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Unread 03-02-2012, 09:48 AM   #1
cwatkin
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1978 CJ7 
 
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Jeep CJ-7 3 speed transmission issue

I recently got ahold of a 1978 CJ-7 in a trade for my farm property. It is in pretty rough condition and I knew that the engine had problems when I got it. Well, a rod finally let loose and I am preparing to swap engines this weekend. It had a 1985 Ford 302 in it that had been so rigged it wasn't even funny. I am realizing just how bad it was as I pull parts off for the swap. They had busted the intake so coolant was leaking into the cylinders, etc. so I had to buy a new one.

The new engine is a 1985 Ford 302 so I am pretty sure this swap won't be too horrid. I am not sure which transmission I have in the thing but suspect it is one called the T-150. This is a 3 speed manual with reverse in the forward left postion and 3rd in the lower right position. I assume it is the original but don't know. Could it be from the Ford that the engine came out of?

Anyway, I have a few other issues I would like to resolve while I am so far into the thing. The transmission seems fine except for one issue. When I am in 3rd gear and let off the gas, it will grind and pop out of gear. I have no other issues with shifting. It goes into all gears smoothly and without grinding or other difficulty. I have no clue if this is a transmission problem or something outside the case.

I have been told the following and don't know what to think.
1. My third gear sychronizer is out. Several have told me that I should have issues going into 1st and 3rd if this was the case but it seems fine otherwise.
2. I have been told my third gear may just be worn out or ground down and needs replacement.
3. It has a 2.5 inch or so body lift and a similiar height of suspension lift. Some suggest this might be the issue but others say I should be fine. I have noticed that the bolts for the body or pretty much loose and I will be tightening them up as soon as I get the flat tire I have repaired and back on the Jeep. I have been told that the body being loose shouldn't be an issue as the transmission is mounted to the frame, not the body.
4. I have been told that the input shaft nut may be working loose. I guess I will find out once I pull the engine. What do I look for here? I assume this will be obvious but don't know.
5. I have been told that the rear driveshaft could be at the wrong angle or not connected properly due to the lift.
6. I have been told that my linkage could be adjusted wrong. Where is this? It looks like my shifter goes directly into the top of the transmission. I ahve also checked to make sure the shifter isn't obstructed due to the body lift.

This is my first time doing this type of work with engines and possibly transmissions so I have help who is better experienced than myself. What else could this be and what simple things could cause this? By simple, I mean something that doesn't require tearing into the transmission.

A couple other notes... Everything about this Jeep seems rigged so I wonder if this is part of the problem. Could it be that something was done incorrectly when swapping the engines before? I have never had the Jeep out of 4WD. It has never left my property since it has been mine so I was always taking it offroad and never put it in 2WD. I was told I should experiment with the transmission with it in 2WD but the engine blew up before I did this.

I also have access to a 1986 Ford 4 speed manual transmission for free but don't know if this would be an easy swap or not. This came from a 1986 F-150 if that makes a difference.

Any suggestions?

Thank you,

Conor

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Unread 03-02-2012, 11:22 AM   #2
stodg73
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Quick pic to see if you have a T-150 trans.

My trans is doing basically the same thing yours is. I need a new set of syncros to put in there.

Tearing the trans apart is not that hard. There are very few parts and vaseline is your friend when putting everything back together.

Others will chime in.
__________________
'79 CJ5, 258 c.i., Carter BBD, T-150, Dana 20, Dana 30, AMC 20, 33x12.50x15, 3" body lift, taking it back to stock, then tearing it apart and putting it back together again!
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Unread 03-02-2012, 11:10 PM   #3
james04si
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Not sure about the issue you are having but I also have the T-150 and had a syncro issue. Basically mine would grind going into any gear you put it in unless you held the clutch in for at least 5 seconds. It's been almost 10 years but I'm pretty sure its 2-3 gear syncros so it would not affect 1st gear if it was that. I bought the rebuild kit which comes with new seals and bearings and also the complete syncros not just the brass rings alone. Come to find out I could have saved a bit by just getting the rings as mine had no teeth left it was just a smooth brass ring. I had never rebuilt a transmission before but had a chiltons manual and more time than money to have someone do it for me back then. I pulled it disassimbled rebuilt and had it back in in a weekend. It was very easy to rebuild even with no experience and just a chiltons manual.
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Unread 03-03-2012, 07:41 AM   #4
SoK66
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The grinding issue could also be a pilot bearing being either dry or worn.

The best first step on any Jeep manual trans that's exhibiting gear clash is to drain the trans oil and refill it with GL4 gear oil. This is a low-sulphur oil that was specified OEM in most manual transmissions back in the day. (Newer ones even have their own dedicated gear oil blends.) It is needed in manual transmissions to prevent synchro wear and gear clash. The stuff you put in differntials is GL5 and will not work well in a manual trans becuase the higher sulphur content makes it "slippery-er", causing the synchro rings to have a harder time stopping the spining gears. We've "fixed" many a manual trans that the owner thought needed synchros by simply putting the right oil in it.
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Unread 03-03-2012, 09:10 AM   #5
cwatkin
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I hope to get into this Jeep today

I will let everyone know what I find and look for possible issues. With how the rest of this Jeep was done, I wouldn't be surprised if there wasn't a pilot bearing. We will see...

As for the wrong gear oil, would this manifest itself once the transmission was in gear? It goes into gear just fine and then pops out once you let off. It is great as long as the engine is under load.

Another guy has told me that the 3rd gear is likely rounded off and that I need a rebuild.

Anyway, it looks like I can rebuild this for $200-300 max if I replace EVERYTHING inside (synchros, gears themselves, bearings, seals, etc) while the remans costs $800-1000. I also have a known good Ford transmission given to me for free. I am not sure if it will bolt right up but that would be the easy solution if I don't find something glaring wrong. Seriously, I wouldn't be surprised to find no pilot bearing or something along those lines. The previous owners did a lot of bad rigs on this thing.

Thanks,

Conor
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Unread 03-03-2012, 11:39 AM   #6
SoK66
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No, the oil wouldn't contribute to that. You were given good advice, that's usualy caused by worn gear engagement components. It CAN be the end result of using the wrong oil for too long. That is, the teeth gring enough times to wear away the teeth on the shift collar and clutch gear to the point they can't hold.

If you can do the work yourself, and those T-150s are pretty simple, you can get all the parts & gaskets for an overhaul for around $200. Add to that the cost of any needed gears, etc. When you're in there replace the main drive bearings and any other serviceable stuff.

That's a really tough transmission, despite what you're experiencing. They take an incredible amount of neglect & abuse and still keep ticking.
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Unread 03-03-2012, 08:26 PM   #7
cwatkin
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Thanks. I also have been given a 4 speed manual from a 1986 Ford F-150. I believe this is a T-18 from what I seen online. Will the T-18 bolt right up or is it a big ordeal? If the 4 speed would just bolt up, I think this would be great as I like the shift pattern where reverse is down and to the right like my other modern manual transmissions. I see that this was used in Jeeps and might be compatible with a 1978 but am not sure.

Thanks,

Conor
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Unread 03-03-2012, 09:10 PM   #8
cwatkin
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Also, I just noticed that the two bolts that hold the transmission to the bell housing on the driver side appear to be loose! Could this be related to my grinding issue?

This is the story of this Jeep. The previous owners did everything really hokey like this.

Conor
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Unread 03-03-2012, 09:27 PM   #9
CSP
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If the trans is moving around and getting cockeyed the clutch may not be totally disengaging the input from the flywheel.
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Unread 03-03-2012, 09:57 PM   #10
cwatkin
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I was thinking this might be an issue. All the bolts look mismatched (been through this on the Jeep before) and these two are backed out maybe 1/4 inch.

I have decided not to get into anything major with this transmission until I am sure there is a problem. Once it is put back together CORRECTLY, I will decide to do something if the problem continues.

Conor
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Unread 03-04-2012, 01:14 PM   #11
cwatkin
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I just pulled one of the trans bolts (one that didn't appear loose) out and I could almost have removed it with my fingers.... It looks like they might have used the wrong bolts in a couple of places too.

Conor
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Unread 03-04-2012, 06:23 PM   #12
cwatkin
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I got the old motor out today. Also, one of the engine mount nuts was MISSING... GONE... while the other was about halfway backed out and would have been removed with fingers if it hadn't been for the dirt on the stud. Also, the many of the bell housing bolts were finger loose.

How could this impact transmission grinding?

Thanks,

Conor
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Unread 03-04-2012, 06:43 PM   #13
aggiejon
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Jeep did offer a t-18 tranny but it is different than the ones put in fords. So an adapter is required. Neighborhood of $400. If you have the tranny already and are facing a rebuild, it is probably worth it to gain the four speeds. I am swapping out my t150 for a t176 mated to a d300 tcase. But they are tough. Just need an extra gear (or two).
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Unread 03-26-2012, 09:42 AM   #14
cwatkin
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Thanks. The engine swap in this Jeep is done and everything is tightened down right this time but I am seeing no difference in the transmission popping out of 3rd gear. I talked to a transmission guy and he said that the current T150 is probably not worth rebuilding as everything being loose likely wore out many different parts and the damage is likely worse much more than a standard rebuild would take care of. He says that since I have a ford T18 on hand, that is the best and cheapest option when compared to fixing the 3 speed.

I found the following conversion online http://www.novak-adapt.com/ and it looks like it is going to be a little more than $520 or so. I was also wondering if I found a Jeep T18, even a broken one, if I could swap parts from this and make it a good working unit. Any other suggestions?

I took a buddy for a ride in the Jeep yesterday and showed him the behavior. He thinks that the 3rd gear may be out and suspects the synchros are fine. Remember this was loose and stuff was likely out of alignment for a long time. The basic idea now is that 3rd gear is bad or some shafts or bushings/bearings are worn. It it was something very simple, I might fix this T150 unit.

Thanks,

Conor
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Unread 03-26-2012, 10:20 AM   #15
cwatkin
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Also, what about gear lube for the trans/transfer case as well as the diffs??? I have heard that you should used GL5 80w90 in the diffs and a GL4 in the trans/transfer case from several people. I am going to change the differentials soon and see no reason to change the trans at this point if I am going to swap it for something else but want to know what I should use after I swap. I am thinking about going with the T18 the more I look as I have found some used parts to convert it over for not too much.

Thanks,

Conor
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