Hi guys,

I'm trying to decide what I want to do for a transmission in my black project car (FD). I'm shooting for slightly north of 600rwhp. I don't drag race, but will beat the hell out of the car in 2nd and 3rd gear and am going to eventually install 335 rear tires. With that in mind I am considering two transmission choices.

-Stock ~$0
-T56 $3000

Based on the above I'd like to see how many of you, going on something more than a simple 'gut' feeling -ie experience, stories, ect think I should use the T56.

 

Are you strapped for cash or not? Pretty simple question too me. You WILL need to start building your rear end at some point in the very near future, if you plan on putting that power to the ground.

 

The single-turbo 20B built by PFS that was featured in the Car and Driver Shootout used the stock gearbox with no problems. IIRC, about 700 hp.

 

It's always simple when it's not your checkbook ! It's really a question of cost-benefit more than anything else. In addition, I like the feel of the stock box. The T56 equipped cars I have played around with feel ok, but definitely not as precise as the FD box. I'd hate to give up that precision if I don't have to. Finally, changing the gearbox will add more time to the project.

George,

Cam at Pettit said whether the stock box is durable enough depends at lot on the driver's age. I've always been part of the smooth-is-fast crowd, so as long as it can handle the stress while in gear I think it will work ok. However, with that said, I've heard a couple accounts of the stock box failing while in gear.

A friend of mine told me that Peter Ferrall said Ed Taylor's car broke 3rd gear on the dyno. Another forum member with a 20b broke 4th gear on the dyno at 700rwhp. Granted, that's more power than I'll be making and it's hard to draw any conclusions based on a few examples without background info, but it does provide reason to be concerned.

 

I have been running a factory gear box on my car, while the Guru is in Transit. Granted, the only real hard RWHP figures have been on the dyno. On the street, there is no traction which is very little load.

You make a good point about drivers age, and I gracefully shift very quickly, vs slamming it in. I also roll on the throttle vs mash it as hard as I can kick.

I can tell you this. In 5th gear, the torque of the engine at 70mph when applying gas (ie to pass someone), will throw it out of gear. The gearbox was near perfect before the 20b install, and this only occurs in 5th gear under boost/load.

 

It seems as if your mind was already made up with what to do. Personally, I dont think the FDs stock box is all that precise. Why not just use it until you break it, then you can make the decision whether to switch.

 

I agree I hate the Stock FD box compared to other higher end cars Ive driven. I actually think its the least precise to third gear because of the driveline twist. Although the driveline was engineered to twist under stock loads to transfer torque, extra load over twists it makes it hard to find 3rd under high rpms/boost.

 

Thank ya'.

 

That's a motor mount/ppf issue not a transmission problem.

 

If it was I wouldn't waste everybody’s time with this thread. Before I put ANY thought into it I was planning on using the stock box.

After getting additional information, some of which I posted above, I concluded that an upgrade was in order. That conclusion has held for several months.

However, after digging a little deeper and discovering that many of the people that have had the stock boxes fail are using them in a way that I can't see myself doing, I'm starting to re-examine my decision. For that reason I have spent a lot of time searching the forum and pming people (thanks red-RX7) to find examples of the stock box failing in gear, rather than being power shifted.

Since I couldn't find much info I decided to post this thread with the hope of soliciting everybody to post their good and bad experiences so I could then make a more informed decision. As I said in my original post "Based on the above I'd like to see how many of you, going on something more than a simple 'gut' feeling -ie experience, stories, ect think I should use the T56." You seem to be very opinionated about this subject. I assume you did read my first post and therefore base your opinion on something more than a 'gut' feeling. However, to this point that is all you've shared with me. It would be very helpful to me if you would give me some facts or your experience to work with.

As to why I don't start with the stock box and upgrade if needed: It is something I am now considering. However, because transmissions vary in length and shifter position I would like to make a choice before I cut the firewall and move the motor back rather than doing it after and having to pay for re-fabrication to get a setup that isn't flawed.

 

I'm planning to use stock tranny. I've talked to few and tranny brace and diff brace will help with twisting and help from breaking. I don't know how true that is, hence I have 4 trannies..
So, are you thinking about cutting the firewall??

 

Why not try a beafed up S2000 tranny? I've always heard how great the shifter was on those. I don't know if it would fit though.

 

Had the same dilemma. Ended up going with a new cryo treated stock box. Hope to get a few years in without problems. Just my 2 cents.

 

I didn't know about Ed Taylor's car. I would have to agree with Cam. I think that applies to a lot of RX-7 durability issues.

The suggestion about having a stock box cryo'd sounds like a good compromise.

 

I agree.

 

How about a Supra tranny adapted to the FD's bellhousing. CLR Motorsports has just such a setup.

 

I run a T56 in my LS1FC and it feels rather truck-like in shifting compared to a stock S2000 gearbox... I dunno about stockFD, never driven one.
The T56 probably feels clunky/heavy because the T56 has biggie-sized internals to handle the LS1's low end torque.

I dunno how it will cost you $3000 to run a T56 but zero money to run stock.
-if you run a T56 you can sell off all of your stock parts for what, $1000?
-if you run the stock tranny, youre gonna at least open it up and replace anything thats on its way out, RIGHT?!
-if you run T56 and have the money to go for the best version, you should look for a Viper tranny, they are as bulletproof as they come, but you could also beef up a normal chevy T56 with some off-the-shelf parts to beef it up.