Transmission woes: Pops out of 3rd

[surfguitar58]

Was feeling really good about the car yesterday after a full morning of folks admiring it at a British Car Day event, then driving home she starts occasionally popping out of 3rd gear. (Sigh...)

This is a type 352 4-speed trans. Is there any chance this is a linkage problem? 250 miles ago the shift linkage felt nice and tight, but Boston's crumbling infrastructure and potholes are shaking bits loose all over the car, and the linkage is looser and has more play than when I first took delivery.

I'm clinging to the hope that there is a simpler and cheaper explanation, but I guess the usual suspects in this situation are worn synchros and/or shift forks. How hard are replacement 352 trans parts to find?

I'd love to swap to a 365 5-speed, if I could find a good or rebuildable one.

Tom

[BDA]

I suspect that your problem is internal rather than linkage but somebody who knows more about it than I might want to chime in about that.

A 365 will fit in your frame, but they are rare and I believe spare parts for it are too. Certainly the 5th speed gear, which was made by Hewland, has not been made for more than forty years.

I would advise that you get an NG3. They are more current and Andy Harwood, with some judicious pounding on the rear hoop, was able to install his in his 352/365 frame. I replaced my rear hoop because it didn't seem like it would fit but maybe I didn't try hard enough. In any case, Richard at Banks sells kits and he'll be happy to advise you.

One difficulty will be the shift linkage. There are two ways to go - the linkage that Richard will sell you with the tranny or a cable shift arrangement. I think the engine will have to come out in order to attach the bracket for the "pivot cross." I'm not sure what or how much is required to implement a cable shifter. Somebody here or maybe even Richard might be able to advise you.

Good luck!

[jbcollier]

First make sure it is going all the way into gear.  If the linkage feels loose, then perhaps it isn't going all the way home.  If it is, and it still pops out, then you have worn synchro hubs and/or shift rail indents.  If it isn't, stop driving it until you repair it.  Otherwise you will quickly wear your hubs.

[4129R]

Otherwise you will quickly wear your hubs.

Please can you explain this?

[jbcollier]

The synchronizer has a splined hub and sliding gear.  The splines on the hub and sliding gear match splines on the gear itself.  Normally the sliding gear goes all the way home on the gear and provides a strong connection between the gear and the hub.  As long as the transaxle is kept full of oil, very little wear occurs.  However, sometimes wear in the linkage, or mechanical obstruction (simple as carpet blocking the shift lever's movement) will have the sliding gear not going all the way home.  This means the retaining indent is also not fully engaged.  Vibration will caused the sliding gear to move back to the neutral position and it pops out of gear.  As there isn't full spline contact, the loads on the splines are higher and increase as the sliding gear vibrates back to neutral.  This wears a ramp in the splines and it doesn't take long until it will pop out of gear even after you have fixed the original problem.

[surfguitar58]

Thanks guys, I will check the linkage first by having my BA shift gears while I check the movement at the back of the trans. Is there a spec for linkage slide distance, or will it be obvious?

First: A sacrifice to the cheap fix gods!

Tom

[jbcollier]

1, 2, 3 and 4 should all move the same amount.

[4129R]

The synchronizer has a splined hub and sliding gear.  The splines on the hub and sliding gear match splines on the gear itself.  Normally the sliding gear goes all the way home on the gear and provides a strong connection between the gear and the hub.  As long as the transaxle is kept full of oil, very little wear occurs.  However, sometimes wear in the linkage, or mechanical obstruction (simple as carpet blocking the shift lever's movement) will have the sliding gear not going all the way home.  This means the retaining indent is also not fully engaged.  Vibration will caused the sliding gear to move back to the neutral position and it pops out of gear.  As there isn't full spline contact, the loads on the splines are higher and increase as the sliding gear vibrates back to neutral.  This wears a ramp in the splines and it doesn't take long until it will pop out of gear even after you have fixed the original problem.

I was associating hubs with the drum brakes, not the synchro.

Thank you for the explanation. Basically if the gear is not fully engaged due to the linkage being restricted, it messes up the synchro.

[RafM]

I know this is an old topic but did you resolve the problem?

My gearbox has started dropping out of 3rd gear recently.

Thanks, Raf.