Engine Bearings Questions

[johnman001]

I will be rebuilding an engine in the very near future and have been reading all that I can on the topic. I have come across someones thread where there was some discussion about bearings.

Instead of hijacking another thread, I thought I would start a new one dedicated to bearings.


The discussion in the other thread is concerning "washboard" wear pattern when using aftermarket bearings. Here is a picture:





Here is a post that raises my concern:

=Steve@Rennsport;5125856]Mike is absolutely right. Glyco's quality has really slipped and the best bearings are found at the Dealer due to PAG's QC checks and standards. We no longer use Glyco rod and main bearings sourced from the aftermarket.

I currently have a set of bearings supplied by our host. Is there a way to tell if the bearings that I have will exhibit this type of wear pattern?

Would I be well advised to discard the bearings I have (or return them to our host) and source the bearings from the dealer instead?

This engine rebuild isn't something that I wish to do more than once. (Don't get me wrong, I will rebuild more, I just don't want to have to rebuild THIS one again.)

Thanks for your replies. And feel free to use this thread to discuss these bearings.




Thanks,

John Flesburg

[LeakProof]

Great,

I just replaced all my bearings, with Glyco.

Hopefully ok for my street car.

Mike.

[Mark Henry]

I've heard the dealer bearings will give you a bit of sticker shock.
I hope they get this sorted...I'm thinking of putting a hold on my 3.0 project and finishing my '67 bug instead.
Almost the same main bearings....about $25 per set...$30 for KS bearings....

I know were paying for the Porsche name...but I expect better than Ugo quality standards.

[lindy 911]

I think you would be hard pressed to measure what you see in the picture above. I'm guessing here but I would say that the "washboard" is .001" or less. As with all moving parts that mate to one another a certain amount of run in will take place, but remember that the crank and rods never touch the bearings. There is a clearance between the two that is occupied by oil and maintained by oil pressure. I am using the same bearing in my rebuild but had them coated.

I do agree that our parts for these cars are overpriced from the manufacturer. I don't believe that the bearings we get from Porsche warrant the price difference between other similar applications. NASCAR rod bearings are half the cost (even with eight rods) compared to factory Porsche parts. These are 10,000 rpm, 850 hp motors and the bearings look new after 500 miles of that. It's all about what the market will bear.

Hey Mark Henry, do the helicopters still fly over head looking for radiation in Port Hope?

Lindy

[Henry Schmidt]

No real comment about the bearings other than we use factory bearings whenever possible and polish the bearings with 600 grit wet dry and then dry film coat them.
Both factory and after market bearing alike.

One quick note: A visual inspection of the case shown below indicates that the main bearing saddles show movement. This shuffling can be minimized by applying a thin coat of LocTite 574 to the contact surface. Short of shuffle pinning the case nothing will prevent movement 100% but the 574 adds shear resistance that can be measured and witnessed during disassembly..

[Mark Henry]

Originally Posted by lindy 911

Hey Mark Henry, do the helicopters still fly over head looking for radiation in Port Hope?

Lindy

I don't think they ever have, we still have LLRW (low level radioactive waste) but it's not the nasty poop in some of your super-fund sites. They are just starting on a complete clean up of this historic waste.

But it makes no difference to me as I live way out in the country...almost 1/2 hour (at 120kph) away, about as far as you can get from the town of Port Hope and still live in the township.

I'm also closer to www.mosport.com than Port Hope.

[lindy 911]

I meant no offense Mark. I did a project in Port Hope about ten years ago that took about a week to finish. Everyday at 10:00 and 14:00 a helicopter would fly over the site in a grid pattern. I was told by the locals that it was monitoring radiation from a dump site. Around here we don't waste our money on helicopters; we just look for the green glow!

Lindy

[Mark Henry]

None taken, but I have lived here for 14years and never heard of it.
We are right in the path of CFB Trenton airforce base and we are the main air traffic corridor in Canada. We have the CG and air amblance running up and down the coast of Lake Ontario all the time.

The historic waste here is not much worse than the normal background radiation present in most basements.

[cgarr]

Looks like a little fretting with the mains goinn on there!

[Henry Schmidt]

Originally Posted by cgarr

Looks like a little fretting with the mains goinn on there!

If you're describing the movement of the bearing web as fretting maybe, but the wear (linear striations) on the bearings is more likely wear exposing a manufacturing defect.

Fretting is caused by small scale oscillatory movements. With journal bearings this can occur through external vibration transmitted to the bearing area. Fretting damage can also occur on the backs of journal bearing shells that are not given an adequate interference fit in the housing.

[johnman001]

Originally Posted by Henry Schmidt

No real comment about the bearings other than we use factory bearings whenever possible and polish the bearings with 600 grit wet dry and then dry film coat them.
Both factory and after market bearing alike.

One quick note: A visual inspection of the case shown below indicates that the main bearing saddles show movement. This shuffling can be minimized by applying a thin coat of LocTite 574 to the contact surface. Short of shuffle pinning the case nothing will prevent movement 100% but the 574 adds shear resistance that can be measured and witnessed during disassembly..

Thanks for the input.

Is the dry film coating proprietary? What is used? Do you sell these bearings and what do they cost? (You can contact me via PM if you like). I may be interested.
1987 911 3.2 Stock.

[lindy 911]

I had mine done by POLY-DYNE in Houston but there are several companies in the US that can do it.

Lindy

[kenikh]

If using Glyco bearings, they should be inspected by an expert mechanic that knows what to look for. My local wrench buys them in batches of 20, inspects them all, creates sets of "good" bearings and returns the rest. He says that about a third of the Glyco bearings he sees don't pass his inspection.

[Mark Henry]

I bet Wayne will love it if everyone starts buying 10 sets of bearings and returning 9 sets....

[kenikh]

Originally Posted by johnman001

Thanks for the input.

Is the dry film coating proprietary? What is used? Do you sell these bearings and what do they cost? (You can contact me via PM if you like). I may be interested.
1987 911 3.2 Stock.

DFL costing services can be had from most coating shops (like Calico) and there are even enterprising Pelicans doing it themselves!

[Henry Schmidt]

Originally Posted by Mark Henry

I bet Wayne will love it if everyone starts buying 10 sets of bearings and returning 9 sets....

With a 15% restocking fee, it would be my pleasure.
Capitalism at it's finest.

[kenikh]

Originally Posted by Henry Schmidt

With a 15% restocking fee, it would be my pleasure.
Capitalism at it's finest.

Makes sense - the mechanic/shop passes on the cost of the restocking plus a little extra for the inspection.

An individual buys several sets to make sure they get the best and send the rest back, losing the restocking fee. Cheap insurance, given the cost of a motor grenading.

Value added by definition.

[Cupcar]

I have had issues with Porsche packaging.

Last time I bought dealer bearings, they came all together in the same box! No individual wrapping of the parts.

Of course the "rough sex" that occurred between the bearing halves during shipping ruined the bearing set.