Drivetrain Upgrade (clutch, trans, LSD, etc)

[Zed Head]

The math still comes out different than your list.  There's a good thread on Hybridz where a guy spent a lot of time building the perfect transmission.  Synchros, ratios, everything.  He found that many of the gears can be swapped to build your own custom transmission ratios.  Or maybe your mechanic just missed a tooth when he was counting.

That is a pretty high, like high speed, 1st gear.  Not a lot pull from a stop.

"Zero gear" - 31 / 19 = 1.632
First gear set 33 / 19= 1.737
Result - 1.737*1.632 = 2.83
 

[Zed Head]

11 minutes ago, blodi said:

The rebuilder told me 5th was an overdrive gear

It can't be direct drive and overdrive.  Just saying.

You can check pretty easily with the rear wheels in the air.  The direct drive gear will cause the propeller shaft to move exactly in unison with the crankshaft.  Put a wrench on the crankshaft and a marker on the propeller shaft and see what happens when you turn the crankshaft.

[blodi]

OK, got the car on jack stands, put it into 5th, marked it all and gave the engine one turn over by hand. Drive shaft rotated ~1.15 turns or so. So...it's an overdrive trans.  

Next, I put it into 1st, marked it all again, rotated the engine 3 times and checked the shaft, it had rotated just under the 3 times, I rotated the engine another ~1/3 turn and it was lined up with the marks again. 

So...I think we've confirmed that it is a wide ratio with a 3.3X 1st and a overdrive 5th. This matches my driving experience with 1st/2nd being short and 3rd bogging a bit by comparison. 

 

Going back to my diff ratio. I'm looking through old images and videos that I happen to have at various engine/vehicle speeds and acceleration through the gears and comparing them to when I plug in the wide ratio gearing, my tires size and a 3.9 rear end to the calculator, and man, they are lining up pretty darn well. Maybe I'm not counting the diff rotations correctly....based on my images/video, the white speedo gear....my high rpm at highway speed....it's all pointing to a 3.9. 

 

Here is the wide ratios and 3.9 rear end:

Compare that to my images here and notes from a video I found:

~87 @~4400

 

~75 @ ~4000- this would be 4th gear.

 

This would have been in 4th given where it was taken, ~51 @ 2900 

 

 

I have a video that shows me shifting at ~6800 @~38mph  then 6800 @ ~58 and topping out in 3rd at 6000 @~84

 

For comparison, here is the same calculator run but with a 3.54 rear end. Doesn't line up nearly as well. 

Edited January 29, 2022 by blodi

[Zed Head]

Weird that your mechanic's gear tooth counts don't seem to correspond to anything.  Oh well.

Going back to your original questions.  A Fidanza flywheel would let you use a 240mm clutch, which should handle your power (it's the turbo and 2+2 clutch size).  The Subaru diff is an R180 which might handle the power just fine but the MFactory helical diff will fit an R200 and give the same effective results in a stronger package.  But, if you want to get rid of that 3rd gear bog, maybe a ZX 5 (not 4) speed is the way to go, with a 3.9 R200.  Find an old ZX to buy and scavenge from.

At least you know what have now for the most part.  Good luck, carry on.

Edited January 29, 2022 by Zed Head

[blodi]

1 hour ago, Zed Head said:

Weird that your mechanic's gear tooth counts don't seem to correspond to anything.  Oh well.

Going back to your original questions.  A Fidanza flywheel would let you use a 240mm clutch, which should handle your power (it's the turbo and 2+2 clutch size).  The Subaru diff is an R180 which might handle the power just fine but the MFactory helical diff will fit an R200 and give the same effective results in a stronger package.  But, if you want to get rid of that 3rd gear bog, maybe a ZX 5 (not 4) speed is the way to go, with a 3.9 R200.  Find an old ZX to buy and scavenge from.

At least you know what have now for the most part.  Good luck, carry on.

So, if you take what we know from the mechanics readings and we know 4th is 1:1....take 1 divided by the 4th gear ratio that he had (.710) and you get 1.408. Take that 1.408 and mutiply it by the rest of the ratios he gave me...and it lines up pretty well...

1st- 33 Main 19 Counter=2.357-this one doesn't work because his math is wrong, but even if you correct that, it doesn't work out, he must have mis-counted the teeth. 

2nd- 28 Main 19 Counter=1.473 x 1.408= 2.075

3rd- 26 Main 28 Counter=.928 x 1.408= 1.307

4th- 22 Main 31 Counter=.710 x 1.408 = .998

5th- 19 Main 31 Counter=.613 x 1.408= .863

Compare that to the wide ratio and it pretty much is dead on:

2010-N3030   3.321    2.077    1.308    1.000    0.864  (wide ratio)

 

Thanks for your help and answers, I think we've gotten somewhere here. 

So a stock turbo/2+2 clutch should hold the power? Any issues with going to that light of a flywheel and having as large of a cam as I do for idle and low speed driving? 

Seems now going to a 280x 5 speed and a 3.90 will do exactly what I want compared to what I have. Raise the gearing slighting for 1st and 2nd so they are closer to 3rd and make 5th a bit taller for high speed cruising. 

 

 

[Zed Head]

There's quite a bit on the site about lightened flywheels and the Fidanza flywheel.  The Fidanza is a light flywheel and it is drilled for either 225 or 240 mm clutches.

Can't remember all of the people that have posted about the topic but @siteunseen and @EuroDat come to mind.  Your cam is probably not as radical as you think it might be.  No offense.  

[siteunseen]

I have a Tilton 10lb 225mm flywheel with a Exedy OEM spec clutch and love it. I guess they quit making them for our cars as I can't find a new one on the internet. I did find this though...

https://forums.hybridz.org/topic/50119-experiences-with-aluminum-flywheel-on-zs/?do=findComment&comment=438416

[EuroDat]

15 hours ago, Zed Head said:

There's quite a bit on the site about lightened flywheels and the Fidanza flywheel.  The Fidanza is a light flywheel and it is drilled for either 225 or 240 mm clutches.

Can't remember all of the people that have posted about the topic but @siteunseen and @EuroDat come to mind.  Your cam is probably not as radical as you think it might be.  No offense.  

In regards to your clutch and flywheel setup. The fidanza and 240mm clutch is a good setup. The 240mm pressure plate is a little heavier than the standard 225mm and the extra lightness of the fidanza compensate nicely.

I'm using a lightened flywheel out of a 280ZX 2+2 with an oem style 240mm clutch. A F5W71B close ratio and a 3.7:1 diff. I like the combination. I don't know what had the biggest driving effect, the diff or the flywheel because they went in the same time.

Lightening a flywheel is not as easy as one would think. You can take a flywheel down to 11ibs and it will repond less than one taken down to 16lbs. Its where you remove the metal that makes all the difference. To get the best effects you will need to mill the outer sections and that costs a lot to a point where you would probably be better of with the fidanza.

[ckurtz2]

I can't say what set up you will like, but here is what I am running on a 77 280z and I love it.

81 280ZX NA close ratio 5speed (love the overdrive)

Fidanza light-weight flywheel

ACT stage 1 clutch kit (great brand, used them on many cars, smooth engagement)

88 Turbo 300zx 3.7 R200 CLSD (rare but if u find one get it). Also all the R200s are direct swaps as long as you get all the parts required for a 280z to 240z conversion.

Personally I would recommend the R200, because they are more robust than the subie LSDs, and more robust then the 240z R160 diff. 

 

 

 

 

 

 

 

 

 

 

[EuroDat]

Here are some diagrams and photos of different attempts to lighten a flywheel.

Edited January 31, 2022 by EuroDat