Author Topic: A7 Sludge trap plug problems  (Read 2456 times)

Offline Degsy

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Re: A7 Sludge trap plug problems
« Reply #30 on: 31.03. 2021 11:04 »
Wow thanks guys you have given me a lot to think about here, in the meantime some more questions…

Berger -  any ideas why someone would decide to drill down through the plug, seems a lot of work for no apparent reason? 

Thanks for all the advice on checking that the oil system is clear and working, I’ll do the crank pressure test when I get the new plugs in (all progress seems to depend on getting the old ones out at the moment).

Minto - Regarding getting the plugs out, I am sure it’s good advice but I don’t have any welding kit and I don’t know anyone up here in Scotland I would be comfortable handing the crank over to do that job.  I am going to go with the old ways, last resort of which is to drill them out, wish me luck.

Swarfcut – Taper ground journals? Excuse my ignorance is that an option I assume you mean ground in the rebuild and not worn that way and why do this? I guess you need tapered bearing shells?  Clearly I need to measure the crank journals, but I want to get the plugs sorted before I get into that. 

One thing I noticed was the drive side bearing shells had thin foil on the back, you can just see it poking out the edges of the bearing in the photo. Is this a legitimate thing to do, I assume it is to increase the thickness of the thickness of the bearing shell by a couple of thou?

This bike seems to be a mix of interesting upgrades and crude bodging. It has an Alton belt driven alternator upgrade and Boyer ignition system.

Cheers
Degsy

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Re: A7 Sludge trap plug problems
« Reply #31 on: 31.03. 2021 11:50 »
I’m late in on this thread but one I would say is that using loctite on large diameter threads eg the plugs can cause probs later, I used loctite std threadlocker on a wheel bearing retainer then due to a mistake had to undo the retainer once it had “set” a few mins and it was nigh impossible to move.

Since then I avoid using loctite on threads bigger than (say) 5/8. If you know its there heat will soften it, but if you don’t......
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Online orabanda

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Re: A7 Sludge trap plug problems
« Reply #32 on: 31.03. 2021 11:59 »
No problem to destroy the effectiveness of loctite with the correct amount of heat.

Online berger

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Re: A7 Sludge trap plug problems
« Reply #33 on: 31.03. 2021 12:28 »
degsy  I think you will find more things out when the plug is removed. without studying it I haven't really got many clues but I think it may well be to do with the end feed . you will have to study it when you have it all cleaned up and see where oil flows to the big ends and relief valve. the ally foil trick was to stop it knocking. I had rods that an end cap had been filed down to stop it knocking and had to get it re bored, its in the bike now and one piston is higher than the other by about 10 thou  but it still goes like stink when I ride it and no problems after a few years

Offline Swarfcut

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Re: A7 Sludge trap plug problems
« Reply #34 on: 31.03. 2021 13:57 »
degsy. Crank journals are ground on a dedicated machine which has a large diameter grinding wheel. From time to time the wheel requires dressing, and this procedure maintains the grinding face of the wheel parallel to the axis of the machine and to the axis of the crank being ground.

 Any error in dressing the wheel will result in a grinding face no longer matching the true axis of the machine. The result is a ground journal which is wider on one side than the other, perfectly ground but actually tapered.  The edge of the wheel also has to be dressed to correspond to the specified radius where the journal meets the crank web. Here you have to put your faith in your crank grinder.

 I jumped the gun with my earlier comment, realising a bit too late that the wear pattern is more typical of a degree of side loading on the rods, rather than tapered journals.

 In view of the chaos you've found, check every single aspect. Con rods can be easily checked for straightness, and worn or fretted  big end eyes can be reclaimed by competent engine reconditioners. Finding one of these may be your biggest problem, as the final quality inspector is you. 

 Swarfy.

Online chaterlea25

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Re: A7 Sludge trap plug problems
« Reply #35 on: 31.03. 2021 22:38 »
Hi Degsy and All,
I have not seen a roller bearing setup like that before ???
What type of bearing is fitted on the drive side? It would need to be a ball race as there is no thrust face on the
timing side
Can you post some photos of the timing covers or fittings that feed the oil to the end of the crank so we can try and understand how the builder intended all this to work ?

John
1961 Super Rocket
1963 RGS (ongoing)

Offline Jules

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Re: A7 Sludge trap plug problems
« Reply #36 on: 01.04. 2021 10:50 »
Here's a thought for the day - the plug has been screwed all the way down to avoid the cavity/void created behind it ie the sludge trap, which then requires the oil channel redrilling through the (sludge trap) plug. The logic being that no cavity = no sludge, what a great idea  *yeah*...........what do you think??

Online Rex

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Re: A7 Sludge trap plug problems
« Reply #37 on: 01.04. 2021 16:21 »
I think its April 1st...
 ;)

Offline Degsy

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Re: A7 Sludge trap plug problems
« Reply #38 on: 01.04. 2021 16:47 »
Some Progress!
I have the timing side plug out.  The ½” drive large screwdriver arrived in the post yesterday and I ground it to a good fit in the plug slot after pushing some putty in the slot to see the right shape. With the crank in my woodwork bench vice which was just wide enough to hold the Blade and stop it jumping out of the slot on a large torque wrench, a couple of bangs with the palm of my hand on the end of the wrench and the plug started moving.
I can see now the pinned hole (see photo) was redrilled to open out the oilway, but why this had to be done is still not clear, if someone realised the plug was too far in and blocking the oilway why drill all the way through the crankweb to create a wide hole, why not just remove the plug and reposition it, that would be much easier.  Perhaps Jules suggestion that they thought they were being cleaver reducing the sludge trap, people do stupid things, it is April fools day after all.  I just watched the A G Engineering guy on Youtube have all kinds of trouble cutting out a very hard magnet that had been expoxied into the hole instead of a normal sludge plug.
OK so now on to the plug on the drive side which was an Allen key hole already damaged and then rounded out completely by me with an impact wrench.  See photo, I have some short socket drive easyouts so I knocked one in and it took a lot of torque and I could have applied more as it seemed to be winding in OK but I chickened out, these easyouts feel like they apply as much expanding force as they do turning force, it just didn’t feel like it was going anywhere and might snap off.
So I have started drilling out the drive side plug and actually it is so far in that I could probably wind the new plug in flush on top of it, but it would be nice to get it out so I can clean the oilway properly.  But therein lies the problem I have stopped because I think the plug is wound all the way up against the crank so I can’t see where the plug ends and the crank starts in the drilled hole, I have been avoiding breaking all the way through to minimise the amount of swarf I get in the oilway. I need to go back to a small drill and drill through the middle to indicate the depth of the plug, I think the Allen key plugs are deeper.  I’ll have a go tomorrow.
I am not happy about the new plugs at £17 for two (from Feked) I expected them to be exactly the same as the originals with a nice wide slot that is dished deeper in the middle but they have a very narrow shallow slot (more visible in the drive side photo) which might be fine to put them in but once the loctite is set they are never going to come out with these weak slots.  I don’t plan to be around when these plugs need to come out again but I am very tempted to have a go at them with a disc on my Dremel and make them wider deeper and dished in the middle.  I decided not to go for allen keyed plugs as that is the one that is giving me trouble.

Swarfcut, Chaterlea25 and all, I am really interested in your comments on the engine its mods and getting it back together, but I think I should start another thread on this and at the moment I am fixated on sorting out the sludge plugs and I hope they will be sorted in the next few days.  By the way Chaterlea25 yes it is a ball race on the drive side and I will do some photos on the timing cover mods.
Cheers all
Degsy

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Re: A7 Sludge trap plug problems
« Reply #39 on: 01.04. 2021 19:41 »
the drive side hole goes in 44mm and same diameter as the plug on the small journal crank I have, it looks like your timing side oil hole has been chewed at so that when that plug was in and bottomed out in the threads the big ends were still getting oil

Offline Minto

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Re: A7 Sludge trap plug problems
« Reply #40 on: 02.04. 2021 01:00 »
Getting there Degsy, getting there.
What's occurring in that first picture, looks like solder dripping out.
Jase
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Online berger

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Re: A7 Sludge trap plug problems
« Reply #41 on: 02.04. 2021 09:00 »
minto that solder that isn't is where its been chewed to let oil flow to the big ends when that plug was screwed in to far

Offline Swarfcut

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Re: A7 Sludge trap plug problems
« Reply #42 on: 02.04. 2021 09:13 »
 Degsy. Just measured the depth of the cavity for the timing side plug. It's 14mm. The oilway at the bottom of the cavity takes a 5mm drill leading to the journal, but interestingly, on this crank at least, the hole is offset  and lying closer to the centre of the crank than to the centre of the plug hole. Compare this to the position of the oilway in the timing side plug hole on your crank.

 From your picture the base of the plug hole looks solid, and your drilling is centred on the centre of the plug hole,  maybe missing the centre of the oilway that you're looking for. To me it almost looks as if  you have removed the plug and you are down to the crank.

 To clean out the oilway a long drill is a good way to remove  the crud. If you invest in a suitable drill then coming down the oilway from the timing side and into the back into the blocked off plug cavity is a possible solution.   With  free access, simply drill  through into the  cavity from the timing side using the oilway as a drill guide.

Then of course theory this is based on the pictures to hand.....

 Swarfy.

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Re: A7 Sludge trap plug problems
« Reply #43 on: 02.04. 2021 09:47 »
mmmm interesting swarfy, the small journal crank I have here is drilled 11mm in on the timing side and then a 1/4 inch oil hole, on the drive side the hole goes in 44mm and is opened up to the plug size diameter.

Offline Swarfcut

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Re: A7 Sludge trap plug problems
« Reply #44 on: 02.04. 2021 10:16 »
bergs. My crank is work in progress. Drive side plug off  to reveal  small cavity completely full of crud.  Drive journal side scored at 60 thou down,  Timing side a poor under 40. So potential  doorstop in the short term. Explored deeper into the oilway with a 5mm drill, but when cleaned up yes more likely to be an imperial 1/4"

 Degsy's crank looks to have a small cavity, like mine with maybe the oilway sealed with an additional driven in plug. Hard to tell from the camera angle.

 Swarfy.