Britbike forum Forums British Motorcycle specific Brands Bsa bulletin board Restoring (to a point) my '68 BSA Spitfire Mk4

I think you have too many zeros behind the point , one thousandth is 0.001".
If it is a half thou, 0.0005" thats a bit on the tight side, book spec is 0.0015" - 0. 003"

Reminder: crank endplay is checked with the primary drive side fully torqued to specs.

Measurement of the bush (to me) is similar to measuring the valves in the guides: any perceptible play is too much. Check for any wiggle front-to-rear and up-and-down. This is easier done with the parts cleaned of any oil (or grime) so having the cases apart helps. Unlike valve guides, though, a used bush is unlikely to be too tight.

FYI: clutch tool is on its way.

I was definitely using an extra zero in those numbers! I just looked in the service manual and it indicates no more than .003 but doesn't give a minimum. I can see a minimum being desirable so things are jammed up. I also don't see a mention of primary side being torqued, just says ""two halves bolted tightly together to enable the end float to be checked".

btw, I cannot detect any movement when moving the timing-side of the crank from side-to-side. I also heard from the PO that there weren't many miles on the re-build, hence how tight stuff seems to be.

I don't think "minimum" is as critical as long as the crank spins freely. If it doesn't bind up when cold, the amount of play is only going to go up from there as it warms up.

If the endplay is in spec and the cam looks alright, are you still planning on splitting the cases? If not, then the engine can stay in the frame (unless you're planning on a professional paint job on the frame).

I can't recall what your big-end bearings felt like on the rods but the 3 main reasons for splitting cases would be rod bearings, crank bush/bearing, and sludge trap. If you think the previous assembly was done correctly and everything checks out, you might not need to go much deeper (unless you're looking to address oil leaks, etc).

Received clutch center puller today (thanks, Marc), SRM oil pump (pretty blue!), release valve and HT leads from across the pond. Received valve spring compressor yesterday, so we'll see how that works out. Got my weekend cut out for me, esp since the wife's out of town!
As to splitting the cases. Would love to save that effort, but I do not know for sure about the sludge trap. It has a slotted plug, but that doesn't mean much. From what I recall, the big ends felt good when pulling up and down on the con-rods. There is some rocking allowed, but I hear a little rocking is OK (It's on a video I made a few weeks back).
I do plan to send the frame out for blasting and powder coating. Much of the rear needs attention and I figure I may as well make it all look fresh at that point and cleaning rust is one of my least favorite activities.

This is where it's at today: https://youtu.be/BvvXNPwvP_I
stubborn clutch!

For your clutch, rapping on the tool won't do much since it's holding on to the clutch center and the shaft, so you'll push both in unison. You could try some heat on the shaft first, before putting the tool on. Alternatively, and I'll say that I've never done this myself, maybe loosen the transmission door nuts a bit, then give some taps to a drift or punch held against the shaft only.

The hope would be to get the clutch center to pop off the shaft taper, allowing you to slide it off. You're not looking to push the entire gearbox out the right side, just enough movement to break the hold. I don't know that this is a good option, though. Just throwing it out there.

As far as the endplay, I would be happy with the .003" you're seeing. Experience has shown me that trying to "nail it" ends up in frustration. Ambient temperature will mess with a gap that small. You might get closer on the workbench only to find out it's back where you started once you've got sealer in place. That's exactly why there's a min/max range: anything in that range is correct.

You didn't show the cam lobes but check those and the lifters for wear. That'll help see if there's anything to be concerned about. The side-to-side movement isn't relevant in the cam (there is actually a spring on the end of the cam). Check for wear on the bushings and cam lobes. Usually not likely to be much wear there.

If you can, try and get a good picture of the sludge trap plug. If the punch marks are on the crank, they may be original. But if they're on the plug itself, that's a good indication that someone's been in there at one point. That may help dictate whether you need to go any deeper or not.

I had a major struggle with a BSA clutch removal as some might remember. Spray some PB blast or other penetrating liquid in and let it work.
I tried all kinds of 3 jaw pullers in combinations but it finally popped off using the puller and shocking it with some hammer blows on a wrench turning the bolt.

Like Nick says, it’s down to how you hit the end, if you don’t give it some conviction then it won’t budge at all. One good blow is what’s needed and not many lighter blows which would do more damage. Heat and penetrating oil then whack. If it needs more than one whack. Recheck and tighten the tool each time.

If you were going to change all those clutch parts (or at least the centre) I’d consider welding on your puller to the clutch centre. The heat will be so much more than a blow lamp would give out. You would also have the tool permanently fixed onto the centre.

I’d check the sludge trap regardless, I would also fit new big end shells. You might even see a poor regrind job on the journals which means you want to change the crank, in a way of preventing catastrophe later on.

That's a fair amount of work. Got the swing-arm off, Shocks as well. Engine is now on the bench! Wire brush on the case works wonders!

The rods have been polished, so the case has been apart. The after-market pistons look like high compression. Spitfires came with AMAL alloy hand controls rather than the usual steel ones.

Regarding the clutch, maybe what you could try is similar to what MarcB suggests, loosen the gearbox trap door bolts on the timing side then fit an old clutch centre nut on the clutch side mainshaft to protect threads, apply heat and use a few sharp taps with a big hammer and alloy drift. Hopefully this should be enough to break the clutch centre from the mainshaft taper without doing damage.

Also, the frame is '68 since it has the angle bracket for the remote located condenser pack.

Since you've gone this far (time, disassembly, money), you may as well finish stripping the frame of parts and get it painted, same with the hubs. That way you can refurbish the spokes, alloy rims and replace the rusty nipples. '68 Borrani alloy rims, particularly the front rim are very hard to source, so you want it to look good.

Info on Wikipedia (as with Bacons books) is not always accurate. I have read multiple inaccuracies in several of their presentations. One that stands out for the '68 Spitfire, is the "hybrid" (which was coined on this forum) '68's, which were dispatched in April to July '68, not March to May as they have stated.

I have also entered your '68 numbers in the '68 Spitfire registry/database that I maintain. Yours is the first 'hybrid' with the 11000 number sequence in the database. All the others are in the 16000 and 17000 number sequences. The 'hybrids' started at number 11577, but were very random to 17892.

I'll see if I can answer things. The pistons are BSA +0.020 pistons, not aftermarket. The hand controls are chromed steel, not alloy (though I've seen those in the CBS catalog).
I'm still deciding on the clutch. I cannot see enough of the sludge plug to see any punches. It is slotted.
About the frame, it has the '67 battery retainer, though that's bolt-on, so who knows. The frame/engine numbers are from '67 though AFAIK.
I am planning to have the frame re-done. I've stripped the wiring harness tonight and bars. Instruments, not quite sure how to remove, but will work on it. Removed 4 nuts under each, but they don't seem to want to come off the mounting plate (which is a nice cast alloy piece). I hope to deliver the frame for blasting/coating next week.
As for the rims, I would like to shine those up nicely. I would rather not have to deal with truing them up, so I'll see if there's a shop that can do that and mount new tires without mucking up the rims (since, as you said, hard to come by and of some value).
I also hope to have a few part to take to the chrome-er in the next week or two. Need to start a conversation to gauge cost.
If I can just spend an hour each evening.... (of course, same could be said for my desk...)

The gauges are just "inserted" into the rubber cups and can come out by simply pushing up from the bottom. There is a ground wire to one of the cup mounting points. You may need to work them out of the top rubber lip on each cup, then they'll pop right out.

Just to muddy the waters.
I have found that tightening the puller with an air impact hammer usually pops most clutches off the taper.
Failing that I use an air hammer, usually with a pry bar behind the clutch to prevent hammering the bearings
20,000 light blows a minute works wonders.

I saw this on the flywheel. I found drill marks on the centerline elsewhere. These make me think it was dynamically balanced, which is a good thing!

Do not loosen he gearbox trapdoor and try to drive off the clutch centre, you will damage something.

The motor seems pretty fresh, end play is fine, big ends seem fine , there is always a little side to side movement.
Persist with the clutch puller, in case someone has used red loctite on the taper , use heat , get to 200 C plus to break the loctite.
The primary drive can be further stripped to expose the clutch centre. Remove clutch plates, pull the clutch cush centre hub off its splines, now remove the outer basket , front sprocket and chain, this will expose the rear basket bearing rollers, leaving the stuck centre on the shaft, if you still cant remove it you can sacrifice the centre and cut through with an angle grinder to split it.

Use your clock gauge to measure gearbox lay shaft end float before stripping the gear box out.

A little progress: https://youtu.be/M8qASIYE_F0
I've had other things to do around the house, but did manage to spend a few hours w/ the BSA.

Hi David, the numbers on the flywheel are pretty standard, not sure what they stand for but they must have meant something to some one at some time, the off set drilling on the flywheel isn’t standard though, if you rotate the crank look for drilling’s in the “pork chop” area. That would be to balance out rocking couple. Your crank may have been statically balanced before now to compensate for the piston weight but not dynamically.

Otherwise it all looks very clean so someone has at least kept on top of oil changes.

Nice job Dave, I have a 1968 Spitfire also that I have been really slacking off with, hopefully I will get back into it soon. just picked up a in real good shape Dunlop rear rim for it, the Borranni was not in good shape. I have a 1967 thunderbolt on the road and it is fun to ride. keep the updates coming.
Bob

This has been very entertaining to read since I have spent the last couple of weeks putting the engine back together in my ‘68 Spitfire after an overhaul and crank conversion to end feed, in which I was dealing with many of the same things you have been here. Just put the pipes on today and trial fitted the Tank, the carbs are off being sleeved, so the end is in sight!!

I haven’t seen a post in a while so hope you haven’t given up!!

In reading about the clutch puller problems, I’m of the “tighten the outer piece of the puller tight, with the bolt backed completely off, then tighten the bolt tight, and hit the bolt hard with a big hammer, then tighten the bolt again, and hit it again” school of thought, and not the “tighten the bolt with an impact wrench” contingent. However, if someone has put valve lapping compound on the taper (people sometimes do this to try to fix damage to the taper surfaces caused by breaking the key) then you will have a very tough time getting it loose and all bets are off, but keep at it, it will eventually come off.