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How to tighten down the heads on a Rapide when running in

BlackLightning998

Well Known and Active Website User
VOC Member
#1
Hi,

Advice please on my running in my Series C Rapide after a full engine re-build.

Terry Prince did the engine and has advised me to re-torque the heads down to 45lbs now that I have 100 miles on the clock and she has been good and warm.

I'm familiar with which four nuts do that (underneath the two head brackets), but wanted some advice in terms of getting to them, and which tool to use.

A standard torque wrench will mean removing the tank, then the cylinder head brackets to allow access for a socket onto the cylinder head nuts. I've never done this before and my "Know Thy Beast" has not arrived yet so I wonder if any member could give me some advice on:

1 - What do I need to strip off to get where I need to get?

2 - Am I right in thinking a standard torque wrench and socket are the best tools to do the job?

And then anything else I should look out for as part of the job.

Advice gratefully received?

Cheers

Stuart
 

Tom Gaynor

Well Known and Active Website User
VOC Member
#2
Retorquing heads

The best tool for the job is a torque wrench and a "crows-foot", which is like a very short open-ended spanner. Mine has a 3/8" square with a square at one end. The square goes on to the torque wrench. 2 inches away is an open-ended spanner. I couldn't get the correct Whit size, but 11/16" AF is perfect. Better still is that it fits between the bracket and the head. All you have to do is slacken the nuts above the bracket, pull up the head nuts, then retorque the nuts above. Took me about 30 minutes.
One ought to adjust the torque to allow for the crowsfoot, but I didn't bother. I expected them to tighten another quarter turn, and they did, and they are all set at the same torque. Good enough pour moi.

For interest, a Manx Norton's head nuts are tightened to 30 lb.ft to avoid distorting the barrel......
 

BlackLightning998

Well Known and Active Website User
VOC Member
#3
Can you tell me where you got the tools from

Hi Tom,

Great news, could you let me know by chance where you got the tools/what brand they are from so I can buy what I need.

From what you've said I think a standard torque wrench with 3/8ths drive will work, the special, non-standard piece is the crows foot.

Much appreciated - cheers.

Stuart
 

Pushrod Twin

Well Known and Active Website User
VOC Member
#4
Stuart,Find a quality crows foot at your Stahlwile or Snapon or British equivalent, tool agent. Remember to fit it to your torque wrench at right angles, 90 degrees, so you do not over torque as Tom appears to have done. Over torquing barrels can be as bad as leaving them loose.There has been discussions about barrels showing signs of nip marks in line with studs,is there any connection?
Roy
 

Tom Gaynor

Well Known and Active Website User
VOC Member
#5
Crows foot

Any error is likely to be swamped by the torque difference between a well-greased nut and washer, and a less well-greased one, but in fact I put the crows foot at 90 degrees to keep the leverage more or less the same. On my set up the maximum error is limited to about 10% anyway.
The one I bought, the only one in the shop (and, the proprietor opined, in NE Scotland....) is American, and I can't remember the name: very well made and finished. I could find out, if you get stuck. My recourse is usually Google, but I'm sure Snap-on will sell you one once you arrange the mortgage. Mine cost about £12. Teng make them too, but only metric sizes were in stock, and 11/16" AF was a perfect fit. Just from the numbers, 18 mm should fit perfectly since the hex size is 0.71 and 18 mm = 0.71. By the same reasoning, 11/16" should be too small, so taking a nut (from ABOVE the bracket....) would be prudent. Slightly too big is better than slightly too small. It takes ages to stone a few thou off a spanner, but packing differences up to 1/32" with shim stock is more or less instant. (It's a useful way to "convert" large, near-unobtainable tube spanners to a smaller size.)
 

BlackLightning998

Well Known and Active Website User
VOC Member
#6
I think I have found one....

Hi Tom,
Thanks for the detailed reply - I think I have found myself an 11/16th AF crows foot - so now a 3/8th's drive torque wrench is the next step.

Interestingly I have a Ducati 851 Superbike and the club does a rental system with the specialised tools you need to do the jobs with. I reckon I may not need these tools again for a very long time (hopes).

Did you bother removing the petrol tank to give yourself a little better access when you did the job?

Cheers

Stuart
 

BlackLightning998

Well Known and Active Website User
VOC Member
#7
Ooops - can we check sizes please?

Hi Tom,

I have just put some spanners on the three items needing to be moved - the locking nut on top of the cast head bracket is indeed 11/16th's or 18mm. The actual nut below it which holds the head bracket in place is slightly smaller than 21mm (sorry I don't yet have BSF/AF spanners to fit so won't be doing any work just yet).
Then the actual head bolt itself, the one I want to torque down, is the same again, a 21mm spanner is a little oversize on the flats so I need something larger that 11/16th I think.
The blue parts book from VinParts does not actually show the sizes of these three nuts/components - can you (or anybody else reading this, thanks) give me the actual sizes for the three - I need a crows foot spanner which is the imperial nearest to 21mm I think, not 11/16th which is too small.

Cheers

Stuart
 
#8
Tools.

Hi Stuart, can I sell you some tools?. Take a look at our website for K70, K71 & K72.
Give me a ring and I can get them in the post for you so that you will be able to spend the weekend doing up all the nuts & bolts that have come loose after your trip to the MOT station :D

Cheers,
Russ
 

Comet Rider

Well Known and Active Website User
VOC Member
#9
Head nut size

Hi all,
It's actually 13/16" same as a 14mm spark plug.

If anyone is passing either the Herts and Beds rally or the A rally then I'll gladly bring the crows foot and a torque wrench as well.

Neil

Give me a call
01763 260595 by Friday night.:D
 

Tom Gaynor

Well Known and Active Website User
VOC Member
#10
Tightening head nuts

My apologies, Stuart, I should have looked, but I'm glad i advised you to check! I forgot to look out the crowsfoot last night, but it must be 13/16" (not 11/16") that I bought, 0.812" nominal, a snug fit on a hex of 0.820" nominal.

I've just gone to look: it might be possible with the tank in place, but I had taken the tank off for some other reason. It's certainly a great deal easier with it off.

For the record, the standard Imperial hex sizes are

1/4 0.445
5/16" 0.525
3/8" 0.625
7/16" 0.71
1/2" 0.82
9/16" 0.92
5/8" 1.01

where the first number is the thread diameter and the second the AF size.

Vincent (and Norton) often use a smaller hex on a nut or bolt than the nominal. From memory (and you are now forewarned about my memory) the head nuts are 9/16" thread, 1/2" hex, then 1/2" thread 1/2" hex, locked by 1/2" thread 7/16" hex.
 
Last edited by a moderator:

stumpy lord

Well Known and Active Website User
VOC Member
#11
torque wrenches

Suart,
If you are still looking for a torque wrench there is a snap on wrench on offer on e bay item 130126013237, which is standing at £25 . You own the best motor cycle in the world , why not have the best tools?
Cheers Norman/.
 

BlackLightning998

Well Known and Active Website User
VOC Member
#12
Thanks to everyone and a word or two of warning...

Thanks to Tom, Russell, Neil, Norman.

I've had some good advice and from Neil the offer of either doing the job for me or lending me the tools - great club spirit and I really appreciate the offer.

I thought I would buy myself a torque wrench in the range 15 through 50 ft lbs - I have a bigger one but this range should suit the Vincent well and would come in useful. Saw a beauty on ebay, looked in great nick, box, instructions and being offered for sale in full working order. Well I bought it, less that a quarter of new price and it arrived yesterday. I thought I would just test it on a couple of cycle part nuts - seemed to take a lot of torque and no slip so I put a stainless half inch nut and bolt together, clamped it in the vice and proceeded to give it 30 ft lbs. It twisted the fastener out of the vice (which I had swung on to lock up) and ripped the jaws without the ratchet clicking in. When I tapped the vice bar locked with a rubber mallet and had another go, it sheared the half inch fastner straight through.

Visions of me being the second customer that Russell has needing a helicoil set for 8 crankcase studs flashed through my mind.

Then the thought that "wrist tight" with an aluminium engine may not be a bad idea at all.

So a word of warning to all - all that glistens may not be gold and if you get a snap-on torque wrench for a fraction of the new cost - then just check it out first!!

I've located a set of crows foot spanners that do the job, so I'm going to get those, and find myself a proper, calibrated and checked torque wrench - I may go back to borrowing one I know works rather than the money snap-on want for a new one.

My Dad parcelled up and sent me all his imperial spanners, including what he had left of a Vincent tool kit, plug spanner, K1 and a few others so a happy few hours has been spent with solvol and wire wool to make them all look nice again. Interesting that these very spanners were used on this very bike 30 years ago, and now here we go again.

Registration number hopefully sorted tomorrow, then Mr Tipper will make me some plates, use Russells solid, tried and tested advice on the head and off we go for a run.

Thanks again to Tom, Russell, Neil and Norman - great to have some advice out there for spanner novices on Vincents like me.

Now, how do I tighten the head races...............

All booked for 3 track sessions including the VOC one at the Festival of 1000 Bikes - can't wait (fingers crossed our Summer pitches up before then).

Cheers

Stuart
 
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