Why a Triumph sludge tube ???

nortriubuell · Mar 8, 2013

Triumph unit 650s and 750s have a sludge tube in the crankshaft. And, the ones I've stripped and rebuilt had lots of crud that did need cleaning out. However, THE Commando crankshaft does NOT have a sludge tube. :shock: And yet, all the (several) Norton crankshafts I stripped had very little "sludge" in them ??? :? :? :? Of course I cleaned them out, and cleaned the Triumph ones out as well. I've even heard horror stories of Triumph sludge tubes getting so clogged up, that the motors seized from lack of oil to the big ends ! (Never heard about a Commando doing this though)

Which brings me to my question ... since I'm rebuilding a 1971 Triumph 650 motor that is now completely stripped, why even bother to install the sludge tube ??? Although I've not heard of anyone leaving it out, seems to me it would be better (like the Norton Commando) to just omit installing the sludge tube ??? Maybe it would even stay much cleaner between rebuilds as well. ALL comments and opinions are much appreciated

swooshdave · Mar 8, 2013

nortriubuell said:
Triumph unit 650s and 750s have a sludge tube in the crankshaft. And, the ones I've stripped and rebuilt had lots of crud that did need cleaning out. However, THE Commando crankshaft does NOT have a sludge tube. :shock: And yet, all the (several) Norton crankshafts I stripped had very little "sludge" in them as well. ??? :? :? :? Of course I cleaned them out, and cleaned the Triumph ones out as well. I've even heard horror stories of Triumph sludge tubes getting so clogged up, that the motors seized from lack of oil to the big ends ! (Never heard about a Commando doing this though)

Which brings me to my question ... since I'm rebuilding a 1971 Triumph 650 motor that is now completely stripped, why even bother to install the sludge tube ??? Although I've not heard of anyone leaving it out, seems to me it would be better (like the Norton Commando) to just omit installing the sludge tube ??? Maybe it would even stay much cleaner between rebuilds as well. ALL comments and opinions are much appreciated

Oil filters on the Nortons?

kommando · Mar 9, 2013

I would say it was down to the shape of the trap, the Triumph is long and small in diameter the Norton is the opposite. Maybe as the Triumph fills up the oil pressure needed to keep the channel open is higher than the pump can supply due to it length and the Norton pump can keep a passage open as it only a short length. We need a fluid engineer to give us the answer.

grandpaul · Mar 9, 2013

For every story of a Triumph seizing up due to a clogged sludge trap, there is a story of a Norton crank blowing up and sending rods through the case for whatever reason. I have heard of only 2 Triumphs blowing through cases, one due to an idiot over-revving a new engine, the other a drag racer trying to win at all costs.

nortriubuell · Mar 9, 2013

kommando said:
I would say it was down to the shape of the trap, the Triumph is long and small in diameter the Norton is the opposite. Maybe as the Triumph fills up the oil pressure needed to keep the channel open is higher than the pump can supply due to it length and the Norton pump can keep a passage open as it only a short length. We need a fluid engineer to give us the answer.

The plunger type oil pump and the passage size, those are most excellent points kommando !!! Never thought about that. :shock: Anyone else wish to chime in ???

Triton Thrasher · Mar 9, 2013

Interesting that ( if) the Norton crank doesn't centrifugally deposit stuff somewhere.

grandpaul · Mar 9, 2013

Yes, of course Norton cranks build up sludge; it's just allowed to be washed into the bearings easier.

swooshdave · Mar 9, 2013

grandpaul said:
Yes, of course Norton cranks build up sludge; it's just allowed to be washed into the bearings easier.

I've seen porn that wasn't that dirty.

acotrel · Mar 11, 2013

The crank in my short stroke 500 triumph was made out of a billet - no sludge trap. However it was raced , not used slowly over thousands of miles of public roads .

dave M · Mar 11, 2013

Nortibuell, I would not leave the sludge trap out under any circumstances, it must be there for a reason otherwise Triumph themselves could have saved a significant amount of money by leaving them out over the years. I don't know the technical reason why but I'm sure there are sound engineering reasons involved.

nortriubuell · Mar 11, 2013

grandpaul said:
Yes, of course Norton cranks build up sludge; it's just allowed to be washed into the bearings easier.

Wow ... that IS some nasty sludge buildup GPZ, thanks for posting. Didn't know Norton cranks could get so clogged, based on my limited knowledge (on the 6 or so that I have actually tore down.)

nortriubuell · Mar 11, 2013

dave M said:
Nortibuell, I would not leave the sludge trap out under any circumstances, it must be there for a reason otherwise Triumph themselves could have saved a significant amount of money by leaving them out over the years. I don't know the technical reason why but I'm sure there are sound engineering reasons involved.

I appreciate your input as well dave M

As this is why I started the thread, to get opinions and information. Many thanks to all who chimed in. I will install the sludge tube, and not second guess Triumph engineering on this. Cheers all.

dave M · Mar 11, 2013

Another thing to bear in mind is that the main British motorcycle designers seemed to move from one company to the next from time to time, so there would have likely been an opportunity to delete this part if it was simply a different design philosophy. They are cheap and fairly easy to clean out and or replace, so let someone else try it and report back while you enjoy your bike secure in the knowledge that it is as per the factory built it.

I recently put a new one in a 1965 Bonneville that I am restoring and had to file a bit off the inner face to get it to fit properly.

swooshdave · Mar 11, 2013

I always assumed that the sludge trap was just that. A pre-oil filter filter.

dave M · Mar 11, 2013

Swoosh, As far as I'm aware Norton only used remote oil filters in their later Commando iterations, the bolt up crank had been around since the early Dominators.

Bernhard · Mar 12, 2013

swooshdave said:
I always assumed that the sludge trap was just that. A pre-oil filter filter.

The correct description for the Norton Dommis/Commando is a centrifugal oil filter, hence why you have to strip the whole crank apart every so often, to clean the hard crud inside it.

phillyskip · Jul 16, 2014

The Triumph Sludge trap acts as a centripetal oil filter that works much like the oil filters found on Honda CB 450s. It needs to be there and it also needs to be serviced every time the engine is totally taken apart. I have never seen a clean one in any Triumph mill. Period.

phillyskip · Jul 23, 2014

Here fellows check this out.....
http://vid136.photobucket.com/albums/q1 ... V07909.mp4

B+Bogus · Sep 18, 2014

When I rebuilt my T140 I binned the sludge tube, but I also fitted a paper element filter in the frame sump-plate, and converted to a gear-type Morgo pump.

Back in the day these engines ran mono-grade oil which didn't contain the detergents found in multi-grade, so particles weren't held in suspension, but would be more easily removed from the oil by centrifugal force. Multi-grades carry the particles better and work better with full-flow filters.

It's what I've been told anyway :wink:

Triton Thrasher · Sep 19, 2014

You reckon "detergents" counteract centrifugal force?

Why a Triumph sludge tube ???

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