auto rear diff in a 5 speed

[lilsam]

I just recently found out that my car was auto to manual swapped, and i was wondering if there was a way to tell if the rear diff is from a auto or a 5 speed. Also, i was wondering is there is anything that is potentially harmful about keeping the rear end if it ends up to be out of a auto.

 

[bryanwheat]

IF you have an auto rear end in there the car will pretty much not move forward without a lot of effort. Because the difference in gear ratio's the drive train will bind up.

 

[jrohner]

Yeah, if you can push the car, the diff was changed.

 

[toofast82]

Also too if you can still read the sticker on the back.. I believe the auto is 3.31 ratio and 5spd 3.55 mayb.
I've done the swap, but its been years and i don't have a dsm anymore so can't quite recall the exact numbers or diff code

 

[lilsam]

Yea I have drove the car so it's been changed Apperntly. Thanks guys


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I am here: http://maps.google.com/maps?ll=42.852301,-87.895208

 

[toofast82]

Yea I have drove the car so it's been changed Apperntly. Thanks guys


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I am here: Google Maps

Not necessarily.. When i did the swap, I drove mine a few miles with the auto diff before swapping.

 

[lilsam]

Well I have put 1000 of miles on my car since I bought it. So I might be in the clear cause there in no tag on the rear diff any other way to find out?


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I am here: http://maps.google.com/maps?ll=42.902779,-87.920957

 

[Bender]

A lot of misinformation here. In fact, everything posted is wrong. Toofast82 was the closest, but he has the ratios swapped.

You won't bind the drivetrain up unless there is a welded center differential. You will just burn the viscous coupler up, and super heat the fluid in the rear end. Chances are, if the previous owner didn't swap the rear end, he burned up the viscous coupler the first time he drove it.

The auto and 5 speed rear ends are identical, with the exception of the ring gear on the differential unit. You can use the rear pumpkin that came with a 5 speed car, you just need to swap the ring gear.

With that said, most people swap the whole diff because it is easier, and they don't need to set bearing preload on the both the pinion and the saddle bearings. What sticker is on your housing? It should say 3.545. If it says 3.307, then you have the wrong diff.

 

[Colt4G63 also]

A lot of misinformation here. In fact, everything posted is wrong. Toofast82 was the closest, but he has the ratios swapped.

You won't bind the drivetrain up unless there is a welded center differential. You will just burn the viscous coupler up, and super heat the fluid in the rear end. Chances are, if the previous owner didn't swap the rear end, he burned up the viscous coupler the first time he drove it.

The auto and 5 speed rear ends are identical, with the exception of the ring gear on the differential unit. You can use the rear pumpkin that came with a 5 speed car, you just need to swap the ring gear.

With that said, most people swap the whole diff because it is easier, and they don't need to set bearing preload on the both the pinion and the saddle bearings. What sticker is on your housing? It should say 3.545. If it says 3.307, then you have the wrong diff.

Why would you superheat the fluid in the rear end, when the VC in the transmission is the one doing all the work? Furthermore, wouldn't you need to swap the ring and pinion together?

 

[Bender]

Pinions are the same, so just the ring gear needs to be swapped.

Should have been clearer. If the center diff is welded, you will superheat the fluid in the rear diff. Typically it gets to the point where you start bubbling the paint off. If it isn't welded is when you burn the viscous coupler up.

 

[Colt4G63 also]

Pinions are the same, so just the ring gear needs to be swapped.

Should have been clearer. If the center diff is welded, you will superheat the fluid in the rear diff. Typically it gets to the point where you start bubbling the paint off. If it isn't welded is when you burn the viscous coupler up.

Dude, if the center diff is welded, and you have the wrong rear, you're going to drag the rear tires.

 

[Bender]

Uhm no.

I have seen (more than once) people forgetting to swap everything over, or using the wrong transfercase when performing the swap. The rear diff just slips, and generates heat.

 

[Colt4G63 also]

Um, no. You're mistaken. The rear diff (rear VC) slips when the rear tires are traveling at different speeds, left and right.

Ps. Transfer cases are 1:1 ratio. Are you saying that you have seen an auto transfer case bolted to a manual, or vise versa?

 

[Bender]

Do you have a welded diff?

You will know that the tire skips when you turn at low speeds with street tires. Now put slicks on it, you have the extra traction, and the tire no long skips. You know why? The differential is slipping. This is the exact same thing. The tires could skip if you have tiny little spares on it with no grip, or you have no weight in the ass end of the car. This isn't the case though.

 

[Colt4G63 also]

Do you have a welded diff?

You will know that the tire skips when you turn at low speeds with street tires. Now put slicks on it, you have the extra traction, and the tire no long skips. You know why? The differential is slipping. This is the exact same thing. The tires could skip if you have tiny little spares on it with no grip, or you have no weight in the ass end of the car. This isn't the case though.

I have a spool, not a welded center diff.

So you're saying that my 300 treadwear tires are not enough to make my VC slip when going around a turn, but your slicks are? By that reasoning, all the cars were dragging thier tires around turns when they rolled out of the showroom brand new, because the stock tires are no match for the super stiff VC the car came with.

Drive in enough circles with your welded center diff. I garantee you are still dragging your slicks.

 

[Bender]

Now you are just talking nonsense, and putting words in my mouth. I never said the stock viscous coupler is stiff. In fact, it isn't stiff at all.

A 300 treadwear radial tire at 35-45 psi is still pretty hard, especially compared to a bias ply slick with 15psi. The driveline bind will slip at easiest part. Stock, this is at the viscous coupler. When you weld it, then it slips at the tires. If the friction between the tires and the road is increased beyond that of the rear diff, it will slip there. When it slips there, it creates a great amount of heat, and gets the gear oil hot enough to bubble paint off.

This is the last I will respond to this thread. I tried having a decent discussion, but it just isn't happening. You have resorted to sarcasm, and putting words in my mouth that I didn't even remotely imply. You are continuing to argue, just for the sake of an argument, when you have no facts to back up your claims. I, on the other hand, have been helping people perform these swaps for longer than you have been a member on this forum.

 

[Colt4G63 also]

The way a differential works is the VC holds the left and right rear wheels together traveling at the same speeds. When it slips, the gears are still meshed, so what one wheel does, is directly related to the other wheel. If the driveshaft turns 3.545 times, the rear diff carrier turns one revolution. Period, there's no slipping there unless the teeth come off the ring and pinion. The axles however are free to both turn once (lets say left 1 turn, right 1 turn), OR the left can turn 2 times, while the right is held still (lets say left 2 turns, right 0 turns). Any combination inbetween is possible, but the left and right must always add up to two. Example (Left 1.5 turns, right .5 turns) So combined, the rear wheels are still covering the same amount of ground.

Now think of the center diff (and VC) as the same thing, because it is. If the center diff is locked, the ratio will always be (rear 1, front 1). When you go around a turn, the front of the car travels a further distance than the back. The front and rear diff's are powerless to transfer any of those revolutions forward or backward, only left to right. Therfore either way, if you have a locked center, you have to drag or spin a wheel to go around a turn. If you lock the center, and the rear, you spin both rear wheels, or drag a front, depending where your traction is.

Now you are just talking nonsense, and putting words in my mouth. I never said the stock viscous coupler is stiff. In fact, it isn't stiff at all.

A 300 treadwear radial tire at 35-45 psi is still pretty hard, especially compared to a bias ply slick with 15psi. The driveline bind will slip at easiest part. Stock, this is at the viscous coupler. When you weld it, then it slips at the tires. If the friction between the tires and the road is increased beyond that of the rear diff, it will slip there. When it slips there, it creates a great amount of heat, and gets the gear oil hot enough to bubble paint off.

This is the last I will respond to this thread. I tried having a decent discussion, but it just isn't happening. You have resorted to sarcasm, and putting words in my mouth that I didn't even remotely imply. You are continuing to argue, just for the sake of an argument, when you have no facts to back up your claims. I, on the other hand, have been helping people perform these swaps for longer than you have been a member on this forum.

You did say that. Here are your exact words:

"You will know that the tire skips when you turn at low speeds with street tires. Now put slicks on it, you have the extra traction, and the tire no long skips. You know why? The differential is slipping."

That would imply that the rear VC is overcoming the traction of the street tires. Is that not what you meant?

The facts state that you are mistaken. The math is above. I'm not trying to argue just to argue. I'm just stepping in to correct some misinformation.

Ps. You can preach how long you have been a member or whatever, but I'm a professionally trained auto tech. I've been working on cars for 25 years, and I've known how a differential works for over 35 years. it was one of those nagging mysteries to me when I was 5 years old, and I made it my business to understand it.

I'm sorry you had to bow out of this discussion rather than just admit you are wrong, but it is what it is.