Took my 996 TTS to the nearest AWD dyno on Long Island to see if it would confirm what my Eurodyne data logging showed.... and sadly heard a dreaded metal on metal clang on the 2nd pull.......

Driving the 60 miles home I heard the low speed clunk clunk from the front RHS of car like ***** running around in a housing..... so that would mean the front diff or crank case is effed according to guys at the porsche boost site...

All the gears operated fine but there was some more movement in the steering... not knowing what it was until later I drove home at normal speeds to 60 mph

If it is just the diff can I just have the whole thing removed and convert to RWD only (I come from a RWD background anyway) and as it is only 430 awhp currently may not even kill myself...

Overall a great week as was at hospital with the old heart palpitations...

Anyway, any advice welcome

I have a front diff if you decide to replace. You can pm me if you want more info.

I would check it out a little more or have it looked at by a good shop if your uncertain. If it was bad I would replace it with good used unit like the one offered above personaly. That is paying to play as they say.

I also have a diff and cardon shaft if you want to stay awd

Don't think the dyno time killed the front diff. More likely killed the fluid coupling case.

These cars can be dyno'd but they have to dyno'd on a particular dyno that I believe keeps the front rollers turning at the same speed as the rear rollers to avoid too great a speed difference which can overheat/damage the fluid coupling case.

But you need to confirm what's making the noise and what's wrong. It could be the cardan shaft bearing is loose.

blessing in disguise. get rid of that dead weight. if you have coilovers, lower the front a little more (1/4/ - 1/6th of an inch) and get it corner balanced and a gt2 specced alignment.

They didn't run the dyno with front and rear rollers unlocked did they?

Thanks for advice.... did a nice 400 mile journey in my old E39 540i y'day, Hamptons-NYC (picked up missus)-Queens-Atlantic City-Queens-Riverhead Veteriniary then home to Quogue = 9 hours 400 miles, no result, no peeing, no food, reminds me of when I used to do NY-Vegas in a TT Esprit in 2 days............ JOY


Got to AC and got a call from my dog sitter saying my border collie had been poisoned

Will look at 996 tomorrow and see what is needed

Thx again for advice and offers of new diffs... will contact if needed

No it looked fine to me... the car just spat the bit on the 2nd pull... got video and a loud METAL on metal grinding sound... not pretty

Thats not quite an answer. Were the rollers LOCKED? Yes. No. "looked fine" seems an odd clarification...

The rollers will spin either way, but unless the dyno locks them to the same rotational speed you can have issues.

Yes the rollers were locked, were they running at the same speed, I do not know but the guy who did the dyno has done many and is out of a racing shop who have their own AWD and RWD cars, including his own...

I took a video of it all but am I going to blame them, probably as it was running well apart from some minor tuning issue (I have videos of the car going down there and the days before with no front end clunk).....

Am I going to do anything about it - no... just get the car fixed and running well... the stupid thing is from the Eurodyne data logging software and times I was running I guessed the AWHP to about 430 and the dyno came out 429.. so I am a dufus for even risking a dyno

Anyway, we live and learn

I will post about what we do to the said car

You can not tell by looking at the rollers. There are different AWD systems in cars. AUDI for example can run unlocked on a dynojet with no issues. Porsche, if they run unlocked blows the diff. Both wheels will spin but at slightly different rates, the eye can not tell. They lock and unlock the rollers regularly as 2WD cars require them unlocked. If they did a RWD or FWD (or audi) with the dyno unlocked then put your car on afterwards and didn't lock the rollers, diff will be blown. Yes it's just that simple unfortunately and there is no way you'll tell by watching the dyno.

Since your diff catastrophically blew on the dyno, I'm fairly certain its unlocked rollers that did it. Diffs that fail on the street usually don't fail with grinding and noises they simply slowly wear out power stops going to the front wheels.

At minimum the one thing you should be doing about it is NEVER going there again. Let this serve as a warning to others looking to go on a dyno, make 100% SURE the dyno is locked. Ask a million times before they roll, better yet make them show you.

King james - I got my car back from my mate's garage today and jacked it up, both front wheels spin ok with no resistance so it it probably not the whole diff... but there is definitely some metal running around down there somewhere.......

I have one of the best guys from here I am taking it to this week.

Also, I was the 1st car at the dyno that day and was there early and watched them set up the dyno for AWD, TOLD THEM it was AWD with a predominance or rwhp and only 5-40% power to the front wheels. Anyway, they had to move the front roller back by unlocking it from the position it was in to fit the wheel base of my car and then locked it (I assume)... once again I cannot tell if both the front and back were spinning at the same speed..... and as it was my 1st ever dyno I woudnt know sheet from shinola...

BTW a few guys from here USE that same DYNO as I have seen their dyno sheets posted here and on other websites...

If I posted the only dyno run that went through it looks quite weird... anyway as you said I will not be going back

uncoupled awd dyno will do that.

That sucks, Maybe trans?