Dave W.

I agree. I've seen two sets of Glyco main bearings with similar flaws on the #1 nose bearing.

333pg333

Michael, what sort of compensation for the stock bearings would you say that dry sumping would play?

michaelmount123

Nope. The bearing width is not an issue.

I do, and they are proper race bearings, similar to the Clevite H bearing.

Yes. My understanding is $350/set gets you the machining to fit the bearing, make the rod big end concentric, set the proper oil clearance, check the balance and check the pin bushing, and includes a set of the 'H' bearings.


The Glyco's have adequate quality control for a STREET bearing. The bigger issue with them is their design and the materials are not appropriate for a performance bearing. They're okay for main bearings, problematic for the rods.

Yes, any rod designed for the 944 crankshaft can be modified, including any of the aftermarket steel or titanium rods.


Absolutely, since they have the same rod bearing issues as the 2.5.


Years ago I built a very trick 2.8L 4V NA 944 for PCA Club racing. It had a carefully designed dry sump, everything was right, and it made 335hp on the engine dyno. Oh boy… It was gonna kick ash… First race weekend the only thing it kicked was a rod out of the side of a fully prepped (expensive) S2 block. Ouch! The problem turned out to be the chitty Glyco rod bearings that gave up under the loads. This was a long time ago, and caused me to start using Chevrolet size rods and modifying the cranks so I could use a Chevy 'H' bearing. In the end, the dry sump probably fixes all of the oiling problems with the 944, but doesn't fix the rod bearing issue.

Paulyy

How much does RPM matter?

topley

My engine is soon to be assembled. So is this something where I could take the new bearings to my machine shop with the stock rods and crank and they could figure it out or is this something that needs to be done at a specific facility (and if so what would they need to accomplish it?)
Thanks,
-jay

333pg333

Right. btw...what oil and weight do you race with? Do you remember what you were using back then?

V2Rocket

not bad at all...how convenient i have a motor needing bearings

michaelmount123

It matters a lot. The higher the RPM, the more the rod big end goes egg shaped. 'H' bearings are designed to accommodate this since they have more clearance at the bearing parting line (eccentricity). Glyco bearings don't consider this (performance/race) feature.


A really good performance oriented automotive engine machine shop could probably handle it. They'll have to create a fixture for machining the rods, precisely locate the new bearing tang grooves, know the appropriate oil clearance and hone the big end accordingly, and be able to check balance and pin bushing wear. I doubt that it's worth it.

Otherwise, you can just send your rods and have it all done for $350 which includes a set of the new 'H' bearings.

I probably used a 10w40 with the dry sump. With a wet sump I'd go with Porsche's recommended weight of oil, but a RACING OIL, not the newly formulated junk.

V2Rocket

Since these bearings are (I assume?) meant for a V8, would it be much more to send all 8 bearings to the customer, so that they can have replacements on hand in the future?

michaelmount123

They're sold in pairs, but certainly spare sets are available. Don't know the price, but they're not expensive.

V2Rocket

Sweet deal.
If/when ready to do it, just get in touch with you for contact info of the shop?

Oddjob

Are saying that bearing surface area has no impact on load capability or longevity, or that this bearing is XX times stronger than a stock bearing so it can have YY less surface area and still handle higher loading?

michaelmount123

Yes! Do understand the importance of the bearing design and its intended purpose:

Mahle/Clevite H - Series Bearings
These bearings were developed primarily for use in NASCAR racing, but are suitable for all types of competition engines. H series bearings have a medium level of eccentricity, high crush, and a hardened steel back. They have a precision wall tolerance of +/- .00015" with strong, extra thin overlays to withstand high loading and resist flaking.

The reduced width is of no consequence. Even the NASCAR Chevrolet bearings are narrower than the 944 Porsche.

Tom M'Guinn

So is there any down-side to running them on a mostly street car -- other than prep costs, etc?

Oddjob

To confirm I understand: you are saying that that this particular Clevite bearing is so much stronger than a stock Glyco bearing that it can have 20-30% less surface area and still handle higher loading, correct?

Not that surface area in general bearing design has no affect on a journal bearing's ability to handle load - right?


This type of flaking?