WC T-5 Speedo Gear Question

[mr_han_solo]

Hello,

 

I am in the process or rebuilding my t-5 to go behind my 350. I was wondering what speedo gear I need to put in the transmission? I have the following gears on hand.

 

 

I am not opposed to buying the gear if I don't have it here.

 

The ratios of the t-5 are :

  1.76 2.95 1.94 1.34 1.00

0.73

 

I am using a stock 1973 240z r180 differential. I also have a differential out of a 1975 280z in case my 1973 ever breaks.

 

My current tire size is 235/60/14. The tire size itself may change due to my build being an autocross car. However, the current tires Bf Goodrich Radial T/A have tons of tread left on them and I dont forsee a big tire size change in the future.

 

Hoping that I provided all of the information needed to choose the correct speedo gear for my application.

 

Thanks.

 

 

 

[dsommer]

If I recall correctly the gears come in a varity of colors that you can match with your rear end gearing and tire size in order to choose the correct one.  It was the output gear (white one pictured above)  I'm sure it can be found on the net somewhere.  I used to have an old carcraft mag that had the formulas and such in there so you could make the correct decision but that was years ago.

 

Also are you running a World Class T-5 (WC-T5) or just a regular T-5?  The WC's are stronger, the way to ID the WC is count the splines on the input shaft, there sould be 26, the non WC I believe are 10 spline input shafts. 

 

Finally your R180.....from what I've seen, it's not going to last long behind a V-8, so be ready to swap it out.  If you've never swapped the rear end read up on how to do the swap to ensure you have the correct parts before you begin.

Edited January 30, 2014 by dsommer

[mr_han_solo]

It's a World Class.

 

I went ahead and wrote down every single rear end part I would nee for the swap before I took the r200 off of the parts 280z so I should have it covered there.

 

Looks like I will have to do some more research on the speedo gear before I put this thing back together. I am hoping that someone else here that has done the swap may have a setup almost identical to mine and can help me out.

[NewZed]

It's the rear differential ratio that matters, not the transmission ratios.  Your 240Z could be 3.36 (manual) or 3.54 (auto).  The 75 280Z diff is most likely a 3.54 if it's an R200.  And it probably has a funky pinion flange bolt pattern.  Better read up on that, it can get you.  Flange patterns are described in the JTR book.

[Miles]

If the rear end ratio is 3.36 or 3.54 the drive gear is 7 tooth and is purple.

 

I have a WC T5 with a 3.54 R200 and 7 tooth drive gear.  The speedo is spot on.

 

 

Note:

 

The JTR book has all of this information. Invest $30 and buy the book. 

 

You need to tell us what gear ratio the differential is.

Edited January 31, 2014 by Miles

[mr_han_solo]

If the rear end ratio is 3.36 or 3.54 the drive gear is 7 tooth and is purple.

 

I have a WC T5 with a 3.54 R200 and 7 tooth drive gear.  The speedo is spot on.

 

 

Note:

 

The JTR book has all of this information. Invest $30 and buy the book. 

 

You need to tell us what gear ratio the differential is.

 

Sounds like I need to go with the purple gear then. I actually have the JTR book, but I didn't even notice the little chart until your post. I'm assuming you have the 20 piece driven gear then? I may just go ahead and buy both the 19 and 20 piece gears to cover both bases. They shouldn't be hard to change out anyways.

 

Thanks for everything,

 

Han

[Miles]

Note:  JTR also sells a 90 deg. speedo gear  adaptor.