Author Topic: BSA A10 clutch push rod length  (Read 6660 times)

Offline huddie

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BSA A10 clutch push rod length
« 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

Offline LJ.

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Re: BSA A10 clutch push rod length
« Reply #1 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.
Ride Safely Lads! LJ.
**********************
1940 BSA M20 500cc Girder/Rigid- (SOLD)
1947 BSA M21 600cc Girder/Rigid-Green
1949 BSA A7   500cc Girder/Plunger Star Twin-(SOLD)
1953 BSA B33  500cc Teles/Plunger-Maroon
1961 BSA A10  650cc Golden Flash-Blue
1961 BSA A10  650cc Golden Flash-Red

Offline dpaddock

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Re: BSA A10 clutch push rod length
« Reply #2 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
David
'57 Spitfire


Offline huddie

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Re: BSA A10 clutch push rod length
« Reply #3 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

Offline trevinoz

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Re: BSA A10 clutch push rod length
« Reply #4 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.

Offline huddie

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Re: BSA A10 clutch push rod length
« Reply #5 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

Offline LJ.

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Re: BSA A10 clutch push rod length
« Reply #6 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.
Ride Safely Lads! LJ.
**********************
1940 BSA M20 500cc Girder/Rigid- (SOLD)
1947 BSA M21 600cc Girder/Rigid-Green
1949 BSA A7   500cc Girder/Plunger Star Twin-(SOLD)
1953 BSA B33  500cc Teles/Plunger-Maroon
1961 BSA A10  650cc Golden Flash-Blue
1961 BSA A10  650cc Golden Flash-Red

Offline trevinoz

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Re: BSA A10 clutch push rod length
« Reply #7 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.

Offline trevinoz

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Re: BSA A10 clutch push rod length
« Reply #8 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.

Offline royboy

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Re: BSA A10 clutch push rod length
« Reply #9 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

Online RichardL

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Re: BSA A10 clutch push rod length
« Reply #10 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
Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Offline trevinoz

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Re: BSA A10 clutch push rod length
« Reply #11 on: 24.09. 2008 23:44 »
Couldn't have put better myself.

                             Trev.

Offline royboy

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Re: BSA A10 clutch push rod length
« Reply #12 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

Online RichardL

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Re: BSA A10 clutch push rod length
« Reply #13 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

Plan on signing up for the world-wide 2020 DISTINGUISHED GENTLEMAN'S RIDEon September 27, 2020 (if it's not cancelled and we are free to move about by then). Watch website at https://www.gentlemansride.com for details.

Offline LJ.

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Re: BSA A10 clutch push rod length
« Reply #14 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*  ;)
Ride Safely Lads! LJ.
**********************
1940 BSA M20 500cc Girder/Rigid- (SOLD)
1947 BSA M21 600cc Girder/Rigid-Green
1949 BSA A7   500cc Girder/Plunger Star Twin-(SOLD)
1953 BSA B33  500cc Teles/Plunger-Maroon
1961 BSA A10  650cc Golden Flash-Blue
1961 BSA A10  650cc Golden Flash-Red