Still grinds into reverse

[Doug&Deb]

I’m still having issues getting my Coronet into reverse. I now shut off and shift into reverse then restart and back up. Not the best solution but better than chipping a gear tooth. I was reading an old Chilton manual and in the DeSoto section it mentions using a straight edge to align the bottom inspection plate to the bell housing. Apparently I missed that step. My question is whether loosening the bolts on the inspection plate and tightening the trans mounting bolts would pull it into alignment or do I need to remove the trans to align the two?

[D35 Torpedo]

Do you put it into 2nd first? Playing with you bellhousing isn't going to fix the transmission. Are you sure the clutch is fully disengaging? 

[Ivan_B]

If this is a regular three speed, then I believe that the above advice was meant to shift into reverse through the third. The same goes for the first, shift second then first. The physics behind this is that is is supposed to slow down the transfer shaft, or something like that. You can also try the gear-clutch-neutral-clutch-gear method to see if it works for your box. Both first and reverse gears are not synchronized. How bad it grinds would probably depend upon your gears' shape and driving conditions.

If that sounds like too much trouble, the older cars did not have synchros for any gears, so you had to catch-a-tooth with the engine in order to shift at all

[D35 Torpedo]

37 minutes ago, Ivan_B said:

If this is a regular three speed, then I believe that the above advice was meant to shift into reverse through the third. The same goes for the first, shift second then first. The physics behind this is that is is supposed to slow down the transfer shaft, or something like that. You can also try the gear-clutch-neutral-clutch-gear method to see if it works for your box. Both first and reverse gears are not synchronized. How bad it grinds would probably depend upon your gears' shape and driving conditions.

If that sounds like too much trouble, the older cars did not have synchros for any gears, so you had to catch-a-tooth with the engine in order to shift at all

Either or...I use 2nd all the time.

[Ivan_B]

Your linkage must be in great shape, then. Otherwise, if you attempt to shift "on the same side" it is easier to miss the right gear as opposed to shifting from the opposite side.

[Doug&Deb]

I have the M6 semi automatic transmission so I don’t know if that method will work. It’s worth a shot though. I’m also going to play with the clutch adjustment again.

[Ivan_B]

For the clutch, you can just check if you can rotate the disk by hand when the pedal is pressed down.

[D35 Torpedo]

On 8/15/2023 at 6:56 PM, Ivan_B said:

Your linkage must be in great shape, then. Otherwise, if you attempt to shift "on the same side" it is easier to miss the right gear as opposed to shifting from the opposite side.

I have done a lot to tighten it up. The main reason I use second is that third gear synchro isn't as happy.

[bartenderfloyd]

On 8/15/2023 at 8:49 PM, D35 Torpedo said:

Do you put it into 2nd first? Playing with you bellhousing isn't going to fix the transmission. Are you sure the clutch is fully disengaging? 

I had never heard of this.  I've been doing this all weekend and not 1 grind.  It has been eliminated.  Thank you for suggesting it!!

[SteveR]

If you are grinding in reverse that indicates your input shaft is still turning. The first suspect is the clutch fully disengaging. I am wondering if the journal of your input shaft is stuck in the bush of the engine. 

I do not remember is 1st gear also grinding even if a little.

[FarmerJon]

On 8/17/2023 at 2:44 AM, D35 Torpedo said:

I have done a lot to tighten it up. The main reason I use second is that third gear synchro isn't as happy.

Would you mind posting what all you have done to tighten up the linkage?

 

Shifting into 2/3 syncro gears, then into 1st/R almost totally eliminated grinding for me. Makes getting into 1st at a slow roll much easier

[greg g]

Haven't seen this mentioned, but what is your idle rpm?  Should be 450 500.   Have you tried lengthening the rod going from the clutch pedal to the throw out fork?  If the disc isn't fully disengaging it will spin the input shaft.

[D35 Torpedo]

2 hours ago, FarmerJon said:

Would you mind posting what all you have done to tighten up the linkage?

 

Shifting into 2/3 syncro gears, then into 1st/R almost totally eliminated grinding for me. Makes getting into 1st at a slow roll much easier

The first thing I did was replace the rubber bushing on the column shift arm. I ended up making one. Then I discovered a ton of slop in the transmission shift levers. I removed the assembly off the transmission and repaired the problem. The levers had loosened up on the shafts. They only index on two flats. The one lever is a weird shape and that probably contributed to the failure. I haven't done anything to the rods as they are not that bad. 

[Doug&Deb]

I’m thinking the input shaft may be sticking in the bushing. I’m going to try loosening the bolts holding the inspection plate to the bell housing and re-tighten the trans. Perhaps I don’t have a completely straight surface. After that I’ll check the clutch adjustment again. I’m using a mish mash of parts so that may be the issue. Right now shifting into low range then reverse is working but that’s a band aid fix. My idle speed is 475 and the transmission operates normally. With the transmission in gear and the clutch disengaged I can definitely hear something spinning. The sound goes away in neutral.