Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET1990LUMINA APV V6-191 3.1LREPAIR AND DIAGNOSISTRANSMISSION AND DRIVETRAINAUTOMATIC TRANSMISSION/TRANSAXLESERVICE AND REPAIROVERHAULREACTION GEAR SET
1990 Chevrolet Lumina APV V6-191 3.1L
Reaction Gear Set
1990 Chevrolet Lumina APV V6-191 3.1LSECTION Reaction Gear Set
1. Rotate transaxle so the case cover is facing upwards.

2. Check final drive sun gear shaft journals and splines for wear or damage, Fig. 44.

3. Check reaction internal gear splines, gear teeth and bearing surface for wear or damage. Install reaction internal gear on the final drive sun gear shaft with the gear teeth up, Fig. 45. Install reaction internal gear to reaction sun gear roller thrust bearing with inner race against reaction internal gear, Fig. 45.
4. Remove reverse clutch housing to Low race selective washer and check for damage.
5. Remove Low roller clutch race, roller clutch assembly, and Low race to reaction carrier thrust washer from reaction carrier and inspect all parts for wear or damage.
6. Check the four tanged reaction carrier to internal gear thrust washer, Low roller clutch cam and reaction carrier bushing for wear or damage.
7. Check reaction carrier pinions for damage, rough bearings or tilt. Pinion pins must be tight and not rotate. Pinion endplay should be .009-.027 inch (.24-.69 mm).


8. Install reaction carrier to Low roller clutch race thrust washer, Fig. 46. Install any rollers that have come out of clutch cage, Fig. 47. Install Low roller clutch assembly into reaction carrier. Install Low roller clutch race into carrier with splined side upwards.

9. Install four tanged reaction carrier to reaction internal gear thrust washer onto reaction carrier and secure with petroleum jelly, Fig. 31.
10. Install reaction carrier and Low roller clutch assembly into reaction internal gear and install Low and reverse clutch housing to Low roller clutch race selective washer.
11. Install reaction gear set into transaxle.
Fig. 44, Reaction sun gear exploded view:
2. Check final drive sun gear shaft journals and splines for wear or damage, Fig. 44.
Fig. 45, Installing roller thrust bearing:
3. Check reaction internal gear splines, gear teeth and bearing surface for wear or damage. Install reaction internal gear on the final drive sun gear shaft with the gear teeth up, Fig. 45. Install reaction internal gear to reaction sun gear roller thrust bearing with inner race against reaction internal gear, Fig. 45.
4. Remove reverse clutch housing to Low race selective washer and check for damage.
5. Remove Low roller clutch race, roller clutch assembly, and Low race to reaction carrier thrust washer from reaction carrier and inspect all parts for wear or damage.
6. Check the four tanged reaction carrier to internal gear thrust washer, Low roller clutch cam and reaction carrier bushing for wear or damage.
7. Check reaction carrier pinions for damage, rough bearings or tilt. Pinion pins must be tight and not rotate. Pinion endplay should be .009-.027 inch (.24-.69 mm).
Fig. 46, Removing low race thrust washer:
Fig. 47, Installing roller into cage:
8. Install reaction carrier to Low roller clutch race thrust washer, Fig. 46. Install any rollers that have come out of clutch cage, Fig. 47. Install Low roller clutch assembly into reaction carrier. Install Low roller clutch race into carrier with splined side upwards.
Fig. 31, Removing thrust washer:
9. Install four tanged reaction carrier to reaction internal gear thrust washer onto reaction carrier and secure with petroleum jelly, Fig. 31.
10. Install reaction carrier and Low roller clutch assembly into reaction internal gear and install Low and reverse clutch housing to Low roller clutch race selective washer.
11. Install reaction gear set into transaxle.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.