IcemanG17

Okay I've been thinking about the 928's I know of that have had rod bearing failure. It appears the vast majority of them are 32V (I don't know of a 16V) and most have the GT-GTS 2.727 rear end or the euro 2.64 rear end (this also includes the 2.54 automatics). So here is a poll to gather some real data from people that have experienced rod bearing failure in their 928's....please restrict your votes to your actual 928's...since I don't want multiple votes from friends of the 1 failure skewing the stats....

I broke the poll into 3 sections.....

1: 32V with 2.20 rear end (early 32V 85-88)
2: 32V with 2.64 or lower 2.727
3: 16V with any rear end.....

& no this isn't a "oil" debate.....just actual occurrences of rod bearing failures....IF you are a shop or mechanic and a client does not post on rennlist...then you can vote multiple times as appropriate....

FlyingDog

The problem with asking this question is that people with track cars seek 2.64 and 2.73 rear ends, so there is going to be a disproportionate number of failures in cars with those rear ends.

You should also ask who has those features and hasn't had a failure.

AO

Here's a pic of my rod bearings at ~140k miles. They look kinda copperish in the pic, but they were actually greyish color with a little staining on a couple of them.

GlenL

This problem is endemic to all 928s and it's occurance comes from how the engine is used.

It's not the heads and it's not the differentials. It's the block, crank, oil pan and oiling system which changed very little over the entire model run.

mark kibort

Or it can depend on the tracks that are being used with similar performance. for example, Thunderhill would force generally higher rpm in the main turn sections, while not so much difference in the straights. (for a 2.5 or 2.75 vs a 2.2 type box)

At other tracks, just opposite could be possible.

mk

IcemanG17

Andrew
Those bearings look fine.....since they are all consistant! Did you have any metal traces in the filter?

Guys I don't think the rear end ratio by itself causes the problem...there might be a correlation that the higher RPM's for a given speed in a given gear could accelerate the problem....

mark kibort

Ive always used the 2.2 and the 2.22 transmissions and have no issues at all.
However, scot has been using the 2.75 and has no issues either, but a lot less race time, but still substantial. multiple seasons with no issues.

Mk

the flyin' scotsman

Tracked or non-tracked cars?

At 160k kms no worries thus far but I will have the OP off tonight/tomorrow and shall inspect the thrust brg and anything else..........its an auto so fingers crossed.

123quattro

I have a buddy that races a 924 in ITA. 924s, 944s, and 928s ALL have this problem.

He puts a new set of bearings in every year. Sometimes that's not soon enough and he puts a new engine in as well on occasion.

Lizard928

John, Would that happen to be Vaughan Scott?

AO

No. No traces of metal at all. I don't think my GT was ever tracked. I replaced these when I did the oil pan gasket about a year ago. Just giving you another data point.

AO

I know Vaughan. He been to a few local Beer nights. Good guy.

mark kibort

For some reason, I have been racing or responsible for (5) 928 engines all that have had no issues. my last engine had 105race days on it over 7 full racing seasons with no signs of wear. same with the 2 valve 5 liter before it, as well as the 4.7 before it! (no accusump, no oil coolers either) It might be my warm up procedure, amsoil racing oil, or the tracks I visit. no one knows for sure. Knock knock!!
mk

GregBBRD

Is this going to be useful information? I don't understand the relevancy.

Lizard928

Andrew, I do agree Vaughan is a standup guy, and a man of his word!

I have an interesting note to add to the origonal discussion.

I have split the girdle on a few of these. And I have seen evidance that the girdle has floated, or slapped alittle, while this is seen on almost every main, it is MOST evident around the main which supplies #2/#6.
Is it possible that some of the failures could be happening because of the block opening up alittle more than normally seen.