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TR4/4A Can't get rear extension off. Help!

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bammons

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I am trying to remove the rear extension and seem to have one that will not budge. I have removed the top cover, cross-shaft, fork, release bearing and sleeve, the speedometer housing, and the rear extension. At this point the workshop manual says use the Churchill puller and the Haynes manual says just tap it off with a soft faced hammer. I fabricated a puller (crude) which put a lot of pull on it before it failed. I have separation of about 3/8" from the main casing but will not go farther. It does not appear rusty but has never been apart before. One of the articles on this (Buckeye club I think) says do not force anything - if forcing is required something is wrong. I have a store bought puller now but it still does not want to move (I could apply more pressure). The Haynes TR250-6 owners workshop manual says after removing the flange to remove a circlip from the end of the shaft. The Triumph workshop manual says nothing about this. I do not see a circlip and I just removed a extension from another transmission and there was not one and although hard to remove it did come off. Am I missing something?
 
You did not mention the drive shaft yoke? Also, did you remove the brass bearing and speedo drive gear? I am a bit confused...we are talking about the aluminum tail housing on the tranny, right? Or are you referring to the release bearing extension (cover) on the front??
 
The Buckeyes are right, if it doesn't come right off, something is wrong. I also made up a crude puller that grabbed the raised boss on the end of the tailshaft housing. Very moderate force required. And John is right, it won't come off without removing the speedometer gear first.
Tom
 
Yes I am talking about the alum transmission housing. Yes as mentioned I removed the speedometer housing/drive. Yes as mentioned I removed the clutch release bearing and sleeve. Yes I have removed the top cover and drive flange, large nut and washer. I am using the Haynes manual and factory workshop manual. I have bolted a block of wood to the mounting holes and tried to persuade it that way and them made a puller that certainly applied "moderate pressure" and now have a bearing splitter type remover bolted to the slight ridge at the end and have applied "moderate pressure " or more with it. I have about 3/8 or so of separation and then have not been able to get more.
 
This is a shot in the dark. But a couple of years ago I was tearing down a TR4 tranny and remember something of what you say. I recall that the gears from the lower layer were interfering in the upper layer moving out the back. I had to drop the lower layer of gears to get it to free up.
Charley
 
Charleyf - That step comes after getting the rear extension off. Against my better judgement I applied more pressure to the puller and succeeded in bending the 1/2 rods I used to hold the bearing splitter halves together with no movement of the mainshaft. Unless someone here can offer something I supposed I will need to take it to a shop that has experience with manual transmissions. Rivergate Restorations is just down the mountain from me (on a previous post that was pointed out to me) but I know he specializes in Midgets and Sprites. But I guess I will start off with him and give him a call. I thought surely someone here would have had this problem and have a solution. Quite frankly I am not having much luck here on this forum but I guess it doesn't cost anything to post and see.
 
Right, now that I think of it you can not get to the lower lay shaft until the rear extension is off. So it seems only something with the speedo cable could interfere.
 
OK...

First off, the tail bearing, which is stuck on your main shaft, is what is holding the assembly together. You need a puller which will press on the end of the main shaft, while holding the tail housing. In other words, do NOT pry between the main housing and the tail housing. This is putting the forces into the wrong string of parts. You need to Hold the tail housing and press the mainshaft. That way only the tail bearing and shaft are loaded, not the entire string of gears.

I always use my cheap Chinese press to do this job...but there are other ways.
 
I made a puller with two threaded 1/2 inch bolts, on one end I welded at right angles another 1/2 inch bolt to mount through the rear gearbox mount holes the other end was a 3/8 inch plate placed over the output shaft with two holes to line up my 1/2 inch bolts and screwed down to apply pressure, it didn't come off easy it needed a few good wacks with a gimpy to get it off.
Good luck

Graham
 
I have made or tried both of the puller attachments described above using the trans attachment holes and the small lip at the end but I now believe CJD is correct in that it is only the rear bearing holding it on. Would it be a mistake to heat the bearing? I did get the oil seal out so I could see better what was going on.
 
Just to be clear, are all parts of the speedometer drive removed? Looking at the vol. 1 TRF catalog, plate CL, parts 24, 20, and 24 have to be removed before the extension can come off. Ater that, using a puller and applying equal pressure and both sides, it doesn't take too much force to separate the inner race from the shaft and remove the extension. http://trf.zeni.net/TR6bluebook/83.php#navbar
Berry
 
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When I had to rebuild my TR3 transmission I heated up the extension housing with a heat gun. It slipped right off when it got hot enough.
 
I am certain it is a matter of corrosion on the mainshaft and/or a burr. Heating may help...just be careful not to overheat.
 
If all else fails, I would probably try to cut that bearing apart with a Dremel and abrasive cutoff blade. Make a notch where you can work each ball out (after cutting the carrier), then you can separate the housing from the shaft. The outer race should tap out easily, but you may have to take the Dremel to the inner race to get it off the shaft.

At least that way you can be sure it's the bearing stuck to the shaft, and not something else.

Since both the shaft and the inner race (which is the joint you're trying to separate) are steel, I doubt that moderate heat is going to help much. And you probably don't want to get too carried away with the heat.
 
Heat the extension which is aluminum that will expand at a different rate than steel. At the right temp the extension will slip off the bearings. Couldn’t tell you degrees but it was to hot to touch with gloves. If I hadn’t rebuilt my transmission on my BMW bike and using heat to take it apart and going back together per the manual I probably would have broken the housing.
 
Did I remember wrong? I'm pretty sure there is a lip inside the extension housing that means the bearing must come off with the housing.
But its been a long time since I worked on a nonOD box, so maybe I'm wrong.
 
You are right, that bearing and the extension are going to come as one off the output shaft.
If all else fails and you are worried about damage, take it to a machine shop. They will press it off for a few bucks.
 
There is a shoulder in the extension housing so cutting the bearing cage may be the only way to remove the housing with the inner race stuck to the main shaft.
IMG_8142.jpg
 
I am not a fan of using heat but if the bearing was put on with red lock tite heat is the only way to get it to come off. Frank
 
I want to thank everybody who has responded to my request for help. I now have the extension off. I decided to give it one more effort before taking it to a machine shop. I am going to outline what happened and how I got it off for the benefit of anybody else who has this problem. First it was very stuck via the rear bearing on the mainshaft. I fabricated a puller and then purchased a puller set from HF. Both of these pullers exerted quite a bit of pressure but did not budge the extension. Because I am not experienced at this I had serious doubts I was doing this right. After reading CJD's reply I realized that it was just simply very stuck and not having a shop press that I would not be able to get it off. Most of you have indicated that a puller worked for you but for those of you that are lucky like me some require a lot of force. Because there was about 3/8" gap between the cases I was able to cut shims and lightly drive them in around the ext base, support the bell housing on 2 x 4's and then hit the mainshaft with a small sledge. After small movement I would reshim and hit again by repeating this I eventually got it off. Also I turned the large castle nut upside down and threaded it even with the end of the mainshaft to help prevent damage to the threads. Once again thanks for the advice.
 
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