Transmission ratios & acceleration

[robftw]

My rear end is 3.545

Current transmission is

1 - 3.321

2 - 2.077

3 - 1.308

4 - 1.000

5 - 0.864

The trans im looking at is this

1 - 3.062

2 - 1.858

3 - 1.308

4 - 1.000

5 - 0.745

I feel when im going through gears the powerband drops off when going to 3rd, i want to remove this.

I also drop a lot of RPM while shifting. with this new transmission my 1st-2nd gear should have slightly slower acceleration but a higher speed in each gear with the benefit of being closer to each other it should be slightly "faster" correct?

Will swapping to the new transmission alleviate this problem?

[24OZ]

If your looking for more low down grunt on an NA car, changing the diff to a lower gear may mean you get the desires results. Have you tried how a 3.9 diff feals?

Edited July 13, 2011 by 24OZ

[robftw]

I don't have access to one, but i do have a 4.11 on its way, its an LSD off the front of a 4x4 nissan patrol.

it wont be here for a few months though.

[mayitin]

Hmm I was checking some of your trans ratios the 1 and second do not match on any of my books. are these tranys from a ZX? usually the only thing different is the 5th gear. the 2+2 tranys have different ratios also but your ratios did not match my books, my books may be old and may not have all the different tranys. in the early days changing to a 77 5 speed cost a lot so many used the 200SX tranys for the 5 speeds at the cost of poor perfomance in the lower gears. Just a thought.

[5thhorsemann]

I think, scratch that, I know you will get a better result with a diff swap to get your car "quicker" with alot less work and money. The gear ratios you list above are just going to move the issues you are having from one gear to another, don't you think?

[LeonV]

Those ratios match the '77-'79 Z/ZX and '81-83 ZX, respectively.

The close-ratio transmission is great, less drop from 2-3 shifts and a taller overdrive, for lower cruising rpm. I have the late ZX trans in my Z paired with a 3.9, and love the gearing. Before I swapped in the 3.9, the rear diff was a 3.54, and I still very much liked it.

Get the close-ratio trans, and if you decide you want even more tractive effort then install a higher ratio diff.

Ratios: http://zhome.com/ZCMnL/tech/GearRatios.html

[sblake01]

I put that trans (81-83) in both my Z and my 810. I loved the gearing with the stock 3.54 in my Z and with the 3.7 in my 810. Though the 810 was an L24E, with the 3.7, it pulled almost as hard as the Z w/3.54. On, and mayitin, you really need to get some newer books.

[Walter Moore]

Yep, the close ratio (81-83) is great! With my 3.36 differential, first and second are ludicrously tall, but with a 3.54 I bet it would be cool.

Oh, and 3.9 Differentials are generally difficult to fined in the U.S. except in an R200.

[tlorber]

I have an '82 tranny with a 3.7 and its a great combo. Walter, with that combination you have I'd imagine you are doing very low rps's on the highway. Out of curisouity what kind of mileage do you get if you keep it around 60-65 mph?

[robftw]

found a neat tool for this kind of thing, this new trans looks like the way to go.

Now for that 4.11 lsd...

[Zed Head]

[ATTACH=CONFIG]46701[/ATTACH]

found a neat tool for this kind of thing, this new trans looks like the way to go.

Now for that 4.11 lsd...

I've seen a similar tool but it doesn't plot the numbers. Is that one available on the web?

There is something odd about your attached picture though. Maybe you didn't redraw after putting in new numbers. 3rd gear plots the same line but 4th gear doesn't even though the values are the same for 3rd and 4th, between the two transmissions.

Anyway, I wouldn't mind a link to the site if you have it.

[LeonV]

I like this one a lot better.