Possibly broke something?

[90AWDTalon]

Went to the 1/8 mile drags tonight. First run got a decent launch, 1.703 60ft and ran a 7.302. My best launch this year, but last year I was able to pretty easily get mid 1.6 60ft times.

On the second run at launch there was a very load snap, people in the staging lanes 500 or 600 feet away heard it clearly. It imediatly felt like something was spinning, but I couldn't see or smell any tire smoke. One of the officials let me try a small launch in the staging lanes, it didn't launch, just felt like I was spinning tire. But I didn't see any smoke and barely smelt any. Afterwards the passenger front was much hotter the rest of the tires so I think this is the one that was spinning. A friend of mine watched from the drivers side and said he didn't see any wheel spin and that the rear end was bouncing and jerking around.

I limped the car home, if I stayed below 30mph the car ran fine. But if I went faster there was a very load sound like a bucket of bolts falling on the ground coming from the rear of the car, also it felt like the rear tires were trying to lock up.

In the morning I'm going to jack one tire up at a time and see if they spin in gear. Any one have any thoughts or suggestions on this?

 

[90AWDTalon]

Broken passenger rear.

Anyone no where I might find a 4 bolt swap?

Couple of pics.

 

[Dream On]

Nicely done. Check in the classifieds or maybe you could score an AWD at the junkyard.

 

[90AWDTalon]

I've been looking for a 4 bolt. No luck so far. None of the local junk yards have any. None on ebay. None on craigslist. Found one on carparts.com, they think one of the axle cups is missing and is suppossed to be checking for me. Emailed a few members that have them listed in the classifieds, but no response yet.

If I end up not finding one, what about cryo treating a 3 bolt?

 

[90AWDTalon]

I have a 4 bolt on the way. Today I tore the stock diff down to see the extent of the damage. A little history, my car is a '90 with out ABS, has the rear LSD sticker on the door jam, and the diff housing also had the LSD sticker. When I opened up the housing I believe I found an open diff, no viscous LSD. Here's a couple of pics, please correct me if I'm wrong. Also a pic of the rest of the axle.

Has anyone else experienced this?
How much was I giving up in both autoX and drag racing with this f***ing open differential?

I thought the boat company I work for was alone is screw ups like this, I guess I was wrong.

 

[90AWDTalon]

I've been looking at pics of differentials on other cars and I think I may have been wrong and this is a viscous LSD. It looks almost identical to a miata viscous LSD. I was expecting to see a large sealed unit similar to the center viscous unit.

 

[jtmcinder]

With the stock 50/50 center, I'm not sure how important a rear VC really is for drag-racing. There's more than 50% of the weight on the rears on a good launch and the springs back there are pretty soft. Put another way: I've seen two 13-second DSMs with open rears launching and neither had any problems in the rear.

For autocrossing, however, you want a rear VC. Inside-rear smoke doesn't help with corner-exit.

In any event, I'd be more concerned about the damage you did to the center VC. I don't know how long a drive home it was, but a half-an-hour can be enough (and then some) to toast a center VC. If you didn't have a rear VC to help, then you could have done the center some serious damage.

- Jtoby

 

[90AWDTalon]

In any event, I'd be more concerned about the damage you did to the center VC. I don't know how long a drive home it was, but a half-an-hour can be enough (and then some) to toast a center VC. If you didn't have a rear VC to help, then you could have done the center some serious damage.

- Jtoby

Now that I realized that I in fact do have the rear VC, do you think I still may have toasted my center VC?

 

[PieEyedPiper]

I'm no expert, but maybe this post by jtoby can shed some light for you.

http://www.dsmtuners.com/forums/showpost.php?p=50388790&postcount=4

 

[jtmcinder]

Now that I realized that I in fact do have the rear VC, do you think I still may have toasted my center VC?

That the car wouldn't accelerate hard means that the rear VC couldn't handle all the torque that was being thrown at it. This implies that you were driving on a combination of the two VCs for the entire trip home. Depending on the length of the drive, this could do a number on either or both.

Too bad I have never seen the spec values for our VCs. (The values for Scoobies are all over the place, but nothing for Mitsu stuff ... at least, not that I've found.) The process of testing them isn't too complicated. As long as you have a device that will rotate one side at approximately 100 rpm, in theory you can measure the VC with a torque wrench.

- Jtoby

 

[jtmcinder]

I'm no expert, but maybe this post by jtoby can shed some light for you.

http://www.dsmtuners.com/forums/showpost.php?p=50388790&postcount=4

I'm flattered, but that post is mostly about testing for a blown diff, not a cooked VC. VCs are rather difficult to measure when still in the car. The standard test, alluded to above, is to spin one side at exactly 100 rpm, while measuring how much torque is required to keep the other side from turning. Thus, when you see the stock Scooby center referred to as a "4 kg VC," what they really mean is that 4 kg-meters of torque is required to hold it still when the opposite side is rotated at 100 rpm.

- Jtoby

 

[90AWDTalon]

I finished installing the 4 bolt rear tonight. When I was done I jacked up the passenger side and had a helper try spinning the back wheel the opossite direction I was spinning the front. This was done with the car in neutral. We were able to spin the wheels in opposite direction with some effert. I went for a test drive, didn't try a launch, everything felt normal. So I think that the center survived the trip home.