T-18 Problem

Hi, all.

I just finished installing a t-18 out of a FSJ pickup into my CJ5.

When I installed the short input shaft, I examined all the gears, etc. Everything looked real good. Nice and clean, no fragments, gears and synchros looked good, etc.

The only thing that was a little worn was two of the nylon caps at the ends of the forks. I got them to stay on, but probably should have replaced them.

I took it for it's first test drive today. It shifted pretty good through all the gears. I was driving along when it jumped out of 4th gear. I had to drive the rest of the way home holding it in 4th gear.

What are the possible reasons for this? Thanks in advance.

 

I have no experience with that particular tranny, but I had a T-90 that would jump out of 2nd gear when the clutch was released. The syncro's were bad in it.

I'd say that or the nylon things might have fallen off again.

 

I'd lean towards the shift fork bushings too.

 

The only thing I can think of is that the front bearing / sychro collar thickness is wrong. I'm no expert on this, but Nick is - maybe he will comment. If you search, you might find some discussion. Apparently there is a thick and a thin front bearing, and the input shaft has to match the bearing/transmission. Fords are all the same, and Jeep used two types (one being like the Ford). Excess end play on the main shaft would allow the shift collar to slide off of the input gear dogs, and it will come out of gear. You have to do something really drastic to make a transmission pop out of 4th, since the only thing happening is that the input gear is locked to the main shaft. Could be that it's not going all the way into gear, but I'd suspect the compatibility problem.

 

Yaa, parts mike has them for less than a buck each. I think.

 

Look at post #28 here
http://www.earlycj5.com/forums/showthread.php?t=47572&highlight=thick+bearing

 

Thanks guys.

I'll replace the nylon caps for sure, then look into the other things that were in the post that Tim dug up. Nice dectective work, Tim!

This kinda sucks, as this swap was pretty challenging for me.

Learned a lot though. Looks like I'm gonna learn a lot more!

 

Just to clarify, ford input shafts primarily could have the Thick or thin input bearing depending on the year of input shaft. I'd definitely pull the top and look at the inserts on the shift forks and see if any have popped off. You also have to match the 3-4 synchronizer assembly to the blocking ring (synchro ring) because if the original trans and input used the "thin" synchro ring the slots that match with the keys are a different width and can cause issues. Usually causes hard shifting into 4th, but without pics of what you're working with it's hard to know. If the fork inserts have fallen off it can cause the 3-4 sleeve to not shift all the way onto the input gear causing it to jump out of gear. If you can post a pic I might be able to help more.

 

Thanks for the info, Nick. I called Novak ( whom I bought the short shaft kit from ) to see whick input shaft bearing comes with the kit.

The guy I preferred to speak with was out, and the guy I DID speak to has given me wrong info before, so I'm not so sure that he's correct.

He told me that the thin bearing comes with the kit, so...that's what's in there now.

The tranny is from a 1979 J-10 with a 360. Do you know which bearing (thick or thin) belonge there?

I'm gonna pull the tower off and start by checking the inserts, find out about that bearing, and go from there.

Thanks, again.

Rich.

 

It depends on the input shaft used, not the transmission. The input shaft that uses the thick bearing (same bearing as rear output shaft) does not use the oil slinger. The input shaft that uses the thin bearing does use the oil slinger between the gear and bearing. If you put in the thin bearing and did not use the slinger then that can allow too much clearance between the input gear and the 3-4 synchro sleeve not allowing the sleeve to fully engage 4th gear. Same thing happens when a thin bearing is used where a thick bearing is supposed to go.

 

Gotcha. Thanks! I'll check it out.

 

Unfortunaltly I know ALL about this particular problem. I too installed the very same tranny in my CJ5. The problem as I remember is the bearings as mentioned above.. There can be more than a few different sizes involved depending on the tranny. Basically what happens is that the space between the input shaft and syncro is too loose as I remember, or maybe it was the gear. . I ended up installing a different size bearing to get the fit correct. It has been over a year since I did this so I am a little fuzzy on the details. I believe that if you do a search for Parts Mike and ask him, he has the down-low on this problem. It is fixable.

 

No need to bug Parts Mike who is a businessman trying to run a business. Already answered the question above. he'll tell the exact same thing I already mentioned.

Also, if a search is done it will bring all this up as it has been covered before pretty extensively. I'll have to do some digging but somewhere I have pics showing the difference in the bearing thicknesses if anyone is interested. I went through all this when Danstew was having the same issue and posted pics, and when someone before him was having issues.

 

Here's some pics...

I believe that the spacer between the pilot shaft and the 3-4 blocking ring IS missing, as Nick said. There is about 1/4" of space between the two. Shows the difference in the second and fourth pics.

The fork inserts were all in tact, amazingly, but I'll replace them anyway.

So...could this possibly solve the problem? If I install the spacer and check the pilot shaft for endplay, and it turns out good, do you think that would be sufficient enough to re-install the tranny?

 

The slinger would definitely help but won't push it back 1/4", but you don't want the cone of the input shaft tight against the blocking ring anyway. Check the clearance between the bearing and front snap ring and see how much space you've got there. If you have the thin bearing in there and no slinger then there should be a gap between the snap ring and the bearing. If no gap and there's no gap between the bearing and the inner shoulder by the gear, then you must have the thick bearing in there and it won't use the slinger. If that's the case, You need to look at the other end of the transmission, like maybe wrong bearing on the output shaft. From the pics it looks like the input gear and cluster gear is not lining up properly which would indicate wrong spacing on the front, but hard to tell for sure. Nickmil

 

I took those pics with the tranny still in the jeep. I'll have to pull it out to check further.

I called Novak, and they said that the thin bearing comes with the kit.

Is it absolutely necessary to separate the tranny from the transfer case to remove the main shaft?

 

If they sent the thin bearing with the input shaft then it most likely requires the thin bearing. It will then need the slinger between the bearing and the gear.

Yup, the transfer case must come off to disassemble the trans. No other way to do it.

 

Well, we took the tranny apart and found that the bearing retainer was heated and cracked all around where the tube meets the flange.

The shaft seal was completely gone...annihilated! All this after just 10 miles of driving the jeep back home from the garage we did the job in!

It appears that the bearing WAS too thin. They apparently come in two thicknesses...20mm (3/4") or 23 mm.(7/8"). My kit came with a 20 mm bearing. The shaft has a dimension of 23 mm from the gear to the snap ring groove. Seems like I need the 23 mm unit.

So the shaft was allowed to slide forward 3 mm.

Here are some pics... The first one is the swapped in short shaft.

The second one is the original shaft. The bearing shoulder is almost 1/8" less.

The third one is the new bearing that came with the kit. It measures 20mm (3/4"). Too thin for the new shaft.

The fourth and fifth pics show the heat discoloration and crack in the bearing retainer.

So... will a new 23mm. bearing, bearing retainer, and seal solve my problem? Thanks for being patient with me. I really appreciate the help.

Rich.

P.S> Why didn't the kit come with either a thicker bearing, or a spacer?

 

If the person who packages this stuff isn't aware of the differences they would think that all Ford T-18 input shafts were the same and send the thin bearing with it as that is what probably 80-90% of them require. The first time I ran into this it drove me nuts trying to figure out why the clearances were wrong until I spoke to an old time trans guru who filled me in. At that time I hadn't run into a late model input that required the thick bearing. The trans I was working on ( I didn't pull it apart) came to me in a bucket. With the thick bearing in place (no oil slinger) you should just be able to get the bearing retaining snap ring on (the one that goes on the shaft holding the bearing in place). If you can't get the snap ring on in any way then the shaft requires the thinner bearing and oil slinger. The thin bearing and oil slinger is still thinner than the thick bearing by itself. I'd speak to Novak and let them know what's going on. Erik is a good guy and needs to know this is going on. The new bearing, seal, and retainer hopefully will fix your problem. Make sure the bearing is oiled when installed or it will run dry until the oil can work its way from the bottom of the trans up to the bearing. This is bad as it will burn itself out until oiled. By that time the damage is done. Also make sure you use vaseline to hold the pocket needle bearings in place between the input and output shaft. DO NOT USE GREASE OF ANY TYPE!!!!!!!! It will not mix with the oil properly, will clog up the oiling holes and cause the bearings to starve for oil. I've seen it time and time again regardless of what some people say. Vaseline will melt away and mix with the oil creating no issues. I use a stuff called Transjel that is transmission assembly lube. It's basically a higher temp Vaseline with some additives in it, but Vaseline works great. In the old days we made our own by whipping Vaseline in a blender and adding ATF, that's right, automatic transmission fluid. Good stuff. By the way, when the thick bearing is required on the input shaft, it is the same exact bearing as used on the output shaft....Let us know how this goes.... Nickmil

 

Good advice, Nick. I called Eric at Novak, explained the situation to him, and he is going to send me free replacements of all the damaged parts, along with the right bearing. He couldn't have been nicer about it.

So...I'll repair it, and let everyone know how it went. Thanks, again.

Rich.