The BSA A7-A10 Forum
Technical (Descriptive Topic Titles - Stay on Topic) => Gearbox, Clutch, Primary => Topic started by: sprint on 09.04. 2013 14:10
-
adm edit: split from http://www.a7a10.net/forum/index.php?topic=6971.0
Sprint,
I would think that you would need a complete gear set plus modifying the cases or at least custom made bushes in place of the needle bearings.
You would also need a new speedo drive.
Much easier to get another box and put yours on the shelf or sell it for really silly money.
Trev.
Hi Trev
Thanks for reply.
Simply replacing the G/B may end up being the simplest way. But I want to fully understand what the implication are of converting a RRT2 box to std before I give up.
-
You might want to check that it is a RRT2 inside! Wouldn't be the first time a standard box has had 'RRT2' stamped on it by somebody.... *eek*
It is confirmed that it has a RRT2 cluster and 23 tooth engine sprocket.
-
Pictures of Tricon switch & headlight switch bezel.
Trev.
Thanks for photos. Really helps to know what you are actually looking for. Doubt that I will ever find an original Tricon though?
-
Doubt that I will ever find an original Tricon though?
I would not be too upset by that, I had lights go out at 90 one dark night in 1962 ish ( I know I know - a gentleman should not venture out at night and defo not go that fast)
it was down to an original Tricon, I have a repro fitted now and so far it's been good, and I have been out at night admittedly not at illegal speeds *smiley4*
Do you know why the switch is Wipac when all the other electrics are Lucas?Huh
No idea other than BSA supply side of things, could be that it was just difficult to get switches for a while after the war so you took what was available or price was right
-
Spoke to Autocycle and they advised that the std mainshaft and cluster would simply slip in? However, the std layshaft would require the removal of the existing needle bearings and a couple of bushes turned up to fit the housings to take the std layshaft? So if that is the case the only parts required would be the need to have a couple of phosphor bronze bushes made and possible a change to the speedo drive gears?
However, when I spoke to somebody else they advised that all you needed to do was the change all the gears on the existing RRT2 shafts to std gears, job done?
Alternatively change the the engine sprocket from 23 to possibly 21 or 20 and leave the G/B alone?
So at this moment there does not seem to be a definitive answer? Possibly only need to change the existing RRT2 gears for std gears or at worst have to find a complete good std cluster (shafts and gears) and remove the layshaft needle bearings and have a couple of bushes made up to accept the std layshaft in the RRT2 box? Or just find a good std complete G/B?
Does anybody actually know if the std gears will fit onto the RRT2 main and layshaft's?
-
Hi Sprint
However, when I spoke to somebody else they advised that all you needed to do was the change all the gears on the existing RRT2 shafts to std gears, job done?
The standard and RRT2 mainshafts are different,
the standard has a spiral groove to take some oil into (or remove it?) from between the 2 bushes in the high speed gear
The RRT2 shaft is plain as the needle roller bearing runs where the spiral is on the std
I will take some photos over the next few days of the different parts and post them
Give me some time as I'm fairly busy at the moment
HTH
John
-
G'day Sprint,
I don't understand the logic in changing the engine sprocket.
As the RGS has a 46 tooth rear sprocket, the 23 tooth sprocket gives an overall final drive ratio identical to the standard models.
John,
I don't have a clue as to why BSA used a Wipac dip switch, maybe Wipac developed it and then flogged it off to the trade.
Different forms were used on the A65, known as a Ducon.
Norton also had them on the Commando.
Trev.
-
G'day Sprint,
I don't understand the logic in changing the engine sprocket.
As the RGS has a 46 tooth rear sprocket, the 23 tooth sprocket gives an overall final drive ratio identical to the standard models.
Trev.
Hi Trev
I think the logic was that with the current RRT2 set up 1st gear pull away means slipping the clutch a lot (hence the reason why I am looking at converting to std) and that by dropping the engine sprocket a couple of teeth it may help without having to change the RRT2 cluster to a std cluster?
-
Hi Sprint
However, when I spoke to somebody else they advised that all you needed to do was the change all the gears on the existing RRT2 shafts to std gears, job done?
The standard and RRT2 mainshafts are different,
the standard has a spiral groove to take some oil into (or remove it?) from between the 2 bushes in the high speed gear
The RRT2 shaft is plain as the needle roller bearing runs where the spiral is on the std
I will take some photos over the next few days of the different parts and post them
Give me some time as I'm fairly busy at the moment
HTH
John
No problem whenever it is convenient to you. Your help and advice is very much appreciated.
As I have not stripped a BSA box before, let a lone a RRT2 box, it is difficult to fully appreciate the differences as there are no exploded diagrams of a RRT2 box that I have seen?
From what I understand the RRT2 box layshaft is supported by two needle bearing rather than the plain bushes of the std box? However, it seems that the bearing journals are a different size so that the two layshafts are not interchangeable?
It is also my understanding that the RRT2 box mainshaft is also supported by needle bearings? I believe it sill has the two roller bearings so does that mean that the mainshaft top gear has the two std bushes replaced by needle bearings?
Your comment about the bearing journal surfaces of the two then make a bit more sense? The spiral groves seen in the diagrams of the std layshaft, as you have indicated, either feed oil to the top gear bushes or try stop it finding its way into the chaincase, which are not present/needed with the needle bearings?
However, it seems that the journal sizes of the two mainshafts are the same size so either could be fitted, but not the layshaft?
There is still the question as to if the RRT2 and std box gears are in fact interchangeable in which case it is only a question of swooping the gears and leave the RRT2 shafts alone?
-
Hi Sprint,
Attached are some photos of the STD and RRT2 gearbox components that I hope will help in showing the differences,
The RRT2 box has a recess machined in the main case for the layshaft thrust washer and two different locations for the detent plunger dependine which camplate is fitted.
It has one needle roller bearing and one bush in the high speed gear
Ask away if you have more questions
HTH
John
-
Hi Sprint,
Attached are some photos of the STD and RRT2 gearbox components that I hope will help in showing the differences,
The RRT2 box has a recess machined in the main case for the layshaft thrust washer and two different locations for the detent plunger dependine which camplate is fitted.
It has one needle roller bearing and one bush in the high speed gear
Ask away if you have more questions
HTH
John
Thanks John
Photos are a great help.
Once I have had a chance to digest I am sure there will be a few questions.
Andy
-
Hi Sprint,
Attached are some photos of the STD and RRT2 gearbox components that I hope will help in showing the differences,
The RRT2 box has a recess machined in the main case for the layshaft thrust washer and two different locations for the detent plunger dependine which camplate is fitted.
It has one needle roller bearing and one bush in the high speed gear
Ask away if you have more questions
HTH
John
Thanks John
Photos are a great help.
Once I have had a chance to digest I am sure there will be a few questions.
Andy
Hi John
A couple of questions that you may be able to help with?
1. Are either the std main and/or layshafts directly interchangeable into the RRT2 box, the RRT2 layshaft looks to be physically longer, but are the bearing journals the same dia's?
2. Does look like it may be possible to keep the RRT2 shafts and simply fit the std ratio gears onto the RRT2 shafts?
Thanks
Andy
-
John,
I am curious regarding your RR sleeve gear and main shaft.
It has been many years but I am fairly sure that the last RR box that I played with had 2 needle bearings in the sleeve gear, no bush and no scroll on the main shaft.
Could yours have been modified at some time in the past?
These shafts suffer pretty badly from wear on the bearing surface and the easy fix is to remove the needle bearings and fit bushes.
Trev.
-
HI Trev,
The mainshaft is plain where the needle roller is and there are two small half scrolls nearer the bush
If two needle rollers were fitted then the shaft would need to be plain all the way and it would need a seal at the outer end????
A new one here looks just like mine
http://www.ebay.co.uk/itm/BSA-GOLD-STAR-A10-GEARBOX-MAINSHAFTS-/261196190651?pt=UK_Motorcycle_Parts&hash=item3cd08193bb
Cheers
John
-
Thanks John,
One tends to forget details after many years! *doh* *doh* *doh*
Trev.
-
Hi Sprint,
Attached are some photos of the STD and RRT2 gearbox components that I hope will help in showing the differences,
The RRT2 box has a recess machined in the main case for the layshaft thrust washer and two different locations for the detent plunger dependine which camplate is fitted.
It has one needle roller bearing and one bush in the high speed gear
Ask away if you have more questions
HTH
John
Hi John
Do you still have the Std and RTT2 gearboxes apart?
If so could you check if the Std 1st and 2nd lay and mainshaft gears fit onto the RTT2 lay and mainshafts? If they do are they the same width when fitted across their faces when fitted to give the same side clearance?
Would like to see if it is/would be possible to just change the 1st and 2nd gears of the RTT2 box with std gears? Only other issue I can see is that the 1st gear on the mainshaft is a press fit which may be a 'selected' fit only and not interchangeable with another 1st gear RRT2 or Std?
-
Hi Sprint,
I had another look at the bits this evening,
I have pressed off and replaced the 1st gear from the mainshaft on a few different boxes, no issues with fit
be careful pressing on the gear as its easy to shatter the circlip by going too far *eek*
It looks feasable to swop std 1st for the RRT2 one, you will also need to change the mainshaft second gear as the engagement dogs are different, the layshaft 2nd gear is identical on both
The RRT2 and STD have the same tooth count on the 2nd gears, the higher gearing on the RRT2 box comes from the higher ratio on the inner layshaft / sleevegear ratio
Std gears on the left, RRT2 on the right
HTH
John
-
Hi Sprint,
I had another look at the bits this evening,
I have pressed off and replaced the 1st gear from the mainshaft on a few different boxes, no issues with fit
be careful pressing on the gear as its easy to shatter the circlip by going too far *eek*
It looks feasable to swop std 1st for the RRT2 one, you will also need to change the mainshaft second gear as the engagement dogs are different, the layshaft 2nd gear is identical on both
The RRT2 and STD have the same tooth count on the 2nd gears, the higher gearing on the RRT2 box comes from the higher ratio on the inner layshaft / sleevegear ratio
Std gears on the left, RRT2 on the right
HTH
John
Thanks John
Your comments and photos are really helpful.
-
Convenient time to pick up this post again.
You may have read in another post the problems I have had with the clutch.
However, before I had to get stuck into that I did manage to do a few miles and have got to say with the close ratio RR2T box it is absolutely impossible to ride on the road. You are having to rev the nuts off it, and it is currently with a complete engine re-built so not good, and slip the clutch just on the level to get going. Trying to pull away on a hill and it just stalls, so something has to be done?
Firstly, while I have the clutch covers off does it make sense to fit a 21 tooth engine sprocket before doing anything else and see what difference, if any, that makes?
I suspects that it will not sufficient on its own and changing some gear gear ratios will also be necessary?
So I am also looking to change just the 1st and 2nd mainshaft and layshaft gears? I believe that they will fit onto the RR2T shafts and are physically the same width?
Can anybody advise on this and is/would changing both the engine sprocket and the 1st and 2nd gears be the right/sensible thing to do as I do not really want to be stripping the whole gearbox out from the frame, though with the the clutch off at the moment it is clearly the ideal time to do both as both shafts can be removed for easier access?
I picked up a very good std layshaft and gears from e-bay so now only need good 1st and 2nd layshaft gears.
-
Could I suggest another course of action, rather than all this cog swapping etc ,seems you've got the basis of another box so why not leave the RRT2 box standard and unmolested and build up another std box ,I've heard of a lot of RGS riders say they have there rrt on the shelf and use the std box for day to day work.You can keep for eventual sale as original or sell it easily or part exchange it but you do have a part there that many people would give there hind teeth for.
I've only ridden a DBD34 goldie with a rrt2 on her which I must say I really enjoyed as the bike was well sorted and I was young then (18) so bullet proof !!
On the other hand could your dislike of the box could just be because of everything else not being fettled yet and would it be worth persevering before you do anything . Please don't don't take offence at this I wouldn't dream of telling someone what they should do with there property ,just offering an alternative to a lot of work and poss reduction in your pride and joy's value and the loss of a very sort after part. Best wishes and hope you sort the bike and get to enjoying it asap, Regards BobH.
-
Thanks for the reply Bob.
Don't really want to have to strip out the existing RR2T box which is why I am looking at the route I am, also even a refurbished std box will be £200/£300.
I would never sell it separately if I took it off as it belongs with the bike.
I understand what you are saying about still fettling the bike but it really is, in my opinion, just simply not practical. In traffic and at junctions you are having to rev the engine and really slip the clutch just to get going and trying to pull away on a hill is really not easy for rider or bike. On a race track or an open road once you have got going it's fine but I use my bikes on all roads and in club runs etc and the RR2T close ration box is simply not usable in those conditions.
Absolutely no offence taken by any of your comment or suggestions.
-
HI Andy,
What engine sprocket is presently fitted?
Also does your bike have the correct RGS 46 tooth rear wheel sprocket?
Standard gearbox is 19 tooth, the higher RGS primary ratio and lower rear drive ratio cancel each other out and the result is almost identical to Super Rocket gearing, I believe the idea was to lessen the stress on the clutch ( my own notion???)
HTH
John
-
Hi John
Engine sprocket is currently 23T with the clutch sprocket at 43T the gearbox at 19T but the rear wheel is 42T!!!!!!!!!!! Absolute madness and no wonder I was having such problems?
What is the best way out of this? Leave the rear wheel at 42 and go ahead with reducing the engine sprocket to 21 and also change the 1st and 2nd mainshaft and layshaft gears to std ratios or do I need too start with changing the rear wheel sprocket to 46T, assuming any are available?
Whilst I have the clutch off it is an ideal time to do any mods to the engine sprocket and gearbox and don't really want to have to strip it down again to be changing the engine and gearbox sprockets/gears at a later time? I would like to go for what ever is the most practical way to have/make the bike rideable for all road conditions now.
Andy
-
Don't you just love this place , the info that is given so freely is beyond price. I hadn't realised the rear sprocket on a RGS was 46 teeth ,as against 42 thats a bloody shock ,no wonder you were having such a hard time everything was out of cinque , well it can only improve from here on, regards BobH.
-
Hi Andy
OMG!!!!
I can only suggest bouncing the sprockets of the sellers head after waking him up with the crank nut *eek* *eek* *eek*
Its becoming obvoius that whoever built (in the loosest sence of the word) the bike had not a clue or purely intended to flog it off to an unsuspecting person
I am now feeling genuinely sorry for you
It maybe cheaper to fit a 21 tooth engine sprocket rather than change the rear an have to get a longer chain to boot
BUT there must have been some reason why BSA used the combination they did?? ( the rivit counters will see this difference!!)
HTH
John
-
Yes very much my own feelings.
Fortunately, I was supplied with the original 21T engine sprocket which will be a lot cheaper than having to replace the rear wheel sprocket and chain. In that configuration the ratios will be as std A10, Super Rocket apart from the RT2T box, which is where I started from.
Even with the 21T E/S I feel that the G/B ratios, particularly 1st and possibly 2nd, are going to be too high for day to day use on all types of road?
Clearly I need to retain the RT2T M/S and L/S's as they are machined to take the needle bearings that are used.
I have picked up a L/S and a good set of L/S std gears and having now stripped the G/B have found that the 1st and 3rd gears of the std gears and the RT2T L/S are totally interchangeable. The 2nd gear of the L/S RT2T box fits either L/S. However, the std L/S 2nd gear with not fit onto the RT2T L/S. The engaging dogs on the RT2T gear are slightly undercut.
So I would like to just replace the L/S and M/S 1st and 3rd gears (3rd gear ratios are the same anyway) of the RT2T box with std gears? I assume that you should change them as pairs so that the dogs match?
What is your feeling about doing that? My main concern is simply getting going and hill starts with the RT2T box which by lowering the 1st gear ratio may solve? There may be a bit of a jump between 1st and 2nd, but I guess it is a case of suck it and see?
As you say, there must have been a reason why BSA changed the ratios but I am not looking for performance and fast or sustained acceleration or top speed for that matter.
The grieve continues by finding the end of the K/S quadrant has broken off so that too has got to be replaced.
Can you advise if the inner of the G/B case and the inner case look right for a RT2T box?
Further I note that with the L/S fitted with the inner case that there is about 1.5/2 mm of play on the L/S between the cases, is that right? It has the hardened shims at each end, approx 2 mm thick and the shim between the 1st and 3 rd gear, approx 1.5 mm thick.
There was a leak from the rear of the G/B which seemed to be coming from the blind L/S needle bearing area. Whilst I have the box apart it make sense to replace it?
It looks like there is a sealing plate on the outer side of the case on the sprocket side?
In any event I need to drift out the bearing and drift a new one in. Can you advise the dimensions of a suitable drift that is required? I assume you drift it out from the inside and the blanking disc will come out at the same time?
-
Hi John
I have measured the distance between the front faces of the RR2T L/S, inc shims and the std L/S, see photos.
The RR2T L/S measures approx 118 mm and the std L/S about 111 mm?
As previously advised, the RR2T L/S has about 1.5/2.0 mm end float play when fitted, is this normal or are extra trust washers needed?
-
HI Andy,
1.5/ 2mm sounds a lot ??, I dont know if different thickness thrust washers are available
The last needle roller box I assembled I had to use two gaskets between the case and inner cover (I was in a hurry *red*) and it would have taken a trip to the city to get at a shim grinder
The STD box with bushes which have shoulders that make the difference between the two measurements
Measurement without the thrust washers should be about equal on both????
""I have picked up a L/S and a good set of L/S std gears and having now stripped the G/B have found that the 1st and 3rd gears of the std gears and the RT2T L/S are totally interchangeable. The 2nd gear of the L/S RT2T box fits either L/S. However, the std L/S 2nd gear with not fit onto the RT2T L/S. The engaging dogs on the RT2T gear are slightly undercut.""
So I would like to just replace the L/S and M/S 1st and 3rd gears (3rd gear ratios are the same anyway) of the RT2T box with std gears? I assume that you should change them as pairs so that the dogs match?""
I'm not quite following you here??????
Gears should be changed in pairs, and the total tooth count of any pair must be the same = 43
I went and checked the boxes that are still apart and both sets of sliding gears (2nd & 3rd) will fit either shaft ???
Go back to the previous page to see the photos of the difference between the RRTT2 and STD gears on the mainshaft ( E & F on chart)
Mainshaft and layshaft STD, E & F are needed to accomodate the STD first gear (G) due to the different engagement dogs
Are we getting mixed up with which each of us is calling second and third???
Too late to think any more tonite *sleepy*
John
-
Have measured the across the faces of the RR2T L/S assy which measures approx 113 mm without any thrust washers compared to the 111 mm for the std assy?
The difference seems to be that the 4th gear is about 2 mm wider than the std 4 gear, see photo. Yes it is fully pressed up against the cir-clip, its just physically about 2 mm wider, but has the correct No of teeth?
The spare thrust washer that I have from the std L/S assy that goes between the 1st and 3rd gear is about 1.5 mm thick and when fitted as well provided only perceptible L/S end play, so would it make sense to fit that to remove the current play I have? The question then which end should it be fitted to?
All the RR2T L/S and M/S's have the correct teeth numbers, though they may have slightly different widths and dog engagements as I have found as the std L/S 2nd gear is not interchangeable with the RR2T 2nd gear on the RR2T shaft with the 4th gear that is 2 mm wider as the RR2T 2nd gear is slightly undercut where the cuts outs are whilst the std 2nd gear is not so you can't slide the two together? Hopefully the photos will explain better?
We may be confusing each other, but as it stands I am currently only looking to change the 1st gear ratio of the L/S and M/S, as that would now be the same as std A10/SR with the 21T E/S and 42T R/S? However, I need/want to maintain the RR2T L/S and M/S's to accommodate the L/S and M/S sleeve gear needle bearings?
Andy
-
Hi John
On looking at a couple of your photos I notice that there is what looks to be a fairly mild counterbore to the rear of the casing where the thrust washer would sit so that the thrust washer will stand proud of the casing?
On mine there is a much more pronounced and deeper counter bore such that the thrust washer is totally lost in the counterbore so the front face is flush with the machined casing face?
If that is the case it would explain why I have the amount of play that I have?
On your outer case I note that there is a radius counterbore cut into the small bearing boss. Was that done during the manufacturing or where the 1st gear has rubbed on the face?
-
Hi Andy,
On my RRT2 box the thrust washer will stand proud about 50% in the rebate
If yours sit flush then the gear will rub on the alloy casing????
Yes at some stage on mine it must have been run without the outer thrust washer *????*
and hence the ""machined "" casing *eek*
HO Hum????
John
-
Well gearbox all back together again. Blind layshaft bearing replaced together with the mainshaft sleeve gear bearing and oil seal (bugger getting the circlip in with a new oil seal) and currently no leaks!
Kept the rear wheel sprocket at 42T and change the engine sprocket to 21T, std A10. Did change the close ratio box 1st gear to std A10 which has made it easy to pull away what ever the incline. However, 2nd gear remains very high and not very usable.
Will put a few more miles on the bike to let it all settle and for me to become more familiar with it all and then may change the rear wheel sprocket to 46T?