crankshaft repair

[types26/36]

I remember this topic being discussed previously but cant seem to locate the thread, I have a 711 crank (1600) that the rear boss where the oil seal runs has become corroded due to a leaking rear welsh plug (freeze plug) .....the engine stood for a long time.
Obviously the seal will not work on the surface due to the pitting but I recall a thread where a "machined adapter sleeve" was available so has anyone used one and any details of the company,work involved to fit,prices and is it a success?

[paddy]

Welcome back Brian.

Paddy

[garyeanderson]

Hi Brian

Here is one of the topics, they product is called ready sleave, it may not be cost effective to do. I think the smaller ones are around $35, not sure about the ones that are 3 plus inches in diameter but they do work. You can probably find another crank if it needs more than the rear seal work.

elan-archive-f16/driveshaft-slip-yoke-repair-t10611.html

oh ya, welcome back.
free-parking-f19/did-loose-another-the-top-ten-talkers-t19894.html

Gary

[robertverhey]

Yep called speedy-sleeve down here, usually used on driveshaft yokes, rear axles and on front of crank. Great care needed when installing to ensure they go on straight. I should know, I've wrecked a few!

For the rear of crank would it be better to just get it machined on a lathe until smooth? There should be enough "spring" in a new seal to still create an oil tight seal....unless we're talking major pitting

Robert

[bcmc33]

Brian,

If it were mine I would turn/grind off the corrosion and get it hard chromed and ground back to the correct diameter. Depending upon what is available in your area, perhaps metal spraying would be more convenient. I'm sure a good engine machinist would have his sources for such work.

[rjaxe]

Brian try this web site for Speedisleeve info http://www.skfmarcomms.co.uk/focus/speedi.htm
Not tried them myself but I do need to recover the seal surface of a crank so I would be interested in how you get on.

[GrUmPyBoDgEr]

How much would a new Crank cost?
It has been asked previously if other work is needed on your Crank & it may be worth weighing up the total costs.
The suggested repairs sound all do-able, particularly the metal spraying or hard chroming but whoever does the job will need to have the expertise to do the job right & offer some sort of guarantee for his work.
The failure modes for all of the fixes (delamination etc.) is a bit scary when you consider that the final fix will mean removing & rebuilding the Engine for a second time.
I think I would see if a re-grind within the given Tolerances (whatever they may be) is possible before embarking on alternative solutions.
If you decide to do that check out that the "Grinder" understands the necessity of the very faint reverse Spiral on the surface finish, that is barely visible to the naked Eye, which induces oil "wind back".
The wrong way round will turn the Seal into an oil pump, causing Oil to exit the Engine.

Good luck
John

[types26/36]

Paddy & Gary etc. thank you for the "welcome back" ......the forum had not lost another "big mouth" Pete & Stuart were right as I was away on the "Dark Continent" with little access to the net while the U.K. guys were knee deep in snow
Not sure what I will do with the crank yet as it is just a spare, I also have another spare 1600 & 1500 as well.
I was just contemplating weather it would be cost effective to repair it, the rest of the crank is standard with little or no wear.
Thanks all for the links and suggestions, I just wondered if anyone had actually used the sleeves and had practical experience of a repair rather then just relying on the manufactures words, I note the words of caution from Robert as to fitting the sleeves and like the suggestion about just cutting it down to remove the pitting but I fear the pitting is too deep.

Richard,The Speedi Sleeve looks like a relatively easy fitting process with no crank work according to the site and may be an option but I have only glanced over the details and have still to understand the releationship of the sleeve to flywheel & crank, I will study it a bit more at leisure.

QUOTE: " the "Grinder" understands the necessity of the very faint reverse Spiral on the surface finish, that is barely visible to the naked Eye, which induces oil "wind back".
The wrong way round will turn the Seal into an oil pump, causing Oil to exit the Engine."

John, that is an interesting comment and something I had not even thought about ....the Spiral effect, I wonder how critical it is on a polished surface?
I think a trip to a machine shop to weigh up my options and their opinion are the order of the day.
Thanks all.

[GrUmPyBoDgEr]

Hi Brian,
may I also say welcome back
Believe me the reverse Spiral is absolutely critical if it's "the wrong way around".
The surface my appear "polished" but a critical design feature of that surface is the practically impossible to see Spiral created by the last pass of the grinding/lapping process.
This surface finish is always specified on the "Engineering Drawing"
In the not too distant past I had to get a large number of engines reworked & all defective parts scrapped due to that Spiral going the wrong way.
(Two suppliers; one did it correctly the other, who came on the scene later, not)
Luckily my employer tested engines before sending them to the Vehicle plant thus preventing problems for the Customer.

I wonder if those suppliers of the "SpeediSleeve" take the direction of rotation into account & supply accordingly

Cheers
John

[bcmc33]

Everything John has said is in line with my ancient education and training. But things seemed to change in my last lifetime before retirement got in the way. In the complex transmissions in which I was invlolved, all the shaft bearing surfaces were hard-turned. I worried about this at the prototype stages and was advised by the foremost European seal manufacturer that as long as we met the surface finish tolerance, the method of manufacture was not important.
Our manufacturing engineers were quite specific in stating that achieving the specified surface finish tolerance (max and min specified by the seal manufacturer) could be best achieved by hard turning and not grinding. To my knowledge, there was never a question to which way the turning 'scroll' went.
BTW, polishing is a definite NO, NO.

As an aside, one of our cusomers (best know to John Pelly) criticised our choice of seal material due to being too expensive. The customer gave the seal manufacturer permision for us to use their 'secret' compound formulation described as "cheap crap" - but the fact remained that it performed as well as the most expensive material in our applications.

However, my advice to Brian - if you decide to grind, use the plunge grinding method.

[reb53]

"BTW, polishing is a definite NO, NO."

I'm curious.
Doesn't it become polished with time anyway?

Can understand why you'd never polish a cylinder bore as rings would never bed in etc.
but why not in this instance ?

Cheers
Ralph.

[CBUEB1771]

I wonder if those suppliers of the "SpeediSleeve" take the direction of rotation into account & supply accordingly

An interesting question. I copied and pasted the following from the SKF catalog:

"The sleeve is sufficiently thin-walled (.011" or .28 mm) to allow the same size of seal to be used. The Speedi-Sleeve? is made of high quality stainless steel SAE 304. The surface is wear-resistant and machined without directionality to a finish of Ra = 10 to 20 microinches or 0.25 to 0.5 ?m. This is, in fact, a better counterface than can normally be achieved on a shaft."

My boldface edit to "without directionality". One would think that an organization like SKF would "get their sums right". There is no differentiation based on direction of rotation in the actual sleeve listings.

[paddy]

I found this site which is an interesting read if you thought, like me, that the seal was simply a bit of rubber that sits around a polished shaft. It does say in here, if you look around, why a polished shaft that is absolutely smooth is no good. Also, the ring that develops on the shaft where the seal touches, which I had always assumed was just "wear", is an intrinsic part of how the seal operates.

It also mentions the so-called bi-directional or bi-rotational seal which works on shafts that can rotate in either direction.

http://www.rlhudson.com/Shaft%20Seal%20 ... shaft.html

As it says, ?A complete understanding of how a shaft seal functions is not arrived at easily.?

It's always a bit scary when you realise how completely ignorant you are of things that you thought could be taken for granted.

Paddy

[GrUmPyBoDgEr]

I wonder if those suppliers of the "SpeediSleeve" take the direction of rotation into account & supply accordingly

An interesting question. I copied and pasted the following from the SKF catalog:

"The sleeve is sufficiently thin-walled (.011" or .28 mm) to allow the same size of seal to be used. The Speedi-Sleeve? is made of high quality stainless steel SAE 304. The surface is wear-resistant and machined without directionality to a finish of Ra = 10 to 20 microinches or 0.25 to 0.5 ?m. This is, in fact, a better counterface than can normally be achieved on a shaft."

My boldface edit to "without directionality". One would think that an organization like SKF would "get their sums right". There is no differentiation based on direction of rotation in the actual sleeve listings.

I was very careful in the wording of my posting because I only post on such threads when I actually have the experience.

"Believe me the reverse Spiral is absolutely critical if it's "the wrong way around".

The Engines for which I was responsible before being put out to Grass had a Wind back Scroll, the dimensional definition of which exceeds my Brains recall capacity.
By the way Brian thanks for the the nudge on "Scroll" = Drall which is what we call it here.
The Scroll cannot be measured by normal methods & can barely be seen by the naked Eye.
The quickest way to check For Scroll direction is to hang a lightly weighted thin Cotton thread over the Shaft whilst rotating it slowly.
When the thread moves either up or down the shaft the Scroll direction can be defined.
Some older Lip Seals did in fact have a fine tangential pattern on the inside of the lip which was intended to draw excess oil away from the Shaft.
For all of the experimenting & development work done by Seal manufacturers in the past the most efficient Seals used in today's Engines is a simple rolled lip molded in "Viton" (PTFE).
The Lip pre-loading being solely dependent on the stiffness of the material. i.e. no spirally wound Seal Spring needed.
Maybe the information offered by Brian about Plunge Grinding is the "safest" manufacturing method for the Shaft surface but that does produce a "formed" surface & in my little "ideal World" a "generated" surface is the one to aim for because the state of the Grinding Wheel dressing does not play such an important role.
By the way SKF supplied bearings to us occasionally but never Seals.
We had about 4 specialist Seal manufacturers on hand whom we used to play off against one another in order to achieve the best technology & of course price.

I think I've done the technology thing to death now

Cheers
John

[bcmc33]

"BTW, polishing is a definite NO, NO."

I'm curious.
Doesn't it become polished with time anyway?

Can understand why you'd never polish a cylinder bore as rings would never bed in etc.
but why not in this instance ?

Cheers
Ralph.

A lip seal will work only when then the lip is lubricated. When not lubricated, the lip will wear and the seal will breakdown and leak. When a seal is immersed in oil there is constant lubrication, but when the seal gets only the occasional splash of oil, the shaft surface finish plays a vital role.
I guess we are all aware of water surface tension (especially when aiming at the pan but still pissing on your shoes), well oil has the same sort of properties, and the surface finish of the shaft is important to use these properties to full affect.
The seal must always have a bead of oil around the whole periphery of the sealing lip, and to achieve this there has to be a level of shaft roughness to allow the surface tension to grip the shaft and the seal lip. Too rough and the seal lip will wear away, too smooth (i.e. polishing), and the oil will run away and not be able to make a lubricating bead ? causing premature failure.
That is why seal manufacturers will specify a max & min surface finish for each and every type of seal, application and type of oil being used.

These are my words ? a seal engineer and tribologist will describe it in much more sophisticated pros, no doubt.