I have been mulling over the idea of running straight cut gears in a 901 or G50 when I swap in the STi engine. Was wondering if any of you have run or are currently straight cut gears in a teener. I kinda like the sound and the extra strength. I'm not too worried about excessive noise since the setup I'm running will be loud exhaust, loud turbo and VERY loud blow-off valve.

What are past experiences and opinions (with reason as to why you feel that way)?

I've searched but have not found what I'm looking for. So if this has already been discussed then please just point me in the proper direction.

I don't know that staight cut gears exist for a 901. I've never seen them in my research.

nor have I....

you make em, im sure you could sell some...

oh but wait...

there are like 30 ratio's available for a 901.... you gonna make 30 straight cut gearsets???

i think they exist for 915's... i think...

try powerhaus II... or weddle

been reading SuperSport or any of those other "tuner" mags???

1st off, do they exist for our gearboxes??

If so, have you priced them?...I'm guessing they'd be in the $5K - $10K range easily..

They are aviable for the subys I'm pretty sure so it would be a no brainer just to use that transmission....

I don't think its going to be the actual gear that fails on your tranny anyways

Fo what you would pay for the privilege of square cut's I believe you could have

a 915.

All of the Hewland and MK5 gear sets are based on the same pinion and input shaft spacing as our 914/901 boxes.

Our tranny is a glorified VW box.

Can he do it? Yes. Will it take some potential special parts? Yes.

Benefit on the street? None.

Benefit for racing? Lift throttle clutchless upshift (or full throttle depending on how often you want to replace the gears) or ignition interupt upshift.


B

HELL NO! Just been doing some reading on circuit cars.



Don't know but my cousin knows someone that could make them for me.

I am however leaning towards the G50.




Neither do I.




If I do this it'll be a weekend warrior/SCCA circuit car at that point. So I'm not looking for benefit on the street. Only on the track.

And this is just a thought. I may or may not actually do it.

And you've gotta admit. Clutchless upshift would be pretty cool.

Now if only there were a way to run a sequential trans... for a semi-reasonable price.

mendiola is coming out with a monster mid engine box... i think you can get straight cuts and sequential or dogless boxes...

All it takes is Cubic dollars, just like everything else fast related.

BJH

John,

gears aren't that easy to make
they are hardened too.

there is a reason that 901 reproduction gears are selling for 500-700 a piece now.

lots of ways to spend money with more returns on a 914 than this

the G50 is going to be a bunch of weight... use the least/smallest/lightest box that your powertrail will allow.

brant

I'll want a setup that'll support 500 horse.

I'm not too worried about the straight cut gears, I just thought it was a cool idea.

My setup will start just over stock at about 320 at the crank or so. And when I decide I want more, which most of us always do, it'll be bumped up to the 475+ area.

You will never use the G50s strength plus it is a very large tranny and twice as heavy as your 901. There is no reason to go to straight cut gears on the street. It will be noisy as hell. It would be cool for about 30min. After that you will pull the box out and put it in the corner.

You will be so outclassed in what ever SCCA class you can run your car in. I would focus more on suspension and brakes. If you want to go to a more modern tranny look for a Boxster tranny or the Subie tranny.

Won't be much of a street car at that point.



Never said I had to win. I'd just enjoy the race. I used to stoplight race my bug against cars that I stood absolutely no chance against; like a GT2 and a 360 Modena. Knowing I wouldn't win didn't make it any less fun.

Them roler bearings in the brass housing is what goes quickly first if I'm not mistaking. Can't we upgrade that component at least and weld the case up like they do for VW tranys?

Why not use the Suby tranny? Am I missing something here? not sure why anyone would use a 30yo tranny behind a Suby engine.


B

There won't be a race. There will be you riding around a race track getting passed by most of the other guys in SPO. Which is an unlimited class.

You will be competing against 700-900hp fully prepped cars with what is vitually a street car. You will spend the whole race looking in your rearview mirror.

Why not use the Subaru gearbox. It is a much better design than the shitty old 901.

The first rule about racing has always been and will always be to read the rule book first.

then build the car that fits into that rule book.

otherwise you are not really a racer.. you are a hobbyist that likes to drive around in circles non-competetively. Racing is about being competetive and trying to win.

I find great joy and accomplishment out of trying to use rules to my advantage and challenge about trying to remain honest and stay within them. In my opinion, that is a huge percent of what racing is really about. Trying to out think, out fabricate, and also out drive the next guy.

Thats racing.. otherwise its just a car hobby.

I'm not trying to unload or be rude. This is bigger than just you and your plans. I have this feeling often with other guys on this club and wish that they could see why I push them and how much they would enjoy it if they had that insight.

brant

Many appologies oh great one. Would you rather I take the alternative and blast around the county roads?




Why waste the extra money on the Subaru gearbox when, as you said above, I'm going to be looking in my rearview the entire time anyway?

That'd basically be me. I just wanna push my car without being arrested and having my it impounded. However, I've yet to find any decent time trial opportunities in the local area. Honestly, if I could shut down some back roads, some nice curvy stretches heading up into the mountains over here, I would rather do that. Unfortunately, that's not an option.



No offense taken. I completely understand where you're coming from.

because with the Suby box you'd end up in a different class, where you'd be less of a moving chicane

OK.. I dont care where he is going to run or with who.

Somebody explain to me why people are not using the Suby box in a 914?

Use the output for the rear diff to drive a prop or something (JK)

This would eliminate adapters/special clutch.. blah blah..



B

they (the suby guys) are working on it...

rear drive block off.. and CV adapters/output flanges to work with 914/911 cv's

I don't know you but asking about square cut's leads me to believe that you

are looking for an advantage. A winner also wants an advantage, even an

unfair advantage. You may be happy with second best for a little while but

eventualy you will want to win. IMHO.

Would the Subaru engine not change his class? Is it the same displacement?

We use quick change Sprint Car straight cut gear, rear ends in the sand toys we fabricate. VERY LOUD AT SPEED!!!!!!!!!!!!!!!!

Dan

Hey B, looks like a good time for me to learn something. How does a tranny with constantly meshed gears (our 901) shift different with straight gears (clutchless upshift)?

Also, why would the straight cut gears be considered stronger as mentioned above? The curved gears have more surface area for strength and load/stress dispersion, I would think.

I guess this is sort of a thread hi-jack, but the suby swap has so much potential.

I also do not understand why people are not using the suby trans. I saw the thread about the Aussie block off plate. That seems like a plan. Couldn't you just leave the shaft haning out the back? Like Brad said "drive a prop or something". What are the specific issues? How complicated is the block off plate?

Why make adapter plates to use Porsche CV's on the tranny side? Seems like what's his face (I can't remember the vendor) who will custom make hollow axles could spline some for you Porsche on one end (944 turbo would be a good pick) and suby on the other. I looked into hollow axles a while ago and I recall the price for a set of axles was like $400. Depending on the cost of suby CV's vs Porsche CV's might come out the same $$ as adapter flanges and be lighter.


Kelly

the benifit of helical gears is they are quiet. the drawback is, part of the force is trying to shove the gear off its axis causing stress and wasted effort as the driven gear is forced against a thrust bearing. recall your trig.

Quick clarification... shifting has NOTHING to do with the gears being straight or helical cut. Shifting is determined by the engagement style. Synchro, standard clutched shifting; and Dog, clutchless upshifting and heel-toe downshifting.
Gearsets for a Sooby run in the $4k-$7k range depending on cut and engagement from PPG. the box itself can be had for a few hundred.

Not so much an advantage as just looking for better performance. The better my car performs, the more I enjoy driving it.




Actually due to the straight angle of the straight cut gears they have more surface area in contact at any given point than a helical setup will. Making it less likely to fail under the force. On a helical setup the contact patch rolls across the tooth rather than being in complete contact the whole time. Which makes it have a smaller contact surface area.

suby engine and box in mid engined config


coverplate


check: http://64.82.22.49/default.asp

Thanks for the info guys. I knew the straight cut gears had no difference on shifting (I have only rebuilt over 100 trannies ) I was just wondering if I missed something. That was a few good explanations of why helical and straight differ in action. Thanks.