please help me

[the Z guy]

i have a Question... i am inheirating a 280z 2+2 that my dad started to put a chevy in about 12 yrs ago. block and tranny r in. it was an automatic so i think that is the strong rearend (correct?)what gears should i run w/ a 350th tranny? what will need to be replaced after these yrs? has been in garage in ca. so

not so much rust expected i will need help whith this so i will have more Questions as i find problems i hav not seen it yet so i dont know how much work to expect thanks!!

[St.stephen]

persoanlly, I cannot beleive that I am even helping with this as any butchering of a Z car makes me cringe, however if you have to have a chevy V8 stuffed in a car that was never meant to have it than so be it.

All 2+2's had the R200 rear. If you are not sure what ratio R200 you have lying around then perform the following:

Remove the rear plate and then rotate the large ring gear until you see numbers stamped on the edge facing you

3.54 will read "39:11"

3.70 " " "37:10"

3.90 " " 39:10"

4.11 " " 37:9

[hmsports]

Support the rear of your car on jack stands.

Put a mark on the rear flange of the driveshaft then have someone turn a rear wheel one revolution. Count how many times the driveshaft goes past your mark. You have to kind of guess-timate from here. If it is just under 4 times, you probably have a 3.90 - if it's 3 3/4, then is a 3.70, over 4, then a 4.11, less than 3 1/2 - 3.36 - right at 3 1/2, its a 3.54.

This will save the time of pulling the cover and the mess too. Not as accurate, but will give you a pretty close guess.

[Royce]

hmsports,

I think that would only work with a locked diff or maybe posi, would require you to spin both rear wheels in the same direction!?

I have just posted something similar that I have used with good success in the "Transmission ratios and suggested rear gears" thread. I got it from www.zhome.com in the technical articles.

Hope it helps!

[hmsports]

See, that's the problem with having a welded differential.

Thanks for pointing that out Royce. I guess you could get two friends to help spin

I guess when I went to the junk yard to find my 4.11 it was on a shelf and I was able to spin both output shafts together.

[Royce]

Sounds like you have to be pretty precise to measure the ratio that way if the diff isn't welded. Something I would not be good at! Typically if you spin one wheel/axle of an open diff with both sides free the other wheel/axle will spin in the opposite direction. This means neither wheel is spinning as much as it should and the calculation would be off. Since the differences are pretty small I think with an open diff I would have a hard time turning the two axles the same and would screw up my calculation. Holding one side still is a little easier to me than spinning both sides equally. But hey, whatever works for you!

Have fun!

[Mr Camouflage]

Ah ok, so what if you only jack up one wheel and leave the other on the ground so it remains stationary. then when you rotate the wheel the only other thing that can move is the input flange, so you could then work out the ratio.

I'm sure that would work, wouldn't it?

[Royce]

Mr Camouflage wrote: "I'm sure that would work, wouldn't it?"

It has worked very well for me! Again see "Transmission ratios and suggested rear gears" thread on this site or go to the original at www.zhome.com in the Z technical library, Index of technical articles and look for "How to determine which ratio..."