4 speed question

[dan juhasz]

On my 66 Coronet I'd like to address an issue with the trans ( I think) that bugged me all driving season. When cruising on highway in 4th I always have to rest my hand on the shifter or it will eventually end up in neutral. It happened faster if I coast then accelerate again, all normal driving not leaning on it.
Pretty sure this unit was rebuilt when the car was restored but I have no proof. It shifts fine, smooth no grinding etc. Trans is quiet no bearing noise or whine etc. The shift mechanism is a hurst /inland conversion from Brewers so I think it is fine.
I'm really considering installing a gear vendor overdrive set up so I'd like to get this problem with the trans straightened out at the same time. I did ask at Brewers and they suggested a syncro issue. I would expect if the syncro's had a problem I would have issues with up shifts?
Appreciate any input, Thanks and Happy New Year to All!!

 

[gkent]

I won't claim to know more than the guys at Brewers BUT it seems to me that even a bad syncro shouldn't be able to move the shifter out of the detent. I'd put the shifter in neutral. Disconnect the rods at the case and adjust them all in the neutral position. If you have stop bolts on the shifter, back those all off then adjust them for each gear. I usually set the bolt against the lever then back off maybe a quarter to half turn and tighten the lock nut.

 

[69Bee]

The syncro dogs or springs are worn and won't hold it in the gear it was in. They allow the syncro to slip into neutral. Mine had an issue with third I think. It would slip out of gear on coast, so I had to rest my hand on the shifter like you do. The only other thing to check first (cause it is easier), is to ensure the trans mount is not damaged, allowing the trans to shake it out of gear.

 

[Fran Blacker]

https://www.forbbodiesonly.com/mopa...ilt-2nd-gear-popping-out-occasionally.101389/

 

[Ernie ingling]

Yep syncros if np noise and/or money and time. Bungee cord works good

 

[davek]

check your linkage first,how long has it been this way?Just started?

 

[moparnation74]

Sounds like synchros.

 

[91r/t]

I had this happen on my Charger. It was a combo of the synchros and the trans not being aligned/centered into the bell housing and pilot bushing properly. Mostly the synchros fixed it though.

 

[Beekeeper]

Yep check that the shift rods are adjusted correctly. Also it could be the clutch dogs.

 

[493 Mike]

Perhaps the detent springs are not correct or weak with age?
Mike

 

[gkent]

Those syncro dogs serve TWO purposes. 1) they keep the brass syncro rings from spinning freely and 2) they center the syncro hub in the neutral position. The springs have ONE purpose only: to hold the dogs in place so they don't fall out. And they don't need much tension to do that.

That said, anyone that thinks the dogs and springs are the problem has their head up their ***.

Syncros, sure that's possible BUT be aware that it will be the whole syncro assembly that's the issue, not just the "cheap to replace" brass rings. The rings serve only TWO purposes. 1) grip the gear cone and "syncronize" the speed of the gear to the syncro hub and 2) help align the syncro teeth on the gear to the syncro hub.

If the syncros are the issue its because the internal teeth are shot AND there's a good chance the syncro teeth on the gears are shot too.

 

[biomedtechguy]

Those syncro dogs serve TWO purposes. 1) they keep the brass syncro rings from spinning freely and 2) they center the syncro hub in the neutral position. The springs have ONE purpose only: to hold the dogs in place so they don't fall out. And they don't need much tension to do that.

That said, anyone that thinks the dogs and springs are the problem has their head up their ***.

Syncros, sure that's possible BUT be aware that it will be the whole syncro assembly that's the issue, not just the "cheap to replace" brass rings. The rings serve only TWO purposes. 1) grip the gear cone and "syncronize" the speed of the gear to the syncro hub and 2) help align the syncro teeth on the gear to the syncro hub.

If the syncros are the issue its because the internal teeth are shot AND there's a good chance the syncro teeth on the gears are shot too.

So what do YOU think the OP problem is?

 

[Beekeeper]

A worn out pilot bushing or excessive wear on either bearing or excessive wear on the tail shaft bushing could cause the issue.

 

[moparedtn]

Those syncro dogs serve TWO purposes. 1) they keep the brass syncro rings from spinning freely and 2) they center the syncro hub in the neutral position. The springs have ONE purpose only: to hold the dogs in place so they don't fall out. And they don't need much tension to do that.

That said, anyone that thinks the dogs and springs are the problem has their head up their ***.

Syncros, sure that's possible BUT be aware that it will be the whole syncro assembly that's the issue, not just the "cheap to replace" brass rings. The rings serve only TWO purposes. 1) grip the gear cone and "syncronize" the speed of the gear to the syncro hub and 2) help align the syncro teeth on the gear to the syncro hub.

If the syncros are the issue its because the internal teeth are shot AND there's a good chance the syncro teeth on the gears are shot too.

It would be appreciated if you could impart your wisdom to us all without resorting to insulting other members.

 

[dan juhasz]

check your linkage first,how long has it been this way?Just started?

Been this way since I’ve owned it, better than 2 years

 

[dan juhasz]

From everything I’ve researched, followed links from members etc I really think it is the 3 , 4 synchronizer assembly. I came across several posts that had identical symptoms and people in the know explained how the inner splines hold it in gear, and that the slightest twist of these splines would result in either popping out of gear under power or popping out during coast, depending which direction the twist is. Made perfect sense to me. So unless brewers or passion has nos or replacement assemblies I wouldn’t even bother because I don’t think the basic rebuild kit with the synchro rings will fix anything.

 

[AR67GTX]

I think you are on the right track. What I call the syncro sliders/collars are not commonly replaced on a rebuild as part of the yellow brass and small parts group. They are visually inspected but wear of the splines is hard to gage from a go/no-go perspective. Additionally, fourth gear is up front and any pilot bushing excess wear, mis-alignment of the bellhousing or input bearing gear wear would exacerbate any syncro slider wear. I've been through a Muncie and a Toploader but never an A833 - and I understand parts are getting tough to find for them. If available, you may want to look at torq-lok sliders for a rebuild. They have the splines slightly dovetailed in the engagement area to assist in keeping the gear teeth locked in. Before removal however I would try and rule out the easy stuff first - re-adjustment of the linkage, back off the shifter stops for a trial, maybe even pull the cover and make sure the shift fork linkage is operating properly. And if you pull the transmission, be sure to check bellhousing alignment with a dial indicator and that it's within .006" of center.

 

[gkent]

I don’t think the basic rebuild kit with the synchro rings will fix anything

Exactly! Brewers sells complete syncro assemblies if need be BUT a long time ago I learned to pick the low lying fruit, meaning start with the easy stuff. Get under the car and adjust the shifter and all linkage before you do anything else. Then realize that if that doesn't solve your problem, the trans has to come out. The temptation to remove the side cover to look inside is a total waste of time. And if necessary, replacing the syncro assemblies is a worthwhile investment.

 

[gkent]

And by the way, rebuilding a 4 speed with the parts on hand is a piece of cake 2 hour job.

 

[Daves69]

Been this way since I’ve owned it, better than 2 years

You could bias the 3-4 adjustment a turn, possibly two if the gate allows you to. Doesn't cost to try.