Ok guys, I've got a question for you. I'm searching the internet tonight and I notice a gearing kit from OS for my FD.
gearing is as follows:
-1st: 2.578 (3.483 OEM)
-2nd: 1.772 (2.015 OEM)
-3rd: 1.289 (1.391 OEM)
-4th: 1.000 (1.000 OEM)
-5th: 0.821 (0.806 OEM)

So here is my question. instead of spending 3K on the close ratio kit then another 1500 plus on a rebuild where could I go online and order the gears myself to cut costs. I wouldn't even mind sending them off to get cryo-treated provided I saved enough. The second part of this question is what kind of performance gains should I be expecting using an R1 as a baseline.

 

If you don't know what the gearing will buy you. You don't need.

and stock US did not use .806 5th

 

Obviously close ratio gears cut back on my top end I'm more concerned with highway cruising, which I have seen someone do the math to in another post. Just because I dont feel like sitting down and figuring it out myself doesn't mean that I dont need to upgrade my transmission. So how about less hating and more helping. Also I have a J-spec transmission.

 

expect faster acceleration

 

Don't expect any performance gain.

With stock gearing on the street you will have plenty of gear at any speed. The OS Giken is a straight cut gearset that will run a hell of a lot louder and handle more power. It will slightly reduce losses inside the transmission but considering that helical gears usually only lose 1% per reduction, that's just a few HP total.

If you're thinking about this gearset, consider for a moment how many stock transmissions you've fragged. If it's more than two perhaps this is a good upgrade. If you've never shredded the gears in your transmission it will do you no good.

Also, I'm not sure what you mean by buying the gears yourself to save money. A bearings kit is a few hundred, plus the cost of the gearset should be everything if you DIY.

David

 

David,
This is going to be in the Bridgeport 20B I just got clearance from the wife to go ahead and start on. The FD will be used on the street occasionally but primarily as a track car that's why I was looking at the Gear set. As far, as I saving money. I am considering making it a DIY project with the transmission as well. Think of it as a budget track car powertrain. So the question would be where can i go to find the gears to install in an FD trans.

 

I think this matter became more confused when you said that highway cruising was a concern. Track cars and highway cruising have nothing to do with each other.

On the track the close ratio will give you more performance because you'll have a better selection of gears. Especially NA bridgeport, which will be all at the top end.

But still, NA 20B on the track is not an all-out gear shattering torque monster. You can probably go through a regular FD transmission to get started and swap in the close ratio kit later.

Dave

 

The advantange of such gear set will be a closer ratio between gears. What is mostly being given up is starting torque (not a big deal on a flying race start) in exchange for closer ratios between gears permitting to to always stay closer to the max torque max hp ponts on the pwer curve. 4th gear is no change and 5th gear is a minor but torquer gear (may acutaly be able to accelerate some).

What I meant by if you don't know you don't need these means that before purchase you should be ploting your gear torque / rpm curves vs shift points and determining what is best ratio set and what rear end ratio is needed to peak your speed at the end on the tracks longest track. Any gearing trans ratio x rear end that does not fit a particullar tracks conditions is useless. Unless class rules may this whole question useless by saying no changes permited.

 

All that is true for gearsets that permit to to choose each gear ratio. But these are complete sets. Unless you have a transmission built with each one, there won't be much ability to match to a particular track. Rear end ratios are probably easier to work with in that regard.

However, regardless of the exact shift points and top speed, these transmission sets have closer ratios that bring 1st, 2nd, and 3rd into a much more usable range.

This all illustrates one important point: if this will be a dual-purpose car that is really track built, it will be very crappy on the street. The short 1st gear plus a puck clutch will be annoying to say the least.

Dave

 

For that much money, and if this car will be mostly used as a track machine, have you looked into the transmission that Damian is using on his race car? He is running a tremec T-5 based dogbox. They are very affordable, and offer an upgrade as far as holding capabilities. Just a thought.

 

It's the popular option for sure. The T-5 has many more options available as far as gearing and the bearings/housing design is much tougher.

The FD was designed for light weight - I've always wondered how much of the additional torque capacity of the OS and Trust gearsets is actually realized before something happens to the stock housing and bearings.

Personally I'd just wait and install the transmission later. 20B setups are complicated enough that the transmission will be a low priority.

David

 

Turbo 20B guys. I'm shooting for 700HP. I have a dream about a car that I'm actually afraid to drive so I turn the boost down for bragging rights. J/K. but seriously. 650ish is my goal around 20-25 psi.

 

I searched the forum and I didn't see anything other than mentions of the t-56 swap. anyone have any help to offer?

 

Depending on your budget, you may want to look into a helical cut PPG tranny. You won't get the whine you would with the dog engagement, but you will get a much stronger tranny then the stock one. A bridgeported 20b with any decent turbo is going to make some serious power. A T-56 is decent but you need something able to withstand 9000rpm shifts. Most domestic tranny's won't last to this. Get the OS, PPG, or Guru tranny. I've been in your shoes.