Bad Clutch Questions 1990 Bronco II

[FredDoug]

I was driving my manual 1990 Bronco II (2.9L, FM146) this last week and I was stopped in traffic. When I went to go (clutch in, shift to first, do the thing) it lurched forward and the engine shut off as if I had tried to engage too quickly. Started the engine back up just fine, but now it wouldn't even attempt to engage any gear.

After safely getting off the road and doing some research, I tested the following few things which makes me believe it's the clutch:

• With the engine off, I can push the shifter into all the gears without pressing in the clutch.
• With the engine on, I can press in the clutch, shift to any gear, and release the clutch without killing the engine. Yes, I can put it in 5th/overdrive and release the clutch and it stays running, there is a difference in noise as if something is slightly engaging but not much.

So first off, am I correct in thinking this is the clutch? Should I test anything else before I go to order a new clutch and all the hydraulic components for it?

Another question, I saw that it's possible that the larger 10" clutch from the first gen explorer fits these transmissions so I thought I'd do that. Is there anything extra I need other than an explorer starter? Has anyone on here done this?

Finally, I do have a first gen explorer sitting around but it doesn't run quite right as I explain in the form linked here. It has the M5OD which I've seen in a few posts might be slightly more reliable than the FM146. Is it worth it to swap over? Or even look for another M5OD from the junkyard instead of replacing the clutch on the FM146?

 

[tw205]

Sounds more like a transmission or transfer case problem. Engine off, in gear, brake off, will the truck roll if pushed or pulled?

 

[tw205]

If the clutch was stuck in engaged position you would not be able to push the pedal. Pressing the padal closes the port to the reservoir so fluid can only flow to the slave. If slave is engaged then fluid cant flow causing no pedal movement .

 

[ireallydontcare]

To answer your first question, I think it's the driveshaft. Most Bronco II's came with a cv style driveshaft, which is weak and can break pretty easily. I've found that some early models have a conventional double cardan driveshaft and it is much stronger than the CV one. You need too find one from an A4LD automatic. It measures the same length as your FM146. The M5OD does as well, but I'm not sure those had the double cardan shaft behind them.

To answer your second question, yes the bigger clutch can be swapped in. I did the 4.0 swap on my 90 and retained the FM146. Used all the 4.0 clutch components and everything went together nicely. The driveshaft was the only thing I had fail, and I beat on the sucker pretty hard. The transmission held up well for the time I drove it (cracked heads and parked it due to severe rust, that was 3 years ago, and I'm just now getting around to tearing it all apart. Maybe I should do a thread.)

To answer your third question, if you plan on swapping the 4.0 it *might* be worth your time to swap the M5OD over. My personal experience having owned several ranger based vehicles with M5s and FMs over the years, is that the FM transmissions had way smoother shifting and all but 2 of the M5ODs I've driven were pretty notchy. Obviously how they were maintained goes a lot into this, but the one in my current first gen explorer has problems staying in reverse, as did the one in my last Bronco II. The one in the X was rebuilt before it was put in the jy with cracked heads.

Good luck with your bronco.

 

[FredDoug]

Thank you both for your responses, the car does in fact move when I push it while in gear, engine off.

After looking at the driveshafts and not seeing a break in the cv joints anywhere I had the wondrous idea of trying the vehicle in 4x4. (I thought I had done this when it had first died but maybe it didn’t actually engage that time?) and guess what? I believe I have a front wheel drive Bronco. This basically convinces me that the transfer case is shot.

However, what do yall think? Is there anything else I should check? And if it’s for sure the transfer case anything else I should fix while I’m in there? Thanks so much again!

 

[ireallydontcare]

Take the rear driveshaft out. Just because it doesn't look like it's broken doesn't mean it isn't. Don't assume its the most complicated problem first. When mine busted it looked fine but moved around when I put it in gear and looked under the truck. Maybe try to do that and see what you see.

 

[FredDoug]

Thanks for the recommendation @ireallydontcare. I ended up doing some more diagnosing this weekend and actually had a helper with me. So we figured out the driveshaft is still spinning just fine when it’s in gear and accelerating and such. So I disconnected the drive shaft from the rear differential. Then I spun the flange in the rear differential and it spins completely freely. So yet again I am led to believe a different diagnosis, thank goodness I asked before I ordered a clutch haha! I didn’t get time to take the diff cover off but should I do that first before looking at a new rear axle?

I figure at this point, if it’s the differential, I might as well replace the rear with the 8.8 with disc brakes and do the extra work to move the mounts. Any suggestions on this or something else I should do?

 

[Cway]

I was driving my manual 1990 Bronco II (2.9L, FM146) this last week and I was stopped in traffic. When I went to go (clutch in, shift to first, do the thing) it lurched forward and the engine shut off as if I had tried to engage too quickly. Started the engine back up just fine, but now it wouldn't even attempt to engage any gear.

After safely getting off the road and doing some research, I tested the following few things which makes me believe it's the clutch:

• With the engine off, I can push the shifter into all the gears without pressing in the clutch.
• With the engine on, I can press in the clutch, shift to any gear, and release the clutch without killing the engine. Yes, I can put it in 5th/overdrive and release the clutch and it stays running, there is a difference in noise as if something is slightly engaging but not much.

So first off, am I correct in thinking this is the clutch? Should I test anything else before I go to order a new clutch and all the hydraulic components for it?

Another question, I saw that it's possible that the larger 10" clutch from the first gen explorer fits these transmissions so I thought I'd do that. Is there anything extra I need other than an explorer starter? Has anyone on here done this?

Finally, I do have a first gen explorer sitting around but it doesn't run quite right as I explain in the form linked here. It has the M5OD which I've seen in a few posts might be slightly more reliable than the FM146. Is it worth it to swap over? Or even look for another M5OD from the junkyard instead of replacing the clutch on the FM146?

This sort of happened to me in my 89 b2. My clutch was useless and went to the floor with no resistance. Could move through the gears, but my clutch was useless.

Took it to the shop and it was my slave cylinder. It's inside the bell housing, and integral with the throwout bearing. Since they had to halfway drop the transmission to access it, I had them replace the slave cylinder, throwout bearing, and clutch plate (plate was not necessary, just preventative since they were already in there). Cost me 700 dollars all together, but it fixed the issue.