The BSA A7-A10 Forum

Technical (Descriptive Topic Titles - Stay on Topic) => Gearbox, Clutch, Primary => Topic started by: Kieranrebecca on 22.10. 2018 21:35

Title: Gear box
Post by: Kieranrebecca on 22.10. 2018 21:35
I have a RGS replica of a sort it's  an unfinished project i aquired don't know anything about it really .It has a gearbox  with RR T2 stamped on it ,what i do know that if this is as stamped it's blooming useless for the road ,what i dont know is how do i tell if internals are as stamped on case , if it is as stamped i will sell it and purchase a road usable gearbox, hopefully it's just the case .picture for clues
Heres hoping someone can help
Respect  KR
Title: Re: Gear box
Post by: trevinoz on 22.10. 2018 21:55
You could select each gear in turn and rotate the main shaft and count the revolutions to turn the sleeve gear once.
This will give you the ratios and you can compare to the chart.
Title: Re: Gear box
Post by: chaterlea25 on 23.10. 2018 00:25
Hi KR,
An RRT2 box will have several exterior features that are different to STD
Whether the ratios are RRT2 is another matter
Underneath the sprocket the layshaft  blanking plug is steel rather than Bronze bush end
RRT2 should have a screwed in plug or detent plunger housing at the top of the main case rather than a blank part on the case, casting number may be also altered
On the rear of the inner plate the cast part number is over stamped on RRT2
Looking in through the inspection cover you should see the end of  the needle roller bearing not a bronze bush on the layshaft
The gear lever shaft on RRT2 has an extension with a groove to take a circlip outside the lever for additional security

There are lots of fake RRT2's out there *warn*

John
Title: Re: Gear box
Post by: RichardL on 23.10. 2018 00:39
...if it is as stamped i will sell it and purchase a road usable gearbox...

...or three road usable gearboxes. Please know that a genuine RRT2 can bring a lot of money.

Richard L.
Title: Re: Gear box
Post by: beezermacc on 23.10. 2018 08:28
I have an RGS replica with an RRT2 box and it is OK. The gearing is a little taller but, because the bike is a twin it seems much easier to get off the line than my Goldie which really is a pig with the RRT2. I would just use it and if you can't get on with it change it later.
Title: Re: Gear box
Post by: Swarfcut on 23.10. 2018 08:52
  No matter what ratios are inside the box, all gearboxes of this design have one common ratio.  Namely the final drive is 1:1 as in top gear the input mainshaft simply locks to the sleeve gear carrying the gearbox sprocket.

   By "useless" you mean first gear is too tall for a non clutch burning, easy getaway?

   I reckon someone has sold you a myth.  Probably someone with the biggest crank sprocket money can buy.  If anything,  a T2 close ratio box would give a more pleasant ride, without the more pronounced  differences in ratios of the intermediate gears of the standard box.  Easy to change the crankshaft primary gear, gearbox sprocket  and rear sprocket to get the ride that suits you, whether you want acceleration, easy cruising, high top speed or economy. A change here from standard of the original  gearbox and rear sprocket will mean the speedo will not be 100% accurate if driven from the box, because the speedo  is chosen by the calculated number of turns of the rear wheel per mile, not from the actual number of turns.  Changing gearbox or rear sprocket changes this calculated value. Changing the engine sprocket alone does not affect the speedo, but alters the overall engine speed for a given road speed. Changing this engine sprocket involves less work than changing an already installed gearbox sprocket

 You may find that inside there are just standard gears, but you have the needle roller layshaft and mainshaft.

    A box with a needle roller supported layshaft is also likely to be smoother and quieter than one with a layshaft running on worn plain bushes.  If it is what it says on the tin, you are indeed a lucky man.

 Swarfy.
Title: Re: Gear box
Post by: duTch on 23.10. 2018 09:12

 I quite liked the RRT2 box in my Road Rocket (first bike), but it was mostly just used around town, except for a misadventure to Sydney....I was told a few times that they went faster in 3rd gear than top, but never had a chance to test it.

 
Quote
.....all gearboxes of this design have one common ratio.  Namely the final drive is 1:1 as in top gear the input mainshaft simply locks to the sleeve gear carrying the chain sprocket..........

 I think 3rd gear *has* the same ratio for all...the best bit is 2nd gear is closer to 3rd for up/downhill twisties, 1st can be a bit of a struggle at times (uphill starts)....I reckon Beeza-Bills box would be the ducks-nuts for an all rounder
Title: Re: Gear box
Post by: Topdad on 23.10. 2018 10:30
My only experience of an RRT was many years ago on a Goldie that I had the luck to be selling for a guy I knew. I never had any issues with it even 2 up ,infact I really enjoyed riding it ,maybe being only 19 then had something to do with it ! However , I also remember that it's the one bike I should have bought but didn't due to an impeding marriage ,the marriage is still going strong I just wonder where that lovely Goldie ended up ? 
Title: Re: Gear box
Post by: Kieranrebecca on 23.10. 2018 11:13
Many thanks for all the advice, think I'll run the bike first and see how it goes,my next problem is finding a nut that will fit the shaft for the clutch ,I've got a Triumph 4 spring because i was informed it would be best but can't for the life of me find a nut,keep been told this is always difficult, I've had two from Dragonfly neither fits been told to get BSA/TRIUMPH nut ,but from where? It took 4months+ to get clutch after ordering then it came without pushrod and a nut that didn't fit .Hope advice is forthcoming thanks in advance.
Don't know why the photo of kieran came up (thats my grandson Rebecca is daughter )it was ment to be photo of clutch case and cogs ,I'll try again
Respect Dean
Title: Re: Gear box
Post by: a10 gf on 23.10. 2018 11:37
Hello, 1st post, nice picture of a very happy child :O)

One can modify posts, incl. change attachments\pictures. Click 'Modify' in the top post menu, untick the picture to be removed (see attachment), then upload the new correct picture.
Title: Re: Gear box
Post by: KiwiGF on 23.10. 2018 11:44
Many thanks for all the advice, think I'll run the bike first and see how it goes,my next problem is finding a nut that will fit the shaft for the clutch ,I've got a Triumph 4 spring because i was informed it would be best but can't for the life of me find a nut,keep been told this is always difficult, I've had two from Dragonfly neither fits been told to get BSA/TRIUMPH nut ,but from where? It took 4months+ to get clutch after ordering then it came without pushrod and a nut that didn't fit .Hope advice is forthcoming thanks in advance.
Don't know why the photo of kieran came up (thats my grandson Rebecca is daughter )it was ment to be photo of clutch case and cogs ,I'll try again
Respect Dean

Shafts look std to me (not rrt2). You may have a std box, it’s worth looking into this as per above posts.

I think I read the “t” in “rrt2” denotes the use of “timkin” needle roller bearings in the main case, whereas std boxes use plain bearings. This is easily checked.

Edit: it may be “t” for Torrington bearings, not timkin.
Title: Re: Gear box
Post by: berger on 23.10. 2018 12:57
yes they are standard shafts my rrt2 is in bits and shafts are different to those [no scroll on layshaft and only one scroll on mainshaft where the outer bush fits 'the inner of the mainshaft runs in the needle roller in the sleeve gear]  they also have a different drive dog arrangement on the sleeve gear and its mate to standard boxes
Title: Re: Gear box
Post by: chaterlea25 on 23.10. 2018 15:06
Hi Dean,
All the nuts that seem to be available  are underside on the threads *????*
Running a 5/8 x 20 tap through them will sort the problem
If you cannot find someone with a tap locally, you could post the nut to me and I will sort out
John