rodC4S

Its the front wheels that are being rotated by the dyno. In the test procedure it says set the parking brake put car in neutral etc.

So, i am thinking that it would not be hard to turn a front wheel at approx 2 - 8 KPH by hand and "feel"the coupling working. This cruder method was suggested in an earlier post. The factory method lends credibility to this method. I dare say that if you tried it with a known to be working car then you could get a feel for whats normal as opposed to needing the dyno readout.

Could some kind C4S rennlister be persuaded to get their flat tire jack out and lift their front wheel off the ground, put the car in neutral and turn the front wheel by hand and tell me how easy or hard it was to turn.

Thanks

graham_mitchell

Oops... my bad! I was thinking of something else.

Actually there is no specific mention of what to do with the rear wheels. I assume they are firmly planted on the ground.

I also assume that if you keep one of the front wheels grounded too and you have a non-LSD up front that you need to rotate the other front wheel at double the speed. How will you maintain 10kph rotation steadily over 20 seconds AND determine the force required? Seems like a potentially wildly inaccurate thing to attempt by hand.

I would suggest a preliminary test by hand to determine that there is 'some force', and then have it measured properly by a knowledgeable independent. Just my $0.02...

rodC4S

Yes, you would keep all other 3 wheels on the ground.

as far as i know all C4S have an open front diff (no LSD).

You would actually need to turn the wheel at 1/2 speed, not double and i think you could just sit there and turn it by hand. It cant need to rotate very fast to simulate 2KPH. Test was to be done between 2 and 8 kph so i guess 1kph would actually work.

500N translates to 112lb by the way. That would indicate that the wheel will probably become quite stiff to turn. I am going to try it in the morning.

rodC4S

Graham,

you are right it would be twice the speed.

Dirt Track Racer

Dude, go to the track. Floor it in the middle of the slowest corner you can find. If you make it, it works. If you wreck, its broke. Then you get two advantages:

1. You can tell everyone that the wreck wasn't your fault, your car was broke.

2. You can have insurance pay for the AWD fix as part of the major repair.

At least thats how we test our race cars. If only insurance would pay for the repairs.

DTR

rodC4S

Guys,

One last time request someone to jack a front wheel up on their c4s (all other wheels on ground) and see how it feels when you turn the jacked up front wheel. Hard to turn, medium or easy ?

My car is going for the wiring harness recall check next week and the dealer will test then, but it would be nice for me and others to establish a concensus on a simple field test.

Thanks, Rod

graham_mitchell

ok, I'll try this tomorrow (it's late at night in Denmark now)

Dick in TN

Hi Rod,

I live near you (Signal Mountain), have a '97TT (AR too, BTW), wanna bring your new steed over & we'll do a side by side test? I've wondered the same thing about AWD as you.

rodC4S

Dick,

See PM.

graham_mitchell

Ok, I jacked the front left wheel off the ground and tried to turn it. Pretty much as soon as it turned at all, I felt a strong resistance. I could only turn the wheel slowly.

Strange thing is, I'm pretty sure my front wheels aren't normally getting the power! Last winter it was pretty obvious when my rears were spinning in the snow, the car was standing still and there was nothing happening up front at all!

So... was this resistance coming from the viscous coupling or somewhere else? Is the front axle equipped with a LSD?

I hope to get my car up on a lift which uses the jacking points, not the wheels, to lift the car. Then I can run the engine, turn the wheels and confirm it one way or the other.

rodC4S

Graham,

The car does not have a LSD up front. Its possible in the snow that one front was spinning and both rears.

OK so you felt strong resistance. I feel resistance on mine too, it takes me 5 seconds to turn the wheel one revolution. Sound about right ?

Would be curious to see how your rear LSD acts as well. if both rear wheels are off the ground and you turn one, which way does the other rear wheel turn ?

rodC4S

Well,

We just tried a comparison with a 993 Turbo 23K miles and his front wheel spun round really easily.

His rear LSD also showed the open diff charectristic.

Rod

Novice

I was curious in how hard it would be to verify that the AWD is working.
I didn't even rev pass 5k rpm on my new P Zero with only 400 miles on them.

It drifted because of the slight incline.

TheOtherEric

Hey Novice, looked at the price of new clutches lately? Youch!

BlkC4S

I recently went through this with my C4S. My viscous coupler was shot, and I never got power to the front wheels.

With 3 wheels on the ground, my front wheel would turn very easily. Also, previously when my transmission fluid was changed, it was very dark.

I first became suspicious after I did an autocross in the rain, and my times were no better than the RWD cars. (Naturally I searched for some excuse other than the driver...)

I also took the car out in a deserted wet parking lot and floored it in 1st gear. The car fishtailed and felt like a RWD car.

So I finally bit the bullet and had the viscous coupler changed. While I was busy spending money, I had a LWF installed at the same time.

I haven't driven the car in the wet since then, but I can tell the AWD difference at autocross. I imagine the track would be the same. I don't notice it in everyday street driving.