1978 928 with 5-speed G28/03 Tranny Problem
#1
1978 928 with 5-speed G28/03 Tranny Problem
Problem: When I shift into 5th gear, the lever feels like it moves excessively far rearward. Resulting in the 5th gear Shift Rod moving the Shift Sleeve so far that it disengages with the splined Guide Sleeve which drives the output shaft. When this happens the transmission behaves as if it is in neutral and requires the vehicle to be brought to a complete stop before the shift lever can move the shift sleeve back in engagement with 5th gear and the guide sleeve and then to the neutral position. All the other gears function fine. I have not dropped the tranny yet, so I am having to rely on illustrations and my experience working on other make trannys.
When 5th gear is selected what stops the 4th/5th gear Shift Rod/Shift Sleeve assembly once it has positioned the 4th/5th gear Shift Sleeve to engaged the input drive shaft/5th gear assembly? Another 928 owner suspected that the Stop in the synchro assembly was bad. Is it the purpose of the Stops (aka Anchor Blocks) in the Synchro assemblies to stop the movement of the Shift Rods/Shift Sleeve? I expected the mechanism that stopped the gear shifter/Shift Rod/Shift Sleeve to be more substantial than the relatively small Stop that I see in the illustrations. Also, what is the function(s) of the Arresting Bushes that appear to contact the Shift Rods? Attached is a photo of the Stop/Anchor Block.
Thanks in advance for any information offered!
When 5th gear is selected what stops the 4th/5th gear Shift Rod/Shift Sleeve assembly once it has positioned the 4th/5th gear Shift Sleeve to engaged the input drive shaft/5th gear assembly? Another 928 owner suspected that the Stop in the synchro assembly was bad. Is it the purpose of the Stops (aka Anchor Blocks) in the Synchro assemblies to stop the movement of the Shift Rods/Shift Sleeve? I expected the mechanism that stopped the gear shifter/Shift Rod/Shift Sleeve to be more substantial than the relatively small Stop that I see in the illustrations. Also, what is the function(s) of the Arresting Bushes that appear to contact the Shift Rods? Attached is a photo of the Stop/Anchor Block.
Thanks in advance for any information offered!
#2
Former Vendor
Problem: When I shift into 5th gear, the lever feels like it moves excessively far rearward. Resulting in the 5th gear Shift Rod moving the Shift Sleeve so far that it disengages with the splined Guide Sleeve which drives the output shaft. When this happens the transmission behaves as if it is in neutral and requires the vehicle to be brought to a complete stop before the shift lever can move the shift sleeve back in engagement with 5th gear and the guide sleeve and then to the neutral position. All the other gears function fine. I have not dropped the tranny yet, so I am having to rely on illustrations and my experience working on other make trannys.
When 5th gear is selected what stops the 4th/5th gear Shift Rod/Shift Sleeve assembly once it has positioned the 4th/5th gear Shift Sleeve to engaged the input drive shaft/5th gear assembly? Another 928 owner suspected that the Stop in the synchro assembly was bad. Is it the purpose of the Stops (aka Anchor Blocks) in the Synchro assemblies to stop the movement of the Shift Rods/Shift Sleeve? I expected the mechanism that stopped the gear shifter/Shift Rod/Shift Sleeve to be more substantial than the relatively small Stop that I see in the illustrations. Also, what is the function(s) of the Arresting Bushes that appear to contact the Shift Rods? Attached is a photo of the Stop/Anchor Block.
Thanks in advance for any information offered!
When 5th gear is selected what stops the 4th/5th gear Shift Rod/Shift Sleeve assembly once it has positioned the 4th/5th gear Shift Sleeve to engaged the input drive shaft/5th gear assembly? Another 928 owner suspected that the Stop in the synchro assembly was bad. Is it the purpose of the Stops (aka Anchor Blocks) in the Synchro assemblies to stop the movement of the Shift Rods/Shift Sleeve? I expected the mechanism that stopped the gear shifter/Shift Rod/Shift Sleeve to be more substantial than the relatively small Stop that I see in the illustrations. Also, what is the function(s) of the Arresting Bushes that appear to contact the Shift Rods? Attached is a photo of the Stop/Anchor Block.
Thanks in advance for any information offered!
Unfortunately, what you are proposing can't happen.
The part of 5th gear that the slider engages has tiny little stops on each engaging tooth to keep the slider from over traveling. Granted, transmissions that have been shifted very hard (abused) will occasionally break some these tiny "stops" off....however even if every single stop was broken off, the slider would simply hit the lower gear that makes up the fifth gear set.
This condition is felt as a "jumping" feeling in the gearshift lever, as each engaging tooth on the slider hits 5th gear, but obviously impossible to push the slider through that lower portion of the gear.
The "stop" in your picture is actually an internal synchro piece, which is what helps align the engaging teeth on 5th gear with the engaging teeth of the slider, so the two can be smoothly engaged while shifting.
#3
Pretty logical conclusion, just looking at a parts diagram!
Unfortunately, what you are proposing can't happen.
The part of 5th gear that the slider engages has tiny little stops on each engaging tooth to keep the slider from over traveling. Granted, transmissions that have been shifted very hard (abused) will occasionally break some these tiny "stops" off....however even if every single stop was broken off, the slider would simply hit the lower gear that makes up the fifth gear set.
This condition is felt as a "jumping" feeling in the gearshift lever, as each engaging tooth on the slider hits 5th gear, but obviously impossible to push the slider through that lower portion of the gear.
The "stop" in your picture is actually an internal synchro piece, which is what helps align the engaging teeth on 5th gear with the engaging teeth of the slider, so the two can be smoothly engaged while shifting.
Unfortunately, what you are proposing can't happen.
The part of 5th gear that the slider engages has tiny little stops on each engaging tooth to keep the slider from over traveling. Granted, transmissions that have been shifted very hard (abused) will occasionally break some these tiny "stops" off....however even if every single stop was broken off, the slider would simply hit the lower gear that makes up the fifth gear set.
This condition is felt as a "jumping" feeling in the gearshift lever, as each engaging tooth on the slider hits 5th gear, but obviously impossible to push the slider through that lower portion of the gear.
The "stop" in your picture is actually an internal synchro piece, which is what helps align the engaging teeth on 5th gear with the engaging teeth of the slider, so the two can be smoothly engaged while shifting.
tthat should prevent the slider from traveling up onto the