Issue Summary:
- Honda and Acura vehicles equipped with the MGHA family of transaxles may exhibit a neutralizing condition on a downshift into first gear.
- Honda and Acura vehicles equipped with the BYBA/MGHA family of five-speed transaxles may exhibit a gear noise.
- Honda/Acura vehicles equipped with the BAXA/B7XA family of transaxles may experience a tie-up in reverse when hot.
- During transmission removal or installation. a Honda CR-V or Element may sustain severe damage to the front fenders.
Before or after overhaul, Honda and Acura vehicles equipped with the MGHA family of transaxles may exhibit a neutralizing condition on a downshift into first gear, or a 3-1 passing-gear neutral. This condition may be intermittent. This neutralizing condition can be cleared up simply by placing the selector in the Manual 1 position.
The cause may be a worn low one-way clutch, or a worn inner race for the low one-way clutch (Figure 1). Honda and Acura vehicles equipped with the MGHA family of transaxle use a low one-way clutch that locks in first gear for takeoff. If the low one-way does not hold in first, there will be no engagement in first until the selector is placed in manual 1.
In this position the low hold clutch is engaged and first gear can be attained. The low hold clutch is used to provide engine braking in manual low and to back up the sprag by holding first gear should the sprag fail. This sprag failure is commonly overlooked, as the low-hold-clutch hub has to be driven out for inspection of the sprag and races (Figure 2).
Using a suitable bushing driver, remove the low-hold-clutch hub from first gear (Figure 2). Refer to Figure 3 for an exploded view of the low one-way clutch and first-gear assembly. Replace as necessary.
Note: The sprag is available for purchase only as a complete assembly. If there is wear on the inner race for the low one-way clutch, first gear will have to be replaced.
Refer to Figure 4 to verify proper freewheel rotation on the low one-way clutch.
- Secondary-shaft low-clutch hub (one-way clutch). . . . .23420-RAY-005
- Secondary-shaft low gear . . . . .23411-P7W-000
Note: Although the one-way clutch is the same for both Honda and Acura, you cannot buy it separately. You must buy it assembled onto the low gear. The part numbers listed are for an Acura MDX. You could buy the MDX assembly and, if the tooth count is the same for the vehicle you are working on, install it. If the tooth count is different, remove the one-way clutch and install it onto the original low gear. Or, just order the entire assembly for the vehicle you’re working on.
Before or after overhaul, Honda and Acura vehicles equipped with the BYBA/MGHA family of five-speed transaxles may exhibit a gear noise on or off the throttle. Note: This noise will commonly sound like a worn ring and pinion.
The cause may be wear in the mid-case where the countershaft ball-bearing outer race is supported. When the case wears in this area, the countershaft, which is the pinion shaft for the differential, will be off center with the differential and idler geartrain, causing the noise.
Refer to Figure 5 and inspect the rear countershaft ball bearing for wear and the area around the bearing in the mid-case. This ball bearing should be very snug in the case and there should be no side-to-side or up-and-down movement of the ball-bearing outer race in the case. If there is movement, the mid-case will have to be replaced.
At this time there are no aftermarket repairs for the mid-case. You’ll have to get a good used mid-case or buy a new one from the dealer.
Note: There are numerous versions of this family of transaxle. Consult your dealer for the correct part number for the application you are working on.
Before or after overhaul, Honda/Acura vehicles equipped with the BAXA/B7XA family of transaxles may exhibit a complaint of a tie-up in reverse when hot.
One cause may be a worn bushing in the main-shaft, or a worn third-clutch feed tube in the back cover, allowing fourth-clutch oil to cross over into the third-clutch circuit, partially applying the third clutch and causing the tie-up.
The partial cutaway drawing in Figure 6 shows the parts associated with the mainshaft including the tubes, bushings, gears and clutch drum.
The partial cutaway drawing in Figure 7 shows the area of concern within the mainshaft where the cross-over leak may occur.
The best way to check for this condition is to conduct a pressure test on the third-clutch pressure tap when the vehicle is hot and the selector is placed into reverse. Refer to Figure 8 for pressure-tap locations on the transaxle rear cover.
If any pressure is present on the third-clutch tap when the selector is placed in the reverse position, it will be necessary to remove the transmission from the vehicle and disassemble it so you can replace the mainshaft. You also will need to inspect the tubes in the transaxle rear cover. If any wear is present on the third- or fourth-clutch feed tubes, the rear cover will need to be replaced, since the tubes are not serviced separately. Refer to Figure 8 for illustration of the mainshaft and the location of the third- and fourth-clutch feed tubes in the transaxle rear cover.
Note: At this time, no bushing replacements are available for this transaxle, which is why mainshaft replacement would be necessary.
During transmission removal or installation the front fenders sustain severe damage.
An engine-support fixture was set on the fender rails. When the transmission was removed and the engine was suspended from the holding fixture, the weight of the engine placed additional stress on the fender-support brackets than they are designed to handle, resulting in severe body damage (Figure 9).
Do not put an engine-support fixture on the fender rails of these vehicles. If the proper holding fixture is not available perhaps a sub-frame from one of these vehicles can be acquired from the local wrecking yard and altered to support the engine during transmission removal and installation.
May 2010 Issue
Volume 27, No. 5
- Honda/Acura MGHA family: Neutralizing on downshift to first
- Honda/Acura BYBA/MGHA family: Gear noise
- Honda/Acura BAXA/B7XA family: Tie-up in reverse when hot
- Honda CR-V & Element: Severe body damage