oroni123

I guess somebody else thought about this before but this topic is relevant to all 928 and the idea is to build an upgrade components that will replace the belt to 2 chains. Will designing such thing worth the effort? I mean, timing chains are not prone to wear out over time if not in use so no need to be changed after 4 years. chains are more reliable in terms of no slip Teeth can take place. what do you think?

The Forgotten On

It's been talked about before and the general consensus is that it is not worth the money and time to do it.

You would have to completely redesign the front of the engine in order to use chains with a proper oiling system along with a redesign of the cooling circuit as you would lose all drive to the water pump.

davek9

^^^ yep agree completely ^^^
And if you look a other chain driven cam systems they still require maintenance/ part replacement.

Our belts usually don't Slip, they brake when another part of the system fails to spin freely, properly maintained they are quieter and less expensive to maintain IMO.

Dave K

drwhosc

I had timing chains on my BMW 740 and the plastic guides disintegrated resulting in a timing belt failure for that engine. Had no warning. the chain and tensioner were all fine. So a chain is not the answer either. Just have to do a regular PM on our belts....

hacker-pschorr

Ask Tim Murphy about that engine, he's gotten pretty good at fixing them. It's not a matter of if but when that system will fail. By 150k it's almost a guarantee you will need to go in there.

Then you have Audi and their ridiculously complex chain system on one of their V8's. By 100k miles the plastic guide pieces are failing and it's a $10k+ job to yank the motor fix them.

The chain is rattling away in my Saab, my mothers Jaguar is way over due for the chains to be updated, and I have a Mercedes in the back of the shop with bent valves due to a failed timing chain.

I'll stick with belts.

Rob Edwards

A 928 timing chain would have to be 6 feet long, unless you wanted to do some sort of multi-chain arrangement that looked like the back of the CE panel. Or like the back of this Audi motor (I never get tired of looking at this, imagine the brain of the guy who came up with it....)

SeanR

Yeeeeeeeeaa..........................nope. Hope to never see one of those in real life with someone wanting me to work on it.

hacker-pschorr

Jim Page (Rennlister) is working on one right now, he bought the car post chain guide failure.

The dealer quoted the previous owner $10k to fix it.

IIRC it has 100k miles on it.


For those not familiar with this engine, you are looking at the back which is up against the firewall. There are jack-shafts going to the front to turn the accessories. The designer of this engine must really hate belts.

Chalkboss

Looks like it was designed by a Swiss watch maker. Remind me to never DIY one of these.

Ranfurly

Hi Rob

Which Audi engine is this? A 4.2 V8 to one of their V6's?

I've currently got a S4 sedan - V6 supercharged - I need to know when I should trade it...

It does look like a Swiss watch.

Richard

hacker-pschorr

Details here:

http://www.audizine.com/forum/showth...cussion-Thread

bureau13

As a piece of art, it's gorgeous, but other than that...well, remind me to never criticize Porsche for "overcomplexifying" things again (yeah, I made that word up I think)

Ninespub

Wow..............google the Audi B6-B7 timing belt and you've got pages of stuff. And we thought the 928 had issues. I wouldn't buy a used Audi at any price. However, being the masochist I am, aside from my 928 I also own a S-type "R" Jaguar. It has a syndrome known as "the dreaded supercharger hose failure". Its a $20 hose that fails UNDERNEATH the supercharger; which of course, requires full SC removal and ultimately the replacement of another 13 hoses simultaneously along with a bunch of WYAIT work. Ask me how I know........it happened to me two weeks ago and I felt lucky I only got hit for a $1600 bill. Beats the **** out of a $8-10,000 bill for an Audi.

upstate bob

There can be serious harmonic issues with chain designs. you might get lucky and not have any, or a calamitous destruction.

PorKen

The closest thing to a chain would be a Gates Racing belt, all new gears, and a PKT.


The Racing belt FAIAP does not stretch.
Newer gears are made from more durable materials.
Audi tensioner/damper system is gentler on the belt and gears. (No flapping!)