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 Post subject: 81 Corona, can't engage a lower gear.
PostPosted: Fri Aug 15, 2014 12:39 pm 
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Joined: Mon Jul 15, 2013 7:11 am
Posts: 66
Cars a 1981 Toyota corona, 12r engine, not sure what the tranny is (4 speed). Shifting up is not a problem, trying to engage a lower gear when revs are above idle is. Next door mechanic keeps telling me my clutch is worn out and needs replacing :shock: . I don't have a single idea how to diagnose transmissions problems but my most likely suspects are no/low transmission fluid or worn sync plates/gears(?). Help please :mrgreen:

Note: Don't hear any strange sounds coming from the tranny when driving. Just the accursed grinding when I forget about the prob and try to downshift while engine is above idle.

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 Post subject: Re: 81 Corona, can't engage a lower gear.
PostPosted: Fri Aug 15, 2014 6:04 pm 
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Joined: Mon Jul 30, 2012 4:36 pm
Posts: 373
Location: Coarsegold California (around fresno)
Are upshifts smooth? or is it like speed shifting without a clutch? How is the clutch on initial take off in 1st?

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 Post subject: Re: 81 Corona, can't engage a lower gear.
PostPosted: Sat Aug 16, 2014 9:02 am 
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Joined: Sat Feb 05, 2011 5:53 pm
Posts: 329
Location: Bay Area, California
Check your clutch master cylinder for low or dirty fluid, or leaks. That component is bolted to the firewall and attaches directly to the clutch pedal. A leak might not be obvious, but wrinkled or missing paint and/or rust underneath the master cylinder is a good indicator there is a leak. The fluid is highly caustic and ruins everything.

The slave cylinder is attached to the transmission, and is what actually pushes on the clutch fork and separates the clutch disk from the flywheel friction surface. Finding a leak here can be more difficult because of all the grease and grime down there already. Have a friend push the clutch pedal and watch the slave movement.

The clutch line could simply need a fluid change, which is just like bleeding brakes.

If neither of these components appear faulty, then you have more serious issues. I've only had one clutch fail on me in the past, and it happened pretty abruptly. So I don't know much about diagnosing clutch problems. The car just stuck in gear and that was it.

As for the possibility of bad gear syncros, is there grinding when you change gears? Does the shifter pop out of gear while driving?

Changing the trans fluid is usually a good idea. Can't hurt


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 Post subject: Re: 81 Corona, can't engage a lower gear.
PostPosted: Sat Aug 16, 2014 1:43 pm 
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Joined: Mon Jul 15, 2013 7:11 am
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@Skellington, yep, upshifts are smooth. No problems at all.

@Matches, already checked both the master and slave cylinders for leaks, actually found a slave repair kit in the trunk when I bought the car and I confirmed the PO already replaced it. I'm also checking the clutch reservoir often and I don't seem to be losing any fluids when I drive. Grinding only felt when I try and downshift while the rev's are above idle, ex: moving at maybe above 50kph can't downshift, when I go below 20 that's when I can downshift, feels like there's something blocking the gear(?) when I force it then I hear a grinding sound. And nope, gears don't pop out even if I dump the clutch. Can a worn clutch cause these issue's?

Thanks for the help guys.

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 Post subject: Re: 81 Corona, can't engage a lower gear.
PostPosted: Sat Aug 16, 2014 3:09 pm 
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Joined: Sat Feb 05, 2011 5:53 pm
Posts: 329
Location: Bay Area, California
Yeah, I'd guess clutch. Sorry man.

Good news is, looks like you can get a replacement really cheap

http://www.partsgeek.com/gbproducts/MC/ ... 7AodT0QAUQ


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 Post subject: Re: 81 Corona, can't engage a lower gear.
PostPosted: Sat Aug 16, 2014 7:33 pm 

Joined: Fri Sep 30, 2011 6:44 pm
Posts: 52
Location: socal
Sounds like the pressure plate is not fully releasing the clutch disc... Check for fl travel of the slave cylinder and make sure you bleed all of the air out of the clutch master and slave cylinder...
I have found on previous cars that the release bearing was not installed correctly..


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 Post subject: Re: 81 Corona, can't engage a lower gear.
PostPosted: Sun Aug 17, 2014 8:25 am 
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Joined: Mon Jul 15, 2013 7:11 am
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@Matches, oh damnit, I was really hoping a simple oil fill up/change would do the trick. Anyways, I'll just decide between replacing the clutch or driving it just as it is and try and find a 5 speed tranny for it.

Again, thanks for the help guys! :tu:

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 Post subject: Re: 81 Corona, can't engage a lower gear.
PostPosted: Sun Aug 17, 2014 8:27 am 
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Joined: Mon Jul 15, 2013 7:11 am
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@frankymo, yeah, I guess I'll replace the pressure plate too when I decide on fixing the turd tranny. hehe.

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 Post subject: Re: 81 Corona, can't engage a lower gear.
PostPosted: Thu Sep 18, 2014 7:21 pm 

Joined: Mon Apr 06, 2009 10:37 pm
Posts: 20
Location: Colorado
pressure plate. replace the whole clutch assembly with machining flywheel and pilot bearing and throwout bearing while you are in there.


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 Post subject: Re: 81 Corona, can't engage a lower gear.
PostPosted: Wed Sep 24, 2014 6:07 pm 
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Joined: Thu Apr 03, 2008 2:38 am
Posts: 50
Location: Moreno Valley, California 92551
Gene wrote:
@frankymo, yeah, I guess I'll replace the pressure plate too when I decide on fixing the turd tranny. hehe.

http://members.iinet.com.au/~stepho/manuals/Toyota/

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 Post subject: Re: 81 Corona, can't engage a lower gear.
PostPosted: Mon Sep 29, 2014 11:22 am 
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Thanks 73gtv!

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