Triumphrat

Wally

Rob, thanks for the generous offer but just as I had prepared to make my own one showed up. I had the material in hand, but a local contact told me he had one. And I now have an inflator to boot. Thanks again for the offer!

Snakeoil

Well, I said I was going to edit the post that talks about assembling the brake backing plates by adding photos, but the site won't let me edit it now that other replies have come in.

So, here are the assembled backing plates, front and rear.

Front




Rear




Then I started to play with the rockerboxes. If you look in the general forum, you will find a thread where I was questioning the order/placement of the thrust washers and thackeray washers relative to the rocker arms and rockerbox. Thanks to experts like Mr. Pete who posted info on this in previous threads (love that search engine we have here) and two links to posts on the same topic on the Britbike forum provided my Morris the Cat, the confusion was cleared up. Below is a pic of the parts in question in the correct order that they should be assembled in the rockerbox.



While I awaited feedback on the assembly order of the parts above, I machined the special tool needed to ease the o-ring on the rocker spindles into the rockerboxes. It's a simple tool but invaluable. I'll probably use STP as a lube for the o-ring.

Here's the tool. The lighter silver section is the tapered area that squeezes the o-ring down to the ID of the rockerbox bore. The straight section ahead of the tapered section is the same size as the rockerbox bore.



I'll post some assembly pics when I put the rocker boxes together, hopefully tomorrow.

regards,
Rob

Garioch43

Snakeoil,

You might want to check out the smaller inside diameter thrust washer on the rocker spindle.

I found that on my '77 T140V, this was a mistake in the parts manual and it should be the same size as the others, othewise the spindle would not locate properly.

PS - Even with the O ring tool, they are a beatch to insert without splitting, so get a few spares.

__________________


Sam Murray

Aberdeen, Scotland

Snakeoil

Thanks Sam. Based on everything I read, the smaller diameter washer is okay for my vintage engine. And that is what those shafts have been using since it left Meriden from best I an tell. But you do raise a good point. I need to go back and read all those threads again.

My personal opinion of the smaller washer is I think it is a better design. The small 3/8 ID washer butts up against the shoulder on the spindle. The washer in turn butts up against the rocker box. This provides a large steel surface area against the box and precludes pulling the shaft into the soft aluminum casting by over-tightening the nut on the banjo bolt. Without that washer the shallow shoulder on the spindle could be made to burrow into the aluminum rockerbox.

This is all conjecture on my part since this is the first Triumph I've had apart and therefore cannot speak to the other set up with the 1/2" washers having the issues I envision.

And, from what I read, the issue was with the order of the washers, not the ability to bring the spindle home. The washers need to go against the rockerarms in '69 and later designs because the modified the oil passages and the washers play a role in that. The error was the factory put the washers agains the case, a la the old design after the change was made. I believe John Healy said a service bulletin called is error out to dealers.

regards,
Rob

Redmoggy

Little washer is correct fro 66.

Rod

Snakeoil

Made a pilgrimage to the local rubber and gasket industrial supply house. They only had US standard o-rings. So, I bought 2 each 011 and 2 each 012 to try. I also asked them about P80 lubricant and they had some. The counter guy pulled out a small container and gave me some. Since the o-rings were $1.30 each, I really did not get anything for free.

Since M&S, the local Brit shop is right around the corner I went there and got 4 correct E3253 o-rings from Steve. All four were $1.00. Talked to Steve at length about installing the o-rings and he said that you always shave a bit off. He said his trick is to smear a little Threebond or black RTV on the cap inboard of the o-ring and then tap it in place using the factory tool. This way, the sealant takes over if you snip the o-ring. He said he's never had one leak using that procedure.

So, from M&S, went home and tried a few experiments first.

First was the 012 o-ring. The CS on that ring is .062, which is larger than the width of my groove. But since the o-ring ID is smaller than required, it is stretched a bit which seems to reduce the CS. It fit. But when I put it into the tool, there was too much interference. I tapped it into the tool, but it sheared off a fair size piece of the o-ring OD.

So I tried the 011, which is what ed-h said he used. It was a bigger stretch, but same result going into the tool. I think the difference is ed's cap groove diameter was 0.490 and mine is 0.550. So he has much less ring compression than I do. Actually a stock o-ring will not seal with ed's spindle caps. There would be zero ring compression. So I suspect ed's spindle caps were machined at some point to take larger CS o-rings.

By the way, in both experiments above, I tried the P80 and was not impressed. I went back to STP.

I tried one of the new correct o-rings and did my best to nurse that ring and spindle into my tool. I won't bore you with the details and number of methods tried. Bottom line is as the ring compresses that last tiny bit, it gets caught by the sharp edge at the outboard side of the groove and shears an extremely thin slice from the back OD of the ring.

Since Steve said he's never had one not slice a ring and since others have had the same results, and given the schmoozing I did to coerce that ring into my tool and then the rockerbox, I'm convinced that Meriden was knee-deep in 0.0005 buna-n o-ring peelings in one station along the assembly line.

There is another piece of the puzzle that makes a perfect ring installation nearly impossible. It is the chamfer at the entry to the spindle cap hole. Even if you could get it into the tool without shearing, when it jumps across the gap made by the chamfer, it's going to bulge out and get snipped there, anyway. I tried to counter that by machining a matching taper on the nose of the tool. And the chamfer is a 60 deg chamfer not 45 deg as reported by others. It's actually 30 deg from the axis of the spindle which is a 60 deg included angle. This is a typical chamfer angle in machine shops. Even with a tool that matches that chamfer and eliminates the gap, it still sheared an extremely small amount off the o-ring.

So, the rockerboxes are assembled. If the spindles leak, I'll try Steve's suggestion of Threebond or black RTV.

Here are some pics for reference.

Here are the three o-ring sizes I tried.



Here's the tool that compresses the o-ring. The view shows the taper I machined on the end to match the chamfer in the rockerbox spindle hole. It's a little beat up on the end from installing the two o-rings. That' a knife edge.



Here is an assembled box and the mandrel I used to align the thackeray and flat washers. Manual recommends making this tool and I second that recommendation.



Here is a close-up of the nose of the mandrel. Note that I rounded the corners to allow it to smoothly engage and position the flat and thackeray washers.



Here's the assembled rockerboxes.



Here are close-up showing the correct positioning of thackeray and flat washers for a '66 big twin rockerbox.





UPDATE: John Healy replied to a similar thread to what I have in the general forum here, regarding these stinkin' o-rings. He says it is possible to get them installed properly and that the factory tool is useless. Here's a link to that thread.
http://www.britbike.com/forums/ubbth...90&#Post464390

regards,
Rob

Snakeoil

Today, I pulled the spindles out of the rockerboxes to attempt the procedure suggested by John Healy. It was partially successful in that I did get a better feel for what it will take to get the o-ring installed successfully.

First, I made a small brass drift to insert into the end of the spindle to make removal a bit easier with no risk of damage to the spindle.

Here's the drift



Here's the drift in position for spindle removal.



First, using the edge of a 3/16" lathe toolbit, I cut a shallow angle taper as a lead in for the rockerbox hole. John Healy said that the original drawing for the rockerbox shows a 15 degree chamfer on that hole, but for some reason, the factory never cut that chamfer. Using the tool bit like a bearing scraper, it was easy to shave a small amount to give a shallow, gradual lead-in for the o-ring.

First try did not go well. I tried to go too fast. I pulled the spindle and removed the o-ring and found it was partially cut. So I installed my last o-ring and tried again. This time I worked slowly and worked the o-ring into the groove with dental tools shown below while tapping the spindle into the rockerbox with very light taps. Although I did much better, it still sheared a tiny amount from the ring. I'm pretty sure I'm getting the feel for just how diligent you have to be in pressing that o-ring into the groove.

So, I have two more of the smaller ID o-rings from John's kit that I'll try tomorrow.

Here is a picture of the second o-ring showing the cut in the side. I thing it might have sealed fine since the cut is along the side. But I want to see if I can do better with more finesse.



Here are the dental tools I used to work the ring into the groove.



This is a close-up of the tool that seems to work the best. I may change the angle I used to sharpen the tip so it can go deeper into the groove.



regards,
Rob

Snakeoil

Today I tried using an 011 SAE o-ring on one spindle. It's just too fat in CS, even in the over-stretched condition created by putting it on my spindle caps.

Hopefully Steve will be at his shop tomorrow and I'll be able to pick up more E3253 o-rings.

I did have another epiphany today. While screwing with the tires, I pulled out my tire lube so I could easily rotate the tires on the rims. It suddenly occured to me that tire lube would probably make a great o-ring lube as I tried to get those rings installed without shearing them. So, I'll be trying tire lube as soon as I get more o-rings.

In the meantime, I modified my wheel balancer to accept the front wheel/axle assembly. K70 only required 14 gms of weight to make it perfect on the front.

Mounted the rear drum to the wheel prior to balancing.

Rear did not require any mods to the stand and it took 28 gms at the valvestem to balance. So, I deflated it, spun the tire 180 degrees and put the little yellow stamp opposite the valve stem and the rear tire was perfectly balanced. No weight required.

Decide to try and do the same with the front. But mounting with the yellow stamp in line with the stem was the best set up and the 14 gms or weight had to remain.

regards,
Rob

Snakeoil

I hereby admit defeat. Today I bought a dozen o-rings from Steve at M&S. He just chuckled when I tossed them on the counter. I brought him coffee so he probably felt the need to restrain the ball-busting.

I tried 4 more times and came to the conclusion I was just throwing away o-rings. I tried my tire lube this time, and it really made no difference.

I suspect that my problem is the 60 deg chamfer is preventing me from getting my tool in to push the o-ring in the the groove sufficiently to prevent it from being snipped. I thought about hitting the rockerboxes with a spot facing tool, but decided against it. I inspected each of the rings for each of the attempts, and they all appeared that they would seal fairly well, but more like a labyrinth seal than an o-ring.

I may try again if I get the urge. But as of this minute, I'm willing to give it them a chance as they are.

I do have one more idea for a tool. It would be a two piece collet type tool with a camfer to match the camfer in the rockerboxes. If it worked it would be great for replacing o-rings on an assembled engine. We'll see if I can conjure up the ambition to machine it.

regards,
Rob

Garioch43

Hate to say it...........

__________________


Sam Murray

Aberdeen, Scotland