New Member - daftmate

[Daftmate]

Dear Forum, I have a nice '56 plunger which I'm fettling post restoration. Almost back on the road after quite a set of repairs/improvements.  I have found the forum so useful over the last few months as a guest I came to the conclusion I'd better join in.

Some of the topics that I found really helpful were:

1.Forks - rebuilt with new bushes and seals and added progressive springs and 2 way damping.
2.Wheel Alignment - much spoke twiddling, what fun.
3.Engine overhaul - Rattly bottom, so all apart.  Bits now with T&L Engineering at Bedford to sort out crank/mains/barrels/new pistons.......I never knew about thin/thick flange barrels now even my wife can tell the difference.  Forum great for sorting out trusted suppliers. Going to have dynamic balance done, let's see the difference.
4. Engine mounts - alignment/shimming and busted gearbox bottom. Getting sorted now..
5. LED rear lights - how modern (and sensible)
6. What oil to use, great to read all the opinions.  I'm definitely going for Castrol Staight 40 no filter, frequent changes.  Definitely, until I read the next post on the topic.

More to tell, I will put some pics together and start pestering with my questions.

Thanks again A7/A10 forum, wonderful source of data and so nicely presented.
 

[WozzA]

   to the wonderful world of A7 A10 BSA's 

[Greybeard]

 

[muskrat]

G'day Daftmate welcome to the forum.
With all that work done it won't be long before you change your name . The later plungers (54-57) are a rare breed. There's a few here. My plunger gets used the most.
Cheers

[morris]

Hi and 

Plungers are great!

[a10 gf]

Thanks again A7/A10 forum, wonderful source of data and so nicely presented.

Appreciated.

[Daftmate]

Sorry its been a while but I've been enjoying my A10 plunger !

Basically its all fixed now (for a while) and runs very nicely.

From what I can recall from the lasts posts...

1. I found a new gearbox casing with good mounting holes except threads.  Helicoiled  these, put correct studs in, dressed frame where it had worn, made custom shims to put the gearbox in the right pace and bolted in firmly in place with strong Loctite.  No probs since with loose mounts, loose nuts...bad memories of getting the engine and gearbox in and out of the frame many times until it 'sat' right.

2. Bottom end rebuild was done by T and L engineering.  Original problem was excessive timing side bearing clearance.  Sludge trap found full of crap which probably caused bearing failure after only 1000 miles since original rebuild. Very nice job by Tand L , including dynamic balance. Has transformed the bike, nothing breaks now with vibration.  Have included the balance sheet for the techies !

3. Old thin flange barrels were cracked, found some thick flange ones (not cheap). T and L supplied new pistons to suit new barrels.

4. Fitted progressive front fork springs and two way damper rods from Goffy.

5. Put the gearing back to solo ratio not sidecar,,,,

6. Fitted a Digital Voltage Reg (very effective and fits in old electro mech box) and a AGM battery again from Goffy.

Think that's the major upgrades.  So far so good, done 2000+ miles no issues.

Hope you like the pics and thanks for the advice and help I have obtained from the forum.  I've even fixed my mates Laverda 668 as the Beezer just keeps going...bloody fuel injection, who invented that.

[worntorn]

Great result!
Could you explain the balance sheet please?
Ive had one dynamic balance done on a custom Vincent crank. It really solved the vibration problem but I did not get much info back, just the temporary bob weight used, amount of crank weight removed and that sort of thing.

How smooth is the bike now on standard gearing at 65 mph?
Could it be an all day rider?

Anyway, it looks terrific
May I call you Daft?

Glen

[Daftmate]

Glen,

I'll do my best.  The guys at T and L would be the best to consult, however.

Here's what I took form the sheet:

1. Three parts Initial Spin/Bobweight calc/Final Spin
2. Its a high speed balancing machine and runs the crank up to 10,000 rpm in 1000 rpm steps which will obviously cover the A10 running range
3. Initial spin shows high out of balance especially on right side.
4. The out of balance force increases as the square of the speed, which is what you expect.  So double the revs 2000 to 4000 means a four fold increase in the force
5. Bobweight part is tricky.  They weigh all the rotating parts and then the reciprocating parts.  Conrod is a mixture of the two, big end is rotating and small end reciprocating. So each end is weighed separately.
6. Now the bob weight needs to provide a counter balance to the reciprocating weight.  But we cannot select 100% as that would sort out the vertical but leave a massive out of balance in the horizontal plane. So, builders recommend a balance factor which does most of the vertical but leaves a bit of horizontal. So trying to get best of both worlds or at least minimize of the worst of the worst worlds...
7. Balance factor selected is 61%, multiply this by the recip weight so 448.2 x 61% gives us 273.40.
8. How you get from the reciprocating factor to the bobweight and half bobweight  numbers I don't know.
9. Final spin numbers as per point 4.  And it was within the 0.5 0z-in limit for both sides.

So, it now rides a lot smoother. 45-50 seems its happy speed.  Had it up to 70 all OK but feels busy and like its working hard.  Time limit in saddle is now the saddle itself.  Indian copy, badly sprung and upholstered.  So that's getting sorted next.

Last comment, for the balance factor selected to work right I make sure all the engine and gearbox mounts are 100% firm and secure as per the book.  I keep then tight, Loctite them and check them regularly.

Hope I've given you some pointers, feel free to come back if any other questions.

DM

PS My name is Steve but DM is 'oft used.  You can use 'daft' but it might hurt !

[worntorn]

Thanks Steve, that makes sense.
I'm considering pulling my A10 down for dynamic balancing.
Right now it's overgeared with a 23 tooth engine sprocket rather than the stock 21 tooth.
The 23 tooth gives very smooth running to 60, but gets a bit buzzy at 65 and above.
It also saps some power for acceleration. I would really like to gear it back down, but then the smooth zone is reduced to 55 mph, a bit slow for traffic here. Actually 60 is too slow for most traffic here.
So it sounds like dynamic balance might help, however I shouldn't count on it to provide glass smooth running at a 4000 rpm cruise.

I guess that is why Norton came up with the rubber mounts for their parallel twin!

Glen

[Daftmate]

Hi Glen,

Wow 23 tooth front, that is tall.  I started from the other direction as mine originally had the sidecar sprocket on the rear, 49 Teeth ?  Anyway I changed that for the solo 42 tooth one, it was still undergeared so I increased the front from 19? to 21.

This feels about right, sometimes have to slip it a bit in first to get away but it motors nicely through the gears.  I don't like taking it on the highway anyway as I spend most on my time hooning round the A and B roads of Lincolnshire round the 50 mph mark and that does me (and the beezer) just fine.

Steve