• Welcome to the website of the Vincent H.R.D. Owners Club.

    Should you have any questions relating to the Vincent H.R.D. Owners Club, or Vincent H.R.D. motorcycles in general, please contact Graham Smith, Hon. Editor and Webmaster by calling 07977 001 025 or please CLICK HERE.

    You are unrecognised, and therefore, only have VERY restricted access to the many features of this website.

    If you have previously registered to use this forum, you should log in now. CLICK HERE.

    If you have never registered to use this website before, please CLICK HERE.

G: Gearbox Gearing - Series ‘C’ Black Shadow


Kiwi_Tim

Website User
VOC Member
Fairly new to vincents and mine has stock wheels and sprockets: At what sort of speed would it could be expected to have the clutch fully released in first gear ? Likewise at what sort of speed would 4th become natural to motor in rather than 3rd
I suspect I have a tall 1st gear option.
 

Albervin

Well Known and Active Website User
VOC Member
Tall or intermediate first gear in Shadows ended about engine 2500. Many were replaced with standard because they are a PITA around town. If you have a standard front and rear sprocket you will need to feed a few revs in and then keep feeding them in until the clutch is fully home. How fast? Really depends on the lay of the land but probably at least 15mph. I too have high first gear and fitted a 48T rear sprocket to make life a bit easier. I usually do not select top gear (on the flat) until about 55mph but sometimes closer to 70 mph. The engines like to rev rather than lugged; about 3,500 rpm is a nice relaxed cruise.
 

Kiwi_Tim

Website User
VOC Member
Mines a late one (Dec 53), and I need around 30mph to be comfortably off the clutch, any slower and the clutch needs to be feathered. I'm finding 50-70mph its happy in 3rd and top needs to be at the top of that range and top feels like an overdrive
 

Albervin

Well Known and Active Website User
VOC Member
Check the size of your sprockets. The rear is easy the front is not. Unusual for such a late Shadow to have an intermediate first gear unless it was retro fitted.
 

Bill Thomas

Well Known and Active Website User
VOC Member
Top is an overdrive, But not that much !, I have never looked at the speedo in first, But yours sounds wrong.
My Ex L/ning will come down to 40 mph in top on the flat.
I think you have a problem with the Carb's or ign', Maybe the ATD is not working right ?.
After all these years, Your gearing could be anything ?, I have one Twin with a high first gear, And one not,
Can't say it makes that much difference, Unless you, Have someone on the back ?, Or lots of stuff ?.
Can you give us what Spec' your Bike is ?, Carb's ign' etc. Cheers Bill.
 

Bill Thomas

Well Known and Active Website User
VOC Member
Tim, Any chance you could have a ride on another Twin ?, Just to see. Cheers Bill.
A very early memory of mine, Was my Brothers friend, Smithy, Bringing me home from Work, I was about 15 years old, On his Blue "D" Twin, He overtook a Car on a slow bend, Wrong side of the road, About 35 40 mph, And changed into TOP !!, I was always Big.
 
Last edited:

Albervin

Well Known and Active Website User
VOC Member
Pulling away from Marcus's place with high first gearing was almost like riding a two stroke. On the road though it is just fine. It would be an utter bastard in a hilly town with stop signs and traffic lights though. Agree that the ATD should be checked as it could be sticking or just lazy. You do say it has STOCK sprockets Tim. Are you sure?
 

greg brillus

Well Known and Active Website User
VOC Member
Standard twin Front gearbox output 21 teeth rear wheel 46 teeth. No overdrive in top gear, one in one out.
 

Bill Thomas

Well Known and Active Website User
VOC Member
By overdrive, I mean it should not be able to pull top gear at 5,800 rev's, Unless the Engine is Tuned.
The Comet is like this also, ie Over Geared.
I have pulled 6,500 rev's on a Road Twin on Standard Gearing, On an Airfield, But lots of Tuning !.
Also I can do 40 in Top Gear with 36mm Dellorto Carb's. Cheers Bill.
 

Chris Launders

Well Known and Active Website User
VOC Member
In the 60s there was a Shadow owner lived near me in S. Yorks and he worked in Dagenham I was told during the week, he'd swap to sidecar gearing when he got home, changing it back to solo to go to work. Once saw him in what must have been frustration with a crawling bus give it a fist full in first passing it, and had the front wheel up through 2nd and 3rd !!
 

Bill Thomas

Well Known and Active Website User
VOC Member
Hello Tim, I have been having a read up, Not like me !.
With the high first gear, 55 mph = 5,000 rev's.
With the low first gear, 44 mph = 5,000 rev's.
So you can see, If you have the high one 27.5 mph = 2,500 rev's, That's near to your 30 mph ?.
I think a twin should run nice at about 2,000 rev's, or lower ?, Which comes back to I think the Carb's or ign' are not spot on, As Albervin says, A lot of people put a 48 rear sprocket on, Which is cheap and easy to do.
Cheers Bill.
 

TouringComet

Well Known and Active Website User
VOC Member
VOC Forum Administrator
Even with the lower first gear, when pulling away from a signal, behind a car, I find that the small lurch in speed when the clutch is just fully home seems to coincide with the car in front slowing down because they are already pulling in their clutch to shift into second.
 

deejay499

Well Known and Active Website User
VOC Member
Pulling away from Marcus's place with high first gearing was almost like riding a two stroke. On the road though it is just fine. It would be an utter bastard in a hilly town with stop signs and traffic lights though. Agree that the ATD should be checked as it could be sticking or just lazy. You do say it has STOCK sprockets Tim. Are you sure?
Hi Alyn. Imagine what it was like with a high bottom gear, standard on my ‘51 Shadow, with a sidecar, family, plus pulling a trailer at times. It was certainly ‘interesting’ pulling away from the lights! Soon swapped for a standard bottom gear. Sidecar rear sprocket of course.
 
Last edited by a moderator:

Kiwi_Tim

Website User
VOC Member
Thanks for the feedback, Not totally sure what the motor spec is and there are some interesting but unsubstantiated rumors about that I hope to have some better insight into soon. It was apparently a detuned race motor prior to the 80's so runs 32mm mk1 amals, 2x front heads, KVFTT magneto. quite likely the race cam, but not hi comp pistons.
It has developed a nasty oil burning problem that is going to necessitate a top end strip shortly.
The back story for the bike that seems quite plausible given a number of parts on the bike... is that the box was ex lightning type (CR perhaps?). While I did mention top being a bit of an overdrive, the gears do all seem quite close and all tall. I do intend to get another club member to give me their opinion once I've resolved my inpromptu smokescreen issue.
 

Attachments

passenger0_0

Well Known and Active Website User
VOC Member
At least this recent oil burning issue will help prevent you new VOC muffler from rusting.
 

Bill Thomas

Well Known and Active Website User
VOC Member
Hello Tim, As I have said, My Engines are L/ning spec, So should still be better than your results.
A Standard Engine, Should run much slower at tick over !!, To hear a Comet running So slow, I have always found Amazing !!, Never had it myself because my Comet is Flash Spec'.
An oiled plug = Misfire , Could give your problem ?, Slow running.
Some of us have had trouble with NGK Plugs, I have gone over to Champion N5 or N9y, With about 20 thou gaps.
If redoing the Heads, With (Mk2 Cams), Have a read up on Valve Guides, The book tells us to take a bit off the top of the lower Valve Guides, Because of the higher lift. Good Luck, Bill.
 

Top