79stickshift

I'm lost. Wheels should spin almost independently of each other when in neutral?

SunnydayDILYSI

I'm not a professional mechanic Stickshift. However, I think it is normal to be able to spin one wheel while the car is in neutral and have the other wheel do nothing (I know mine does the same). Before spending any money, I would consult with a pro.

Socko

I want to do this test. I been writing up something for a while here but it got way to technical and long.

This test really should be done in neutral with 1 wheel on the ground and a torque applied to the other axle nut.

Does anyone know if the diff is 1 way 1.5way or 2 way? It would matter for testing relative to which way you spin stuff if its not 2 way.

talon95

Uh no it won't. On an open diff car, you can't turn one wheel with the other on the ground and the car in gear (and not turn the motor). If you could, the car would never move.

It must be in the service manual, although I can't find it in the electronic version I have. I did find this Dana manual with the procedure which does say to put the car in neutral.

http://www2.dana.com/pdf/5315-3.pdf

SunnydayDILYSI

Link to a good video explaining LSDs.


Given this, it sure looks to me like the wheel is made to freely spin when in neutral. Engagement of the gear is required to bind the two half shafts together, which is what creates the equivalent of a solid differential until enough torque is applied to one wheel vs the other, which then breaks the clutch free. It looks like the motor would not move when the clutch slips, as the clutch is between the half shaft and the drive shaft (i.e., the slipping is what keeps the engine and the other wheel from turning while the one wheel with the torque being applied does turn.

Rookieracer

Found this, post # 7

https://www.corvetteforum.com/forums...the-fluid.html

And this;

https://www.corvetteforum.com/forums...l-is-shot.html

froggy47

I will do it over & shoot the vid tomorrow when I put my street wheels back on, but I already tried it b4 I shot this, in neutral the wheel just turns easy, don't think I will get any torque reading at all.

Some of you guys are getting confused with how a limited slip diff works vs none limited diff when BOTH WHEELS ARE OFF THE GROUND.

We are NOT talking about that here. It has no bearing on testing the clutches torque.

Stay tuned.

talon95

I agree, if that's the type of diff our cars have, then it appears there is not a hard connection (I think because the cross pin in the diff he's drawing does not go through the case). OTOH, some of the limited slips do have that pin going through the case which would provide a hard connection.


(but maybe this is the cheaper type of diff that wears out quickly like in some (all) of the older f-bodies??)

I'm thinking this is why we see wildly varying TQ values for our cars. Some checking in neutral, some in gear. Just like Xian, my cars both show a fairly high TQ value in neutral. Although my C5 only shows around 70 ft-lbs, but my C6 shows 100+. Both checks were done in neutral. I know my C5 shows a much higher value in gear (because I've accidentally started to check it in gear before), but I've never tried to get an accurate number in that case.

froggy47

Here ya go:


As to my "high" reading, I use Redline. If YOU are using the stock fluid with the slip additive, maybe that's why your break away torque is different. The whole POINT of the additive is to change the torque on the clutch break away.

So if you don't know who changed your fluid last or how much or little slip additive they used, well .........

YMMV



BTW, no, I did not inadvertently loosen the axle nut, It's on at about 165 lbs & my gut tells me that my wrench, when set to 150 lbs is probably closer to 125-135 give/take. Torque wrenches, in general, are not "that" accurate at the extremes of their settings.

talon95

Neither of my cars will turn freely like that in neutral with one wheel on the ground. I have redline in mine. I've had M1 also. Same result with either.

mountainbiker2

I just checked mine. In neutral, it takes about 75-80 lbs. to break loose. Just for kicks, I did both the passenger side and drivers side with same results. GM diff. oil with one bottle additive. My axle nuts were loose though.

froggy47

So you mean the nuts were just "hand tight"? That should not matter, right?

froggy47

I hope you also checked it in gear, just for fun, and forgot to post it.

If not, for crying out loud, do it in gear, so we can figure this puzzle out.

79stickshift

I can turn mine by pushing the tire with my hand with one on the ground whether it's in gear or in neutral.

mountainbiker2

Dosen't matter. They can be off, and get the same results.

I did try it in gear and I didn't want to bust my gut trying to move it. It was like yours in gear.

pelloni

Just checked mine. 02 ZO6 fresh rebuilt diff with carbon fiber clutch packs and DTE hd belleville washers.
One wheel on ground, tranny in neutral: breaks at 130 ft lbs.
Tranny in third gear: 240 ft lbs. no movement. (maxed out torque wrench)
Parking brake off.

froggy47

I apologize in advance for this question, but, all you guys do have the parking brake full off, right? No fair testing the break away of the parking brake. I know it's a habit for some guys to pull it on.

froggy47

If that's an older Vette (screen name) I don't know if they had Positraction back then.

froggy47

Are you twisting on a lug nut or what?

79stickshift

It's an '02 Z06. Used to have a '79 when I made the name. Can't figure out how to change my user name.