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So as said in the title I have recently been experience loss of power, and slow acceleration. I have a 79 and it really struggles in fourth gear, sometimes if I give it to much gas in fourth when at the low end of rpm's (2000) it revs really high as though the gears are slipping or I'm riding the clutch or..? I am at a loss and any help would be much appreciated.

Mine did this when it was stock. I ended up putting a new clutch and pressure plate in and it solved the problem. You might be able to adjust the clutch a little and temporarily solve the problem.

Yeah, I would like to install a new clutch and pressure plate. Even more so than that, I want to replace the throwout bearing, I have known for quite sometime that I have at least one bad bearing in my transmission. Whenever the clutch is disengaged I can hear the grinding coming the bad bearing. Actually, I am quite certain that the whole reason I have been experiencing power loss is because of the bearing. However, I have never worked on a transmission before, so if someone could point me towards a good pictorial thread on the site showing the process that'd be great. Also having a RWD 79 Luv, what clutch (manufacturer, size, specs, etc.) should I get?

Is replacing the clutch/pressure plate/throw out bearing a difficult process, Am I in over my head??? Also while the transmission is out, what else should I go ahead and check out/fix/replace?

Thanks everyone!

If the grinding noise is when the clutch is depressed it's your throwout bearing, not the tranny, until you release the clutch pedal there is nothing spinning in the tranny. The most common tranny bearing noise first appears idleing in neutral with the clutch pedal released, allowing the engine to spin the mainshaft, eventually it will get bad enough to hear in at least one gear, then it will eventually fail.
Replace the clutch & TOB, see if that cures the problem. If it doesn't replace the tranny, rebuilding one is not for the inexperienced and it is too costly as well.
2wd & 4wd clutches are different for a 1.8 engine, different flywheel mounting pattern. Brand doesn't matter a lot, Excedy probably made the stock clutch.

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'78 Chevy LUV,1.9,4sp,headers,31's,SAS Dana 30,Dana 20,SOA rear w/Aussie Locker, rough body, bought new 12/4/78.
'87 Trooper,2.3,5sp,headers,31's,ball joint flip & spacer,Aussie Locker rear,Superwinch hubs,brush guard w/5.5K winch,more to come.

Yes, the grinding noise happens, and is most apparent, when the clutch is depressed in neutral. Furthermore, in retrospect to the aforementioned information, I can safely assume that my throwout bearing is completely destroyed because not only can I hear the noise in neutral I can hear it in first, second, third, fourth, and reverse. I have been driving the truck in this condition for quite sometime, could this lead to other problems?

I think whats going on here is the throwout bearing is worn out, probably from running all the time against the pressure plate fingers. It should not touch the fingers until you press in the clutch to release it. What this means is it is also not allowing the clutch to fully engage and causing it to slip like you reported. All this is caused by the clutch cable not adjusted properly (free play).
I would pull the transmission and replace the throwout bearing and maybe the clutch assembley while you are in there.
Make sure then that the clutch cable is adjusted properly when done.

yeah, I recently had to custom fab up a little clevis for the clutch cable/pedal after the original one broke, and in the midst of it all the cable became a bit tweaked. However I did some quick adjusting and it seemed to help with the slippage. The Throwout on the otherhand... still, of course, making horrid noises. I definitley see a project in my near future.

thanks for the advice and tips everyone.

So, I replaced the clutch,pilot bearing, and throwout bearing. But, the scraping whirring noise persists! I now believe that it is most likely my mainshaft bearings. can anybody think of what else it could be? also, am I able to replace these bearings without dropping the tranny? I am thinking I may just go ahead and do a 5spd swap, id really like to be able to sustain 75mph on the freeway for once. apparently the picknpull has a 1990 isuzu "pickup," would its tranny bolt up? And i guess i need to snag its front slip yoke too which can be swapped on my driveline, right?

No, because the one on that truck won't fit your driveshaft unless you have it spliced on. It had the larger U-joints.

I just posted a "For sale" listing for the slip yoke you would need.
viewtopic.php?f=8&t=27246

Jack

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'83 Isuzu P'up Diesel LS - Original Owner
JoeIsuzu@IsuzuPup.com
IsuzuPup.com