What HP level requires transmission upgrades?, I have 200 HP to the wheels, what do I need? Options

[FourBlades]

I realize it is probably torque that kills a transmission, but I don't know the torque output of my engine.

I am building a 901 transmission for my IMSA 914 and wonder what upgrades it will need. I have some possible upgrades I could do now.

First, I have a set of 930 stub axles, CVs and the corresponding sway-away axles for a 914. They are stronger and the CVs are available for $80 from pelican. Downside is I have to destroy the existing rear bearings in my axles to use them, which were rebuilt by PMB.

If I have 200 HP to the wheels are the 930 CVs a necessary or worthwhile upgrade?

Second, should I upgrade to the billet intermediate plate at this HP level?

If I do, will I have to reset the pinion depth? That is something I can't do myself and would need to find a shop here in Florida that can do it. I know this is overkill for a typical 914, but with 12 inch rear tires and a 2.5L six, is this when the upgrade is worth while?

I am not adverse to starting with the 914 axles and upgrading down the road. Pulling the engine and transmission is not that time consuming. I would hate to break the smaller axles or CVs the first time at the track though.

I have a stock gearset and know there are probably better gear choices for Sebring, Daytona, etc. No idea where to start with those.

I will be running a transmission cooler to start and may move to gear set spray bar over time. I have read that the mesh point of the gears is where to aim the cool oil sprays, not sure this is correct.

I appreciate any advice people have.

John

[FourBlades]

Thanks Steve, this is really a big help!

I have not picked a wheel and tire combination yet, so I will hold off on picking new gears. I imagine some of these gear sets are rare and expensive.

John

[wndsrfr]

I'm at 215rwhp and run about 10 events per year on the 901's. Yes, driver error adds to transmission becoming a "consumable" like tires. I'm using two trannys now, one is AFMSX for short tracks like Roebling and Summit Point and the other is AFNSZA for VIR, Daytona, Sebring, Watkins Glen. I'm on 24 inch diameter rear tires. There's a really neat worksheet here:
http://www.914world.com/specs/regearing_901.php
--it's an excel spreadsheet that you can experiment with to choose tire diameter & gearing.
I pull the magnetic drain plug after each event & usually find a halo of "hair". ON occasion there will be a chip or sliver from driver clumsiness. I've found that one box or the other needs medical attention maybe once a year. In my opinion, get two trans's--keep one stock gearing and set the other with AFNS for 1-4th and find a ZA for 5th or just use a flipped N for 5th as a Z to start with. As you gain experience you'll likely try different combo's.
Not a "real" expert but I think if you replace intermediate plate then you'll need to set R/P depth again...

[stownsen914]

My racecar has ~260 hp and has run a 901 for years. It's generally held up well. After 80 hours, I did lose a couple gears, so time for a rebuild. Stock 914 CVs were replaced a few track hours ago - they held up pretty well.

[Justinp71]

My racecar has ~260 hp and has run a 901 for years. It's generally held up well. After 80 hours, I did lose a couple gears, so time for a rebuild. Stock 914 CVs were replaced a few track hours ago - they held up pretty well.

Stock 914 cvs and axles are holding up well on the track with 260hp???