If we really have a glass diff....
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From: Studio City, CA
UL, good post...
When I did the rebuild, I didn't see a whole heck of a lot of extra space in there for much of anything. I do think that wheel hop is a MAJOR contributing factor. I have gotten wheel hop under acceleration (not a clutch drop, just acceleration) on uneven pavement that I didn't see ahead of time. I always let off as soon as I felt the uneven pavement, but sometimes that's too late. As UL said, this was also a problem with the 93+ RX7s. Wheel hop will kill a gear type ATBD and do just about no damage to a clutch pack LSD.
But I still think the real problem is the materials and manufacturing. Even though I had experienced slight wheel hop on a couple of occasions, there was no visible damage or wear on ANYTHING in the rear end when I did my rebuild. It simply just didn't work right. I don't know what the insides looked like on the first rear end since that one was warranteed, but at least with the second, there was no failure or wear.
When I did the rebuild, I didn't see a whole heck of a lot of extra space in there for much of anything. I do think that wheel hop is a MAJOR contributing factor. I have gotten wheel hop under acceleration (not a clutch drop, just acceleration) on uneven pavement that I didn't see ahead of time. I always let off as soon as I felt the uneven pavement, but sometimes that's too late. As UL said, this was also a problem with the 93+ RX7s. Wheel hop will kill a gear type ATBD and do just about no damage to a clutch pack LSD.
But I still think the real problem is the materials and manufacturing. Even though I had experienced slight wheel hop on a couple of occasions, there was no visible damage or wear on ANYTHING in the rear end when I did my rebuild. It simply just didn't work right. I don't know what the insides looked like on the first rear end since that one was warranteed, but at least with the second, there was no failure or wear.
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From: Chicago
By going to a wider tire you increase both lateral and longitudinal (in-line) grip, all else equal. Differences in tire construction and compound can skew this generalization. A good example is the Kumho vs. Hoosier race tires. Different construction and compound with almost identical tread-width. Yet the Hoosier has very little longitudinal grip, and the Kumho has lots. Thats one reason we went with the Hoosiers, to be easier on the drivetrain...
But Luis, to answer your question - All else equal, wider tires = more grip lateral and longitudinal.
But Luis, to answer your question - All else equal, wider tires = more grip lateral and longitudinal.
Joined: Oct 2000
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From: Lisbon
I can't see why.
All else being equal the contact patch area remains basically the same when you go to a wider tyre. You are just changing its shape. Have a look at http://www.tirerack.com/tires/tiretech/contact.htm to see what I mean.
With a wider tyre you add width but reduce length of the contact patch. I always thought this was the reason why dragsters have "skinny" wheels. They don't care much about lateral traction.
Anyway, that's just my 2c. Let's get back on topic.
All else being equal the contact patch area remains basically the same when you go to a wider tyre. You are just changing its shape. Have a look at http://www.tirerack.com/tires/tiretech/contact.htm to see what I mean.
With a wider tyre you add width but reduce length of the contact patch. I always thought this was the reason why dragsters have "skinny" wheels. They don't care much about lateral traction.
Anyway, that's just my 2c. Let's get back on topic.
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From: Chicago
Simply not true, Luis... not trying to flame/argue, just don't want you to go on believeing something that is false. 
The wider a tire is, the wider the contact patch... there is no change in the length of the patch. This is why wider tires increase grip. Think about it in extremes...
Are you saying that a 205/50/17 would have the same contact patch 'area' as a 255/40/17? It's just not possible. The contact patch is a imprint of the bottom of the tire, so the wider the tire, the wider the contact patch.
And as for drag racers, the common practice for Hot Rodders is to shorten their axles and tub-out their frames to house 2-foot wide tires! Believe me, they are not just doing this for looks!
Wider tire = more grip in every direction.
BTW... the tirerack's description is a generalization, and it show tires of different constructions. Remember my point that construction can skew the above generalization, but if you think that the narrow tire on their page has the same grip - in any direction - as the wider one, you're quite mistaken.
Also, the changes in the patch length shown on their site are due to aspect ratio differences... they compare a 205/70/14 with a 315/40/17. If you could find a 315/70/17 (dang that would be one tall ass tire!) it would have the same length contact patch as the 205/70... but much wider.
The point is - the only safe generalization to make is this: Wider tires, all else being equal, will increase grip. That's the theory part. In practice, it almost always follows that wider always increases grip.
I hope that makes sense... if not, have fun in "Luis world!"
[Edited by Jason Saini on 03-07-2001 at 03:33 PM]
The wider a tire is, the wider the contact patch... there is no change in the length of the patch. This is why wider tires increase grip. Think about it in extremes...
Are you saying that a 205/50/17 would have the same contact patch 'area' as a 255/40/17? It's just not possible. The contact patch is a imprint of the bottom of the tire, so the wider the tire, the wider the contact patch.
And as for drag racers, the common practice for Hot Rodders is to shorten their axles and tub-out their frames to house 2-foot wide tires! Believe me, they are not just doing this for looks!
Wider tire = more grip in every direction.
BTW... the tirerack's description is a generalization, and it show tires of different constructions. Remember my point that construction can skew the above generalization, but if you think that the narrow tire on their page has the same grip - in any direction - as the wider one, you're quite mistaken.
Also, the changes in the patch length shown on their site are due to aspect ratio differences... they compare a 205/70/14 with a 315/40/17. If you could find a 315/70/17 (dang that would be one tall ass tire!) it would have the same length contact patch as the 205/70... but much wider.
The point is - the only safe generalization to make is this: Wider tires, all else being equal, will increase grip. That's the theory part. In practice, it almost always follows that wider always increases grip.
I hope that makes sense... if not, have fun in "Luis world!"
[Edited by Jason Saini on 03-07-2001 at 03:33 PM]
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