Check the condition of the clutch release shaft in its bearings; there should be minimal wear. The clutch release fork must be tight to the shaft; service as required. Lubricate the rounded thrust pads and the spring clip cavities in the fork with multipurpose grease. Assemble the bearing to the fork; the bearing is prelubricated. Secure the transaxle to the transmission jack and push the jack into position under the vehicle. When installing the transaxle, it may be helpful to use two locating pins in place of the top two transaxle-to-engine block bolts.
Make the locating pins from two regular trans-axle case-to-engine block bolts. Remove the bolt heads and cut a slot in the end of the bolts to fit a screwdriver. Slightly round the slotted ends with a grinder. Install the locating pins into the engine block and proceed with transaxle installation. After transaxle is in place, remove the locating pins and install the proper bolts. Replace clutch cover. Install engine mount and connect anti-hop dampener. Remove the transmission jack. Reinstall starter and install the drive shafts to the transaxle and hubs. Torque steering knuckle clamp bolt to 95 Nm (70 ft.-lbs.). Connect all other disconnects. Tighten hub nuts 245 Nm (180 ft.-lbs.) with brakes applied. Check lubricant level. Start the vehicle and check the shifts. Lower and road test.
The Big Three watched as the sales of European and Japanese compact cars ate into their profits, and they finally decided that a smaller, fuel efficient front-wheel-drive car was what the buying public wanted. The oil crisis of the late 1970s helped to speed up this decision for them. To do battle with the imports, Chrysler was first off the mark with the Dodge Omni/Plymouth Horizon. The Omni/ Horizon are compact cars with engine and transaxle designed as a transverse mounted front-wheel-drive unit. The transaxle houses an automatic drive or a standard transmission with a combined differential; the automatics are identified as the A404 series. Updates on this transaxle follow as the A413, A415, and A470.
The automatic transaxle combines a torque converter, a fully automatic three-speed transmission, final drive gearing, and differential into a front drive system. The assembly is housed in an aluminum casting with cooling being provided from the radiator. Internally the gearing is very similar to the Chrysler TorqueFlite. The major difference is that the output torque is delivered through helical gears to the differential ring gear. The assembly is of metric design and special tools are needed to service and overhaul this unit. You must remove the transaxle to service either the transmission or differential.
If the transmission seems to be causing a problem during normal driving, begin by checking out the easiest accessible variables: fluid level and condition, manual cable adjustment, and throttle cable adjustment. If the problem still exists after checking and correcting any of these three variables, a road test can be taken and hydraulic pressure tests must be done. If the hydraulic tests indicate internal transmission problems, you should be able to remove the transaxle and deliver it to a service shop where it can be repaired.
Both the automatic transmission and differential assembly use the same Dexron II automatic transmission fluid. However, even though they share the same housing, they are internally sealed from each other. To check fluid level, place the selector in Park (P) and allow the engine to idle. The fluid should be at operating temperature. Check the dipstick. The fluid level is correct if it is between the “FULL” and “ADD” marks. Do not overfill the transmission or the fluid will be churned into foam, causing the same symptoms as a low fluid level and possibly leading to transmission overheating, with the fluid being forced from the vent. The differential oil level should be to the fill hole in the differential cover.
Check the condition of the fluid; it should not have any metal flakes or bits of friction material in it. If there are, check the fluid for a burnt smell. This is an indicator that the transmission has been operated at a pretty heavy load and it is possible that the bands and clutches have started to break down. Service the filter and change the fluid. A milky fluid appearance indicates water contamination. The transmission cooler may have a leak in it.
The starter should only operate in Park (P) or Neutral (N) if the linkage is properly adjusted. If not, either the neutral switch is bad or the linkage needs adjustment. The adjustable swivel block must be free to slide on the shift cable. If not, clean or repair as necessary.
This adjustment controls the manual valve in the valve body, which determines shift speed, shift quality, and part throttle downshift. If the setting is too short, early shifts and slippage between shifts will be the result. If the setting is too long, shifts may be delayed and the part throttle downshifts will be sensitive. The engine must be in good tune and up to operating temperature with the carburetor off fast idle. Loosen the adjustment bracket lock screw. The bracket must be free to slide on its slot. If necessary, disassemble and clean or repair. Lubricate with Lubriplate. Hold the transaxle throttle lever firmly rearward against its internal stop and tighten the adjusting lock screw to 105 inch-pounds (12 Nm). This automatically removes cable backlash.
Road test the vehicle. Shift to each position to check for slipping or any variation in shifting. Record the speed at which the downshifts and upshifts occur. Listen to the engine speed. If the upshifts are delayed or harsh, the front band may need adjustment. The rear band cannot be adjusted. You will notice that this troubleshooting is very similar to that for standard sized transmissions with rear drive. The adjustments are much the same, so if you have not worked on a front-wheel-drive transaxle, do not make a big event of it. Treat the transmission as a stand-alone edition and work on one problem at a time.
Many of the shift problems are related to the operation of the valve body and the servos or the governor. These include harsh or delayed engagements, runaway or no upshift or kickdown, erratic shifts, slipping in all positions, and no drive in any positions. It is possible to service the valve body, the sealing rings on the servos, and the governor without removing the transaxle from the vehicle. These same problems can also be caused by leaking hydraulic circuits in the transmission, so check the pressure before disassembling the transaxle.
You will need a tachometer, two pressure gauges (one 100 psi and the other 300 or 400 psi), and a “T” fitting. Hook up the engine tachometer and route the wires so it can be read under the car. Raise the vehicle to a safe working level. The front wheels must be free to turn. Disconnect the throttle and shift controls so they can be shifted from below.
PRESSURE TEST 1 (Selector in First) - This test will check the pump output, the pressure regulation, and the condition of the rear clutch and servo hydraulic units. Hook up gauges to the line pressure port and the low-reverse pressure port (rear servo). Adjust engine speed to 1000 rpm. Shift into “1” position (selector lever on transaxle all the way forward). Read pressures on both gauges as the throttle lever on the transaxle is moved from the full forward position to full rearward position. Line pressure should read 60 to 66 psi with the throttle lever forward and it should gradually increase to 97 to 103 psi as the lever is moved rearward. Low-reverse pressure should read the same as the line pressure to within 3 psi.
PRESSURE TEST 2 (Selector in Second) — The purpose of this test is to check the pump output, the pressure regulation, and the condition of the rear clutch and lubrication hydraulic circuits. Keep the gauge on the line pressure port and, with a “T” fitting, hook into the lower cooling line to read the lubrication pressure. Adjust engine speed to 1000 rpm. Shift into the “2” position. (This is one “detent” rearward from the full forward position.) Read pressures on both gauges as the throttle lever on the transaxle is moved from the full forward position to full rearward position. Line pressure should read 60 to 66 psi with the throttle lever, forward and it should gradually increase as the lever is moved rearward, to 97 to 103 psi. Lubrication pressure should read 10 to 25 psi with the lever forward and 10 to 35 psi with the lever rearward.
PRESSURE TEST 3 (Selector in Drive) — The purpose of this test is to check the pump output, the pressure regulation, and the condition of the rear clutch and front clutch hydraulic circuits. Attach gauges to the line pressure port and kick-down release port. Adjust engine speed to 1600 rpm. Shift into “D” position. (This is two “detents” rearward from the full forward position of the selector lever.) Read pressures on both gauges as the throttle lever on the transaxle is moved from the full forward position to the full rearward position. Line pressure should read 60 to 66 psi with the throttle lever forward and it should gradually increase as the lever is moved rearward. The kickdown release port is pressurized only in direct drive and should be the same as the line pressure within 3 psi, up to the downshift point.
PRESSURE TEST 4 (Selector in Reverse) — The purpose of this test is to check the pump output, the pressure regulation, and the condition of the front clutch and rear hydraulic circuits. Also, at this time, a check can be made for leakage into the rear servo due to case porosity, cracks, and valve body or case warpage, which can cause reverse band burnout. Attach the 300 psi gauge to the low-reverse pressure port. Adjust the engine speed to 1600 rpm. Shift into “R” position. (This is four “detents” rearward from the full forward position of the selector lever.) Read the gauge pressure. It should be 176 to 180 psi with the throttle lever forward and it should gradually increase as the lever is moved rearward to 270 to 280 psi. Move the selector lever on the transaxle to “D” position. The rear servo pressure should drop to zero, since even a little pressure can cause the band to apply and burn up.
If the pressure readings from minimum to maximum are correct, the pump and pressure regulator are working properly. If there is low pressure in “D,” “1,” “2” but correct pressure in “R,” there is leakage in the rear clutch circuit. If there is low pressure in “D” and “R” but correct pressure in “1,” then there is leakage in the front clutch circuit. The transaxle will have to be removed for service.
To remove the transaxle, follow the procedures in the service manual. The transaxle and the converter must be removed as an assembly, so make a suitable engine support using a “J” bolt and a length of pipe.
If there is low pressure in “R” and “1” but correct pressure in “2,” then there is a leak in the rear servo circuit. If there is low line pressure in all positions, then there could be a bad pump, stuck pressure regulator valve, or clogged filter. Check the valve body and the filter first.
If during the road test the transaxle shifts at the wrong vehicle speeds and the throttle cable adjustment is correct, the problem may be caused by a sticking governor. Check the governor pressure. Connect a 0-150 psi pressure gauge to the governor pressure take-off port, located at the lower right side of the transaxle case below the differential cover. Operate the transaxle in “Drive” position and read the pressures at the listed speeds. Compare with the accompanying chart. The pressure should respond smoothly to any change in rpm and should drop to 0 to 3 psi when the vehicle is stopped. If there is high pressure at standstill (more than 3 psi), then the transaxle will be prevented from downshifting. Replace or service the governor.
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