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Pre unit rear wheel alignment issue 61 T120 Part 2 #786617 10/09/19 2:18 am
Joined: Dec 2007
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Oil Changer Online Content OP
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Hoping someone can save me from myself. I am back to "beating a dead horse", but it may be entertaining. Previous thread Part 1 Whining
Here is the condition I am determined to correct-
[Linked Image from pic20.picturetrail.com]
I am wondering if someone would have a good straight lifting handle on the shelf that could check my measurements. According to the duplex frame scale picture below, courtesy of Jonnie Green, The swing-arm offset is .8124 or 13/16".
[Linked Image from pic20.picturetrail.com]
That said, if the center of the rear wheel is aligned with the center of the backbone of the frame, all the other corresponding parts should also be offset - chainguard, brake lever, fender mounting tabs and lifting handle, correct? I have triple-checked my wheel backspace. My chainguard, brake lever fit and align well. I decided to remove the lifting handle and rear fender in order to run a line down the frame to make sure the rear wheel was aligned with the backbone.
[Linked Image from pic20.picturetrail.com]
It does. I then put the lifting handle on the bench and check the offset. The measurements are ID.
[Linked Image from pic20.picturetrail.com]
[Linked Image from pic20.picturetrail.com]
While visually, the rear of the lifting handle is offset, my measurements say otherwise- .0625/1/16".
I also measured the offset on the new fender, which is approximately .700.
[Linked Image from pic20.picturetrail.com]
Important information is, this build, while numbers matching, was a complete basketcase. The lifting handle and rear fender was missing... The lifting handle and rear fender shown are new, because I could not source a proper original. Thanks. Chad

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Re: Pre unit rear wheel alignment issue 61 T120 Part 2 [Re: Oil Changer] #786621 10/09/19 2:39 am
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I suppose I would need an OD measurement from an original part as well at the same spot of "measuring". I have what appears to be approximately 11.200"
[Linked Image from pic20.picturetrail.com]
I would probably need to cut and add approximately .500 to adjust it? When I took the lifting handle off, it was under tension and the fender relaxed closer to the correct "state".

Re: Pre unit rear wheel alignment issue 61 T120 Part 2 [Re: Oil Changer] #786627 10/09/19 8:08 am
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HawaiianTiger Online Content
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Like a badger biting a stick, you ain't gonna let go of this one. More power to you. I did have the other poster add a pic of the rear of his original '62 TR6 and what I saw of that showed that the rear fender was angled a bit so that the tip aligned with the center of the tire. That's one way......apparently the Triumph way. Well, keep at it, You just might find the secret to making these look better. However, you'll never correct the fact that the seat is offset from the center line of the bike. Nothing to be done about that.
Cheers,
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Black Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: Pre unit rear wheel alignment issue 61 T120 Part 2 [Re: Oil Changer] #786660 10/09/19 8:53 pm
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Oh, knowing "Oil Changer," I'll bet he will find a way to correct the seat as well!

Re: Pre unit rear wheel alignment issue 61 T120 Part 2 [Re: Irish Swede] #786661 10/09/19 9:01 pm
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Ugh, Bill made a good point, that I finally get. I believe the sides of the seat fit over the rear frame "hoop". I have to check when I get home. I also need to get a hold of an original lifting handle. I am convinced my new one has no offset in the rear and wrong offset up front. I might need to erase some of it's "memory". Not giving up yet.

Re: Pre unit rear wheel alignment issue 61 T120 Part 2 [Re: Oil Changer] #786664 10/09/19 9:25 pm
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HawaiianTiger Online Content
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I have an original lifting handle on my '57. It doesn't have any offset that I can see. Since the single down tube frame doesn't have the seat loop, the way they managed to get the fender aligned with the tire was to just bend the whole mess to the right, so the fender and handle are at an angle from the center line of the bike. However, the seat comes with a mounting bracket that does have the off set built in so the seat actually sits right in the mid line of the frame. Cool. Then they made the duplex frame......and well that's where you're at right now....
Cheers,
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Black Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: Pre unit rear wheel alignment issue 61 T120 Part 2 [Re: Oil Changer] #786688 10/10/19 3:24 am
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So after Bill enlightened me that the seat will theoretically follow the centerline of the rear frame loop, I installed the RK Letghton seat without the rest of the parts. The seat pan is centered between the parallels of the rear frame loop. With a straight edge in the center of the "incorrect" Dunlop tire, (no worries, I have an Avon SM waiting...) the center of the tire is .3750/3/8" off.
[Linked Image from pic20.picturetrail.com]
I then enclosed the new "lifting handle" to my welding table, squared it up with edges and took some measurements. Appears as though there is too much offset to the front and NO offset to the rear. I will stare at this a bit before proceeding.
[Linked Image from pic20.picturetrail.com]
[Linked Image from pic20.picturetrail.com]
[Linked Image from pic20.picturetrail.com]

Last edited by Oil Changer; 10/10/19 3:26 am.
Re: Pre unit rear wheel alignment issue 61 T120 Part 2 [Re: Oil Changer] #786962 10/13/19 4:52 am
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the complete mess is .300 off the centerline at this point. I will attempt to split the difference. going back together, Mounted the correct Avon SM tire.][Linked Image from pic20.picturetrail.com]

Re: Pre unit rear wheel alignment issue 61 T120 Part 2 [Re: Oil Changer] #786978 10/13/19 1:26 pm
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Laudable persistence in sorting all this out. I think we still give more credit than is possibly due to the build quality of this stuff: no-one had time to stand back and mull over how parts sat when these were going along the assembly line.
'British Customer Service' of the day would have got you short shrift if you decided to challenge the dealer about a wonky mudguard: the best you could hope for would have been for various bolts to be slackened and everything heaved about when you weren't there to watch.

It's also worth noting that 1 degree of offset gives you about 0.2" difference over a foot - just over half of your offset.

I've had similar battles with a low-volume production 1920s lightweight (not a Triumph), with rear suspension.
The more I looked at it, and the closer I measured offsets etc, the worse the alignment issues seemed to become.
I've done what I can, but have also reached a fairly 'Zen' level of acceptance that the whole lot bolts together and averages out to an acceptable compromise.
That I'm the only person on the planet who knows or cares is a small bonus.

"File to fit, paint to match", as one of the wise heads on here has said before.

Nick


"1967 TR6R"
Re: Pre unit rear wheel alignment issue 61 T120 Part 2 [Re: Nick_Smith] #787001 10/13/19 6:49 pm
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Originally Posted by Nick_Smith

I've done what I can, but have also reached a fairly 'Zen' level of acceptance that the whole lot bolts together and averages out to an acceptable compromise.


"File to fit, paint to match", as one of the wise heads on here has said before.

Nick


That was a quote from an engineer I used to work with. I never actually wrote that on any drawing I did. We used to joke about the buildup of tolerances. That means when you dimension something, Everything should be based or measured from one data point or you get a buildup of tolerances. ie. if the tolerances are + or - .010, by the time you've measured ten times you are now at + or - .10.

I'm sure the draftsman who drew up the assembly drawing knew that basically nothing would line up on the back of a Triumph. That would have left to the production engineer whose thankless job was to make the engineer's drawings actually producible.

Believe me, I understand the frustration when some well meaning person will point out that everything on the back of your spotless restoration doesn't seem to line up. When you tell them that's just the way they were, they stare at you with open mouth, guppy style.....

Cheers,
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Black Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: Pre unit rear wheel alignment issue 61 T120 Part 2 [Re: Oil Changer] #787004 10/13/19 7:30 pm
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reverb Online Content
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...man; in that photo the wheel does not look in line; looks tilted in the upper part to the RH side; seeing the rear shocks etc. I had the same problem with a 67 frame. How about to try to put that wheel better in that case the line on the tape would be very near good.

-your shop looks ultra clean and you have the tools etc so "oil changer" is a nickname somewhat "little" for your level.

Re: Pre unit rear wheel alignment issue 61 T120 Part 2 [Re: Nick_Smith] #787010 10/13/19 8:59 pm
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Originally Posted by Nick_Smith
"File to fit, paint to match", as one of the wise heads on here has said before.
Nick

Funny you bring this statement up, until Bill finally got it through my head that the seat alignment is "non-adjustable", I was getting ready to section and weld the lifting handle. I appreciate the comments, being new to attempting "proper restoration", I struggle between that term and improvement or over-restoring. I have to understand that the factory was about production, time and sales more than precision. They also didn't have the tools and finishes we now have. I suppose something like a "torque wrench" probably wasn't used until later.
Originally Posted by HawaiianTiger
Believe me, I understand the frustration when some well meaning person will point out that everything on the back of your spotless restoration doesn't seem to line up. When you tell them that's just the way they were, they stare at you with open mouth, guppy style.....

Yes, and this was ME after looking at pictures of other beautiful restorations or bikes on display, though I would never point it out.
Originally Posted by Reverb
in that photo the wheel does not look in line; looks tilted in the upper part to the RH side

Thanks for the comments Reverb, I'll attribute that angle to inebriated photography. I not real good at capturing good shots or angles on a photo. One thing I have that the assembly line in 1960-61 didn't have is a cheap mounted laser on a tripod from Harbor Freight.
Anyways, I am going to attempt a few tweaks and twists and see where I end up. I will post the success or failure.

Re: Pre unit rear wheel alignment issue 61 T120 Part 2 [Re: Oil Changer] #787075 Yesterday at 07:06 PM
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'+1' on the laser (or in my case a magnetic level with a digital read-out to 0.1 of a degree). I found it a great help in making sure things were properly horizontal, upright, or parallel, and it still gets regular use on various 'makes'.


Another choice quote from a time-served engineer when folks got a bit too deep into the minutiae: "We're not building a watch."

Last edited by Nick_Smith; Yesterday at 07:11 PM.

"1967 TR6R"
Re: Pre unit rear wheel alignment issue 61 T120 Part 2 [Re: Oil Changer] #787085 4 hours ago
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BILL, that "buildup of tolerances" problem became all too familiar when I worked in the design engineering department of the (now defunct) Barber-Greene heavy equipment manufacturing company.

Back in 1968 I was the kid who was sent out onto the shop floor to find out why something didn't fit.
In those days, "datum dimensioning" wasn't used at that plant. When two halves of welded mainframes were to be bolted together, the joining holes were often as much as 6 inches "off."
The shop guys made their own templates to drill new holes where they ought to have been if the engineers had designed it right.

The design engineers were always too proud to make corrections to their blueprints, afraid that changing anything would "destroy interchangeability."
But without correcting the problem there WAS NO "interchangeability." God help the guys in the field who had to repair this junk!

The real HEROES were the production engineers, who had to figure out how to actually MAKE the stuff the design engineers dreamed up.

Re: Pre unit rear wheel alignment issue 61 T120 Part 2 [Re: Oil Changer] #787100 1 hour ago
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So I don't like it, but I think I will have to live with it. In the previous post I said I was off .300 and I would split the difference. I am now at .150 and will move on in respect to a 59 year-old motorcycle. My RK Leighton seat brackets where .1250 so I clamped 1/8 body shims in the shock mounts to do my bending an twisting. I have seen several resorations with axle shims and custom axle nuts for smoke an mirrors. I could spin that stuff on my lathe but this bike is not a custom. I am attempting my 2nd Triumph pre unit restoration, not a custom billet chopper. In my pics, you will see the rear of my seat is "catty-wampous", but it may settle after riding. Glad they didn't use the seat stencil until what, 66?
[Linked Image from pic20.picturetrail.com]
[Linked Image from pic20.picturetrail.com]
[Linked Image from pic20.picturetrail.com]
[Linked Image from pic20.picturetrail.com]
[Linked Image from pic20.picturetrail.com]
[Linked Image from pic20.picturetrail.com]
[Linked Image from pic20.picturetrail.com]
[Linked Image from pic20.picturetrail.com]
[Linked Image from pic20.picturetrail.com]

Re: Pre unit rear wheel alignment issue 61 T120 Part 2 [Re: Oil Changer] #787102 15 minutes ago
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reverb Online Content
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I have 3 Triumphs; One, still not finished bit I had that same problem and most of it was with the swing arm. I did my best (I do not have the right tools) to try to let both arms at the same distance from the ground (or flat surface under)
The bad tilt of the wheel (that I still see in these new set of photos) almost disappeared.


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