Who does FD transmission rebuilds that incorporate a more usable 5th gear ?

 

pablo mobius motorsports

 

KDRotary in PA will do it too. I'm doing my own in the next few weeks... got the parts from Mazda!

Brian

 

What ratio is the 5th gear changed to?

Thanks...........

 

Well there are a couple available to you for new 5ths. Two that I know of are:

Gear : Ratio : Approx theoretical top speed
Stock 93 : 0.719 : 200 mph
Option 1 : 0.762 : 188 mph
Option 2 : 0.806 : 178 mph

option 1 comes from a pickup or a MPV van I think, and option 2 is from the type r bathurst RX-7 in japan. I do not know what options any particular shop will do... I got my stuff from the dealership to install myself. I bought option 2 for my car.

Brian

 

Brian, nice!

I have a spare tranny laying around that I'd like to get done. I like option #2 also. Do you have the part numbers for the parts? Thanks.

Rich.......

 

Yes, I do have the part numbers... BUT BUT BUT

I haven't actually picked up the parts and held them in my hand yet to confirm that they have the right number of teeth and therefore the right ratios... maybe you can check with me in a few weeks after I get around to picking them up and installing.

counter gear r50417308
fifth gear r50417610a

Brian

 

Ok Brian, I'll be in touch in a couple of weeks. Hope it goes well.

Thanks....Rich

 

What about a different 5th for an FC. Any options?

 

I think the bigger concern would be at what rpm would the motor be at say 80 mph in 5th. I don't see too many RX-7s reaching the 170-180 mark unless you're out in the salt flats where you would most likely swap to a taller 5th anyways. I'm guessing this is for a track car, but some might drive on public roads as well. Even PFS couldn't get his 20B to reach 150 on a "REAL" track.

 

Use the .756 5th gear from the GTUs model, it's a direct bolt-in. Get it from Mazda Comp, less than $200 I think. There are others from old 626s and such, but most ITS guys run the .756 gear. Usually works out to around 145 mph on a 245/45/15 tire and a 5.12 rear gear at 8500 rpm. And it's the only ITS legal 5th gear we can run.

 

Actually, option 1 comes from a Zenki FC3S turbo...


-Ted

 

Ted,

Actually, I thought it was from a Turbo II as well because of the gear ratio... But Ray Crowe at Malloy Mazda told me that it is from a pickup truck. He said that despite the fact that the ratio was the same, the TII gear doesn't fit in the FD trans. I'm not arguing with you, just stating where I got my info from.

I'm getting close to doing my swap (waiting on a few parts), and when I do it, I'll take measurements/pics of a TII 5th vs a FD 5th and post about it.

Brian