1967/1969 Bonnie Rebuild Desert Sled Project

[grandpaul]

heres one i made to torque the base nuts i just stick it on the end of a half inch torque wrench

this makes the total torque wrench six inches longer, so i reduce the reading on the wrench proportionally. to get 35 poundsfeet on a cylinder base nut, i think i apply 27 to the wrench, iirc

heres an online formula

https://www.norbar.com/Support/Calculators/Torque-Wrench-Extension-Formula

PERFECT pictorial answer.

 

[Sundance]

cant remember exactly when triumph went from british standard to unified threads. mid 69? or not until 70? were the 12-point base nuts ever anything but UNF?

if those base nuts are UNF, go buy a cheap half-inch 12-point combination wrench somewhere and then grind or file the box end down until it drops over the nut.

you can fit a half-inch torque wrench into the open end of the wrench when you put it back together and calculate the reduced figure to use to correctly torque the cylinders back on.

OK, I like this idea, elegant in a way.

 

[Sundance]

You would be even more chagrined if you bought "12 point Whitworth wrenches" ... as the nuts are UNF thread, 1/2" AF for the 3/8"UNF, 7/16" AF for the 5/16"UNF.

Plus you "need very thin 12 point" AF wrenches. While there might be other "thin" wrenches that will not break when you pull hard on them when loosening or tightening the nuts, you might want to consider Snap-On. Not cheap but (should be) no quibble replacement if you do break one.

However, if you will be concerned about correct torque when reassembling, if you buy just a plain wrench with 7/16" AF at one end and 1/2" AF at the other, when reassembling you will need to cobble up something like a fish-weighing scale hooked into the other ring combined with calculating the necessary pull on the scale based on the length of the wrench.

Otoh, certainly Snap-On offer tools with the 12 point ring at one end and a square drive hole at the other end for connecting to a torque wrench. If you have Magpie Syndrome, a Snap-On van is particularly dangerous for your bank balance ...


Regrettably nonsense. When the head was cast, how would the caster know it was going to be a "replacement"?

From information posted on A.N.Other forum, at some point HDA was acquired by a British aircraft maker (Hawker-Siddley?). Primary reason for this was several makers had experienced aircraft crashes, some regrettably with loss of life, subsequent investigations identifying casting errors in one or more critical components (e.g. main wing spars ...) as causes. This aircraft maker acquired HDA so it could apply stricter quality control to castings; one q.c. measure was to stamp every casting with a furnace and batch code so, any subsequent failure, all castings in the batch could be identified easily. Educated guess says, once the furnace/batch code was being stamped on castings, the previous year-number-month-ticks marking wasn't necessary?

When the aircraft maker acquired HDA, Triumph was already one of HDA's customers, HDA continued to cast for Triumph for many years.


It is stamped because it is indented into the casting; "cast" would be raised, like the "H.D.A." and the part number.


Better would be find some proper AF wrenches to remove the cylinder ...?


The UNF/UNC barrel base studs (UNC into the crankcase) and 12 point nuts first appear in the 69 twins parts books. However, aiui they were actually first fitted to bikes made in late (May or June?) 68 production (along with other "69" parts like the 6-3/4" centres fork yokes); iirc there's a 'from' engine number buried in A.N.Other forum?


Just to confuse, aiui there have been (a) aftermarket batch(es) of Cycle 12-point nuts ...


Given the state of the fasteners in your images, the ground/filed box end could well break unless the nuts loosen easily. Earlier this year, I lent such a modified wrench I had owned for years to a halfwit who had apparently tightened his spark plugs with a three foot breaker bar, but then did not carry a plug wrench (or the three foot breaker bar) in his bike's toolkit ... Ime, particularly barrel base nuts, if you did not tighten them with a ground/filed box wrench, luck for loosening them with one.

Great history and advice. So it seems I need to learn a bit more about the many different kinds of fasteners of the world. I would imagine at some point Triumph made a wrench just for this purpose? And perhaps those are not easy to come by? I have been looking at the snap on products to see if they have the perfect piece for this, but will probably end up with the 1/2 inch and some filing/grinding.

 

[Sundance]

heres one i made

to torque the base nuts i just stick it on the end of a half inch torque wrench

this makes the total torque wrench six inches longer, so i reduce the reading on the wrench proportionally. to get 35 poundsfeet on a cylinder base nut, i think i apply 27 to the wrench, iirc

heres an online formula

https://www.norbar.com/Support/Calculators/Torque-Wrench-Extension-Formula

OK, these are great photos - thank you. I see how to do this now. Thanks!

 

[Sundance]

PERFECT pictorial answer.

Yes, yes!

 

[Rudie]

imagine at some point Triumph made a wrench just for this purpose?

60-1907. It is shown illustrated correctly in a 69 parts book but mis-described as the earlier "D370 Ring spanner 3/16 x 1/4 in. Whit."

And perhaps those are not easy to come by?

Correct. Ime, almost anyone who has owned a new Triumph seems to have kept either the whole tool kit or at least that wrench when they sold the bike ...

"Tricor Andy" sells his version but I do not know if any US spares dealer sells them, or whether the 1/2" wall thickness is thin enough.

I have been looking at the snap on products to see if they have the perfect piece for this, but will probably end up with the 1/2 inch and some filing/grinding.

I did post, "if you will be concerned about correct torque when reassembling" ... before I discovered all the exotic shiny tools that could be used to tighten Triumph barrel base nuts to the n'th degree of accuracy, I hand tightened with just a 1/2" box wrench ... no problems ...

seems I need to learn a bit more about the many different kinds of fasteners of the world.

Starting with what you "should" find on your bike ...

67 cycle parts, fasteners 1/4" diameter and larger, Triumph used British Standard Cycle thread, most fasteners will be 26 tpi except large diameters like wheel spindles, which will be 20 tpi. Exceptions:-

. fuel tap threads which are always British Standard Pipe (correct abbreviation is just "BSP", not "BSPP" or other confusing ones used by some in the US);

. if your bike has a 69 onwards front brake, the spindle/nut is UNEF (Unified Extra Fine), the scoop gauze fasteners are 4-40 (UNC).

Note BSC is commonly abbreviated to just "Cycle", Triumph publications often helpfully label it "CEI" (Cycle Engineers Institute, the threadform's abbreviation before BSC) ... and it is incorrectly called "Whitworth" in the US ...

69 engine, fasteners 1/4" diameter and larger, Triumph used Unified (UNF and UNC), which range from 20 tpi (1/4"UNC) through 24 tpi (5/16" UNF and 3/8"UNF) to 28 tpi (1/4"UNF). Exceptions:-

. The 3/8"-26 Cycle bolts/studs into the cylinder block though the head and rocker boxes.

. The oil pressure switch, which is one of the 1/8" National Pipe threads. They are almost always NPS (Straight thread) but some early 69 had NPT (Tapered thread) - this depends on the timing cover, not the age of the engine by the VIN.

Nevertheless, as the bike is already a bitsa and both cycle parts and engine are over fifty years old so have had an unknown number of d.p.o. (previous owners with low competence ...), a wise addition to your toolkit will be an inexpensive set of "screwpitch gauges".

If you search the quote online and look at the returned images, you will see each "gauge" is a piece of metal with serrations along one edge and a number printed on it. Metric sets are so-marked, Imperial are marked either "Whitworth" (common) or "Unified" (less common).

Sets are used trying gauges in turn lengthways along a fastener until a particular gauge's serrations fit in the fastener thread exactly. The number printed on the gauge indicates tpi (threads per inch) if is Imperial or pitch (distance between adjacent peaks or troughs) if its metric. Combined with the diameter of the male thread, you can look up the thread online.

The last paragraph is not as tedious as it looks - most fasteners are between 1/4" and 3/8" o.d., irrespective of whether they are Cycle or Unified, as above, their tpi will be between 20 and 28, most Imperial screwpitch gauge sets only have even numbered individual gauges.

You do not need separate "Whitworth" and "Unified" sets, either is good enough for all Imperial threads. Otoh, useful will be:-

. an Imperial set combined with Metric; ime some d.p.o. are not averse to using easily available metric fasteners;

. the "Whitworth" or "Unified" set with gauges for 19 tpi and 27 tpi - respectively fuel tap BSP and oil pressure switch NP, so useful when parts do not fit.

Finally, I deliberately only mentioned "fasteners 1/4" diameter and larger" above. Fasteners smaller than 1/4" diameter are almost always BA - "British Association" ... but I have mentioned the UNC thread in 69 onwards front drum brake with a gauze shield over the airscoop ...

BA uses prefix numbers to summarise diameter and tpi/pitch. 0BA is the largest (not used by Triumph), thereafter the bigger the number, the smaller the screw. 2BA is the most common, thread diameter a gnat's under 3/16".

Be aware 2BA is very similar to both 10-32 (UNF) and M5 (5mm metric). However, they are not the same - both 10-32 and M5 are a slightly - but significantly - larger diameter than 2BA. Avoid the temptation to believe the reason a male thread does not 'fit' is because the female thread is just corroded, when in fact you have been sold a 10-32 or M5 male thread, which will break something if forced into a 2BA female thread ...

Also be aware that, while most screwpitch gauge sets contain gauges with very fine serrations, ime they are actually useless above the 28 tpi of 1/4"UNF; i.e. no good for telling the difference between 2BA, 10-32 and M5 ...

 

[Sundance]

Rudie, grandpaul and speedrattle, thanks for these recent replies. I've been looking all over for a 1/2" crowfoot 12 point wrench that might work for the cylinder nuts but haven't found one. So I did buy an inexpensive 12 point 1/2 inch box wrench and filed it down carefully this evening till it would fit the nuts. I had to file quite a lot. I got all but one nut loosed, then the last one I had to file the wrench down a bit more to fit. Unfortunately it then failed. So perhaps I should have bought a more formidable wrench to alter. This weekend I will try again.

 

[speedrattle]

might have been corroded in place. that wrench i modified ive been using for years. clean up the threads and nuts and you might not be needing so much force next time

 

[speedrattle]

whrn you buy the wrench make sure its forged and not cast

that may be why it broke

 

[Sundance]

60-1907. It is shown illustrated correctly in a 69 parts book but mis-described as the earlier "D370 Ring spanner 3/16 x 1/4 in. Whit."


Correct. Ime, almost anyone who has owned a new Triumph seems to have kept either the whole tool kit or at least that wrench when they sold the bike ...

"Tricor Andy" sells his version but I do not know if any US spares dealer sells them, or whether the 1/2" wall thickness is thin enough.


I did post, "if you will be concerned about correct torque when reassembling" ... before I discovered all the exotic shiny tools that could be used to tighten Triumph barrel base nuts to the n'th degree of accuracy, I hand tightened with just a 1/2" box wrench ... no problems ...


Starting with what you "should" find on your bike ...

67 cycle parts, fasteners 1/4" diameter and larger, Triumph used British Standard Cycle thread, most fasteners will be 26 tpi except large diameters like wheel spindles, which will be 20 tpi. Exceptions:-

. fuel tap threads which are always British Standard Pipe (correct abbreviation is just "BSP", not "BSPP" or other confusing ones used by some in the US);

. if your bike has a 69 onwards front brake, the spindle/nut is UNEF (Unified Extra Fine), the scoop gauze fasteners are 4-40 (UNC).

Note BSC is commonly abbreviated to just "Cycle", Triumph publications often helpfully label it "CEI" (Cycle Engineers Institute, the threadform's abbreviation before BSC) ... and it is incorrectly called "Whitworth" in the US ...

69 engine, fasteners 1/4" diameter and larger, Triumph used Unified (UNF and UNC), which range from 20 tpi (1/4"UNC) through 24 tpi (5/16" UNF and 3/8"UNF) to 28 tpi (1/4"UNF). Exceptions:-

. The 3/8"-26 Cycle bolts/studs into the cylinder block though the head and rocker boxes.

. The oil pressure switch, which is one of the 1/8" National Pipe threads. They are almost always NPS (Straight thread) but some early 69 had NPT (Tapered thread) - this depends on the timing cover, not the age of the engine by the VIN.

Nevertheless, as the bike is already a bitsa and both cycle parts and engine are over fifty years old so have had an unknown number of d.p.o. (previous owners with low competence ...), a wise addition to your toolkit will be an inexpensive set of "screwpitch gauges".

If you search the quote online and look at the returned images, you will see each "gauge" is a piece of metal with serrations along one edge and a number printed on it. Metric sets are so-marked, Imperial are marked either "Whitworth" (common) or "Unified" (less common).

Sets are used trying gauges in turn lengthways along a fastener until a particular gauge's serrations fit in the fastener thread exactly. The number printed on the gauge indicates tpi (threads per inch) if is Imperial or pitch (distance between adjacent peaks or troughs) if its metric. Combined with the diameter of the male thread, you can look up the thread online.

The last paragraph is not as tedious as it looks - most fasteners are between 1/4" and 3/8" o.d., irrespective of whether they are Cycle or Unified, as above, their tpi will be between 20 and 28, most Imperial screwpitch gauge sets only have even numbered individual gauges.

You do not need separate "Whitworth" and "Unified" sets, either is good enough for all Imperial threads. Otoh, useful will be:-

. an Imperial set combined with Metric; ime some d.p.o. are not averse to using easily available metric fasteners;

. the "Whitworth" or "Unified" set with gauges for 19 tpi and 27 tpi - respectively fuel tap BSP and oil pressure switch NP, so useful when parts do not fit.

Finally, I deliberately only mentioned "fasteners 1/4" diameter and larger" above. Fasteners smaller than 1/4" diameter are almost always BA - "British Association" ... but I have mentioned the UNC thread in 69 onwards front drum brake with a gauze shield over the airscoop ...

BA uses prefix numbers to summarise diameter and tpi/pitch. 0BA is the largest (not used by Triumph), thereafter the bigger the number, the smaller the screw. 2BA is the most common, thread diameter a gnat's under 3/16".

Be aware 2BA is very similar to both 10-32 (UNF) and M5 (5mm metric). However, they are not the same - both 10-32 and M5 are a slightly - but significantly - larger diameter than 2BA. Avoid the temptation to believe the reason a male thread does not 'fit' is because the female thread is just corroded, when in fact you have been sold a 10-32 or M5 male thread, which will break something if forced into a 2BA female thread ...

Also be aware that, while most screwpitch gauge sets contain gauges with very fine serrations, ime they are actually useless above the 28 tpi of 1/4"UNF; i.e. no good for telling the difference between 2BA, 10-32 and M5 ...

Rudi, OK, I will keep this conversation in my notebook for reference. I've got a screwpitch guage recently and will have to put it to work. I am sure my from wheel and fork is 1969 from the measurements of the fork, but sure I will have some questions when I take it apart. The cylinder nut removal has been a trial. thanks

 

[Sundance]

whrn you buy the wrench make sure its forged and not cast

that may be why it broke

Yes, first one forged as well as second one. 2 fails. I think it may be due to the lack of clearance on the cylinder since it is a larger barrell - Routt 800CC?

 

[Sundance]

Well, tonight I finally got the cylinder off the engine. I ground down 2 12 point 1/4 inch box wrenches and ended up having both fail, but got enough purchase to finally get the nuts off. When I look at how much clearance there is between the nuts and the cylinder, I can see why a wrench doesn't fit. I wonder if this is because the clearance is different due to this having a Routt 800cc cylinder? If I use this I think the only way to get this back on and torqued will be with a crowfoot wrench that will fit.

So I got the cylinder off and cleaned it up a bit. I'm wondering the best way to get rid of the rust on the fins, especially in between the fins. So wondering if there are any suggestions apart from some kind of blasting. I also noticed some kind of scoring or corrosion in the barrels, curious as it seems sort of organic rather that the result of scraping. Any suggestions on how to determine if this is still a good cylinder to use is appreciated. There are some identification numbers cast into the cylinder. Oh, how about tips at getting gaskets and goo off the mating services - without damaging them?

I removed the tappet blocks, etc and have some photos. These don't look like others I've seen in photos. For one they don't have an oil hole drilled, but maybe that was another year.

I was attempting to remove the pistons, and got the snap rings out of one but the wrist pin did not slide out. I believe I read somewhere that one shouldn't drive this out but should heat the piston to enable the wrist pin to slide out?

On the rocker boxes, what does one look for to determine if something needs replacing? From what I've read, there is the replacing of several washers as well as an O ring in each box.

OK for now. Thank you for all the help so far!

 

[grandpaul]

Have the cylinders checked against the specs, by a competent machinist, unless you have the right micrometers.

I would take a tiny dremel tool and clear a bit mire clearance around that one nut location.

 

[Sundance]

Have the cylinders checked against the specs, by a competent machinist, unless you have the right micrometers.

I would take a tiny dremel tool and clear a bit mire clearance around that one nut location.

OK, thanks. Great idea. Although it makes me wonder how they got the cylinders on in the first place and torqued? It seems a crowfoot 12 point would be the right tool for this. I've a caliper, but no micrometer(s). I'll get the pistons off to see what shape they are in.

 

[Sundance]

I got the pistons off today. One wrist pin slid out easily but I had to heat the other piston a bit to get that one off. So now I've several photos of the pistons. I am new to this but I think these may be too worn/damaged to use again. There are several places on the piston skirts that look like a lot of contact was made with the cylinder. Also, I cleaned the carbon off the domes and there is a number there 090 or 060, not sure how to read this. Inside the pistons there is a couple of identifiers: ROUTTS, and TRW, under TRW is another number. As far as I can tell there are 2 numbers (possibly) that I cannot make out, then "3 - 99".

I was told by the previous owner that this was an 800cc Routt kit. I'm not sure how to read the number on the piston domes, but wondering if these can verify that it is 800cc.

Then, any comments on the condition of the pistons would be appreciated. They seem pretty worn. I suppose this will be important because of I want to use the barrels I'll have to find and have fit another set of pistons for this.

Thanks for any comments. Cheers.

 

[Greyfell]

The left piston looks like it may be recoverable, but certainly not the right - with all that abrasion.

You're right, those numbers under the TRW are hard to read, but based on the snippets I can read it looks like, to me, 283-99.

 

[Sundance]

The left piston looks like it may be recoverable, but certainly not the right - with all that abrasion.

You're right, those numbers under the TRW are hard to read, but based on the snippets I can read it looks like, to me, 283-99.

Thanks Greyfell for the comment. I suppose that it is probably better to replace both rather than just one? The right piston had quite a bit more carbon on it and looked like it had gotten hotter than the left - if that's possible. The right piston needed a bit more help getting off the rod as I had to heat it and then gently drive the pin out, while the left piston's pin slid out with the push of a finger.

 

[speedrattle]

sundance, your motor suffered a partial seizure. the scuffing on the right piston is from the piston getting hot and expanding so much that the aluminum melted to the cylinder walls and then broke free. look above the striations on the right piston and you can see melted aluminum smeared up out of place near the piston pin bore. time for new pistons, and a hone on your cylinders at least. the right hand pin is blued from the heat.

the 060 on your piston tops means they are 0.060-inches oversize from stock. thats close to the last re-bore size you can expect from stock triumph cylinders, which would be 0.080, and is usually not recommended. i don't know about the routt kits-- they may be good to go to 0.080 over. maybe they have enough extra metal to explain your difficulty getting a wrench to fit over the nuts.

the pistons dont appear to have a lot of carbon on them. i have heard that some big bore kits are shipped with tight piston clearances-- if these aren't honed to the correct 0.0045-inches or so before running, they can seize after a short time. according to the internet, the routt kits appear to have been offered with 8.9 compression as standard. those pistons look closer to 11 to 1, rather than than 8.9 to 1. TRW pistons were supposedly one of the piston brands used in the kits, but those are unusual.

get a pretty good ruler and measure the diameter of your cylinder bores across the top. a stock 650 triumph will be 71mm, and a 750 will be 76mm, and 0.060-over will add 1.5mm. your cylinders have the routt triangular casting mark, but looking at those high-compression pistons im interested in what you find.


FWI these pistons are 11 or so to 1

 

[speedrattle]

by 0.60 from stock on your pistons, i mean from whatever the routt bore size was, not the stock triumph 71mm

 

[Sundance]

by 0.60 from stock on your pistons, i mean from whatever the routt bore size was, not the stock triumph 71mm

Thanks speedrattle. I saw what looked like melted piston and wondered how that might occur. i also noticed the bluing being particularly bright on the right hand pin.

On the carbon on the pistons I'm not familiar with what to expect so thought there was a lot. FYI for the photos I had cleaned the carbon off the dome so I could read the markings. That stuff is tough to remove!

I measured the top of the bores as best as I could with my caliper - set to inches, and got 3.051 and 3.042 for measurements of each. Converting this to mm is 77.59 and 77.27. Does that seem to make sense?

On a hand written note I got from the PO, it says the cylinders are Routt 800 kit and the pistons are 10.5 - 1.

The Routt kit was something that happened to be on the bike I bought, I wasn't looking for a big bore. I suppose if it is no longer serviceable I might find something closer to stock. I see Routt/Morgo kits new for sale out there, but only find them in 750cc, so I'm not sure where to find the original dimensions of the 800cc kit I have. I see some possibilities in the MAP catalogue.

Thanks for the interpretation of my parts!