The BSA A7-A10 Forum

Technical => Clutch, Primary, Gearbox => Topic started by: huddie on 11.08. 2008 11:14

Title: BSA A10 clutch push rod length
Post by: huddie on 11.08. 2008 11:14
Hi You guys I've decided to add this as a seperate topic to Frankenstiens cus it is subtly different. My A10 which you have all helped with has now passed its MOT, first time of asking. Am i chuffed about that. I have now tried it along the road all looks fine so far except I haven't been able to stop the clutch dragging (4spring type). This means i cant find neutral without stopping the engine, and it creeps when i blip the throttle with the clutch disengaged. I have now stripped it out, and decided to go for broke and replace all the plates, springs and the push rod. All the bits arrived this morning but my prob is that the push rod has to be cut to length and then have the end hardened. HOW LONG DOES IT HAVE TO BE??. My old Haynes manual gives no info at all.
The old one I took out measures 303mm as close as i can get with a ruler. The new one is 347mm uncut!!. Can anyone help?
I will post a few pics of it now its legal, when i have cropped them down a bit.

Regards Huddie
Title: Re: BSA A10 clutch push rod length
Post by: LJ. on 11.08. 2008 11:49
Not sure about rod lengths, I don't think there is any written recommendations for how long they should be. You could re use the old one if you pop a ball bearing in the pressure plate socket where the rod often is inserted, thats unless you have one there already, just gotta be careful that it don't fall out, bit of tough grease holds it in.

But as you have a new one to play with... I have always cut my push rods to oversize and worked my way shorter until it all *Looks* about right. Ensure that the pressed in ball bearing in the lever rolls around to prevent wear on the end of the rod. (gearbox end)

And finally... hardening the ends of the rod is an absolute MUST and must be done properly too. It will wear down quickly if not.

Congrats on your successful MOT.
Title: Re: BSA A10 clutch push rod length
Post by: dpaddock on 11.08. 2008 14:31
Pushrod from my '57 A10 is 11.96 inches (304 mm) long. Pushrod length depends on the thickness of the clutch pack and the length of the mainshaft; try 12 inches and use the adjustment screw to get the lever arm parallel to the gearbox joint. Saw a bit off the rod if you run out of adjustment.

Harden the ends if it makes you feel good, but note that the compressive stress on the ends is a nominal 2000 psi - well within the yield strength of hot rolled steel.

See my posting 10.8.08
Title: Re: BSA A10 clutch push rod length
Post by: huddie on 11.08. 2008 17:09
Thanks you two for a quick respopnse. I'm off to try it at 12" see how i get on. I will post the result when I have it right.
Regards Huddie
Title: Re: BSA A10 clutch push rod length
Post by: trevinoz on 11.08. 2008 22:29
According to my info there are two rods listed. 42-3108 for six spring clutch and 42-3274 for four spring.
42-3108 = 11.5",  42-3274 = 12".
As stated before, it is essential that you have the plates lifted square and running true when disengaged. It also helps to have a handlebar lever with 1 1/16" fulcrum instead of 7/8" type typically fitted. I had a clutch with all the symptoms as above even though it was set up running as true as possible. I changed the lever to the 1 1/16" type and all the problems were solved.
I make my own rods from 1/4" bright shaft and case harden the ends.
     Trev.
Title: Re: BSA A10 clutch push rod length
Post by: huddie on 12.08. 2008 08:38
Thanks Trev. As already suggested i have cut my new one off to 12" and reassembled it (as yet untried). I am sorry to be a bit thick but i don't understand what you mean about the lever fulcrum. Can you enlighten me more?
In terms of trying it i was going to put the bike in gear and try turning it over on the kick start (plugs out) to see if that shows me that the clutch is fully disengaging. Any other test metods out there?
regards Huddie
Title: Re: BSA A10 clutch push rod length
Post by: LJ. on 12.08. 2008 09:50
Quote
i don't understand what you mean about the lever fulcrum. Can you enlighten me more?

Phew! thank goodness I'm not the only one, Yes please Trev, I need enlightening too! Although I **think** (ever-so-slightly-though) I might know.

Huddie... Sounds like your getting there, but you cant beat a good ride around with tools to finalise and set up the clutch. But! that aint gonna happen for a few days yet with all this rain wer'e having in the UK. It's terrible up here in Cambridgeshire this morning.
Title: Re: BSA A10 clutch push rod length
Post by: trevinoz on 12.08. 2008 23:27
Measure the distance between the fulcrum screw and the centre of the cable nipple. Fulcrum screw is the one which holds the lever onto the bar assembly.
    Trev.
Title: Re: BSA A10 clutch push rod length
Post by: trevinoz on 12.08. 2008 23:31
When I test for run-out, I tape the lever hard to the handle bar, engage top gear and spin the rear wheel by hand. I use a dial gauge to check, probably being too fussy. A pointer of some description is just as good.
                         Trev.
Title: Re: BSA A10 clutch push rod length
Post by: royboy on 24.09. 2008 22:16
 ????Hi all I am new to the forum so sorry for being a bit thick. I may have missed something ref the discussion on clutch push rod lengths. trevinoz's reply on the 13.08.08 "When I test for run out.........." what is this referring to? Is it to another thread or is it to testing the clutch discussion?
regards royboy
Title: Re: BSA A10 clutch push rod length
Post by: RichardL on 24.09. 2008 23:17
I probabaly should let Trev answer this, but I will give it a try, just to be sure I understand. I believe Trev is saying that he wants to assure that the clutch pressure plate releases evenly within the clustch basket when the lever is depressed. By doing this, one could fine-tune the clutch springs so that there is near-perfect in and out movement of pressure plate thus spreading the pressure evenly over all the friction surfaces in the clutch when the lever is partially released.

Trev, jump in and tell me I am full of "Horse" stuff, if I am incorrect.

Richard
Title: Re: BSA A10 clutch push rod length
Post by: trevinoz on 24.09. 2008 23:44
Couldn't have put better myself.

                             Trev.
Title: Re: BSA A10 clutch push rod length
Post by: royboy on 25.09. 2008 10:06
 *smiley4*Thanks very much I did say I was a bit thick. All the info on setting up the clutch is great as I am doing battle with my A7's clutch at the moment.
 cheers
Title: Re: BSA A10 clutch push rod length
Post by: RichardL on 25.09. 2008 12:07
Robroy,

By the way, welcome to the forum. If you are like me, there will quite a bit that can be learned here about your motorcycle and techniques to get it and keep it running.

I don't know if Trev's dial indicator approach is for everyone, but some means of judging that the pressure plate moves true and square to the basket (perhaps, a kean eye) should be employed.

As always, we look forward to pictures, if you can.

Richard

Title: Re: BSA A10 clutch push rod length
Post by: LJ. on 25.09. 2008 17:51
We are all in battle with our clutches at times Roy! Welcome along to the forum.

...and Pssst!... Richard... unless he's a scotsman its Royboy.  *smile*  ;)
Title: Re: BSA A10 clutch push rod length
Post by: RichardL on 06.02. 2010 16:31
LJ, et al,

Reading form our long log of A7/A10 tricks, techniques and little-known facts, I was looking back at the 11 August 2008 post that says that the ball on the end of the the screw in the clutch operating lever (inside the gearbox) should roll free in its captivity. Is this a fact to a certainty, because mine doesn't, I haven't figured out how to fix it without ruining the screw, and, once again, I am impatient to complete the reassembly.

Thoughts, facts and insults welcomed

Richard L.
Title: Re: BSA A10 clutch push rod length
Post by: trevinoz on 06.02. 2010 20:48
Richard,
               I am sure the ball should be free to roll.
I have several examples which are worn badly and the ball is locked solid.
I have some new ones and they are free excepting one. I put this down to the generally poor quality control of pattern parts.
As to a fix, throw it away and get a new one.
Trev.
Title: Re: BSA A10 clutch push rod length
Post by: RichardL on 06.02. 2010 22:03
Trev (and LJ),

Thanks, very much. I will acquire a new one. In thinking about whether it should spin or not, I forgot how easy it is to replace after assembly.

In the process of all this I also decided my clutch rod was too short, a residue from when I assembled the gearbox in 2005 and knew even less than I do now. I went with the ball-bearing-in-the-middle-of-the-rod trick and that seems to have it at a good length. I also hardened all four rod ends. I didn't get too exotic with the hardening procedure, but I think I got them hard enough, heating them with a mapp/oxygen torch and quenching in ATF. I read somewhere that ATF did a fair job in quenching, being a refined mineral oil. In this application, "good enough" is probabaly good enough.

Richard L.
Title: Re: BSA A10 clutch push rod length
Post by: David on 09.07. 2016 14:31
I know that this is an old thread and I hope that someone picks up on it. I have 57 Road Rocket that I've had for many years. I had the gearbox overhauled by SRM over 20 years ago and have started putting the bike back together over past couple of years. I'm pleased to say that it's very near to completion. Yesterday, I started building the clutch. I went for a Triumph 4 spring cush-drive clutch. The push rod engages with the clutch face plate by the use of a small 'Top Hat' shaped fitting. At the outset, the clutch rod appeared to be too short, but delving further, I have found references in a BSA Service Manual to the fact that there is a steel ball that sits in between the grub screw in the clutch operation arm and the end of the rod. (gearbox end)  I can't seem to find any reference the ball in any BSA manuals and yet there is a consensus amongst friends that the ball should be there. I'm wondering if I should just find a ball of suitable size and drop it into the shaft prior to inserting the clutch rod. I eagerly await any advice please? Thanks.
Title: Re: BSA A10 clutch push rod length
Post by: bsa-bill on 09.07. 2016 15:26
used to be a common mod to cut the pushrod in two and insert a ball in the centre to allow some movement, however you may be talking about the ball in the end of the pushrod adjuster as seen in this pick (65-3403) and available here for a little bit more than a fiver
Quote
http://www.draganfly.co.uk/index.php/bsa/bsa/a710--b3133--c101112--m202133/category/909-4-spring-triumph-type-with-cush-drive
other suppliers are available also
Title: Re: BSA A10 clutch push rod length
Post by: David on 09.07. 2016 15:30
Bill, I can't see a ball in the picture. Is it captive in the adjuster of does it just drop in?
Title: Re: BSA A10 clutch push rod length
Post by: bsa-bill on 09.07. 2016 16:06
yes captive, I think I read on here of it being replaced (anyone aware of how to) but for the price I would not consider it worthwhile, from memory (dodgy) I think I replaced the whole thing last job I did (everything in the pic except the lever)
Title: Re: BSA A10 clutch push rod length
Post by: David on 09.07. 2016 16:41
I had the gearbox refurbished and presume that they replaced it. I will have to take off the inspection panel and have a look. I was reluctant to do it because it was sealed with compound.
Title: Re: BSA A10 clutch push rod length
Post by: ellis on 09.07. 2016 20:52
Hi David,

Open it up and take a look to be sure. Just slacken the clutch cable off and turn the arm out and you will see the adjuster and the ball bearing is peened on to the adjuster thread. If not I got mine from Draganfly in Bungay Suffolk Tel 01986 894798 for about a fiver. Just a light smear of gasket goo is all the cover plate needs. 
Title: Re: BSA A10 clutch push rod length
Post by: chaterlea25 on 09.07. 2016 21:00
Hi David,
The adjusting screw will need to be set once the bike is together,
the angle of the arm/ cable and the alignment of the adjusting screw to the pushrod is vital to get a good
clutch operation
Do a forum search and or look up the relavent service sheet

John
Title: Re: BSA A10 clutch push rod length
Post by: duTch on 09.07. 2016 23:59
Quote
I will have to take off the inspection panel and have a look. I was reluctant to do it because it was sealed with compound.

 Don't be scared to remove an inspection cover, that's what they're for *smiley4*; and you'll need to take it off to check if there's oil in there, and add if necessary.
Title: Re: BSA A10 clutch push rod length
Post by: RichardL on 10.07. 2016 00:38
I think Dutch means that you will check for oil by removing the overflow indicating plug from the gearbox cover and adding a bit of oil until some comes out of that hole. So, David, that's one sealed plate that will be coming off somewhat regularly. 

Richard L.
Title: Re: BSA A10 clutch push rod length
Post by: duTch on 10.07. 2016 07:00

 
Quote
I think Dutch means that you will check for oil by removing the overflow indicating plug from the gearbox cover and adding a bit of oil until some comes out of that hole. So, David, that's one sealed plate that will be coming off somewhat regularly.

Richard L.

 But in addition, the Inspection cover can be easily removed periodically to inspect if there is a good amount of oil in there ;)...(note to self *eek*)
Title: Re: BSA A10 clutch push rod length
Post by: David on 10.07. 2016 17:11
Thanks to all that replied to my quest. I have the gearbox cover off and I realise that the ball is actually captive inside the grub screw. I kept hearing about the ball and assumed that it was a separate item. The rod is 11 9/16" and is too short. I have to get the 12" one. Thank you all again. David.
Title: Re: BSA A10 clutch push rod length
Post by: RichardL on 10.07. 2016 18:24
You could cut in half and put two 1/4" ball bearings in the miidle, then, trim one section to fit. Don't forget to harden four ends.

Richard L.
Title: Re: BSA A10 clutch push rod length
Post by: David on 10.07. 2016 18:35
The clutch nut has a cupped washer behind it. Does the cup face to the back or the front please?
Title: Re: BSA A10 clutch push rod length
Post by: RichardL on 10.07. 2016 19:09
I think that answer must come from someone familiar with the Triumph 4-spring clutch. Obviusly, I'm not.

Richard L.
Title: Re: BSA A10 clutch push rod length
Post by: chaterlea25 on 10.07. 2016 19:28
Hi David.
Quote
The clutch nut has a cupped washer behind it. Does the cup face to the back or the front please?

Which nut ??
The nut holding the 4 spring  clutch to the mainshaft has a special thick washer behind it ??
please post a photo?
John
Title: Re: BSA A10 clutch push rod length
Post by: David on 10.07. 2016 20:12
The nut with same washer shown in planes. Just need to know which way round it goes. Thanks. David.
Title: Re: BSA A10 clutch push rod length
Post by: chaterlea25 on 10.07. 2016 21:59
Hi David
I have not seen a washer like that  before ??????
the washer needs to butt against the shaft adaptor, the inner drum may or may not sit flush with it
Does the nut fit in the recess? but then what happens if you use the lockwasher???
All the washers I have fitted are plain both sides about 5mm thick, theres a spigot on the nut to centralise the washer

 *????* *????*
John
Title: Re: BSA A10 clutch push rod length
Post by: David on 10.07. 2016 22:43
Hello John. This one's about 4mm thick but it has the recess. You are correct in that the nut has a shoulder and it's the same size as the hole in the washer and so it's a perfect fit. I have tried fitting the washer with the recess facing and I have been able to get the cush-drive tight on the shaft. I just want to do the right thing. David.
Title: Re: BSA A10 clutch push rod length
Post by: trevinoz on 11.07. 2016 22:24
The recess faces inwards.