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E85 / E86 Z4 (2003-2008)
E85 Z4 Roadster, E86 Z4 Coupe, E85 Z4 M Roadster, and E86 Z4 M Coupe talk with our BMW gurus here.

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  #1  
Old 09-17-2013, 04:39 PM
england1987 england1987 is offline
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Location: High Point N.C.
 
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Z4 M Rod bearings failed

So, a little background. My 2006 car has 59000 miles. All oil changes have been made. The car has not seen track use, but I do autocross, plus I have a lead foot. The car is not abused, but I do drive it as an M should be. Last week it started making a strange ticking noise (a bit louder than the normal valve tick), so I changed the oil (I did not inspect the oil, should have). The sound got worse basically straight away. I had the car towed to the stealership. They diagnosed the problem as a faulty VANOS at a cost of $4950. It was a plausible explanation, but I wasn't convinced. The sound was not coming from the front of the engine, but rather sounded like it was coming from around cylinder 4 or 5. I went by the dealership yesterday and they had changed their mind. The SA said that they have found metal shavings in the oil, and that they had discovered worn rod bearings. I did not get all the details about which ones had failed, but I will hound the SA when I get the car back for full details. I sent an email to BMW yesterday to see if they would provide any assistance. I have not heard back and don't honestly expect to.

Just wanted this info out there for other owners. Be wary, the bearings be going! Also, the cost as far as I have been told so far will be $2800.
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  #2  
Old 09-17-2013, 05:38 PM
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shipkiller shipkiller is offline
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I am sorry to hear about this. More and more Z4M's are having this issue. About the same as the E46 guys..

I also hate to say, but you paid twice what a good independent shop would charge for a rod bearing replacement, by going to the dealer.

Hindsight is what it is, but now you should think about doing an oil analysis every oil change. This would have given you a very good indication that your rod bearings were going south and scheduled the 'maintenance' at your leisure. This was how I found my rod bearing issue (43ppm of lead) and had my bearings replaced a month or so ago. Total cost out the door was $1600.

Ask for all the bearings back. You will find that ALL of them are worn.

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  #3  
Old 09-17-2013, 07:33 PM
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pal pal is offline
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I have replaced mine twice already- details below. Glad you got it done before a spun or seized bearing caused the pistons or rods to ventilate the block.

Rod Bearings Replaced Again
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  #4  
Old 09-17-2013, 10:00 PM
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Randy Forbes Randy Forbes is offline
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Quote:
Originally Posted by england1987 View Post
So, a little background. My 2006 car has 59000 miles. All oil changes have been made. The car has not seen track use, but I do autocross, plus I have a lead foot. The car is not abused, but I do drive it as an M should be. Last week it started making a strange ticking noise (a bit louder than the normal valve tick), so I changed the oil (I did not inspect the oil, should have). The sound got worse basically straight away. I had the car towed to the stealership. They diagnosed the problem as a faulty VANOS at a cost of $4950. It was a plausible explanation, but I wasn't convinced. The sound was not coming from the front of the engine, but rather sounded like it was coming from around cylinder 4 or 5. I went by the dealership yesterday and they had changed their mind. The SA said that they have found metal shavings in the oil, and that they had discovered worn rod bearings. I did not get all the details about which ones had failed, but I will hound the SA when I get the car back for full details. I sent an email to BMW yesterday to see if they would provide any assistance. I have not heard back and don't honestly expect to.

Just wanted this info out there for other owners. Be wary, the bearings be going! Also, the cost as far as I have been told so far will be $2800.
I'm still doing them for a little less than half that__for polymer coated bearings__the swap with plain bearings would've been 1/3 of what you were quoted.

Next time

A batch in the oven:

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  #5  
Old 09-17-2013, 10:27 PM
Vladi Vladi is offline
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I passed by the stealer two days ago asking if they can make oil analysis since I feared my bearings (2006 Z4 M Roadster) could be failing although so far no symptoms (a bit less than 35,000 miles). The stealer told me they don't make oil analyses but here in Switzerland all S54 cars with potential bearing problems were called off. Those were mainly M3s and Z3 Ms. He also told me deffective bearings rarely fail without signs (clatter at low rpms and sudden high loads). In principle it's true (have seen it on two cars already, one of which went through at least 10,000 miles like that) but not sure how much time does the owner of a S54 have to catch failing bearings before they fail completely and turn the engine into an oily mess. So I am considering taking a sample from the oil before the next change and send it to Blackstone for analysis.
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  #6  
Old 09-17-2013, 10:35 PM
Vladi Vladi is offline
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Quote:
Originally Posted by Randy Forbes View Post
I'm still doing them for a little less than half that__for polymer coated bearings__the swap with plain bearings would've been 1/3 of what you were quoted.

Next time

A batch in the oven:

Randy, do you coat those bearings with some polymer? I am a thin film engineer and was thinking more about something like DLC (Diamond-Like Carbon) or titanium nitride coating... We had excellent results with DLC on a camshaft during my PhD study.
Actually, what's the problem with the original bearings - starved lubrication resulting in wear? I guess that since the contact stresses in a sliding bearing like this are not so high, a simple hard coating would do great job protecting the softer core material...
Also, do you know what's the surface roughness (Ra or Rz) of a brand-new bearing?
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  #7  
Old 09-17-2013, 11:33 PM
noviceZ3M noviceZ3M is offline
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Randy,

I currently own a 2000 M Roadster and M Coupe. If I ever get into an 01-02 or Z4 I will call you immediately. Love to support a guy with a passion.

Thank you for all you do.

tj
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  #8  
Old 09-18-2013, 03:20 AM
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There is a long discussion over on another forum on this subject. Check out this bit of information: http://www.langracing.com/finding-a-...aring-failure/
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How does something immoral, when done privately, become moral when it is done collectively?
Furthermore, does legality establish morality?
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  #9  
Old 09-18-2013, 06:15 AM
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Randy Forbes Randy Forbes is offline
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Originally Posted by Vladi View Post
Randy, do you coat those bearings with some polymer? I am a thin film engineer and was thinking more about something like DLC (Diamond-Like Carbon) or titanium nitride coating... We had excellent results with DLC on a camshaft during my PhD study.
Actually, what's the problem with the original bearings - starved lubrication resulting in wear? I guess that since the contact stresses in a sliding bearing like this are not so high, a simple hard coating would do great job protecting the softer core material...
Also, do you know what's the surface roughness (Ra or Rz) of a brand-new bearing?
I'm using a dry-film lubricant; I don't think you'd want to increase the hardness of the surface, as part of the bearings job is the ability to embed small particles__if any__that pass through the oil filter, sacrificing itself to protect the crankshaft/camshafts, or what have you.

As an engineer, you're probably a lot more familiar with the in depth analysis; me, I just go with what works. I've been using these polymer coatings (dry-film lubricant, thermal barriers and thermal dispersant) for over twenty (>20) years, and have had the opportunity to go back inside engines with 80k+ miles after the coating process, seeing negligible wear. I'm sold on the product manufacturer's claim about their validity. These technologies were developed during NASA's Space Shuttle program, reaching the private sector as a result of Reagan's push to transfer technology during the late 80s. I got onboard with them pretty quick, and since then, some major component manufacturers have implemented the process (the S-54 pistons originally had just the skirts coated with a dry-film lubricant). It's a labor intensive process; it takes time, and time costs money, otherwise we'd be seeing a lot more applications than the current offerings.

I'm assembling an S-54 engine right now that's had a full compliment of coatings, and I have another engine already en route to me, plus the owner of this engine is supposed to be sending me the one he competed with this past season.





The complete tear down, coating and rebuilding of this engine__still in progress__can be followed here: http://www.spcarsplus.com/gallery3/i...hp/TM-S-54-O-H
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1999///M Rdstr Cosmos Black Eurosport Twinscrew S/C
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  #10  
Old 09-18-2013, 06:29 AM
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Randy Forbes Randy Forbes is offline
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Quote:
Originally Posted by shipkiller View Post
There is a long discussion over on another forum on this subject. Check out this bit of information: http://www.langracing.com/finding-a-...aring-failure/
TechLine's TLML (dry-film lubricant) does have the ability to retain oil, so that's a plus for people that opt to go with a set of coated bearings, versus one of Lang's re-engineered crankshaft/rod (std or longer stroke) kits.

Though it doesn't show up well in pictures, you can see how this lightweight (Total Seal) assembly lube for the piston skirts appears to penetrate into the surface. Slippery stuff!

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1957 Austin-Healey 100/6 Wine Red
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1995///M3 Coupe Dakar Yellow Eurosport Twinscrew S/C
1999///M Rdstr Cosmos Black Eurosport Twinscrew S/C
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Last edited by Randy Forbes; 09-18-2013 at 06:32 AM.
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  #11  
Old 09-18-2013, 11:06 AM
Vladi Vladi is offline
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Quote:
Originally Posted by shipkiller View Post
There is a long discussion over on another forum on this subject. Check out this bit of information: http://www.langracing.com/finding-a-...aring-failure/
Thank you for the link! From what I understood, it is starved lubrication after all. Even without modifiyng the design of the bearings, surface treatement plus thicker oil would do the trick. As proven by Randy.
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  #12  
Old 09-18-2013, 12:05 PM
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shipkiller shipkiller is offline
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I talked to James Clay of Bimmerworld when I was at VIR in May, he said that they are seeing less wear on the rod bearings going to a thinner oil, like a 15W50. That's the weight I am running right now.
I have a three day track event this coming weekend and will be changing the oil after that. I plan on sending off a sample to Blackstone to establish a baseline since my bearings were replaced just over 3000 miles ago.
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How does something immoral, when done privately, become moral when it is done collectively?
Furthermore, does legality establish morality?
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Old 09-18-2013, 12:08 PM
chickdr chickdr is offline
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Quote:
Originally Posted by shipkiller View Post
There is a long discussion over on another forum on this subject. Check out this bit of information: http://www.langracing.com/finding-a-...aring-failure/
From that article:

"Letís get down to what I consider the main problem: when the piston is on its compression stroke and the mixture is ignited a tremendous pressure is imparted on the top of the piston, down the wrist pin, through the rod, and into the rod bearing. Some engines have trouble or weakness upwards of this chain but what the S54 does is squeeze out all the oil causing the bearing to wear on the top side. This is a simple conclusion to reach when you dissect S54***8242;s day in and day out, the bearing wear tells the story. This situation is also what makes me a bit uneasy about the common suggestion that a coated rod bearing is a great solution on the S54. If a coated bearing is adding material to a rod bearing then, obviously, it must also be reducing the bearing clearance on the crankshaft journal. Some rod bearing treatments are designed to allow the bearing to retain oil better, which, if they do actually do that would be helpful. Still, I donít believe that these bearings adequately address the original engine design flaw."

I would be interested to hear Randy's opinion on this. PAL has had both coated and OEM rod bearings and said there doesn't seem to be any difference in lifespan. It sounds like a more extensive fix is needed to solve the problem. Otherwise you are just putting rod bearings on the maintenance schedule as you do with valve adjustments.
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  #14  
Old 09-18-2013, 01:31 PM
england1987 england1987 is offline
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Thanks everyone for the responses. I will be taking a different approach if/when this happens again in the future. I don't have the car back yet, hopefully tomorrow. I did read where people were using Motul 15W50 Comp oil. This will probably be what I do when I changed the oil next. It appears that I should also add oil analysis to my regular maintenance.
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  #15  
Old 09-18-2013, 10:29 PM
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Randy Forbes Randy Forbes is offline
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Quote:
Originally Posted by chickdr View Post
From that article:

"Let's get down to what I consider the main problem: when the piston is on its compression stroke and the mixture is ignited a tremendous pressure is imparted on the top of the piston, down the wrist pin, through the rod, and into the rod bearing. Some engines have trouble or weakness upwards of this chain but what the S54 does is squeeze out all the oil causing the bearing to wear on the top side. This is a simple conclusion to reach when you dissect S54***8242;s day in and day out, the bearing wear tells the story. This situation is also what makes me a bit uneasy about the common suggestion that a coated rod bearing is a great solution on the S54. If a coated bearing is adding material to a rod bearing then, obviously, it must also be reducing the bearing clearance on the crankshaft journal. Some rod bearing treatments are designed to allow the bearing to retain oil better, which, if they do actually do that would be helpful. Still, I don't believe that these bearings adequately address the original engine design flaw."

I would be interested to hear Randy's opinion on this. PAL has had both coated and OEM rod bearings and said there doesn't seem to be any difference in lifespan. It sounds like a more extensive fix is needed to solve the problem. Otherwise you are just putting rod bearings on the maintenance schedule as you do with valve adjustments.
I've got another S-54 engine (loose) arriving on Friday for a rebuild, just like the one I'm wrapping up right now; I'll make it a point to compare a random set of coated bearings with a non-coated/plain set to compare running clearance.

Personally, I don't believe the dry-film lubricant that I'm applying adds any perceivable build thickness (it's applied .0015" thick and then burnished back). We did the Plastigauge on Pal's coated bearings, in part because the rod bolts needed to be put through a tightening sequence three (3) times, and every one was between .0015 - .002". In fact, if you have a situation where your clearance is too great, there's a product that sprayed onto the backside of the bearing shell to reduce running clearance.

I don't know, I've been doing the polymer coatings for over twenty (>20) years (building engines closer to 40 yrs...) so if it wasn't working, I'd be getting lots of phone calls...

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1957 Austin-Healey 100/6 Wine Red
1961 McCulloch R1 go-kart Screaming Yellow
1995///M3 Coupe Dakar Yellow Eurosport Twinscrew S/C
1999///M Rdstr Cosmos Black Eurosport Twinscrew S/C
1999///M Coupe Estoril Blue Eurosport Twinscrew S/C
2001///M Rdstr Steel Gray
2011 X5 35i Sport Deep Sea Blue/Cinnamon

Last edited by Randy Forbes; 09-18-2013 at 10:38 PM.
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  #16  
Old 09-18-2013, 11:34 PM
Vladi Vladi is offline
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Quote:
Originally Posted by Randy Forbes View Post
I'm using a dry-film lubricant; I don't think you'd want to increase the hardness of the surface, as part of the bearings job is the ability to embed small particles__if any__that pass through the oil filter, sacrificing itself to protect the crankshaft/camshafts, or what have you.

As an engineer, you're probably a lot more familiar with the in depth analysis; me, I just go with what works. I've been using these polymer coatings (dry-film lubricant, thermal barriers and thermal dispersant) for over twenty (>20) years, and have had the opportunity to go back inside engines with 80k+ miles after the coating process, seeing negligible wear. I'm sold on the product manufacturer's claim about their validity. These technologies were developed during NASA's Space Shuttle program, reaching the private sector as a result of Reagan's push to transfer technology during the late 80s. I got onboard with them pretty quick, and since then, some major component manufacturers have implemented the process (the S-54 pistons originally had just the skirts coated with a dry-film lubricant). It's a labor intensive process; it takes time, and time costs money, otherwise we'd be seeing a lot more applications than the current offerings.

I'm assembling an S-54 engine right now that's had a full compliment of coatings, and I have another engine already en route to me, plus the owner of this engine is supposed to be sending me the one he competed with this past season.


The complete tear down, coating and rebuilding of this engine__still in progress__can be followed here: http://www.spcarsplus.com/gallery3/i...hp/TM-S-54-O-H
Hi Randy,

Thank you for posting those details!

Indeed, a hard coating would not make sense in this case since the bearings are killed by starved lubrication. So a harg coating would, no doubt, protect them but the wear will shift from them to the crankshaft and the rods.

Your solution (using a solid lubricant) seems to be very adequate for this tribological system. In the coating world there are many solid lubricants varying from soft metals (gold, lead, silver, tin) through polymers (mainly PE and PTFE-based ones) to "laminar solids" (typically graphite, sulphides of transition metals such as molybdenum and tungsten, boron nitride). The choice of which one to use is often very difficult and depends on many factors:

1. Contact stress - soft metals and polymers work well with low contact stress but often fail when the stress becomes moderate to high - since they are soft and not very strong, they get either pierced through or simply shear. Some of the "laminar solids" need some stress threshold above which they become lubricants and below which they provide no lubrication whatsoever - this is related to stress-induced phase transformations (most often crystallization) at the point of contact. Those transformations turn the non-lubricating solid into a lubricating one;

2. Temperature - here, it's the temperature of the contact zone, not necessarilly the temperature of the environment. Those two can differ by orders of magnitude. Clearly, a soft metal can not be a solid lubricant above its melting point. Polymers usually do not resist temperatures above 300-350 degrees Centigrade on the long term but even if they are semi-molten, they provide lubrication. The inorganic solids can be used to very high temperatures, unless those temperatures cause chemical reaction with the environment and/or the substrate or the friction counterpart;

3. Environment - what surrounds the coating can react with it chemically. This reaction can be either detrimental (in most cases) or beneficial. For instance, the soft metals (except for gold) corrode in air, water, acids, etc; sulphide-based coatings oxidize in air and/or humidity, etc. For the Diamond-Like Carbon (DLC) based coatings humidity is beneficial because it creates saturated bonds on the surface of the coating thus increasing lubricity. This is why those coatings perform best in humid environments and sulphide-based coatings perform best in inert environment (nitrogen, vacuum) and are used in space applications.

These are, in a nutshell, the main factors that dictate the choice of solid lubricant coatings. But, as with many other things, the final choice is made on the basis of trials and errors.

Another possibility to fight starved lubrication is to structurize the surface in such a way that it retains oil even if the oil film is squeezed out of the contact zone due to high contact stress. The usual way to do this is to make the surface porous. Some years ago we experimented with laser treatement:

http://journals.cambridge.org/action...ne&aid=8067595

(V. Spassov is me)

which gave very good results. The laser creates microscopic pits that serve as oil sources once the oil film is no more in the contact zone.

Another thing that I devoted years of my research (and the topic of my PhD study, actually), was mixed coatings consisting of a hard matrix with inclusions of solid lubricants. But I am not sure at all those coatings would be suitable for sliding bearing lubrication since they need a certain contact stress in order to become lubricants:

http://edoc.unibas.ch/898/
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Old 09-18-2013, 11:39 PM
Vladi Vladi is offline
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Quote:
Originally Posted by shipkiller View Post
I talked to James Clay of Bimmerworld when I was at VIR in May, he said that they are seeing less wear on the rod bearings going to a thinner oil, like a 15W50. That's the weight I am running right now.
I have a three day track event this coming weekend and will be changing the oil after that. I plan on sending off a sample to Blackstone to establish a baseline since my bearings were replaced just over 3000 miles ago.
Interesting! It completely contradicts the shift of BMW to the thicker 10W60 in an attempt to address the bearing problem. Also, it's logical to expect thicker oil to support higher contact stress before the film is squeezed out. Of course, at high rpm the shear forces on a thicker oil are greater so it can shear off easier than a thinner oil. I guess the solution depends on a balance between those factors and maybe just a little bit thinner oil is better for track days...
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Old 09-18-2013, 11:51 PM
Vladi Vladi is offline
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Quote:
Originally Posted by chickdr View Post
From that article:

"Letís get down to what I consider the main problem: when the piston is on its compression stroke and the mixture is ignited a tremendous pressure is imparted on the top of the piston, down the wrist pin, through the rod, and into the rod bearing. Some engines have trouble or weakness upwards of this chain but what the S54 does is squeeze out all the oil causing the bearing to wear on the top side. This is a simple conclusion to reach when you dissect S54***8242;s day in and day out, the bearing wear tells the story. This situation is also what makes me a bit uneasy about the common suggestion that a coated rod bearing is a great solution on the S54. If a coated bearing is adding material to a rod bearing then, obviously, it must also be reducing the bearing clearance on the crankshaft journal. Some rod bearing treatments are designed to allow the bearing to retain oil better, which, if they do actually do that would be helpful. Still, I donít believe that these bearings adequately address the original engine design flaw."

I would be interested to hear Randy's opinion on this. PAL has had both coated and OEM rod bearings and said there doesn't seem to be any difference in lifespan. It sounds like a more extensive fix is needed to solve the problem. Otherwise you are just putting rod bearings on the maintenance schedule as you do with valve adjustments.
Well, there are two ways to address a problem like this:

1. Remove the cause altogether;
2. Make the system resistant to the cause.

Those guys have chosen the first and Randy has chosen the latter. Apparently, they both work. Which one works better (i.e. lasts longer) is, apparently, hard to tell. The choice of which one to use is a question of price, availability, logistics, etc.

I wouldn't be too worried about changing the bearings' sizes by applying a coating on them. A typical tribological coating is usually not more than 1-2 Ķm thick (exceptions are well known though) and in this case one can go with even thinner than that.
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Old 09-19-2013, 06:42 AM
chickdr chickdr is offline
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Originally Posted by Vladi View Post
Well, there are two ways to address a problem like this:

1. Remove the cause altogether;
2. Make the system resistant to the cause.

Those guys have chosen the first and Randy has chosen the latter. Apparently, they both work. Which one works better (i.e. lasts longer) is, apparently, hard to tell. The choice of which one to use is a question of price, availability, logistics, etc.

I wouldn't be too worried about changing the bearings' sizes by applying a coating on them. A typical tribological coating is usually not more than 1-2 Ķm thick (exceptions are well known though) and in this case one can go with even thinner than that.
#1 seems a much better solution to me as #2 seems like a band-aid. Solving the problem(if possible) is certainly a better plan IMHO.
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Old 09-19-2013, 07:24 AM
Vladi Vladi is offline
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Originally Posted by chickdr View Post
#1 seems a much better solution to me as #2 seems like a band-aid. Solving the problem(if possible) is certainly a better plan IMHO.
All other conditions being the same - yes, removing the reason for a problem is the best solution "a priori". However life is such that "all other conditions being the same" is rarely the case. There is a myriad of cases where removing the reason for a problem causes one or more other problems... To me "band aid" is more a synonym of a temporary solution until a better solution is found that eliminates the problem. In this line of thoughts, if coating the bearings eliminates the problem with their wear, it is a final solution, not a temporary one so I can't consider it "band aid". It just attacks the problem from a different side.
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  #21  
Old 09-20-2013, 05:41 AM
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Randy Forbes Randy Forbes is offline
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Originally Posted by Vladi View Post
Well, there are two ways to address a problem like this:

1. Remove the cause altogether;
2. Make the system resistant to the cause.

Those guys have chosen the first and Randy has chosen the latter. Apparently, they both work. Which one works better (i.e. lasts longer) is, apparently, hard to tell. The choice of which one to use is a question of price, availability, logistics, etc.

I wouldn't be too worried about changing the bearings' sizes by applying a coating on them. A typical tribological coating is usually not more than 1-2 Ķm thick (exceptions are well known though) and in this case one can go with even thinner than that.
Thank you; you clearly have a practical handle on not only the engine's needs and its immediate short-comings, but also the processes involved to each solution.

Quote:
Originally Posted by chickdr View Post
#1 seems a much better solution to me as #2 seems like a band-aid. Solving the problem(if possible) is certainly a better plan IMHO.
Indeed, and it only comes down to deciding if you want to spend $10,000.00+ or $1,000.00+ to address the issue. Simple as that.
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  #22  
Old 09-20-2013, 10:30 AM
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I guess that is my question- do the coated bearing actually fare better than non-coated? Pal's car didn't seem to have any longer wear with the coating than without. Is this typically the case? Randy- in your experience does replacing with coated bearings give twice the longevity? 25% longer?
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Old 09-20-2013, 06:30 PM
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Originally Posted by chickdr View Post
I guess that is my question- do the coated bearing actually fare better than non-coated? Pal's car didn't seem to have any longer wear with the coating than without. Is this typically the case? Randy- in your experience does replacing with coated bearings give twice the longevity? 25% longer?
That is not typically the case; by Pal's own admission, he's become a better driver, abling him to reach faster sppeds / higher RPMs sooner and holding them longer. If you're going to be subjecting any engine to racing conditions, then it has to be maintained as such.

As to quantify the benefits of reduced friction and increased efficiency, I have to ask, under what conditions? Racetrack (sustained high RPMs) daily driver (cold starts, stop and go traffic, lugging around at lower RPMs with an occasional burst to the redline) or...? I've taken apart one of my own fully coated engines after I put 80,000 miles on it (a replacement hardened valve seat dislodged, causing really minimal damage); I had the cylinder head rebuilt and reassembled the engine with the same bearings, pistons__with a fresh set of Total Seal "gapless" rings__and continued to use it (74-1/2 MGBGT) as a daily driver for several more years (who knows, my X may still be driving it...).

Dry-film lubricated parts reduce friction and increase a machine's efficiency, how long they last will be entirely up to the user. If you don't agree with that, well then, don't use them.
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Last edited by Randy Forbes; 09-20-2013 at 06:33 PM.
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  #24  
Old 09-21-2013, 06:50 AM
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Originally Posted by Randy Forbes View Post
That is not typically the case; by Pal's own admission, he's become a better driver, abling him to reach faster sppeds / higher RPMs sooner and holding them longer. If you're going to be subjecting any engine to racing conditions, then it has to be maintained as such.
Additionally, I believe Randy's coated bearings did the job by being the initial sacrificial layer before getting down to the lead. Under racing conditions (DE is only that for the driver, for the car its racing), a high revving and high stroke engine that has small and narrow bearings like the S54 will lead to wear. The idea is to ensure that the wear is not damaging to the engine and provides enough protection to be replaced/rebuild - in this case the bearings.

If I were not contemplating a bottom end rebuild down the line and if I was not in a tight time crunch (Blackstone report came in on Tue and I had a track event at Watkins Glen the following Monday), I would have gone with another set of coated bearings. And may do so next time around ...

This time I plan to use the Motul 300V Competition 15w50 racing oil to see if it helps with life and wear rates.
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  #25  
Old 09-21-2013, 07:27 AM
chickdr chickdr is offline
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Quote:
Originally Posted by Randy Forbes View Post
That is not typically the case; by Pal's own admission, he's become a better driver, abling him to reach faster sppeds / higher RPMs sooner and holding them longer. If you're going to be subjecting any engine to racing conditions, then it has to be maintained as such.

As to quantify the benefits of reduced friction and increased efficiency, I have to ask, under what conditions? Racetrack (sustained high RPMs) daily driver (cold starts, stop and go traffic, lugging around at lower RPMs with an occasional burst to the redline) or...? I've taken apart one of my own fully coated engines after I put 80,000 miles on it (a replacement hardened valve seat dislodged, causing really minimal damage); I had the cylinder head rebuilt and reassembled the engine with the same bearings, pistons__with a fresh set of Total Seal "gapless" rings__and continued to use it (74-1/2 MGBGT) as a daily driver for several more years (who knows, my X may still be driving it...).

Dry-film lubricated parts reduce friction and increase a machine's efficiency, how long they last will be entirely up to the user. If you don't agree with that, well then, don't use them.
Not trying to get into an argument Randy. I don't know the answer and this is why I asked. When it comes time to do my rod bearings just want as much info as I can get.
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