Friday, May 22, 2015

Gearbox Re-Assembly

Prior to assembly...most of the new parts are not shown here.
This is a rather lengthy post...probably my longest, so if you are not interested in some of the more mundane aspects of Triumph Spitfire gearbox assembly, it will be rather dry. You can look at the pictures, though!

Started on the gearbox re-assembly last night. I actually was able to put the entire gearbox itself (i.e., not the rear extension or bell housing) back together in only a few hours. I'm not sure if I was lucky or if it just isn't that hard, but I expected more issues. All of the measurements that I was able to take were good. Unfortunately, a lot of the parts that I ordered either didn't fit or I chose not to use. Well, to be clear, they were more "minor" parts like thrust washers and such. The lion's share (all new bearings, new synchro rings and, of course, the 3rd/Top gear hub that was damaged) I used.

I tried to follow the workshop manual including all measurements and assembly order. I deviated at some points, but not significantly enough that I had a "lesson learned" from how I did it. However, I should have deviated at one point where I didn't and I discuss that at the very end.

While I was in the Navy, and some of my fellow squids will remember, we referred to a little tidbit of knowledge or something that was obscure, but good to know, as an "oolee" or "ooly". There are some Urban Dictionary entries for this, none of which match my definition, of course.
Anyway, I'd like to share some of the oolies (yes, that's the plural spelling...according to me) I discovered putting the gearbox back together. I've included a parts diagram below (separated so I could try and make it bigger and more readable) and will reference it a few times (e.g., 22).

Left side of gearbox from parts manual.

Right side of gearbox from parts manual.
First, I inspected and compared old and replacement parts (I won't say "new" because some of these were definitely NOS). Most everything was exactly the same with the exception of two things: the 3rd gear washer (22) and the rear countershaft gear thrust washer (45).

3rd gear washer (22). New part on left. Notice the shoulder. This was an updated part and acceptable for use...just not mine.

Rear countershaft gear thrust washer (45). New part on left.
So, while both of these parts were brand-spanking new, I didn't use them. The old ones were in fine shape but, more importantly, the new ones just didn't fit. The 3rd gear washer would not fit fully snug down the mainshaft and resulted in way too much end float. The rear countershaft thrust washer was just a bit too thick (I could sight the thickness difference) to install and would have also resulted in too little end float for the countershaft gear. So, after several tries with the new stuff to make sure I wasn't being an idiot, I used the old stuff.  I did use a new forward countershaft thrust washer (43), however.

New forward thrust washer (43), "greased" in to prevent movement. This part was identical to the old.
All of the circlips throughout (6, 23 and 39) were replaced with new. This is a no-brainer, I think, and I recommend you use new circlips. I ordered a few extras of each of these items because they were cheap and I had some if I messed one up.

The countershaft gear (41) (I'm used to calling it a cluster gear) and countershaft (40) went in with no issues (once I used the old rear thrust washer). I used a lot of heavy grease here to hold everything in place, as specified in the manual. In short, you install the countershaft gear and countershaft, measure the end float and then pull (only) the countershaft back out. This causes the countershaft gear to fall into the gearbox a bit to allow installation of the mainshaft and all of its gears. I was convinced at this point that I was going to loose control of either the rear or forward thrust washers (or both) and have to pull everything back apart, but I soldiered on.

View of the rear countershaft thrust washer and the reverse gear and spindle. Notice the fulcrum (part 54) for the reverse gear operating lever...I'll refer to it in a second. 
I then installed the reverse gear spindle (50), operating lever (53) and fulcrum (54). When I was installing it, I did not fully screw down the operating lever fulcrum (you can see in the picture above where the knurled portion of the fulcrum is not fully engaged into the gearbox). This prevented me from mating the operating lever knob (at the bottom) with the groove in the reverse gear. It took me a few minutes and some mild cursing to figure out that I was doing it wrong by not fully tightening the nut (followed by slightly less mild cursing).

Next up was assembly of the mainshaft (1). This was where all the action was and it made me the most nervous. With the exception of the previously mentioned washers, synchro cups (or rings, as I am used to calling them) and the 3rd/Top hub assembly, I used all old parts here because the replacement stuff that I ordered just didn't fit (5, 20, 38). I did, however, replace all of the springs (11) and balls (13) in the 1st gear hub assembly. The new 3rd/Top hub assembly came with them already installed. This was probably my biggest deviation (or, more correctly, omission) from the manual as I did not take the tension test that is called out for the hub assemblies. I took the liberty of assuming that the 3rd/Top was correct as-built and the 1st gear felt about the same after replacing only the springs and leaving the existing shims in there...so I went with it. I guess we'll see if I'll be sorry for this or not.

One other thing I did measure, though probably not too well, was the 2nd and 3rd mainshaft gear end floats on bushes (10, 19). I followed the manual within my capabilities and the measurements came out good. Thankfully, the spec was rather large (0.002" to 0.006") in my opinion.

My end float on bush measuring rig. That's a socket holding it all up and a punch as my parallel piece (not the best choice).
I then assembled the mainshaft with all of the bushes and washers but no gears to check the overall float and this came out fine as well. I sacrificed one of my mainshaft retaining circlips (23) here so, like I said, order some extras.

That being good, I went on to assemble the mainshaft. I pushed on the mainshaft bearing (4) and speedometer drive gear (3) using the bearing puller I got from Harbor Freight. This took some creative arrangement, but nothing too extreme.

Pressing (or pulling, in this case) the new mainshaft bearing on.
Of note, I had to use the bearing cup part upside down for the speedometer drive gear because the taper of the bearing cup caused the plastic gear to start to separate from the metal collar of the drive gear.

Hard to see, but the plastic gear and metal collar are slightly separated. Once the metal collar seated, it all flattened out.
Then it was on to stacking all of the parts onto the mainshaft. You have to do this with the mainshaft sitting in the gearbox, of course. This all went smooth and the mainshaft circlip went on much easier than it came off and it didn't appear to get stretched out at all.

Mainshaft circlip installation. I used small screwdrivers from this point on to push it down the shaft until it clicked in.
One thing I messed up here was that after the circlip goes one, the 3rd/Top hub assembly goes on and it just sorta sits there. It isn't "locked in" until the input shaft is installed. After I got the mainshaft all assembled, including the 3rd/Top hub assembly, I started to knock the mainshaft bearing into the gearbox case. Unfortunately, the 3rd/Top hub assembly had made its way down the mainshaft as I moved the gearbox around and fell down onto the smaller diameter end. As I knocked in the mainshaft bearing, the hub assembly got trapped between the mainshaft end and the countershaft gear. I had to knock the mainshaft bearing back out a bit to provide some room, re-install the hub assembly, and then pay attention as I knocked the mainshaft bearing back home. Thankfully, there wasn't any damage.

The new 3rd/Top hub assembly after "fixing" it.
It was then onto the constant pinion (input) shaft (33). The first thing I did (which, in hindsight, was a mistake) was install the needle roller bearing (34). It is pressed into the gearbox side of the constant pinion shaft where I had earlier found remains of the old one and had to grind it out of there. Thanks to a recommendation from my favorite forum, I knew I shouldn't press the needle roller bearing in so far as to block the oil passages (there are three). I found the holes with no problem, but they were filled pretty solidly with what was probably old needle roller bearing material and I used small finishing nails and light tapping from a small hammer to clear out the passages.

Oil passage cleaning apparatus (a.k.a, finishing nail).
I envision that, as the needle roller bearing started to eat itself, it was a self-fulfilling prophecy once the oil passages filled up with material. I kept the nails in there to prevent driving the needle roller bearing too deep into the constant pinion shaft and I used a small hammer and a socket to drive it home.

Nails through oil passages to prevent driving bearing in too far.
Next up was the constant pinion shaft bearing (36). Like I said earlier, this would have been better done first, but the manual had you install the needle roller bearing first and that's the way I went. The reason I would have done the constant pinion shaft bearing first was that, because of the bearing puller (er, installer) that I was using, I needed to push against where the needle bearing goes (see picture below). I didn't want to put that pressure on the needle bearing, of course, so I came up with another solution.

Using a large wrench as my pushing pressure point. My first attempt was with those two metal straps you see on the right. How'd that work out for me? And, beer...
Once that was done, I installed the constant pinion shaft and knocked the bearing in the same way as the mainshaft (with a small hammer, working my way around 360-degrees). Holding my breath and using that punch from before as a guide/pry bar, I successfully installed the countershaft. Close inspection revealed that all of the thrust washers had remained intact. I rotated everything and engaged the gears by sliding them with my hands. Everything worked, including reverse, and it felt smooth. I was even able to teach my youngest (remember the kid on the pogo stick?) how it all works by showing the rotational speed differences through the forward gears between the constant pinion shaft and mainshaft and then reverse (he was especially amazed by this). So much basic mechanical theory. That, my friends, was what made (and makes) it all worth it.

Once full assembly is complete, I intend to run it through the gears using the gearshift and see how it feels. I'm considering trying to come up with some way to rotate it using a drill. Not sure if this is worth it or feasible, but we'll see. All told, it took me about 3.5 to 4 hours of work to get from the first picture to the last (below; took me half that time just to write this blog entry!). Like I said, this was less time than I thought. So, either it will come apart in a spectacular and catastrophic way once I test drive it or I got lucky and it's put together correctly. Hey, at least I didn't have any extra parts!

Though I've had the car for a while now (two of them, actually), this is really the first time I've done some major work that required disassembling and reassembling (well, outside of the carbs, I guess, but I didn't use the workshop manual for that...probably why I didn't do a great job). My point is that the workshop manual is very well written with good photographs and pretty clear instructions. While it is a factory manual and therefore refers to a lot of special tools (the Churchill stuff), I found that it works just fine as long as you are familiar with the way manuals are generally laid out and have some grasp of vehicular vernacular (I like that phrase...a Fisher original!). Take this from a guy who operated a nuclear power plant in the Navy for 24+ years...verbatim compliance to procedures was my life and I know the difference between a well written procedure and one that sucks. The ones in the workshop manual don't suck. I don't want to link directly to someone's website without permission but if you do a Google search, you will find several sites where you can review or download a copy for the Mk1/Mk2 (and Vitesse/Herald) for free. I do like my hard copy, however, and would recommend you try to secure one of these (what fun is it getting the computer/tablet all greasy!).

Another resource, especially if you have a full-synchro gearbox, is here. I've linked to the start of his tear down. There are several posts following this that fully document (better than I did) his rebuild. Hopefully between his and mine, all of your questions and concerns are taken care of and you dive into your gearbox rebuild without fear!

Nice and pretty.


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