I might have hurt my LT77 need advise - Defender Source
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  #1  
Old May 3rd, 2009, 03:01 PM
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I might have hurt my LT77 need advise

After picking up my 1984 D90 2.5 NAD from Dougís today I was driving to meet Trevor from Rover Labs to go over the fluids and give it a pre trip check

On the way I noticed a noise and just thought it was the diesel motor and how much noise they make. Once I arrived at the shop Trevor noticed the noise and asked me what it was and thought it might be a throw out bearing. After listening to it again he thought it might be coming from the transmission.

We were using Trevors dads shop so we were unable to look into it too much as he needed to leave.

On my way back to the hotel I was thinking about what it could be and realized that when coming to a stop and when trying to put it in first gear I went too far and hit reverse and it made a small grinding noise.

I pushed the clutch in immediately and it did not engage reverse just a slight grinding of the gears (almost like the sound my 95 disco made going from 1st to 2nd if I shifted too fast)

Here are the symptoms

With the clutch in everything is quite and sounds like it should.

With the clutch out there is a noise coming from the transmission

It now seems harder to shift from 1st to 2nd all other gears seem fine

The best way for me to explain the noise it that it sounds like a transmission that I had in the past that was misadjusted and the reverse gear would partially engage making rattling / diesel kind of noise.

Would bending (or knocking out of adjustment) a shift fork cause this. Is it that easy to bent a shift fork?

Any guesses on what it could be? I am supposed to leave Monday morning but I am not sure I want to do that now

Other than the noise and having to replace a few light bulbs the 90 is better than I anticipated
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  #2  
Old May 3rd, 2009, 03:13 PM
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Tony Brooks
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I can't help much beyond offering up transfer case guts if that turns out to be the problem. Were you able to check the fluid at all?
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  #3  
Old May 3rd, 2009, 03:18 PM
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Checked the tcase and it was good, need to check the trans waiting for it to stop raining...
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Old May 3rd, 2009, 03:24 PM
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steve
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I would drain it (both the tranny and t-case) and have a look to see what comes out.

I'm not sure of the lt77 but I don't think there is much room for adjustment.
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  #5  
Old May 3rd, 2009, 03:30 PM
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David Lucas
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You should swing by Ron's place. He probably has a spare LT77 or R380 in his freezer... or maybe he keeps the transmissions in the bathtub.

Good luck getting home.
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  #6  
Old May 3rd, 2009, 03:47 PM
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Transmission is in the closet. But it is a 300Tdi R380 not an LT77 (sold that one off). I have a DI R380 in the attic too. The only parts in the freezer are bushings. No parts in the bathtub, I use that to clean parts though.

Ron

PS frankly, I would just make sure it is full of fluid and no chunks come out and I would start driving.
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  #7  
Old May 3rd, 2009, 03:59 PM
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have you reached out to Doug -- he may well have a spare.
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  #8  
Old May 3rd, 2009, 04:12 PM
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I have not tried Doug yet. wanted to get a chance to check the fluid.

is the LT77 a top loader transmission? If so maybe I can take the top off and see if I can see the issue.

Ron the noise is loud, it is louder than the motor
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Old May 3rd, 2009, 04:14 PM
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Call my cell dave. I can talk you through a diag.
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  #10  
Old May 3rd, 2009, 04:22 PM
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Charles Galpin
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Does it perhaps sounds like a bad throwout bearing (if you know what that sounds like). The symptoms sounds like that to me.

But I agree you should drain the fluid and check what comes out. If no chunks come out, I can't imagine your *almost* shift into second could have caused any harm. I'd be in the "run it anyway" club.

But if there are chunks, I'd be pretty concerned.

What's Janey got - an LT77? Welcome to mine if you need it Would give me the impetus to do the rear main on the engine. Doug knows my numbers.

charles
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  #11  
Old May 3rd, 2009, 06:24 PM
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Janey has an LT95. If it is that loud, it is probably something bad. Is it quiet in 4th?
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Old May 3rd, 2009, 06:35 PM
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I have an LT77 in New York if that helps.
I took it out of my 1985, it was issue free.
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  #13  
Old May 3rd, 2009, 06:35 PM
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Cabell Crowther
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clutch in = all quiet
clutch out = noise
This is what my lt77 throw bearing did when it was checking out.
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  #14  
Old May 3rd, 2009, 06:51 PM
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If it is just a throw out bearing it may be worth changing it or just risking it. Is there anyway to get some grease on it while it is still on the truck?
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  #15  
Old May 3rd, 2009, 06:58 PM
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J. Michael McCaig
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The throw-out bearing only turns when the clutch pedal is depressed (unless the clutch is way out of adjustment) because the clutch fork uses the pedal pressure to push the bearing against the pressure plate to disengage the clutch. As others have said, if is is making the noise with the clutch pedal depressed it is most likely the throw-out bearing. If it is is making the noise without depressing the pedal and the transmission is in neutral, it is most likely the tranmission mainshaft bearings or something related because that shaft is now turning.
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  #16  
Old May 3rd, 2009, 07:00 PM
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Also, does it go away if you slightly press the clutch?
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  #17  
Old May 3rd, 2009, 11:28 PM
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Ron and I spent a bit of time talking on the phone tonight and he found the following information on ashcrofts site.

-------------------------------------------------------------------------------------------------------------------------
My gearbox rattles on idle, in neutral, with the clutch up

This is very common on both the 200 and the 300 TDi engined vehicles. The clutch friction plate has a ring of springs, which are there to soften the knock of the diesel engine to stop it being transmitted to the driveline. Often especially with a new clutch these springs are quite tight and a lot of the engine knock goes through to the gearbox and makes the gears "chatter" together when the box is in neutral and the clutch up, it goes when the clutch is depressed. This can sound quite bad and does vary from car to car but is not detrimental to the life of the gearbox and we view it as an undesirable characteristic of the LT 77 and R 380 as opposed to a fault with either the gearbox or the clutch.
--------------------------------------------------------------------------------------------------------------------------

I do not remember it being as loud at Dougs place and mine is a 2.5 NA diesel so I am not sure if the info even applies. It would be great if the info applies to the 2.5 NAD as it might explain the noise I am hearing.

Anyone out there with a 2.5 NAD and LT77 that does the same?

IMHO based on my past experience with other transmissions it sounds like a straight cut gear trying to engage. The only straight cut gear I see in the transmission is the reverse gear / idler gear. Looking at the overhaul manual there is a alipper pad and some adjustment I am going to keep looking at the overhaul manual and see if I can figure something out.
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  #18  
Old May 3rd, 2009, 11:29 PM
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Robert Dassler
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Dave,
There is no easy way to bend a shift fork, and slightly grinding the reverse gear isn't going to do that level of damage. The LT77 is a top loader, but removing the shifter is only going to let you inspect 5th gear. Reverse gear is all in the main case. Basically, when you select reverse, you move a reverse idler gear into mesh with the reverse teeth on the countershaft as well as a ring of teeth on the outside of the 1/2 synchro hub. In reading your post, I'm understanding that the transmission is making this horrible noise anytime the clutch is engaged, no matter what gear is selected or if neutral is selected...is this correct? With the clutch engaged the input gear and countershaft are always rotating, whether in gear or in neutral. I can tell you that the early LT77s (D&E Suffix) had really small bearings on the countershafts and they are prone to fail. This leads to the countershaft sittting low in the case, and in some cases the countershaft teeth will start eating into the case if it gets bad enough. I'd inspect the oil and see what is on the magnet first, and go from there. I don't bother to rebuild the early D&E suffix boxes as they are usually damaged beyond economical repair. If your transmission is damaged, the best fix will be to get a later LT77s box from a NAS V8 truck and rebuild that with a 4 cylinder input shaft to fit your application. It has beefier bearings as well as a larger oil pump and some other improvements. You can reach me at the shop tomorrow or the cell phone tonight if you need anything.
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  #19  
Old May 4th, 2009, 08:56 AM
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Save, hope you get this figured out, and sorry for the partial hijack here.

So I'd like to hear opinions on the rattle (really not that loud) that I hear with my LT95 I hear when cold although this may still be there when warm - will have to pay more attention. Clutch in == quiet, and when out and in neutral I hear the noise. I don't hear it while driving, but it might just be masked my general road and engine noise at that point. I always thought it was the throwout bearing.

Also, Cabell, was the throwout bearing all you changed to fix your issue, or was more replaced? Just trying to understand if you are sure yours was indeed the throwout bearing.

thanks,
charles
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  #20  
Old May 4th, 2009, 09:39 AM
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Charles, we replaced the TO bearing, clutch and pressure plate at the same time. The pressure plate and clutch disc that we removed were in very good shape. The bearing was dry as a bone, didn't spin smoothly and was the problem in my situation.
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