Author Topic: Swing Arm OR Plunger ?  (Read 2929 times)

Offline renos-a10

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Swing Arm OR Plunger ?
« on: 22.02. 2012 10:21 »
 G'day to all,

 Last week i drive my brother's a10 plunger . Later i drive my a10 swing arm . At the corner the swing arm is much better than plunger.
About riding also the swing arm is better. But the plunger has better look and exhuast noise.
That's my opinion. What you think about that?

Renos
1954 BSA A10 Plunger
Cyprus

Offline LJ.

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Re: Swing Arm OR Plunger ?
« Reply #1 on: 22.02. 2012 12:50 »
This is a good question Renos... I think the swinging arm is better for solo riding but riders with sidecars often say that the plunger is better for the outfits. Maybe solo riding with a plunger takes a little getting used to? I noticed only last week with my plunger bike loaded up that there was a feeling of the back end 'dropping' while cornering. That sudden dropping is not a nice feeling and I wonder if this is common amongst plunger bikes. I wonder why the plunger does this? is there a likely fault?
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 renos-a10

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Re: Swing Arm OR Plunger ?
« Reply #2 on: 22.02. 2012 13:26 »
Hi LJ

 That's feeling i like very much but i wish not raining.I think that's not a problem but this is plunger riding cornering.
This  I beleive is the big different with 2 frames. The swing arm riding is like 'limusin' .

 Renos
1954 BSA A10 Plunger
Cyprus

Offline a101960

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Re: Swing Arm OR Plunger ?
« Reply #3 on: 22.02. 2012 13:43 »
Quote
I wonder why the plunger does this? is there a likely fault?
If you think about it the swing arm set up is a rigid structure, whereas the plunger suspension spring units are free to move idependantly of one another. The plunger suspension relies on the rear wheel spindle to keep everything in line. On swing arm suspension the arm is a rigid structure, and therefore the ability of the wheel drop on one side due to differing spring tension, and wear factors while cornering, is not going to be a problem.

John

Online muskrat

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Re: Swing Arm OR Plunger ?
« Reply #4 on: 22.02. 2012 19:12 »
 I love'em both. The plunger has a few short comings, but you get used to it. I don't mind what the rear end is doing (grew up on dirt) as long as the front goes where I point it.
 John is spot on with his diagnosis.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline LJ.

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Re: Swing Arm OR Plunger ?
« Reply #5 on: 22.02. 2012 21:58 »
Thanks for that informative reply John... and that leads into the next question... lol. So, possibly the best solution is to fit stiffer springs in the plunger pots to make it more like a swinging arm? I've never had plungers to bits so I dont know how difficult a job it is in changing the springs. I think I can live with things for now though.
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

Online Brian

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Re: Swing Arm OR Plunger ?
« Reply #6 on: 23.02. 2012 00:59 »
Bit of a hard subject really. I also have both swingarm and plunger and rigid bikes.

There is no doubt the swingarm frames handle better and give a better ride.

But, I enjoy riding my plunger bikes just as much as the s/arm. Different horses for different courses.

One thing that does need looking at on both plunger and rigid bikes is the front seat mount if you have a sprung saddle. I have had many people say that their bike handled badly and once the front mount is repaired the handling problem is magically cured. When the front mount is worn it allows the seat to move from side to side giving a most uncomfortable feeling. I use a adjustable reamer to true up the hole and them make an oversize bolt to suit

I have never felt the need to alter the springs in the plunger units, the only thing I always check is that the springs are the same length. Its not unusual to dismantle them to find one spring 1/2 or even 3/4 of an inch different in length. If the springs are the same length and there is no or very little wear in the shafts or bushes they will work as well as they ever can.

Offline BearKat

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Re: Swing Arm OR Plunger ?
« Reply #7 on: 23.02. 2012 12:39 »
thought you might like to see this lovely combo pic,i saw it on another forum,can,t remember which,but i wonder who owns it?
Ex RASC "DON R"1958/60,(BSA M20 /MATCHLESS G3)