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HybridZ

Tire Size and Gear ratio


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Totally depends on what you are doing with the rest of the car. Going +1, +2 or +3 on the wheels and tires has no effect on your gearing, speedometer wise, if it is done right because the rolling diameter of the tire remains essentially the same.

It will have an affect on your braking and accelleration depending on the wheel-tire combination and it's inertia vs stock. I've had 3.54, 3.90 and now 3.70 R200's. The differential changes had nothing to do with going +2 on wheels & tires but everthing to do with changes in the rest of the drive train.

My rear brakes are stock and the front have the Toyota 4x4 upgrade. For daily driving they are plenty adequate. I expect I'll notice a lot of fade in them when I start working them hard at Texas Motor SPeedway this Friday.

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I was curious about this as well.. I got to thinking if I could swap in some gears/rearend with a little higher ratio, I could make my car a bit quicker on the street (just because of the mechanical advantage) without loosing the ability to cruise the highway... Anyone have a list of the rearend ratios that are/were offered for the Z's?

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The most common ratios were 3.36, 3.54 & 3.90 with a 3.70 LSD being the hardest to find. The 3.90 with the 81-83 5-spd. gives the best all round performance. If you are going for flat out accelleration with OK highway speed rpms then opt for the 76-79 5-spd. It has higher numerical gearing in 1st, 2nd & 5th with 3rd & 4th being the same as the 81-83 T5. It wil get yo off the line a bit faster but with a .86:1 OD 5th the engine will be a bit busier at highway speeds than the .745:1 OD 81-83 T5.

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If you have a cammed L6, try to find a ZX 5 speed. The ratio thing is the same for the trans as for the diff as Phantom stated before. The ZX 5 speed has closer ratios so it won't drop you out of the powerband. The 280Z 5 speed is particularly bad in the 2-3 ratios if you have a narrow, higher rpm powerband.

 

For turbos and probably V8's too that have lots of low end, a wider ratio tranny will do better.

 

For the diff the best thing to do is figure out your tire size and work backwards from there figuring your top speed, highway rpms when cruising along, etc.

 

Jon

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