The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Gearbox, Clutch, Primary => Topic started by: manxman on 01.06. 2020 23:01
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I have come across a RRT2 gearbox. It has the top plunger location so I guess it is genuine. It has SC stamped under the RRT2. Idid not know they made scrambles RRT2.
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Neither did I know that. I suspect that most of us on this forum will be surprised.
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Something not quite right there as a scrambles box would not have a reverse gear shift pattern.
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The shells are all the same on these special gearboxes. The cluster inside is the main thing,you can count the teeth to be sure whats inside. The only different are rollerbearings the RRT2 has also rollers at the sleevegear. The others only at the layshaft.
cheers Klaus
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Brother had gearbox on his goldie marked CA T2, presumably Catalina spec. Had drillings top and bottom.
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mine has drillings top and bottom with a big plug in the bottom hole, it has one needle roller and a bush in the sleeve gear and two needle rollers for layshaft, when I have put the clutch back together with the correct parts if I don't get on with the rrt2 it will be taken back out. not really had enough miles yet because of the dodgy miss matched parts triumph clutch
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There was an SCT2 scrambles box used on only the 1957 Spitfire.
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It must have SC T gears, don't you think ?
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have a look it only takes 5 minutes
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have a look it only takes 5 minutes
My words
you can be lucky if its a Scrambler gearbox, its much more better with the gearing than the Racing box.
I use in two bike the Scrambler box and it is fantastic.
cheers Klaus
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It is stamped RRT2 with faint SC under the RRT2 stamping. I am stripping the box for clean and service and I will post results.
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And once again one might ask weather the box & the bike left the factory together 70 years ago. ?
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Hi
Post photos of the box and any numbers you find stamped on it,
check the main case and sandwich plate for changed numbers, there are other differences internally too
There are hundreds of "forged" RRT2's out there
John
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Thanks for the reminder, this set of cases came in a job lot. T is for Torrington?
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Hi TC,
That is an SCT box that would have needle rollers on the layshaft only
The number on the back of the sandwich plate and the main case should be over stamped where the cast numbers were, and a steel blanking plug at the end of the layshaft bearing under the sprocket bearing.
John
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Slightly off topic here but couldn't help looking at the cover closely (because of my clutch lever dilemma!) and noticed that the grease nipple used on this cover is the same as mine with concave sides, how do you use a grease gun with this type of nipple, my old gun has to "snap over" the nipple, which is what all the other grease nipples are???? cheers
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No mystery.....that was how grease nipples used to be. The gun just has a cone to match the nipple.
Back in the day, before motor vehicles had maintenance free suspension joints, it was a regular maintenance task to grease these suspension joints frequently. The joints were generally unsealed, no rubber boots and the grease attracted road grit, and along with water, salt spray etc they wore, so only low pressure was required to grease the joints as the internal clearances opened up. The cone connection was adequate for these simple type of joint.
Then came progress, non return valve in the nipple, and sealed ball joints, all requiring higher pump pressure. The push on cone was barely adequate, useless in most cases and the clamp on design became the new standard, so all you need is either an early cone type gun to match the nipple or a modern nipple to fit your gun.
Regarding the problem with the gearbox cover, thin wall bushes can be removed by carefully splitting length wise with a small hacksaw, just cutting enough to weaken them to allow them to be collapsed inwards. I would use heat on an alloy casting to aid insertion of any bush. Big pressure and old castings always carries the risk of cracking. Chance the casting was cracked when the bush was inserted, and being non standard, the interference fit would have been more likely by educated guess rather than by calculation.
Swarfy.
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Agree, thanks Swarfy, so looks like I'll have to replace that old style nipple with the later snap on type, cheers
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Agree, thanks Swarfy, so looks like I'll have to replace that old style nipple with the later snap on type, cheers
1/4 SAE nipples fit just fine *smile*
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I finally got around to counting gears. Counstant mesh 26T, mainshaft sliding 22T, mainshaft sliding 25T, mainshaft 18T. Layshaft 17T, layshaft sliding21T, layshaft sliding 18T, layshaft 25T. Gears in order from output end , layshaft runs on needle bearings, mainshaft on caged rollers. Opinions?
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Another unusual numbering , on the inner cover 67-3345 cast in it with 42-3083 stamped beside the cast numbers.
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Hi
Attached chart should help with the ratios fitted
That changed stamping is normal for a needle roller sandwich plate, what about the main case?
Is there a needle roller bearing in the high speed gear "A" ?
There are difference in the engagement dogs and gear widths between standard and RRT2 gears to add to the confusion
John
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Main case is 42-3005, outer cover 67-3352
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The only gears on the table matching mine are the Daytona !!
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Hi Manxman,
That's fairly rare *ex* I believe,
Having needle rollers on the layshaft would signify DAY T
It must have had been built from parts or had parts replaced at some time??
A search on the net found this topic on Britbike, One owner of a DAY gearbox is very happy with one in his Goldie
http://www.britbike.com/forums/ubbthreads.php?ubb=showflat&Number=684101
I have an RRT2 gearbox for my RGS project but have bought a pair of modified A65 first gears in a bid to make it more usable on the road (Yet another project that has stalled *sad2* )
John
John
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hello john I have the A65 layshaft 26t and a 17t main shaft in the RRT2 now, its a step up from the STD 16t and 27t and works well, I have just put the 4 spring clutch together with the correct parts after finding it built with wrong parts so hopefully I will be able to try out all the gears with a working clutch.
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Hi Berger
Looking forward to hearing how the mod works *smile*
John
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well john this is the update on the first gear 26t layshaft and 17t main shaft in the rrt2 on my bike 500cc shooting star engine. I have now got the 4 spring clutch set up with the correct parts and it is working as it should do so I went for a ride. my bike with standard gearbox fitted and 20t engine sprocket and 20t gearbox sprocket was a thing of beauty to ride. I have only done about 15 miles today but soon found out that in a small traffic build up the first gear was to tall for my liking. once the clutch was fully engaged and I got going it seemed ok regarding the gap from first to second now the clutch is behaving. however it is coming out because I like the Derbyshire hills and dales and two up [ her indoors likes a blast ]first gear would be a problem. I don't want to mess with the 20t engine and gearbox sprockets because it works really well with the standard box i built a while ago. also the whine has come back in my ears in 3rd and the standard box is quiet. so when the time comes it will probably do what I got it for in the first place and go in the norbsa project with a smaller gearbox sprocket.
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Hi Berger
Thanks for the up date, much appreciated
With a 650 and a 19 tooth gearbox I think it would be good?? I will do the maths at some stage
I am not sure what the fate of the RGS will be? I have my SR with a lot of personal preference modifications and history
Not a lot of point of having two such similar bikes
John
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i think your right, and i think that first gear combination could be ok if i dropped my 20 gearbox to 19 but i am not messing anymore because i got the set up just right for the std box through all four gears, even though 2nd to 3rd on a std box takes it off song … for a second or two *whistle* and i can live with that so long as i can do a standing start two up on a very steep hill which i know would be impossible as is without unnecessary revs and slipping the clutch , so here i go again back on the spanners. it would be nice to have loads of old back wheel sprockets and a wheel to match with all the same hole centres and just keep playing with a few extra links of rear chain . single sided drum doesn't let me do that
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Hi Berger,
This Ratio is not listet in the Goldstarboock *eek*
So please tell us the other other sprocket combinations.
Extra Close is 25/18
Extra Close (1956) 24/19
Standard 27/16
cheers Klaus
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hi Klaus no it's not listed , it is a modification using a 17t layshaft std gear that goes with the 26t sleeve gear on a std box. this 17t gear is machined down on the edge to make the step/shoulder to fit in the hole in the sandwich plate next to the main shaft small ball race. this is then matched up with a 26t A65 layshaft gear. hope this explains it.