Grey Flash 2751

The history and restoration of a Vincent HRD Grey Flash

Much debate has ensued about the finishes racing Vincents left The Works with, and no more so than that of the brake drums and especially the brake plates. The consensus is that GFs left Stevenage with drums and plates painted/enameled black (as per BL) or grey but I would like to challenge this latter notion.

Firstly, let’s look at blow-ups of period shots of 2751.

Well, the drums definitely are black – and the plates are definitely not black.
Yup, black drums for sure – the plates could be grey though…
Hang on…
Yeah, GREY!

Well, the brake drums seem to be enameled black, no ambiguity there.

The brake plates, however, appear in some shots to be black and in other shots almost grey. I would suggest that this is because they are one of the following:

  1. Left in the raw – or as-cast. They would have been machined and the machined areas would have initially appeared as any freshly machined alloy. Over time all exposed surfaces would have oxidised resulting in a grey “skin” that gradually darkened over time.
  2. Finished with a chemical process to prevent deterioration by oxidisation and damage from external elements such as water and salt. The most well known of these processes is the Dow#7 dichromate process which appears to produce a dark grey/black finish.
  3. Finished with a protective coating of black paint.
These are the plates that I acquired from Paul Woelbing.
The visible finish seems to cover all fittings and fasteners.

This matte finish appears to closely match that in the period shots of 2751. The plates appear to have either been subject to some kind of treatment or blown-over with a protective layer of paint/sealant.

After I acquired the plates, and on the advise of those far more learned on the subject than I, I sealed them with black paint to prevent further deterioration. This paint has been stripped off and al surfaces cleaned. The rear plates are probably original to the bike and had been painted grey.

The rear plates after paint removal and cleaning.
All four plates.

I rue the fact that original finish has been lost but the cold fact remains that these Elektron magnesium components needed properly cleaning to prevent further damage by oxidisation. The front plates, in particular, were quite pitted whilst the ones on the rear were in much better external condition having been protected by paint. A uniform finish for all plates is desirable and this can be achieved by either leaving them to darken over time or covering them with a suitable protective sealant – any comments much appreciated.

Other blow-ups of period shots:

These appear painted black.
As do these but with unpainted air scoops.
Black seems more common though.
Shot of the Ehret BL whilst in the ownership of Franc Trento.

At no point have I seen bulletproof evidence that plates were ever painted grey. What appears to be a grey painted finish in some period shots (such as the group of GFs in Brazil) is in fact one of the above listed finishes.

I thought I’d post a shot of the timing chest today.

This is what we were presented with once the cover had been removed.
Compared with a period shot taken of Terry Prince with the motor in his workshop.

Peter Johnson: “Although many of the ideas were generated by me, many came from Terry Prince… I had a lathe and mill so did lots of work fabricating bits and pieces right through the Flash. Then later, the Rapide outfit and most of all my Egli. Followed (later) by the Tighe Vincent hillclimb car by which time I was quite competent and made things once only… Terry is an extremely fine machinist, tuner and engineer and without his help my racing days would have been quite different.”

Peter Johnson always keeps an eye on this blog and is kind enough to share his recollections with me by email. Peter’s comments on the clutch:

“The original clutch was used at first… Sadly, the splined hub was soft, and kept sinking onto the output shaft… Went to see an old man who had an engineering firm close to home – wonderful place full of machinery! Only him left, sadly, to hob a new spline in better material .
He suggested the simplest fix was to make a simple washer/spacer out of cast iron , grease both sides and place it between the shaft shoulder and clutch – it was very effective. I think it was hobbed with the right spline. Previously, I needed to adjust the clutch pushrod clearance between races. Now I didn’t need to. Just checked before a meeting.

However, as time passed and I was given/bought more bits, this (clutch currently fitted) came up and, being Norton, had a rubber Cush drive which the Albion did not have + plates were readily available. Lighter, more efficient and simpler. Not sure what happened to the original”

Thank you Peter.

2751 left the factory with an Albion racing gearbox and Albion clutch.

Visible in this period shot.

Whilst the bike was being raced and developed by Peter Johnson a lighter more efficient clutch setup was employed. From what we can ascertain a Norton Dominator clutch was altered to fit the Albion mainshaft spline.

This is what we were presented with.
Once removed we can see how the clutch drum was modified to fit the Albion gearbox mainshaft spline. Very ingenious!
The beautifully lightened basket is a work of art…
These will need to be replaced…

Whilst this modified clutch is not original equipment it is inextricably linked to the racing history of the bike and will be gone through and refitted as-is. In the meantime I will try and source a correct Albion clutch to keep with the spares. If anyone has a lead on the correct pattern clutch I’d love to hear from you.

On a racer a dynamo is unnecessary, so the Grey Flash was fitted with a blanking plate in place of where the dynamo would usually be.

This is what was fitted and worked just fine but is of incorrect pattern.
Timing chest: clearance between this idler and the lip of the hole is tight.
New items were manufactured to correct specifications from drawings held on file.
Correct pattern blanking plate in place.
A tight fit but with the idler pushed hard inwards there is still 0.012″ clearance, so acceptable.
Finished with a period locknut – great result!

Whilst on the subject of casting stamps… These inspection stamps are now visible.

The crankcase mating numbers are, I believe, on the portion of the cases hidden by the barrel. The engine is as last overhauled by Terry Prince and will not be dismantled unless it’s determined there are issues that prevent it from running – and it will be run.

This is a continuation to the last post on why the timing chest cover build number (96) differs to that of the build number for 2751 (42). I sent an email to the VOC Registrar, Simon Dinsdale, and he got straight back to me with some interesting information.

So, I wish to correct something that I wrote. I stated that all 128 “B” Meteors would have been branded “HRD” – this is incorrect and the truth is somewhat more complicated…

2751 is recorded as being manufactured on 27th August 1949 and left Stevenage with “HRD” castings and a “Vincent” transfer on the tank.

The “HRD” to “Vincent” logo branding changes occurred across all series “B” & “C” bikes manufactured during an 18 month overlap period between 1949 and 1950. I knew this and I also knew that towards the end of this period, bikes left Stevenage with a veritable mishmash of logos on castings and painted onto petrol tanks. As the new “Vincent” branding project gathered momentum some stocks of “HRD” castings had this old logo removed and left The Works in a plain state. To make matters even more confusing, Simon tells me that it is believed that some early “Vincent” logo castings also had the logo ground off as they had been badly cast…

The series “B” Meteor & series “C” Comet were introduced at exactly the same time with the 1st production machines leaving The Works in August 1949. To quote Simon: “The first Comets & Meteors being HRD bikes with ‘HRD’ crankcases and the change occurred in late 1949 to ‘Vincent’ – so the last ‘B’ Meteors (made up to mid 1950) actually had ‘Vincent’ on the tank and ‘Vincent’ crankcases with a few plain crankcase bikes thrown in as well. So basically don’t assume an ‘HRD’ single is a Meteor and a Vincent single is a Comet.”

I’m not sure of the exact numbers but certainly “HRD” branded singles are exceedingly rare.

Now, why the correct pattern timing chest cover with the incorrect build number…? Simon managed to shed some interesting light: “This leads to your HRD timing cover with mating number 96. I know from the records mating number 96 is from a series ‘C’ Comet that was despatched to a dealer called Weston Webb in New Zealand on the 30/09/1949 and this was the 40th series ‘C’ Comet made. The rest of the engine was last reported to be in New Zealand in the 1980’s but I have nothing since. The UFM for this Comet was reported to have been for sale on eBay in USA in 2005 but again nothing since, so it looks like the bike was broken up a long time ago.”

2751 was also originally exported to Weston Webb, so, therein lies the “rub”!! Now we know what happened. Whether it was an intentional swap (if the original cover was damaged) or whether the covers were inadvertently swapped whilst work was being undertaken in the Weston Webb shop we may never know… This has all been very interesting and another reason why complete transparency is important and can often tell a fascinating story.

And there is a faint possibility that the original timing chest cover – stamped “42” – is still out there…

Thank you Simon!

The timing chest cover has the “HRD” script cast into it. This makes it a very hard-to-find item because compared to a total of 3,791 postwar “Vincent”-branded “C” singles (all Comets) manufactured only 128 “B” Meteors were produced. These Meteors, as far as I’m aware, would have all been “HRD”-branded. There might have been some variation in the way the tanks were painted but the engines would have all had the “HRD” logo castings. So, the chances of 2751’s timing cover being original to the bike seemed highly likely. Once it had been removed it was inspected.

Oh… The build number for 2751 is “42”
As visible on the inner primary chaincase…
So why is the timing chest cover stamped “96”?

One clue is the absence of the two cover locating dowels. This cover is not original to the bike and the inclusion of the dowels would mean that it didn’t mate to the crankcases correctly – the covers were each mated to their respective crankcases. I know that a timing cover was included with the disassembled bike and parts that Peter Johnson bought. I also know that a cover was present with those parts in NZ when the bike was offered for sale – it’s mentioned in the list.

Assuming that this is the cover currently fitted then it must’ve come from an “HRD”-branded Meteor that lived in NZ. Hard to imagine what went on here – was the original cover damaged and replaced with a similar “HRD” item? This scenario seems very unlikely due to the scarcity of this part. Also, when the parts were gathered together for sale by Bill McCahon, in the late ’60s, there would have been surely little interest in trying to find an “HRD” timing chest cover when “Vincent” scripted ones would have been much more readily available. A more likelier scenario is that 2751’s original cover was inadvertently swapped with the cover of a “B” Meteor. On the off-chance I’m going to take this up with VOC numbers guru Simon Dinsdale and see whether any “B” Meteors still exist in New Zealand.

I’m a bit disappointed to have found this but at least we have the right component even if it wasn’t the one the bike originally left the Works with.

The rear chain adjusters, which were made for me, to pattern, by Vic Olsen have been fitted up.

These t-bar adjusters were a special racing item. They are easier to adjust under racing conditions and also give an easy visual indication enabling each side to be adjusted incrementally. I had them cadmium plated and it doesn’t appear to have taken very well – the resulting patchy finish fits the project perfectly.