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Alan's B175 restoration
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SpacedMarine
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April 25, 2020 - 8:50 am
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Think I tend to agree here my old rod was the same where it had been rubbing on the flywheel.I tend to believe that my old rod was an alpha aswell.The bearing surface around the big end was also worn down on the old rod and I had similar distortions around the hole in the crank where it had previously been pressed in.My old big end pin was also a couple of thou" larger in diameter aswell so when I came to fit the new rex big end which was bang on 3/4" the fit was extremely sloppy requiring me to source another crank.A real pain.On the good side though once I'd sorted that the new rod was significantly lighter than the alpha and it runs lovely now apart from boiling batteries.Screenshot_20200425-084300_Gallery.jpgScreenshot_20200425-084252_Gallery.jpg

Note weight difference and copper coating.I'll try and find a better pic of the old rod.

Hth.

What's 7/16 in mm again?

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Alan.Moore
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April 26, 2020 - 10:01 pm
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Update on progress...Still not able to find any data on original size/tolerances of crankpin and conrod eye? Anyone got them ?

As suggested on the forum (and elsewhere) I've been advised that the groove in the drive-side flywheel means its not suitable for use as it is and I think trying to locate a decent second hand one is the way to go. I may have found a B175 one for sale but haven't seen any pics. If anyone knows of one going spare (for sale) let me know.

I do have a spare B175 engine which came out of my 1969 B175 'Cafe racer' so I've stripped that down..... but I think the cranks a D14 (am I correct?) Its got riveted on covers and a 3/4 inch holes in the flywheel for the crankpin.

SDC13501a.jpg

The conrod, crankpin bearing dia and roller bearings/cage measure up about the same as my B175. 

The cranks in good condition (inc the mainshafts) but the Conrod eye has a visible wear band on the bearing track and rollers are a little bit undersize (3.97mm). Like the other crank there is about 2.5 thou total wear but I couldn't feel anything pulling and pushing on the rod.

SDC13514a.jpg

Cheers

Alan

sp_PlupAttachments Attachments

1939 Ariel VH, 1942 Ariel WNG, 1951 Triumph 6T Thunderbird, 1970 BSA Bantam B175, 1980 Honda CB250N, 1986 Yamaha SRX600

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April 27, 2020 - 12:37 am
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Alan.Moore said
 "I think the cranks a D14 (am I correct?) Its got riveted on covers and a 3/4 inch holes in the flywheel for the crankpin."

Yes it is and the rivets like to work loose on occasion, as they did on mine in the `70s.

Nothing`s materialised re your required tolerances. All I`ve spotted is Alpha rod casting no 90-1525 for D10-B175.

Worth giving Alpha Bearings a ring or dropping them an email? Were still trading after sad loss of their main man in 2018, but who knows how C-19 has affected them, some businesses are still ticking over.

....** Please log in to view **

Just found a couple of reviews from last year, last one Sept/Oct time, both good...knowledgeable(that`s promising), fast and well-priced.

Blue

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Alan.Moore
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June 11, 2020 - 5:18 pm
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Its been a while since I last posted but I have made some progress.

Having stripped the frame down and cleaned everything up it was clear that what I thought was all original paint had been over-painted in quite a few places and elsewhere there were patches of rust. Looks like the frames were originally dipped in a bath of enamel paint (no sign of any primer or undercoat) , left to drip off the excess ( lots of drips apparent on the underside of some of the frame castings) and then baked on (stove enameled). What was left of the original paint was very hard 'powdery' when sanding it back and even industrial paint stripper would not touch it.

I've previously sprayed my frames with a spray gun and enamel paint, but its a messy process with lots of overspray and wasted paint. So this time I had a go at brush painting. I used some of Aldi's oil based self priming alkyd enamel (same sort of stuff as Rustoleum CombiColor but a lot cheaper). It takes a long time to fully cure/harden but provides a very tough finish that's resistant to chipping, oil and petrol. Very pleased with the results which are, if anything, a bit too glossy but I think once its fully hard I can knock the shine back with some fine cutting compound.

SDC13593.JPG

One of the centre stand mounting lugs had snapped off sometime in the past right through the middle of the threaded hole! I made a replacement part and heavily 'V'd it both sides so I could get plenty of weld in the joint. I also formed it with a couple of 'ears' to extend up the side of the old casting to give a bit of extra support. 

SDC13576.JPG

SDC13581.JPG

The hole for the bolt needed to be drilled through the weld...well the weld was so hard even a Cobalt drill bit in the pillar drill would not touch it!. Eventually managed to drill / grind my way through using carbide masonry drills with a back angle ground on the tip. Then two hours to tap it out using an HSS hand tap and loads of lubrication!

SDC13585.JPG

SDC13587.JPG

Got a second hand stand off ebay, which will need the feet extending a bit as its off a D7, but the jobs a 'good un'

 

Cheers

Alan  

sp_PlupAttachments Attachments

1939 Ariel VH, 1942 Ariel WNG, 1951 Triumph 6T Thunderbird, 1970 BSA Bantam B175, 1980 Honda CB250N, 1986 Yamaha SRX600

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Alan.Moore
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June 12, 2020 - 1:38 am
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Another update.....

Have had no luck to date finding a second hand B175 flywheel half to replace the one I have with the groove worn in it by the conrod. Probably going to take on the advice to have the flywheel counterbore face machined flat (only needs 20 thou taking off) and fitting a hardened washer which will be held in place by the crankpin. Anyway to make it feel like I'm making progress I've cleaned up the cases with scotchbrite, polished the outers, bead-blasted the head and barrel and given them both a coat of high temp paint. 

SDC13534.JPG

SDC13535.JPG

I've just received a set of bearings from LCB. I contacted them and they confirmed the crank bearings were C3 clearance. No makers names on them but I thought they were worth a punt just to see how 'modern' replacement bearings would fit my crank, bearing in mind the problems others have had and that even the Rex Caunt ones are sold as having been 'lapped' on the ID.

Looking at the spec sheets from bearing manufacturers shows that bearing OD and ID's (nothing to do with the C3 internal clearance rating) are 'graded' to certain set tolerances. For the size we are looking at (0.750") the internal bore tolerance for a Class 0 'Normal' grade bearing is +zero to minus 10 microns (0.010mm / 0.00039" - about 4/10 of a thousands of an inch. Higher class/grade bearings have lower tolerances (the best quality/grade being +zero to -2.5 microns). This shows it is possible for replacement bearings to have a smaller ID, albeit very slight. 

I tried a bearing on my D14 driveside mainshaft and it slid on perfectly, I could feel a slight rubbing as it went on but no force was required. I measured the shaft with a micrometer at 0.7498" so 0.0002 or 2/10 of a thou under 0.750".

I could not get a bearing on any of the other shafts of my B175 and D14 cranks without using some force so didn't try. Whilst these shafts all measured similar on the area where the bearing sits (0.7496 to 0.7498) they were bigger on the leading sections all being 0.7502".

Using 400 grade wet and dry with WD40 I 'polished' the upper area of the shaft only (used washers to cover the area where the bearing sits as I did not want to make this any smaller in dia) and when i got to 0.7498" the bearings slid on nicely. 

So, in my case, the difference between fitting and not fitting only accounted for 0.0004" and was easily remedied with a light polishing. 

A point of note here is that if I had increased / lapped the inner bore of the bearing to enable it to slide down the leading part of the shaft (i.e. I had not polished that section of the shaft) there would have been quite a bit more clearance when they reached the section where they normally sit. So in my opinion lapping the internal bore may not be the correct way to go.

The old bearings (hoffman) slid down the polished shafts really easily with non of the 'rubbing' felt when fitting the new bearings. Its likely that they had 'spun' on the shafts to some extent during their lifespan probably accounting for slight wear in their bores and the slightly small Dia where they sat on the shaft.

Cheers

Alan

sp_PlupAttachments Attachments

1939 Ariel VH, 1942 Ariel WNG, 1951 Triumph 6T Thunderbird, 1970 BSA Bantam B175, 1980 Honda CB250N, 1986 Yamaha SRX600

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June 12, 2020 - 2:26 am
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Some elbow grease gone into your engine Alan, a real showpiece.

Re the stand lug, did you use an arc welder with high tensile rods or several heat cycles? 🙂 Job`s a goodun though eh, that`s not going to snap again. I`ve got one to do, identical, quite common place for them to snap. Never worked out if it`s from folk sitting on the bike with stand down...or bike`s been down the road?

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cocorico
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June 12, 2020 - 7:59 am
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Bravo for the useful and informative description of checking the fit of the bearings, so much more interesting than some of the 'Lockdown' padding that's appearing now.

Engine is looking good and you obviously have engineering skills and equipment ideally suited to restoring old machinery.

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Alan.Moore
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June 12, 2020 - 2:54 pm
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Blue

Combination of E6103 arc and mig wire (I'm not an accomplished welder and my kit is underpowered for that thickness of metal). I did make quite a few passes.... so is it likely that the several heat cycles caused the weld to be so hard? I don't think its going to come off fingers-crossed I think they probably break / weaken due to folks sitting on the bike and then pushing it forwards of the stand

 

Cocorico: thanks for the comments. Good to know my ramblings are of interest.

1939 Ariel VH, 1942 Ariel WNG, 1951 Triumph 6T Thunderbird, 1970 BSA Bantam B175, 1980 Honda CB250N, 1986 Yamaha SRX600

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cocorico
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June 12, 2020 - 3:18 pm
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Alan.Moore said
...Good to know my ramblings are of interest.  

Ah, but your ramblings go from A to B without deviation to Z. wink

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Alan.Moore
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June 24, 2020 - 6:10 pm
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A bit more progress....The tinware and petrol tank were still in its original factory black paint and a good going over with slightly abrasive polish brought back a nice deep shine. However the rear mudguard had quite a few 'spider' webs of rust under the top coat and at some time the battery had spit acid over the front part and pitted the actual metal. I decided to rub it down and re-spray in Jet black cellulose.

First step was to use 600 grade wet and dry (use wet) to sand away the flawed areas. This revealed a light grey undercoat/primer that appeared to have been 'pored' on judging by the presence of numerous drips running from the top down the side of the mudguard. These 'drips' did not showed up in the black finish but were definitely there. I've read that a lot of manufacturers 'dipped' parts in tanks of paint or 'ladled' paint over them before letting them drip dry. 

SDC13640.JPG

Followed the rubbing down with a coat of etch primer and then a coat of red primer. 

SDC13644.JPG

Then three decent coats of grey filler primer. The reason for the red coat is so that when the grey filler primer is rubbed down if the red starts to show through I know that I should not sand in that spot anymore as I'm nearly down to the base metal.

SDC13645.JPG

After the filler primer a thin guide coat, in this case just a blow over with the red primer. The idea is that you flat back (600 wet and dry used wet)  until all the red guide coat has gone as the guide coat will remain in the lowest parts of the surface. When its all gone the surface should be uniform.

SDC13647.JPG

Initially you can still see where the original factory primer had run down the mudguard as the filler primer was being flatted

SDC13648.JPG

I keep flatting until all the guide coat has gone finishing off with 800 grade W&D used wet

SDC13650.JPG

When the primer has had a couple of days to dry I sprayed three decent wet coats of the black gloss. The photo below is the finish straight from the gun after a couple of days of drying...no polishing 🙂

SDC13653.JPG

Cheers

Alan

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1939 Ariel VH, 1942 Ariel WNG, 1951 Triumph 6T Thunderbird, 1970 BSA Bantam B175, 1980 Honda CB250N, 1986 Yamaha SRX600

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thornebt
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June 24, 2020 - 6:52 pm
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That black mudguard is so shiny I thought it was chrome!  It's going to be better than any bike that came out of the BSA factory!  Nice job.  Cheers.  Bruce.

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June 24, 2020 - 8:59 pm
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Hi you may be a professional polisher you can do mine anytime 😎Les 

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Stoo63
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June 24, 2020 - 9:49 pm
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Beautiful, Alan. There was a discussion about powder-coating on the forum recently. I doubt you could ever get a beautiful finish like that without the effort you've put in. Classic!

'52 D1 direct lighting plunger; '58 Square Four (project); '55 D3 Battery; '59 D1 direct lighting plunger;  '59 Tiger Cub; '60 5TA;  '76 FS1-E '97 Honda Sky SGX50.

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cocorico
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June 25, 2020 - 7:10 am
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I've read 'Crome Yellow', but never seen Chrome Black - it's not April, is it?

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Alan.Moore
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June 25, 2020 - 10:29 pm
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Its a very fine line between putting enough paint on to get a really deep high gloss and too much so you get runs. It's far easier/safer to just lay on a few extra thinner coats with a medium gloss and then flat it back with 1500-2000 wet and dry, used wet with some dishwashing liquid, and then use a polish (not a wax polish but something like Meguiars ultimate polish/ pre waxing glaze) to get the shine, applied with an old cotton tea shirt. Doing it this way also lets you sand out any runs or orange peel. I use a small touch up spray gun for mudguards...less overspray and a small fan size. I got lucky with this mudguard as I really put too much paint on in the last coat...but it did come out nice. 

Its been too hot to do any more spraying so have done a few of the nuts and bolts etc in Zinc plate and the fork top nuts and side panel fasteners in Replica chrome.

SDC13655.JPG

SDC13654.JPG

 

Cheers

Alan

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1939 Ariel VH, 1942 Ariel WNG, 1951 Triumph 6T Thunderbird, 1970 BSA Bantam B175, 1980 Honda CB250N, 1986 Yamaha SRX600

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June 25, 2020 - 11:58 pm
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Nice work...great to see someone with a more subtle approach than stainless steel.

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Alan.Moore
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June 27, 2020 - 7:48 pm
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A bit more painting today. I've been trying to find a good match for the wheel brakes plates / hubs plates and rear shocks. There was still original paint on the inside of the front brake plate which was a mid grey/silver colour, slightly metallic. 

Lots of the images I'd seen of 1970ish B175's had hubs that were a lot lighter and more 'silver' than what I was looking at, even taking into account photos do not really show a true representation of colours.

Went on-line and spent hours searching all the BSA forums, owners Blogs and facebook.....nothing really specific regarding folks saying "this colour is a good match" other than a guy who said RAL Classic 9006 was a match for the BSA conical wheel hubs in 1970 and another post saying that Simoniz 5 wheel silver was good.

I had some of the Simoniz wheel silver...too light and too silvery.

I have got a proper RAL colour chip card and 9006 it did look close so got a couple of cans from RS-online (surprised that they were very well priced and free post arriving next day) . It was close but still too silvery...needed to be a bit grayer.

So, having seen a few posts on google of Hammerite smooth silver spray being used on motorcycle engine cases I took a punt and tried it. Have to say its as close to the original paint inside the hub as makes no difference.

Its almost impossible to take a photo which shows the true colour of painted surfaces, especially silvers and metallics, on a computer screen but the one below is pretty close to how it came out. 

SDC13664.jpg

Oh...the damper on the left is a D7/D14 shrouded type with the shroud cut off. One of mine had no damping and a kind chap on facebook sent me a second hand shrouded one. Thanks Ian if you read this.

Cheers

Alan

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1939 Ariel VH, 1942 Ariel WNG, 1951 Triumph 6T Thunderbird, 1970 BSA Bantam B175, 1980 Honda CB250N, 1986 Yamaha SRX600

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Alan.Moore
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June 29, 2020 - 11:11 pm
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Today's main job was re-fitting the swinging arm. The spindle and bushes looked fine when I removed them and although the ID of the bushes were 4 thou bigger than the upper end of the factory specs (given in the B175 manual) and the spindle 1.5 thou smaller than the lower spec there is no discernible free play. I did have to loctite the bushes in the arm as they were only a light sliding fit.

The spindle took a good deal of force to remove using a 4KG copper hammer and brass drift. I cleaned out the frame with some emery, polished the spindle and left the spindle in the freezer overnight. It still needed to be knocked in but nothing like the force needed to get it out.

1939 Ariel VH, 1942 Ariel WNG, 1951 Triumph 6T Thunderbird, 1970 BSA Bantam B175, 1980 Honda CB250N, 1986 Yamaha SRX600

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cocorico
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June 30, 2020 - 7:04 am
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Alan.Moore said
...using a 4KG copper hammer and brass drift. ... 

Wow, that sounds a bit of a beast!

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Alan.Moore
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June 30, 2020 - 4:00 pm
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cocorico said

Alan.Moore said
...using a 4KG copper hammer and brass drift. ... 

Wow, that sounds a bit of a beast!  

As they say its not the size of the tool its how you use it smile ........ and I was bragging a bit, its a size 4 Thor hammer, only weights 2.8KG thumbs-up

1939 Ariel VH, 1942 Ariel WNG, 1951 Triumph 6T Thunderbird, 1970 BSA Bantam B175, 1980 Honda CB250N, 1986 Yamaha SRX600

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