Newbie needs transmission and transfer gear help

[WPS 73 Bronco]

I’m a corvette guy (64 & 72 restomods I’ve built) and recently bought my first classic Bronco. It’s a 73 with a 302 HP crate motor, C4 auto and 2 1/2” lift. It was body off restored 8 years ago and looks and runs great……until I drove it over a speed bump in a parking lot going 5 mph.

When I went over the speed bump, it kicked out of gear. When it rolled to a stop, I was able to shift it into reverse, but no forward gears. I believe it was in 2H, but not sue. It could have been 4H. Anyway, I called my Bronco advisor to help me figure out what was wrong. I tried shifting the J shit into each of the gears (2H,2L,4H) while in neutral or park. It would only engage 2L, but stil I was only able to get the transmission to go into reverse.

I took it to an auto shop I trust and they told me there’s a transmission issue and they fear it needs a rebuild. They didn’t suspect linkage as the steering shift was properly shifting the transmission. I think they overlooked the transfer case linkage/lack of engagement issue. My Bronco was taken to a transmission shop that told me the torque converter was shot and the transmission needed a rebuild. They said since reverse is low pressure, that’s why it engaged. Yesterday I went for the test drive and same issue appeared. No 2H or 4H engagement. I now have R and forward gears Only in 2L. They are now looking at the transfer linkage & gears. I’ve lost confidence that this transmission shop knows what they’re doing.

Thoughts about what is wrong? I’m stuck with this shop so I need to help guide them.

 

[WPS 73 Bronco]

Bumped for some thoughts.

BTW….. I’m getting the 20” wheels replaced by 17’s.

 

[Yeller]

It would be helpful to know your location.

 

[WPS 73 Bronco]

Houston

 

[Broncobowsher]

What transmission do you have? It sounds like you have an automatic. Have you checked the fluid level? Unlike an engine, this is checked with the engine running. Ideally when fully warmed up, but in your case that doesn't matter. Most dipsticks have marks for cold fluid as well. Anything above the (hot or cold) fill marks is enough. Never overfill.
Is the fluid still a nice pink/red color? Black or brown are bad, looking like roofing tar and you are screwed.

My guess, the filter in the transmission fell out when you hit the bump. Probably not installed correctly years ago. Now the transmission isn't sucking fluid off the bottom of the pan, but near the top of the fluid level. And sucking air along with it. This causes low transmission pressures. Low pressures cause slippage. If you tried to drive it to much with excessive slippage you burn up the clutches. If you got lucky, didn't try to drive it too much and burned stuff up, you might be able to drop the transmission pan, install a good filter, refill the trans and be ready to go.

 

[WPS 73 Bronco]

Transmission has been fully rebuilt, this week.

 

[WPS 73 Bronco]

C4 auto

 

[Viperwolf1]

It's not a transfer case problem if reverse works. There are no clutches or sprags in a D20. It's all gear drive.

You could have a weak pump in the C4 that can't hold the forward clutch tight or the forward clutch seals or sealing rings may be leaking. Could be low fluid level too. Reverse actually generates HIGHER pressure so that could be why reverse still works. Low range is about 2.4:1, so you only need about 40% of the forward clutch holding force to move. Problem is inside the C4. Have them test pressure and figure out where the leak is.

 

[WPS 73 Bronco]

Viper, I shared your comments with the transmission shop and they agreed with it.

When we completed the test run after the Trany rebuild, it ran in both R and forward gears in 2L.

But there seems to be a different issue with the transfer gears. it won’t engage properly in any of the 3 locations. we tried to change the transfer case into 2H and it wouldn’t engage. Same for 4H. Then it wouldn’t go back to 2L. Then we finally got it into 2H, but nothing else. They believe I have something not right going on in the transfer case.

shifter?
gear slop?
?????

any thoughts

 

[Viperwolf1]

Worn out J shifters can be really sloppy. You can remove it and shift the tcase with a pry bar to help diagnose the problem.

 

[WPS 73 Bronco]

The shop did just that, put it in 2H and worked like a charm. They are ready to give me the Bronco back as they don’t work on shifters. So now it’s time to diy or take to another shop. I do recall that shifter seemed extremely loose and wobbly.

When I look for replacement shifters, I don’t see what I need. I have a single transfer case J shifter and all I see are twin shifters.

what am I looking for?

thanks

 

[brewchief]

Bronco graveyard and I'm sure other venders have new J shifters or you can swap over to a twin stick, pricewise it's pretty close.

Sent from my SM-G965U using Tapatalk

 

[Apogee]

Twin stick it...they shift so much easier than the original J-shifter, and don't wear out in the same way or quickly. Jon at JB Custom Fab is the man for twin sticks.

Tobin

 

[thegreatjustino]

When I look for replacement shifters, I don’t see what I need. I have a single transfer case J shifter and all I see are twin shifters.

J-Pattern Transfer Case Shifter, 1973-77 Bronco | James Duff Inc.

This J pattern shifter is a brand new unit with a revolutionary design. Our design is spring-loaded for smooth shifting and includes brass oilite bushings which never need to be lubed…

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