AWD experiment.

[LSfan70s]

Originally Posted by hammertime

Smaller wheels do spin more. In order to spin the wheels faster at the same engine RPM, you need a lower numerical gear, not higher.

285/35/19 = [(285 * .35) / 25.4] * 2 + 19 = 26.85
235/40/18 = [(235 * .40) / 25.4] * 2 + 18 = 25.40

26.86 ~ Tire revolutions at 60mph: 751.02
25.40 ~ Tire revolutions at 60mph: 793.97

Engine Rev's at 60mph 751.02 * 3.15 = 2365
Gear Required for 2365 engine rpm with 793 tire revs = 2.98

Doing the math, you might be better off with a 235/45-18 front tire and a 3.08 gear.

Great info. Thanks! But.... I just found out the front tires I gave are wrong. Woops

The actual dimensions are: 245/45/18. With the great math provided by hammertime, the front gear should be: 3.17.

So the difference is (if im not mistaken): 0.63%.

Would I be ok with that difference? (if using same gears)

[Old SStroker]

Originally Posted by LSfan70s

Great info. Thanks! But.... I just found out the front tires I gave are wrong. Woops

The actual dimensions are: 245/45/18. With the great math provided by hammertime, the front gear should be: 3.17.

So the difference is (if im not mistaken): 0.63%.

Would I be ok with that difference? (if using same gears)

That should be fine using the same front and rear gear ratios. There is often that much difference between tire brands.


Jon

[Bowtie70SS]

Originally Posted by LSfan70s

Wait wait, do not lock it yet please. I just want to know why the 4L60 I have is not going to like all that traction.

Thanks.

If you have a Silverado SS transmission it is a 4L65e just a upgraded 4L60e. I broke 2 output shafts on my Silverado SS with a magnacharger and a trailblazer converter on street tires. I had to buy a cryo'd output for like $500 OUCH.

[LSfan70s]

Originally Posted by Old SStroker

That should be fine using the same front and rear gear ratios. There is often that much difference between tire brands.


Jon

Thanks Jon. Now I got a new dilemma; seems kind of hard to find a 3.15 front differential. 'guess I'll need the rear one too to match the late gears available. Does anyone has suggestions on that? The only ones I have found are from BMWs.

[CarsandWomen]

^^^ why not find a matching set of diff's out of a single vehicle? maybe like a 4wd Colorado or Canyon? Or a half ton truck? the colorado/canyon axles are a little narrower i think. If you have drive train out of a TB then get the driveshafts too and you wont have to buy new yokes to mate to oddball diffs. Simplify things IMO, it outta keep the cost down too. if you find 3/4 ton or 1 ton stuff itall be alot stronger too so you shouldnt have to get upgrade performance stuff.

[The Dark Side of Wil]

Originally Posted by LSfan70s

Thanks Jon. Now I got a new dilemma; seems kind of hard to find a 3.15 front differential. 'guess I'll need the rear one too to match the late gears available. Does anyone has suggestions on that? The only ones I have found are from BMWs.

If it has the ratio you want and you're converting an non-AWD chassis (IE, fabbing your own front diff mounts anyway), then why shouldn't you use a BMW diff? The large case diffs used in the 5 and 7 series cars are quite strong.