Dyno might have ruined my visc. coupl.
 

I did a Dyno test on a "AWD" Dyno set up at Thunderhill here in C.A. Two roller table and I had done it a couple of years ago. The difference this time was that they removed the belt that coupled the two rollers together. First pull had both wheels spinning. That was the last time they spun.
I think I know the answer to the question, but I'll ask anyway. Would the difference in speed between the two rollers (not coupled) be enough to wreck the viscous coupler? I limped the car home below 70 mph and was smelling gear oil by the end of the 3 hours. Sounded different too. No rattling, just friction noise.

If it's an obvious yes, where does that leave me in regards to compensation from the shop who (in my mind) should have known that they can't do my car on that equipment. Your honest opinions would be greatly appreciated. I know that these guys up there aren't making a lot of money but I can't afford to make this repair either.
Thanks for your advice.

Unfortunately, I think it may be fried. Usually when you dyno a car, they have you sign a release just for such occurances.

You're in America. Sue the bastard! Judge likely to sympathize and in British common law, and maybe your case law, waver is void if there's negligence.

Yes there was a waiver, but I'm thinking that it might not hold up due to the incompetence factor. I'm not sure it should be my responsibility to know if it's compatible.

Dealer retail replacement of vc is 3k easy. Indy will be significantly less but part still comes from the fatherland only.

any documentation stating the front wheels were spinning on first run? If not it's your word against theirs. But the threat of litigation should get them to agree to half an indy repair. just a thought. Also they should have insurance for this sort of thing (if their was no waiver)

I'm sorry but an all wheel dyno (unless coupled mechanically) is a no no on these cars, well documented on these boards with multiple threads on the topic.
Should have checked here first prior to doing your
Dyno session. These cars are not that common, you have to do your homework.

Yes but I think it is the supplier of the service's legal responsibility to know. Guess that if you file suit they will settle for full amount out of court. Good luck.

I don't know.. I would think it is use at your own risk sort of thing.

Qwen, sorry about your V coupl
 

Have you thought about going rear wheel drive? Did you ever get that lean problem resolved? I was going out to Thunderhill around June 6th 7th Ill keep a heads up before I dyne there again. I have done it twice there with no problems. We finally have a fellow here in Reno that has a 4WD dyne. I have posted this video before but I will put it out again.

The safest way to dyno is to just unhook the coupler in front of the trans, takes only few minutes and then you can use any dyno/rear wheel dyno.

it's this thing here, just loosen through the access hole and slide forward to uncouple the front drive

Thanks for the thoughts.
As stated in the post. I had done it there successfully 2 years ago when they had the coupling belt. I had no idea they had taken the belt off.
AirRick, yes I did resolve all of my issues, car was running super strong. This was the first venture out in a long time of niggling little issues. Now a bigger issue to deal with. Good to hear from you.
I have thought of 2 wheel drive but eventually this car will be for sale and I know that it will sell better in awd.
Do NOT have your AWD car dyno'd there. Not that I needed to say it at this point, but...

Take the front wheel drive off. It's ruining these cars. I have a 993 TT that I race. Why dyno these anyway? They are too powerful for street driving as they are.

Do you drive you car in the rain, or at least as much rain as we get on the west coast? I use the AWD drive system lots, and the car would struggle to put the power down in marginal conditions with two wheel drive. I am keeping the AWD intact, it's really makes these cars great in all kinds of weather. :)

Cheers,

Mike

The guy in the vid looks like a hillbilly, there's alot them up there.

I agree, I love the AWD. Really gets the power down as designed. As to "why dyno" my car was rebuilt to 3.8 with lots of goodies and I later updated/upgraded this set up. Wanted to see the difference before and after. Just to have more knowledge of my car and the health of it. Why NOT dyno? Except for the obvious possible problems involved.
@OverBoosted28. Not sure what looking like a hillbilly has to do with ANYTHING.

Hi,

Sure sounds like the VC was damaged. Given the limited knowledge of these cars by most dyno operators, I'm not surprised about this as I've seen my fair share of this issue. One simply cannot assume that people who don't specialize in these cars will understand how the powertrain function sufficiently to prevent damage.

For me, I ALWAYS disconnect the front driveshaft when running these cars on a roller-type dyno, no matter what kind it is: Dynojet, Mustang, Superflow, etc. The only exceptions are the wheel hub style such as Dynapack, etc.

Then fix it properly. On your dime. Don't waste your time with a lawsuit. Lesson learned. With the hot aircooled Porsche market, you'll get your money back.

Actually you can put the power down better with 2 RWD even in the rain if the wheel Is straight. Nothing projects you in the rain, if you lose grip or hydroplane. All wheel drive was put in place to prevent power oversteer. The car actually understates at high speed because of the AWD. Terrible for racing or driving fast. It up to you to do what you like but I am giving some feed back from track excursions. Of course, it's different fOR street driving.

Not sure how you know why the factory decided to put AWD in this car (you have an inside source?), but I was talking about non-track driving, but regular street driving in non-dry conditions (and I do track my car BTW, and have in the dry and wet).

So you are telling me on a straight stretch of road that you can put more power onto the ground with two wheels than four - i would very much like to see the physics behind that. I can see some transfer losses going on, but the capacity of four wheels to transfer power to the road is better than two. If may impact turn-in, or other things, but for straight transfer, it's clear to me.

I can understand that you do not like the factory setup understeer that the AWD cars have, but that can be corrected, and I can understand for racing on the track, 2wd can be great since it's much easier to get the tail out, but for putting down power in the rain on a road with 3 months of oil from cars driving during sunny weather without having the tail come out and get the driver into trouble - give me my AWD anytime.

Cheers,

Mike

The comment was in jest in regards to having people touch a car they may not have any idea about. I am sorry you have to deal with this. Just another example of why NOBODY will touch my car unless I am 200 % sure they know our cars completely. I can't afford to screw it up myself and surely couldn't afford to pay for someone elses mistakes. Hope it all works out.

I did this in late April on my AWD 996 TTS, broke the front RHS axle and viscous coupling.... you will hear it if is the former as it will clunk around when you drive...........

Even though I used an AWD dyno it was obvious when the screech occurred that they did something wrong.... not taking action, just not dynoing again as my logging gets whp and torque pretty close

I am converting to RWD now

owen - post on 6 speed that you want to buy a front diff as there are usually a few for sale over there on the very cheap in good nick... I got offered 5 different 996 front diffs at $650-$950

The VC of the 993 is inside the front part of the transmission so no need to get a new front diff.
The VC can be replaced without dropping the engine by removing the front diff, tilting the front part of the transmission down and sliding the torque tube forward out of the way.

Thank you everybody for your comments. I enjoyed them all. If I think of it, I'll let you know how it turns out.
Thanks.

what kind of nonsensical BS is this?

:rockon::rockon::rockon::rockon:

Going Rear wheel drive ?
 

What is involved in going rear wheel drive. What parts are needed ? I remember Viper Bob had some sort of kit may years ago. Also if done is it reversible down the road at sale? Sure would lighten up car for the track. :typing:

https://rennlist.com/forums/showthre...ferrerid=28499
:)

Thanks
 

Man thats a lot of work ! I guess Ill just have to wait for my GT3 RS or Caymen GT4 :jumper:

I have a long winding driveway uphill to my home about the length of a football field. Kinda cool way to arrive at home....a nice hill climb before I tuck her to bed.

When my VC was down she fishtailed on the "hill climb" around the corners (kinda predictably fun with the kids in the back) Fixed the VC...no more fish tail...and I mean nuthin. BIG difference.

Joe

At a Porsche dealer the other day. Talked to the tech about dyno testing these AWD cars. (I have a 996 Turbo.) and mentioned your situation.

He said if you directed the dyno operator to disconnect the belt that connects the rear rollers to the front to see how much rear wheel HP the car produces this is on your head. (The techs said often the owner requests this not knowing the ramifications are of this.)

If the dyno operator disconnected the belt for whatever reason the shop is responsible for the damage.

It just happens there was a 993 Turbo in one of the service bays in for a ruined VC. Seems the car broke down -- I do not know what the initial problem was -- and the tow truck operator insisted on towing the car in on its rear wheels only.

The owner, a woman, tried to tell the tow truck operator the car should not be towed that way but she got the standard BS response from the operator something to the effect he's towed lots of Porsches before and he knows what he's doing blah blah blah.

So, rather than escalate the confrontation the owner let the tow truck operator have his way.

Well, of course, by the time the car got to the dealer the VC would in pieces. It just came apart.

Tech estimated cost to repair roughly $3K. He said the tow truck company was picking up the bill.

NO tow truck operator is gonna tell me how the car will be towed. The driver has to be a complete idiot to look at the car and say he's gonna drag it from the front. Even at stock height the tips should have scraped. Crazy

They should also throw in a pain/suffering amount.

Thank you Macster for that info.
I did not ask for the belt to be removed. The shop had removed it in order to be able to do 2 wheel drive cars as well as some other AWD cars.
I feel the same as the dealer explained.
Thank you.

When I heard this I thought how the heck did the exhaust tips and in fact the rear of the car not sustain any damage from the front wheels in the air tow?

Anyhow, unfortunately, tow truck drivers are often complete idiots. They manage ok as long as they are dealing with vanilla vehicles but toss something like an AWD Porsche at them and well, they are out of their depth.

I pity the woman owner. She I'm sure tried to convince the tow truck operator to do the tow correctly but got overruled, shouted down, and maybe a bit physically intimidated by the operator.

Once or twice I've had an encounter with a tow truck operator, a disagreement about how to handle the car, that I felt had I pushed it we could have come to blows.

For instance, tow truck operators all insist on using the tow eye to hold the car on the truck. This has the eye sustaining load not in direct line with the long axis of the eye and its bolt and which the owners manual says it should not be subjected to.

But I can't get any tow truck operator to disconnect the line from the eye once the car is on the bed and secured by hold downs.

I object but get overruled -- unless I want to duke it out with the tow truck operator and I don't -- so I bank on the fact that the eye and where it secures to the car is over engineered and no real harm will happen.

Then in my layman's opinion the shop is at fault and should pay to have the car properly repaired.

Once again what Rennsport Steve said, the belt has to be Disconnected, on roller dynos. I have seen my fair share of blown VC on high HP cars but not from dyno damage. Also from dyno the wrong way though. But what came first? The chicken or the egg, lol.Just saying.

Many years ago, a small group of 993TT owners went to a "dyno day" at a shop in inland SoCal. One after another, we saw the front wheels stop spinning after the first dyno run. It finally occurred to us that all those viscous couplers were being trashed by a 4WD dyno that didn't have a "driven" front roller. Luckily, I was last in line, and declined my dyno run. The shop was setup for WRX AWD dyno runs.

I think you should reread what Rennsport Steve wrote. He wrote the driveshaft should be disconnected.

Here I'll save you the trouble of searching out his post:

"For me, I ALWAYS disconnect the front driveshaft when running these cars on a roller-type dyno, no matter what kind it is: Dynojet, Mustang, Superflow, etc. The only exceptions are the wheel hub style such as Dynapack, etc."

This is a bit of work to protect the VC and the rest of the front drivetrain when dyno-ing the car but perhaps worth the peace of mind.

But the peace of mind one gains on the one hand is countered by the concern I would have about doing this disconnect. That is, I am not up on if any fasteners can be reused or instead should be replaced but I would familiarize myself with the correct procedure for disconnecting then reconnecting the front drive shaft.

If the car is put on the dyno the wrong direction that is the fault of the dyno operator.

It boils down to the dyno operator owes you a reasonable level of skill, experience, and caution in what is to be done. It is not like you have a dyno and are pulling a stranger off the street to operate it for you. You are seeking out a shop that offers this service. If your car is accepted then the shop is making a contract with you that essentially says it knows what it is doing,and it is selling its ability to apply this knowledge to accomplish what you want, and you of course agree to pay for this.

Frankly, based on what I've read, the horror stories, I would no more dyno either of my Porsches than I'd drive them through an Afghan mine field.

In fact given the choice, dyno or mine field, I'd ask how big is the mine field.

Dyno is a pretty good way to know how much power your mods make....

http://youtu.be/wy2_rNMc6xw

Nice....527rwhp. You're car must feel fantastic! Is that the new motor? Sorry to take the thread a bit off-topic.

...Well its the same case and crank, but most of everything else is new. I had to send out the ecu to get it re-programmed for the new components. It leaned out as boost came on under WOT. That pull was in 3rd and it was getting wheelspin on the dyno. They had to re-calibrate for 4th gear. It makes a silly amount of power - and that was at 1.1bar boost. I'll be putting it back on the dyno when I get the ecu back.

That's a ton of power. My one run before damage showed 438 (?) rwhp and a bit more than that for torque. The shop confirmed that it's the viscous coupler. $1200 on the part from Porsche and about $3500 on labor. I didn't realize the coupler was in the trans. I was thinking that the Diff in front was the coupler. Not so. Lot's of labor getting the coupler out and back in. The shop also feels like it's obviously the dyno shops responsibility. I have no previous relationship with this shop so I feel as though it's a good professional opinion.
Thank you everybody for your responses and thoughts. We can let this thread go now unless someone has any other questions.

$3500 for labor?
I was the dude Steve was talking about who trashed a VC on the dyno a few years ago.
My tech swapped it out in about an hour and a half.

My tech said it can't be done without dropping the engine so decided to do it with a friend of mine. Took us first timers a damn lot more than an hour and a half but still managed to do it without dropping the engine and saved me a lot of money.

Yes it can be done without dropping the engine.
I saw it with my own eyes, since I was handing him wrenches.

Presumably then he removed the VC without first pulling the front diff and torque tube?

Yes, lot's in labor. The VC is inside the transmission, hence a bunch of time opening up the trans. I was originally thinking the front diff. was the problem, not so.
I will say that this guy charges $150 an hour! I'm thinking that's a lot. My last shop was $130 which I disliked. Anyone else want to report there mechanics hourly rate?
Thanks.

$120 over here in Reno good shop ! Rennsport (775) 331-4366 factory trained (Matt) many years ago so very familiar with our 993TT's also Steve he's $110 per hour , he has done a lot of work for me.

I'm not sure that's true... I think the viscous coupler is a separate unit that's attached to the nose of the transmission. The transmission doesn't have to be opened. Pretty sure about this.

The VC is inside the front section of the transmission. You need to open the transmission front cover to replace the VC. Two of the bolts that hold the cover in place are hard to get when the transmission is attached to the car. The cover can't be removed if you don't first remove the front diff and push the torque tube forward.

Ahhhh, I believe we were also fixing a leaking front diff at the time.....

Either way $3500 in labor seems crazy high to me. Scott's wrench is mine as well and the guy sure knows his stuff. I think you are in NorCal so we are probably too far for you to use him. His name is Mike Schatz and owns MKS Performance down here in Camarillo. Top notch wrench.

Thanks for correcting my error and not making too much fun of my mistake! I'm glad to know the actual facts.

https://www.youtube.com/watch?v=GWXk...ature=youtu.beWorking on my car… Thought I would check if the AWD system still works…Kind of cool seeing it in action.

Kevin should know better than that! Even if the car could be run like that the ABS would be going crazy on some cars that have traction control. I feel like it was done out of laziness. They were likely testing a 2wd car before and did not want to go through the trouble to put the belt back. There is no good reason to run a car without the roller connected.

I like the guys at Thunderhill but you gotta remember they work on anything and everything. One of my friends had a shop there and had a few horror stories. They are a bit rough around the edges. It's in the sticks after all.

so I'm going on the dyno next week. Looks like I should disconnect the front drive shaft. Wont this car still need to go on 4 rollers so the traction control ABS stuff doesn't go crazy? Im glad I read this before going on the awd dyno

^ shouldn't be a problem, ABS is for braking and our cars don't really have traction control -they have ABD 'automatic braking differential' or something like that - looks at wheel speed side to side, kind of like lsd using brakes afaik. A lot of us have disconnected the front drive permanently...