Author Topic: Cam Chain Case Screws.  (Read 1950 times)

R3SC

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Cam Chain Case Screws.
« on: November 23, 2013, 08:23:29 PM »
Hi Guys,

I've just come round to remove the cap screws that hold the cam chain cases to the crank case, I only want to do them one at a time in order that I can have them re plated after replacing temporarily with some substitutes. However, after trying to remove said screws with a 5mm Allen key, no joy as it's too big. I then tried a 4mm Allen key as suggested in the manual, no joy as it's too small.
 
As it turns out these screws are an imperial size, 3/16AF and on removal the thread is a course pitch and I would suggest is either 1/4" Whitworth or 1/4" UNC.

Is this standard on the V1000? I understand the reason for using course threads in soft materials but it seemed a little strange that they are detailed as metric in the manual!

Anyone else encountered the imperial option?

Regards

Pete.

Miti

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Re: Cam Chain Case Screws.
« Reply #1 on: December 08, 2013, 09:10:39 PM »
Hi Pete;

Mine are M5 x 20mm - no imperial nonsense...

Also on the camcain cases, I've been looking into sealing the fixed camchain lipper blade securing pins (quite a mouthful..!)

I started to strip part of this engine this weekend and was finally able to see what's what with these screw-in pins:

Pic:  Camchain case assy with rigid slipper blade fitted.

Pic:  Camchain case assy - disassembled.

Pic: Camchain case assy - alternate view.

The threaded section of the support pin (and the thread in the case, of course) are M16 x 1.5mm.  The thread is 9mm high.  The "pin" is 5.8mm wide (hole in the tensioner is 6mm) and 19mm long (28mm overall).

The threads had silicone sealant smeared into them and both screws were barely hand tight...

It could be that cleaning up the threads, debreasing and applying a modern anerobic thread sealant will sort the problem - but these screws cannot be removed once the camchain case is fitted to the engine, so I need to be sure of my solution...  I'm thinking a couple of redesigned bolts, with a wider head to accept a dowty seal, is the way forward.  I just don't like there being no proper mechanical seal...

Am I being paranoid, or would others go the same way..?

Jeff
1974 Triumph T160 Trident (New Project)
1981 Yamaha XS1100 Sport (Trike Project)
1981 Yamaha XS1100 Sport (Red Sport)
1982 Hesketh V1000 (Production/Development Engine)

R3SC

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Re: Cam Chain Case Screws.
« Reply #2 on: December 08, 2013, 10:17:32 PM »
Hi Jeff,

Does the current bolt bottom out onto the end of the 5.8mm dia plain section? If not and there is no reason for it to do so then I suggest your option of a larger head with either Dowty or copper washer fitted would do the trick.

The fact that your sock to crankcase screws are M5 indicates some serious evolution as time went by!

Not to worry!

Regards

Pete.

Miti

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Re: Cam Chain Case Screws.
« Reply #3 on: December 09, 2013, 03:01:31 PM »
Hi Pete;

I don't know if the pin bottoms out into the chaincase first, or if the underside of the head bottoms against the slipper blade casting first - I'll need to check...

I like the idea of a new, larger headed, bolt and a dowty washer, but that won't eb an easy fix... The threads are M16 x 1.5mm and M16 bolts normally come in 2.0mm pitch... My donor bolts will be some sort of special order... Additionally, the lower bolt will seriously impede access to the lower inside chaincase/crankcase screw (making that one nearly as much fun as the inner middle one to get access to...!!)

As I posted up elsewhere; one of the problems that plagued the early V1000s was that the different rates of expansion twixt camchain cases and cylinder barrel/head assy meant that the small bolts at the base of the sock were sometimes (literally) pulled out of the crankcase, with distressingly oil results... :o

Some attempts at curing this centred about making the chaincase/crankcase joint more robust and larger screws abounded... If your bike has been in possession of a hands on Brit bike enthusiast, that'll be why and where your larger, non-metric screws have come from... ::)

Jeff
1974 Triumph T160 Trident (New Project)
1981 Yamaha XS1100 Sport (Trike Project)
1981 Yamaha XS1100 Sport (Red Sport)
1982 Hesketh V1000 (Production/Development Engine)