Differential Woes?

[DynastyLCD]

got the blue car goin again. today i got on it in 2nd, and it just shot sideways, it felt like all the power was going to the rear wheels. tried to take a tight corner to get it in the garage, front wheels skip and bind up. also, if the wheels are turned, it requires more effort to move forward.

is this the signs of a worn center differential, as it cant transfer the power front and rear anymore? or is it related to the front differential?

my other question is, if the center diff is damaged, will replacing it with a welded center diff and viscous coupling eliminator fix my issue?

its an older trans/tcase i had layin around, the clutch is a (properly adjusted) like new PTT, and all the axles are good, nothing popping out of the boot or physically binding.

 

[broxma]

I'm gonna pull this back up because Steve and I are both having a similar issue. I am not sure why both of our cars are doing this. My car has a fresh Stage 2 ShepTrans in it and a rear LSD and during low speeds, in a turn,the car will try to come to a stop. I had originally figured the transmission I got had a locked center diff but I had the car off the ground the other day and the wheels spin opposite from each other when raised.

The only thing on my car which has not been replaced with new as far as the drivetrain goes is the transfer case. I am going to call the dealer this week to see if the recall has been done on 379 or not. My best guess thus far actually has to do with the geometry of the suspension. I think the lowering of the car with the different heights I have on the corners is making the low speed turns a bear. At low speeds, the diffs don't act as fast as they do at high way speeds.

Is your car sitting stock height or has it been lowered? Steve's car is lowered and has what I call a funny stance to it. Mine is raked heavily to the front.

Anyone have anything on this.

/brox

 

[SouthCaliVR4]

best guess, original poster blew his center diff or maybe transfer case & yours is welded or a limited slip of some type. the center diff hooks front to rear & if welded or locked is just like driving a 4x4 it has four tires going four different distances in a turn & if the fronts are hard connected to the rear it's not gonna want to turn or corner well, too much binding.

 

[mitsuturbo]

Quoting broxma:
I'm gonna pull this back up because Steve and I are both having a similar issue. I am not sure why both of our cars are doing this. My car has a fresh Stage 2 ShepTrans in it and a rear LSD and during low speeds, in a turn,the car will try to come to a stop. I had originally figured the transmission I got had a locked center diff but I had the car off the ground the other day and the wheels spin opposite from each other when raised.

The only thing on my car which has not been replaced with new as far as the drivetrain goes is the transfer case. I am going to call the dealer this week to see if the recall has been done on 379 or not. My best guess thus far actually has to do with the geometry of the suspension. I think the lowering of the car with the different heights I have on the corners is making the low speed turns a bear. At low speeds, the diffs don't act as fast as they do at high way speeds.

Is your car sitting stock height or has it been lowered? Steve's car is lowered and has what I call a funny stance to it. Mine is raked heavily to the front.

Anyone have anything on this.

/brox



If you have a welded center, and open front/rear diffs, i believe you could still feel what you're describing while still seeing what you did with the car in the air.

 

[broxma]

No the center is definitely open. I am taking toe and camber measurements right now actually. I can see visually that my drivers wheel is clearly pointing out by at least 2-3 degrees by my measurement thus far. In addition, the passenger side has about a degree of camber more than the driver. This is regardless of the camber plates which read totally opposite of that.

/brox

 

[fuel]

the center diff controls split between the front and rear axles and is coupled by a viscous LSD so it is effectively 50:50 split with a little bit of variance. Having a locked or open center diff isn't going to affect how the front wheels act in relation to each other, most VR-4 gearboxes have an open front diff which would mean the front wheels would spin in opposite directions without moving the front diff crown wheel and the gear which drives it, therefore the center diff isn't getting drive to move the rear wheels.

 

[jepherz]

+1, you all have some form of locked center diff, whether it was welded up on purpose or not.

 

[broxma]

Steve's car, has the same old beat ass tranny it has had for 20 years in it. It's not locked. It's not welded. It just developed this issue, out of the blue. It's not the diff. His diff is not locked. Neither is mine. Neither of us, have welded up anything, at any time. My car did this with my current transmission, and the last one. According to the line of reasoning I am hearing, there are nothing but welded and locked diffs all over creation. That is clearly not the case. I believe it is a geometry issue with the suspension, probably to do mostly with incorrect toe and camber after changing suspension.

I checked the toe settings on my car last night and found the front drive wheels to be be pointing away from each other some 7 inches at a distance of 5 feet off center. I also noticed the angle of the strut mounts is different and the car has a natural few degrees more camber on the passenger side. My adjustment to bring the toe back closer to center resulted in an offset steering wheel but the car drives much straighter and does not bind up as bad. I'm going to get some magnetic laser levels and make a few calibration boards for the garage so I can see whats going on with the rest of the setup.

/brox

 

[jepherz]

Okay, but honestly it sounds like the test you did for the center diff above won't prove anything. Also, if it happened out of the blue, did you hit something or why would your friend's car have started this all of a sudden? I don't see how it can be related to the transfer case.

 

[broxma]

I agree with you. I don't think it is either. He did some suspension work while he car was down. We both run adjustable AGX's up front, he has cut stock springs and I am running Evo sprint springs. I just think the suspension geometry is so badly off even after my alignment that the wheels are not dialed in right. A good example. The camber plate on my driver side is at full camber and it registers less camber than the passenger side at center. I don't have camber bolts at the strut so I attribute this to the noted difference in angle of the strut mount on the chassis.

Regardless of the camber, I think the toe issue is the real issue. Seems the AGX's on dropped springs affect the toe especially as dropped as mine is in the front. In addition, my toe problem most likely stems from the replacement rack from the GSX I put in. I have had the car aligned twice now but I have never been happy with the results either time. I just got back from a short drive and, after my adjustments last night, it drives straighter now than it ever has, but again, now the steering wheel is cocked off a bit. My final solution may to simply go with a full coil setup so I can adjust ride height independently.

/brox

 

[broxma]

For those actually reading this, let's set up a hypothetical.

Let's say you lift the car completely off the ground so all 4 wheels can spin freely in gear. You have an open diff front, LSD rear, unknown center. What would expect the wheels to do? Would you have three wheels rotating at the same speed? Would both rears go forward, provided you're in say first gear? What would happen to the front wheels given the open front diff? What would change if you put the car in reverse?

Just a hypothetical. I didn't take video or anything...

/brox

 

[jepherz]

They'll all rotate around the same speed as there's no load on any of them.

 

[broxma]

Mine don't. My front driver rotates fine, the passenger side sort of hops. The rears are rotating slower than the front. Both rears rotate the same direction. I did take video actually. I'll post it in a bit.

/brox

 

[jepherz]

That doesn't sound completely alarming to me. There's not anything in your front diff ensuring the two sides are spinning the same. The combined rotation of the fronts should equal the combined rotations of the rear, if the center diff is working correctly or welded. It sounds like this still may be the case. With your car in gear, and your e-brake on, rotating one front wheel by hand should result in the other side spinning in the opposite direction at the same RPM.

 

[broxma]

It does. But the rears definitely turn slower. It may be what your saying about the combined speed of the front equaling the rear. My only concern at this point is the hopping of the passenger wheel and why it binds up. Mind you it binds badly in reverse at slow speed, so much the wheels skip, but I can prove they are not locked or welded. In forward gears it is only noticeable at very low speeds like parking lot style. It just doesn't make sense to me and I have been dealing with it now all day.

I did however get the toe dialed in and the car drives much straighter and actually wants to take a turn now instead of being forced to do so. My front driver wheel, with the steering locked in center position, was out of toe by 18mm in and the passenger side was out by 6.5 in.

/brox

 

[solidviper89]

web page

link at tuners with many tests... by toybreaker? is it the same toybreaker?

 

[fuel]

I would be investigating why that front wheel is binding up - perhaps it's a stuffed wheel bearing or CV joint? Could perhaps be something inside the gearbox?

I know with my weak original viscous LSD rear I could jack just one side up and put a chalk mark on the 12 o'clock position on both side tyres and then rotate the front wheel and the rear wheel would follow suit, and vice versa. Though if your LSD is mechanical/plate type or a really good viscous one I don't think you could do the same.

 

[DynastyLCD]

i just saw this thread, and this was actually internal transmission failure #1 of 4 so far... in 540 miles. figure ill share my expieriences.

i broke every gear except for the gear that spins on the smaller half of the center diff (the part that unbolts)
it was definetly a stock unit.
(failure #1)


took a spare center diff, and had it welded. life was good for a short while.

then i managed to break the shaft the center diff sits on, that drives the front wheels (back to RWD again)
(failure #2)


upon disassembly, found trans case cracked at bellhousing, swapped cases and put it back together.
(failure #3)


acting like an idiot launching and hammering through the gears, broke the 3-4 shift fork at the pin, locked it in 4th...
(failure #4)


vehicles current driveline setup: 91 trans, factory front 2 spider differential, welded center differential, 4 bolt LSD rear end.

personal expieriences: with the welded differential and the LSD, i have to turn it all the way to the end of the rack to get any sort of skipping. its very minor as well. sometimes i forget its even welded during some situations. a friends 1g which i believe had an open rear was much more of a bear to drive, and took alot less for the front wheels to skip.

so now im getting very good at the teardown/re-assembly of a 1g trans. hope this was entertaining to you all!