Newbie With A Silly Question

[Dughr]

I have been riding for 50 years now and I finally bought a 1971 Triumph T100C, unmolested, matching numbers, never painted, a survivor.

My silly question is what will probably sound silly to a seasoned Triumph pro, but what is the lever on the transmission with e "W R" on it do? I guess I'm not too old to learn new stuff!

Thanks!

 

[Greyfell]

I look forward to learning, also.

 

[Dughr]

I look forward to learning, also.

I think I just figured it out. It is nothing more than a gear position indicator.

 

[Greyfell]

Cool!

 

[Rocky]

The pointer is the gear indicator to the numbers that are worn off the crescent shaped plate.
If the plate was not wiped clean those numbers , left to right, would be 4 3 2N1.
WR has nothing to do with gear position, but it may be an indication to what's inside the transmission/gear box - possibly competition gears or something like that.

 

[speedrattle]

its been almost 50 years since i sold my T100, but i remember that pointer.

i'm guessing that the WR refers to "wide ratio," or standard gearing, inside the box. competition models would be modified with close ratio transmissions. close ratio boxes have always been rare and are sought after by people who still road race these machines.

 

[Rudie]

WR refers to "wide ratio," or standard gearing, inside the box. competition models would be modified with close ratio transmissions.

"wide ratio" is different from both "standard" and "close ratio"; in the case of a '71 T100, all three gearsets are shown and listed in the parts book, pages 26-29; page 29 also says the wide ratio gearset was "Standard on East Coast T100C".

The semi-circular plate and securing screws (they are screws, not rivets) are parts #31 and #32 in the book, Triumph numbers 57-1417 and 60-0208 respectively.

It is possible to extract the existing screws with care. Use a thin, flat blade screwdriver under the plate beside each screw to lift the screw; when the heads are clear enough from the casing to grab with vise grips, pull them out twisting anti-clockwise. When they are out, you'll see they have flutes spiralling around the shank.

You can attach the new plate (with the "4 3 2 N 1") with new "Hammer drive screws", a punch with a concave end and a small hammer. I prefer to measure the diameter of the shank and tap the case holes for similar diameter conventional roundhead slotted screws.

 

[grandpaul]

I prefer to measure the diameter of the shank and tap the case holes for similar diameter conventional roundhead slotted screws.

Oh my.... OH MY!!!!!

You must set rivet counters on edge, just riding by!

 

[speedrattle]

well then, there you go, Dughr.

at one time in the past, there were three gearboxes available. thats interesting to me.

you have one of them, and yours is labelled "WR."

if you ever tske jt apart, would you please post the numbers of gear teeth?

im curious as to whether the "WR" corredonds to the middle ratios that rudie has pointed out

 

[Josheezpapa]

Again, im no expert.. heck, im barely a spurt.. but heres what I think,
I think there are 2 basic 500cc 4 speeds... both have the same top gear ratio of 1:1, the wide ratio would have a lower low gear ratio for off road, log crawling, hills, etc.... the wider set getting from lower low to the same high might be less desirable on the road, as it would lead to a larger rpm drop when shifting... and. Would require a shift sooner leaving stop signs. Etc .... I think t100c's should have the off road wr box.
The 5 speed probably offers the best of both, a lower low and closer ratios.
Scouring parts books should verify some of this, ior spec manuals

 

[Rudie]

There are 2 basic 500cc 4 speeds.

all three gearsets are shown and listed in the parts book, pages 26-29; page 29 also says the wide ratio gearset was "Standard on East Coast T100C".

parts books

On my monitor, "the parts book" in this post and post #7 appears in a different colour from the remainder of the text. This different colour means it is a hyperlink - if you click on it, it will take you specifically to the Triumph 1971 T100 parts book (the o.p. having a 1971 T100R) on the British Only site. If you then go to page 26 and scroll down from there, you will see the three gearsets shown and the separate parts listed.

The 5 speed

The Triumph 5-speed gearset does not fit the 500.

 

[grandpaul]

The Triumph 5-speed gearset does not fit the 500.

I believe there are custom made 5-speed clusters that were made for racing, but no, not from Triumph OEM...

 

[Rudie]

The Triumph 5-speed gearset does not fit the 500.

I believe there are custom made 5-speed clusters that were made for racing,

"for racing" because no kickstart.

 

[Josheezpapa]

I accept correction easily, because I really don't know it all about these.. and I'm working from a pretty gray memory... I don't remember the close ratio box... was that a flat track thing? I know a guy with some awesome and pretty well known flat track stuff, would be interesting to ask him..
I stand corrected on the 5 speed, I thought the trans case was the same for 500 as 650/750... but apparently not.. ive not been around 500s much... when I had my Trident, an occasional riding buddy rode one, but it never needed anything that I recall...

So how does that tr5t trophy trail trans fit in to this? I'd assume low 1st, so wide ratio? I never rode one, I assumed they would be a 5 speed.... but apparently not ? It was a 500 twin.. early 70s

 

[Rudie]

don't remember the close ratio box... was that a flat track thing?

Unlike the 650's, with the exception of 1970, Triumph never produced separate US and UK & General Export parts books for the 350/500. So the close-ratio gearset in the 500 books was essentially available anywhere in the world.

So how does that tr5t trophy trail trans fit in to this?

TR5T is 73 and 74, they were is essentially 71 T100C engine in modified BSA B50 frame. Triumph modified the TR5T cylinder head fastening to the block and the rocker boxes similar to the 71 650 for the same reason, the B50/TR5T frame is OIF, has a large diameter top tube over the engine, that the earlier long head bolts could not clear for fitting/extraction.

If the gearset teeth numbers in the TR5T parts books are correct, TR5T used a mixture of wide ratio and standard ratio cogs.

 

[sikatri]

Nice info y’all!