Which did I break... Viscous Coupling or Spider gears?

[larsrya8]

I've been reading for the past hour, and I can't find a definite answer to my problem.

Last night I started my car, put it in 1st and started to pull forward down my driveway. As soon as the car moved I heard a *snap* and the car moved forward. I assumed it was the parking brakes popping loose or something. I then tried to accelerate briskly down the road. The RPMs and speedometer both increase like normal, but the car accelerates much slower. When I let off the gas the speedometer drops down to my real speed. There is also a clicking sound that varies with speed (whether in neutral or in gear). So I'm convinced that there is something wrong with the center differential.

But what, exactly? I've read several accounts of people having the symptoms of a slipping clutch but with the speedometer moving correctly, which means that it's the center diff. Most accounts talk about the car becoming rear-wheel drive. I don't know if that happened or not... I haven't launched it in the 1.5 years I have owned it, and I'm still running the stock clutch. I did notice a skipping when taking a hard right turn, but nothing when turning left. That happened after hitting a nasty pot-hole though... might be unrelated.

If it's the spider gears, I should not drive the car anymore. The spider chunks can ruin my output shaft. If it's the VC... can I still drive it? I'm assuming that is a self-contained unit, and it won't affect anything other than my nerves?

 

[steve]

Sounds like the only reason the car moves is because of the VC units and you have broken a diff somewhere down the line.

Regardless as to what broke you shouldn't be driving the car anymore.

Steve

 

[larsrya8]

Sounds like the only reason the car moves is because of the VC units and you have broken a diff somewhere down the line.

So you're thinking the spiders are broken? Or the VC is letting enough power to go to the front to move it? I'm going to jack it up tomorrow and start taking the transmission cover off. Hopefully the differential housing isn't too messed up.

I'm still confused as to how this happened... I thought the differentials break after a hard launch. If the stock clutch is still holding fine, the center differential shouldn't break... right?

I'm probably going to replace it with the TRE spool. I don't plan on running anything other than street tires, so they'll chirp before they break an axle or something. I'll have to see the extent of the damage first though... maybe a repair kit is all I need.

 

[jtmcinder]

Or the VC is letting enough power to go to the front to move it?

The VC connects the input to the rear, not the front. AWDs that blow the center diff in the middle of a drag-race finish the run as RWD, not FWD.

Do the standard tests:

1) lift one front wheel and try to turn it with the car in gear: you shouldn't be able to ... if you can, then either the front or center diff is gone.

2) lift one rear wheel are try to turn it with the car in gear (and the parking brake off, of course): you shouldn't ... if you can, then either the rear or center is gone.

Note that these tests assume that you have not snapped an axle. If you aren't sure, check them all first.

When doing these tests, turn the wheel slowly but with some strength. There will be some slop, but if you can rotate the wheel more than 90 degrees, then the test was clearly failed. (Note to the confused: "failed" = wheel can be turned.)

If the car fails #1 but passes #2, it's the front diff.

If it fails both, it's the center.

If it passes #1 but fails #2, it's the rear.

- Jtoby

 

[larsrya8]

I will jack up the car tomorrow to do those tests, as well as to check the axles.

jtmcinder, do you have any idea which part is broken based on the symptoms outlined in my first post? When breaking the center differential in a drag race and ending up as RWD, do those people break the spider gears or the VC? Or is the VC not really considered part of the center differential? I would think that breaking the center differential would result in no power going to the rear wheels...? I guess I'm just confused about the way power is transferred through the drivetrain.

Also, would my car exhibit the "slipping clutch" symptoms no matter which differential is broken?

 

[larsrya8]

The outside clamp on the outside CV boot on the front driver's side axle is missing. That CV joint is broken... the axle and the wheel turn seperately. I'm assuming that the car was slipping enough power to the back wheels via the VC which is why I could still drive the car to the garage, but there wasn't enough/any resistance to help lock the VC into 4x4 mode (which would've been nice).

So... time to find a new axle. I'm going to start researching prices, unless anyone can point me in the direction of a great deal on the driver's side front axle for a 2G AWD?

 

[steve]

You can find cheaper axles various places but you'll be hard pressed to find better ones and service from Raxles. http://www.raxles.com/default.aspx

Steve

 

[larsrya8]

You can find cheaper axles various places but you'll be hard pressed to find better ones and service from Raxles. http://www.raxles.com/default.aspx

Steve

I was planning on giving them a call on Monday. My searching showed that many people have had great success with Raxles. I'm assuming I just need to call them up and tell them the model car and the axle I need right? I notice there aren't any prices on their site... anyone remember how much Raxles charges (approximately)?