86.5 with LSD ??
#1
Three Wheelin'
Thread Starter
86.5 with LSD ??
Guys, Got a few observations & questions on LSDs. My car has the manual tranny and does NOT have the 220 option code although I THINK I have a 40% LSD... am not sure.
I was under the assumption with a standard differential that if you turned one rear wheel by hand it would turn the other side wheel in the oppoisite direction... and visa versa... correct?
I was also under the assumption that turning a rear wheel on an LSD it would turn the other side wheel in the same direction... correct?
With my 86.5 / Manual tranny up on jack stands, in neutral, you can turn the driver side OR pass side rear wheel by hand without turning the wheel on the other side (at all) in either direction. Strange...??
When put into gear, if you turn one wheel by hand it will turn both wheels in the same direction...
Needless to say, I'm confused... which isnt saying much... Any thoughts on what kind of differential is in the car?
I was under the assumption with a standard differential that if you turned one rear wheel by hand it would turn the other side wheel in the oppoisite direction... and visa versa... correct?
I was also under the assumption that turning a rear wheel on an LSD it would turn the other side wheel in the same direction... correct?
With my 86.5 / Manual tranny up on jack stands, in neutral, you can turn the driver side OR pass side rear wheel by hand without turning the wheel on the other side (at all) in either direction. Strange...??
When put into gear, if you turn one wheel by hand it will turn both wheels in the same direction...
Needless to say, I'm confused... which isnt saying much... Any thoughts on what kind of differential is in the car?
#2
Former Vendor
Open differential. No limited slip.
#4
Three Wheelin'
Thread Starter
O.K. I'll take it as gospel, but... how??? Ya know, so some other guy doesnt have to ask the same question... yeah, thats the ticket... so someone ELSE doesnt have to ask it...
#5
Former Vendor
Here's the best way to understand the one data point that told me you absolutely didn't have a limited slip
If you have a limited slip that works, both axles will turn in the same direction, if the transmission is in nuetral. The two axles are "joined" by friction discs and will turn together, with a limited slip, until the friction between the friction disc is overcome and one or the other "slips".
The fact that one axle turns and the other doesn't, with the car in nuetral, actually tells you a couple of things. It tells you that the axles have nothing connecting them (no limited slip)....otherwise they would turn together, in the same direction. It also tells you that there is less resistance to turning the entire differential, ring gear, and pinion shaft, than the differential simply turning the other axle.....in the opposite rotation. To me, that means a brake is dragging or the axles are dry and resistant to rotation.
The problem with your second data point is that you say that if the transmission is in gear, the axles turn in the same direction.
If the transmission is in gear, the pinion shaft can't turn, unless the engine turns or the clutch is pushed in. If the pinion shaft can't turn, neither can the ring gear. That means the differential "carrier" can't turn. Consequently, the only direction the other axle can turn, regardless if there is a limited slip or not, is in the opposite direction.
I suspect that you must have the clutch pedal depressed or have something disconnected, when you have it in gear. This allows the entire ring gear and carrier to rotate, turning both axles in the same direction.
#6
Three Wheelin'
Thread Starter
No brakes dragging... but axles dry and resistant to rotation is a definite possibility. I'll look into it... Thanks for the tutorial - I learn more everytime I log on here... again, thats not saying much
#7
Racer
Join Date: Oct 2012
Location: San Ramon, Calif.
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Here's a relative question...
I have an 88 Trani that I'm putting into my car soon. It has 110K miles on it. Should I rebuild the LSD (if it has it) and how do I know if it will need the rebuild?
I have an 88 Trani that I'm putting into my car soon. It has 110K miles on it. Should I rebuild the LSD (if it has it) and how do I know if it will need the rebuild?
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#8
Three Wheelin'
Just jack the car up in the rear and open the fill plug and have a peek with a flashlight. There is quite a significant difference of what you will see in the differential between LS and non-LS. Pictures are on here somewhere in some past threads.
#9
Rennlist Member
Last edited by Dave928S; 11-07-2012 at 03:13 AM. Reason: clarification
#10
Former Vendor
Put the transmission into gear and turn one of the flanges with a torque wrench. 7-25 pounds is the specififcation for your differential. Start with low torque and work you way up with the torque setting. Since the bolt torque is 32 ft lbs, the opposite flange should turn before the bolt gets too tight. Less than about 10 ft lbs.....it needs attention. More than 25 ft lbs...you've got some serious grief.
#11
Race Director
Okay I don't know much about transmissions....or LSD's........................but what I DO KNOW is Doc Brown does know!!!! My freshly rebuilt transmission in my race car is WORLDS better than what I had before.....I can actually floor it mid corner and the car accelerates.....before it was an endless 1 tire smoke show....sometimes at 90+ mph.... Here is a video of my worn out LSD
#12
Banned
Check it.
Put the transmission into gear and turn one of the flanges with a torque wrench. 7-25 pounds is the specififcation for your differential. Start with low torque and work you way up with the torque setting. Since the bolt torque is 32 ft lbs, the opposite flange should turn before the bolt gets too tight. Less than about 10 ft lbs.....it needs attention. More than 25 ft lbs...you've got some serious grief.
Put the transmission into gear and turn one of the flanges with a torque wrench. 7-25 pounds is the specififcation for your differential. Start with low torque and work you way up with the torque setting. Since the bolt torque is 32 ft lbs, the opposite flange should turn before the bolt gets too tight. Less than about 10 ft lbs.....it needs attention. More than 25 ft lbs...you've got some serious grief.