Dyno might have ruined my visc. coupl.
05-27-2014, 01:37 PM
#16
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.
@OverBoosted28. Not sure what looking like a hillbilly has to do with ANYTHING.
05-27-2014, 03:08 PM
#17
RL Technical Advisor
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.
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.
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.
05-27-2014, 03:58 PM
#18
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05-27-2014, 08:23 PM
#19
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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.
05-27-2014, 09:07 PM
#20
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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.
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
05-28-2014, 02:11 AM
#21
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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.
@OverBoosted28. Not sure what looking like a hillbilly has to do with ANYTHING.
05-28-2014, 01:12 PM
#22
Rennlist Member
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.
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.
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
05-28-2014, 01:16 PM
#23
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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
05-28-2014, 02:48 PM
#24
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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.
05-29-2014, 09:15 AM
#26
Race Director
05-29-2014, 01:34 PM
#28
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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. 
