The BSA A7-A10 Forum

Technical => Clutch, Primary, Gearbox => Topic started by: mike667 on 07.02. 2009 21:46

Title: primary oil n things
Post by: mike667 on 07.02. 2009 21:46
Hey gang
 well with the temps in NY climbing into the low 40s i decided to install the new 389 carb i got from amal today - was able to use the cables from the 930 through they are not ideal- but she fired up 3rd kick after having sat dormant for 2 months (did not sump!) and idles sweetly when warm after adjusting the mix screws - sweet!
 one thing i did notice was that the clutch was not freeing up the gear box -  if the bike was in gear activating the clutch really had little effect on it and i could only kick the bike over if in neutral even with the level full in -  with the bike running getting gears was impossible without grinding away

i am thinking that oil has gotten into the clutch plates from the long sit, probably from toppin it off with to much oil etc during the summer as i  did just kinda pour it into the primary  - my question- is  regular engine oil the "preferred" lub for the primary or do some you folks use ATF (i know some norton guys do) to allow the clutch plates to  operate a little more freely when the lub gets on the plates?

 also i am thinking of the SRM clutch pressure plate- if i need to open the primary up the clean the plates off as they are not to much $
- any comments if it is a worthwhile upgrade or just a "glitter" item ...
Title: Re: primary oil n things
Post by: bsa-bill on 07.02. 2009 22:01
Hi mike - I can recommend the SRM pressure plate, makes for a nice light clutch.
I still get a bit of drag, I rekon I need to slacken the springs off a bit this is mentioned in the fitting instruction that come with the plate but you know how it is - got give them a little extra in case they slip, well there is no slip at all but selecting neutral is difficult due to the slight drag.
Lyford Classics sell an alloy pressure plate a bit cheaper than the SRM one but it does not have the little needle bearing in the end, on the on the other hand you don't need to cut the push rod as you do with the SRM one.
Little tip I heard of ( afer I had set mine up ) is to cut the pushrod in the centre and install a ball bearing inbetween the two halfs, gives a bit of movement on the push rod so it pushes in a straight line ( have I explained that well enough)

All the best - Bill
Title: Re: primary oil n things
Post by: trevinoz on 08.02. 2009 21:02
Mike, if your clutch was OK before you stopped using it, it is most likely still OK.
Clutches tend to stick together during periods of non use. Try putting the bike in gear and locking the back wheel and pull in the lever and kick. It may free up and using it will clean the plates.
If this doesn't work it may be simply a case of stripping and cleaning the plates.
As to the fancy pressure plates, if it ain't broke why fix it?
Title: Re: primary oil n things
Post by: mike667 on 08.02. 2009 22:51
thx Bill/Trev -
 yes i am/was thinking the plates were just stuck too, i drained all the oil out and put some ATF in - bike goes into gear easy now after shoving it into second and driving around the block, figured I just spun the oil on the plates out, probably would worked with out draining the primary of motor oil

   -  while the SRM sounds good as Bill suggests -  if it only makes the clutch lighter i am not to bothered - my bevel ducati and laverda triple have clutches so heavy that even most vintage guys grimace when they feel them  -  make drving in traffic a real treat!
take care
Title: Re: primary oil n things
Post by: BSA_54A10 on 09.02. 2009 10:52
There are fundamental problems with using a lump of pressed steel as a pressure plate.
This comes from the fact that the mechanical properties are different in the rolling direction ( with the grain) than across the rolling direction ( across the grain) .
Even worse is the fact that they ended up with a random orientation due to the way they were made.
So some will have a much more uniform stiffness than others.
To a large extent this explains the difference between owners who tell you that they a fine and give no trouble and others who end up stark raving mad trying to get the pressure plate to lift square.

Next there is the lifting mechanism itself.
Trying to push a rotating plate out squarely with a ball is just plain bad engineering.
Any of the after market pressure plate kits that use a "top hat" or "mushroom" lifting mechanism is a very worthwhile modification.
Apart from turning a wrist strainer clutch into a two finger clutch you will get cleaner gear changes and far less wear to places like the pivot of the handlebar lever, bearing surfaces on the clutch arm and the cable itself. All of which are good engineering and make for much more fun riding.

I have an alloy pressure plate fitted to the OIF A65L and an even better ( spun cast one ) fitted to the B50T .
At the time I could not get alloy pressure plates in the smaller size to fit the B40 so it just has the Devemead lifter fitted which will simply screw into the hole that the BSA adjuster is in.
A bloke in WA was making non threaded lifter cups that fit into the 6 spring pressure plates which I had fitted in my old A10 (long since dead).

As for using ATF in the primary, it is a good idea, if for no other reason that being pink it allows you to work out where those spots of oil on the garage floor originated.

Bike Beesa
Title: Re: primary oil n things
Post by: orabanda on 09.02. 2009 11:29
Hey Trevor,
That bloke in WA (Colin Tie) is still making the 6 spring clutches; I just improved the clutch on a B31 immensely, by fitting one.
Title: Re: primary oil n things
Post by: BSA_54A10 on 10.02. 2009 01:51
Thats the bloke.

I have lost his contact detail could you post them please ?
Better check with him first if he wants them on an open forum but his stuff was really good & I do need some more.
Bike Beesa