Author Topic: Valve springs diameter wrong?  (Read 1552 times)

Online KiwiGF

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Valve springs diameter wrong?
« on: 21.09. 2011 11:35 »
Hi I just got some new valve springs from dragonfly and they do not fit the collars I have

The question I have is are the new springs wrong or are the collars and springs I have wrong

The springs are Mca firebrand part d402b

Head is iron bike is 56 GF

The old springs are 1.00/1.31 id/od
The new ones are 0.96/1.26 id/od

The old inner springs are 0.65/0.85 id/od
The new springs are 0.70/0.91 id/I'd

The length of the new outer spring is 1.95 but Haynes says 1.875 is STD
 
Thanks!

New Zealand

1956 A10 Golden Flash (1st finished project)

1949 B31 rigid “400cc hot rod” (2nd finished project, + favourite bike)

GL1800 Goldwing, well, the wife likes it

KTM 950 ADV, cos it’s 100% nuts

1952 Armstrong Siddeley Whitley for rainy days (with wife)

Offline chaterlea25

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Re: Valve springs diameter wrong?
« Reply #1 on: 21.09. 2011 12:03 »
Hi Kiwi
I'm not much help on the dimensions, but
A few weeks ago I went to fit a set of MCA springs to a B33
one outer spring was ok, the other had 3/4 of a turn extra on it which meant it was getting coilbound at full lift *eek*
Just another thing to check

Cheers
John O R
1961 Super Rocket
1963 RGS (ongoing)

Offline Beezageezauk

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Re: Valve springs diameter wrong?
« Reply #2 on: 21.09. 2011 19:28 »
Hi KiwiGF,

Roy Bacon's book "BSA Twin Restoration" lists the valve spring lengths but not the diameters.

Data shown for the 1951-63 A7, A7ST, A7SS and A10 is 1.875 inches for the Outer and 1.531 inches for the Inner.

Data shown for the 1954-63 A10RR, A10SR and A10RGS is 2.125in. for the Outer and 2.000in. for the Inner.

Hope this helps.

Beezageezauk.

Online muskrat

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Re: Valve springs diameter wrong?
« Reply #3 on: 21.09. 2011 20:58 »
G'day Kiwi,
              I have the opposite, got new top and bottom collars and they are tight on the springs. The springs are Terry's and a tad thicker wire than the original, but fitted the old collars.
 You might have been given the wrong ones, I'm not sure of the mca brand. Just got some fork seals with that logo, don't like the look of them.
Cheers
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
Australia
Muskys Plunger A7

Offline bikerbob

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Re: Valve springs diameter wrong?
« Reply #4 on: 22.09. 2011 12:13 »
Hi there
 The problem is the company that is supplying your springs I have had first hand experience with products from that company in the past they have supplied me with inlet push rods that were too short tappet adjusters that snapped when only nipped up and carbon pick ups that were too soft, I would only use their products if I could not source elsewhere. I complained to them by letter about the push rods they asked for them to be returned which I did including an original BSA one which proved that theirs were too short. The reply I recieved was that they had been making BSA push rods for over 20 years which were made to the original drawings and if I was not satisfied I should purchase push rods elsewhere. I returned the faulty rods to Dragonfly who admitted that they were indeed too short comparing them with originals and they apologised also thanking me for bringing it to their attention as the rest of the stock they had were also too short they sent me a set of orignal BSA steel inlet rods which have now been in my A10 for about 15 years.

Offline MG

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Re: Valve springs diameter wrong?
« Reply #5 on: 22.09. 2011 19:30 »
Copy that, when rebuilding the A10 I got a set of faulty cam followers (one made from stainless steel) - labeled MCA Firebrand.
1955 A7 Shooting Star
1956 A10 Golden Flash
1961 Matchless G12 CSR

www.histo-tech.at - Restoration, Repairs, Racing

Austria

Online KiwiGF

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Re: Valve springs diameter wrong?
« Reply #6 on: 23.09. 2011 13:10 »
Thanks everyone it looks like I'll be posting the springs back to uk from nz always a pain eh

From the info above they are not rocket springs so its not as simple as me getting those instead of iron head springs

Has anyone got an old spring they could measure the diameter of just before I send these springs back?

The rest if this lot of parts order (how much!) look ok so far .....Ive started the gearbox sleeve bearing replacement job tonight as the new bushes look ok I'll post some pics of that job on another topic

The new anti wet dumping spring looks little better than the one Im replacing and the new PRV spring looks a lot less stiff  As well so maybe I'll reuse the old ones
New Zealand

1956 A10 Golden Flash (1st finished project)

1949 B31 rigid “400cc hot rod” (2nd finished project, + favourite bike)

GL1800 Goldwing, well, the wife likes it

KTM 950 ADV, cos it’s 100% nuts

1952 Armstrong Siddeley Whitley for rainy days (with wife)

Offline Beezageezauk

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Re: Valve springs diameter wrong?
« Reply #7 on: 23.09. 2011 15:42 »
KiwiGF,

Yes, you've definitely had the wrong springs sent to you.

I've just measured some spare second hand springs that I will be using in a cast iron A10 head and the results are as follows.

Outer  1.00" I/D  x  1.31" O/D x 1.85" long.

Inner   0.65" I/D x 0.85" O/D x 1.5" long.

These figures match up with your original springs.

Beezageezauk.


Online KiwiGF

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Re: Valve springs diameter wrong?
« Reply #8 on: 24.09. 2011 06:58 »
Thanks a lot for taking the time to do the measuring beezageeza

I'll send em back now and see if dragonfly can re supply good ones
New Zealand

1956 A10 Golden Flash (1st finished project)

1949 B31 rigid “400cc hot rod” (2nd finished project, + favourite bike)

GL1800 Goldwing, well, the wife likes it

KTM 950 ADV, cos it’s 100% nuts

1952 Armstrong Siddeley Whitley for rainy days (with wife)

Offline chaterlea25

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Re: Valve springs diameter wrong?
« Reply #9 on: 30.09. 2011 17:25 »
Hi KiwiGF,
Have you had a reply from Draganfly?
I have just bought a lot of BSA head hardware from Ebay
I  contains a set of new correct valve springs for your application, I have measured up and the dimensions are correct
Unfortunately for me they are wrong for an alloy head model!!
If you need them you can have them for what they cost plus post
At least then you would be sure of getting the correct size
Send me a pm if I can help you

Regards
John O R
1961 Super Rocket
1963 RGS (ongoing)

Online KiwiGF

  • Last had an A10 in 1976, in 2011 it was time for my 2nd one. It was the project from HELL (but I learned a lot....)
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Re: Valve springs diameter wrong?
« Reply #10 on: 11.10. 2011 07:00 »
Sorry John that was a good offer but Draganfly are sending replacements they reckon are correct so hopefully the problem is sorted a bad batch apparently

I just wish they would send me the new pistons and 6 spring inner basket as well! (I'm at the assembly stage of an unplanned resto)
New Zealand

1956 A10 Golden Flash (1st finished project)

1949 B31 rigid “400cc hot rod” (2nd finished project, + favourite bike)

GL1800 Goldwing, well, the wife likes it

KTM 950 ADV, cos it’s 100% nuts

1952 Armstrong Siddeley Whitley for rainy days (with wife)