Need a taller 2nd gear? Options

[GaroldShaffer]

So this year I am taking my AXing more serious and really trying to be more competitive. I run my 914 in DSP. It's a 70 with a 73 2.0L and side shift trans. Of course I have suspension mods and such, but motor is stock FI and trans is stock also.

I started last year running in divisonal SCCA AX along with my local region. While I do ok in the divisonal series, my region is a very small pond and I am the only DSP car. My goal is to keep pace with the STU & STX guys along with CSP & FSP. I hold my own on tight courses, but the more HP friendly course I run out of 2nd gear and bounce off the rev limiter. I know, shift too 3rd gear, but in some cases the by the time I would shift to 3rd I would need to down shift back to 2nd.

It seems to me I need a taller 2nd gear, yes? I need to read up on the DSP rules to see what I can do to the trans. This is still a street car and will stay that way so I would like to find the best of both worlds (street & AX).

Any thoughts?

[J P Stein]

There aren't many options short of the 904 mainshaft. That puppy will give you all you would want in 2nd gear....H thru I.$$$$$
The standard 914/6 second is GA which improves thngs somewhat.
IIDC, RacerChris can weld up what you want tho I don't know exactly what ratios he offers.
It takes a fairly stout motor to pull a higher 2nd all the way thru a run on a course with tight turns.
You may be better off with a flipped ZD for 3rd. That would add another approx 20 mph over your stock F 2nd and it's an easy up/down shift.

[jjackson]

There aren't many options short of the 904 mainshaft. That puppy will give you all you would want in 2nd gear....H thru I.$$$$$
The standard 914/6 second is GA which improves thngs somewhat.
IIDC, RacerChris can weld up what you want tho I don't know exactly what ratios he offers.
It takes a fairly stout motor to pull a higher 2nd all the way thru a run on a course with tight turns.
You may be better off with a flipped ZD for 3rd. That would add another approx 20 mph over your stock F 2nd and it's an easy up/down shift.

We ran a ring and pinion out of a sportomatic for most of one season.Did not last.Have to cut splines further up shaft for it to work.Currently run B 1st and HA 3rd.Our torque lets us stay in third once we get there.
Tire choice is critical to the equation.In our experience, 68 to 70 MPH is necessary for National level courses.
You are going to need a lot of torque to limit your shifts.
JJackson

[GaroldShaffer]

Thanks for the input guys. I think I will try the flipped 3rd gear. I have an extra sideshift trans that needs going through anyway and I see the good doctor is selling gears in the classified section. (IMG:style_emoticons/default/idea.gif)

[Chris Pincetich]

I like the flipped ZD in 3rd for AX. I have had it for 2 yrs, 6 AX races.
It won't solve your original problem, but it will provide a satisfying experience when you shift to 3rd at 5k rpms, and instead of a delay for power, you are right in the sweet-spot. It's always a crap shoot to shift vs. not when any small error outweighs the gains.
Good luck (IMG:style_emoticons/default/beerchug.gif)

[bam914]

Anything but stock gear ratios in DSP is not allowed. You can try a taller tire.

[GaroldShaffer]

Anything but stock gear ratios in DSP is not allowed. You can try a taller tire.

(IMG:style_emoticons/default/dry.gif) Yep just read that today in the GCR.

[campbellcj]

I don't autox but have an A-GA-Ka-Q-V box since my car is set up for short/technical tracks. With a high-revving six this works well and rough max speeds at redline are 40, 70, 90, 110, 130. I typically shift a bit lower than that unless I'd be upshifting too close to the next turn, then I hold the gear and avoid the rapid upshift/downshift.

[neilca]

I run club racing and have A,I,N,S X box. A machine shop in Atlanta grinds off the old gear and replaces it with whatever you want. I really need to move to a N second gear for Road Atlanta. The I just isn't high enough. Be sure to have the gear and shaft heat treated or you will get an early failure.

[ottox914]

Anything but stock gear ratios in DSP is not allowed. You can try a taller tire.

I'm planning a flipped 3rd for my next box- but with the turbo I'm a spork at a gun fight in ssm.

Wonder if you swapped 3rd for 5th, and 5th for 3rd, and kept all the same "ratios", just not in the same "places". You'd probably get protested, but you'd have to do some winning and make a few folks nervous first...

[stownsen914]

I run club racing and have A,I,N,S X box. A machine shop in Atlanta grinds off the old gear and replaces it with whatever you want. I really need to move to a N second gear for Road Atlanta. The I just isn't high enough.

I know a guy who used to run SCCA GT2 in a 914/6, and he ran a J first gear at Road Atlanta. Talk about tall ...

Be sure to have the gear and shaft heat treated or you will get an early failure.

Neil - A couple years ago I tried to get some information about this when I was having a new welded up mainshaft made. Never found what I needed, so I'm running un-heat treated. Are there any "specs" you can share? Thanks in advance.

Scott

[neilca]

Scott,

My buddy Cliff Faull was having problems shearing second gear teeth. He would usually get about a season before it happened. I did not want this problem so I asked him for one of his damaged shafts. I took it to a local college that had hadness testers. I found the gear teeth were about RC 22 when the shaft was about RC55. Apparently, The machine shop was letting the shaft and gear air cool after welding.

I found a heat treater in downtown Atlanta that for $125 would heat treat up to 10 shafts. Cliff had 3 and I had one. They batched processed them and we have not had a failue yet. That was 5 years ago.

Cliff runs an M for second. I have an I and it is too low. I think my next shaft will be an N second since I use that in third now and like it.

[jpnovak]

Neil,

What does the rest of your stack look like? That is a tall second.

I currently have an AGaJOU box in my 911. Love the spacing but want more top-end. it was built for MSR here in TX where the front straight is not very long.

I think an F first followed by an IOU and then a reasonable 5th that would max out at 140 or so would be ideal.

[neilca]

My stack is A I N S X. At 7500 I get 139 MPH. I am running 23.5 diameter slicks.

[stownsen914]

Neil,

What does the rest of your stack look like? That is a tall second.

I currently have an AGaJOU box in my 911. Love the spacing but want more top-end. it was built for MSR here in TX where the front straight is not very long.

I think an F first followed by an IOU and then a reasonable 5th that would max out at 140 or so would be ideal.

Depends on the track ... at Lime Rock and Watkins Glen, for example, an I second with 23.5 tires and 7500 RPM gives about 80 mph. That's slightly short for the tracks mentioned above. I run a "KA" second (ZA 5th flipped and welded to the mainshaft), and run 25.5" tires. It gives around 95 mph at 7500, and is just about perfect for the slowest turns at LRP and WG.

For reference, I have GA (also welded up, made from a GA mainshaft), KA, P (flipped X in 3rd gear position), S, U in my box.

Scott

[stownsen914]

I took it to a local college that had hadness testers. I found the gear teeth were about RC 22 when the shaft was about RC55. Apparently, The machine shop was letting the shaft and gear air cool after welding.

I found a heat treater in downtown Atlanta that for $125 would heat treat up to 10 shafts. Cliff had 3 and I had one. They batched processed them and we have not had a failue yet. That was 5 years ago.

Thanks Neil - that's helpful. When you had the shafts heat treated, did you just tell the guy "treat them to RC55" or something like that? I'm not familiar with metallurgy terminology (IMG:style_emoticons/default/smile.gif)

[brant]

I think an F first followed by an IOU and then a reasonable 5th that would max out at 140 or so would be ideal.

I run an FJOSV and really really like it a lot
the spacing is ideal
you loose reverse gear though when you go to the F in 1st
some sanctioning bodies (I think SCCA) require a reverse gear

F is wide enough that you have to modify the tranny cover a bunch. Ours was bored out inside to make room and then actually bored through the cover. Then magnesium welds were laid onto the cover to close up the hole.

brant

[neilca]

I cannot remeber what I told him. I am sure he came up with the temperature, time and cooling method. It is a gear for a transmission I am sure most heat treaters know what to do. I did not know the alloy or the carbon content of the steel. Maybe I did tell him RC55? That was many beers ago.

[bam914]

I will be running AJNSX in my EP 914. I am a little worried about starts in it. I have thought about going up on 1st but since I am running a 7.25" clutch and a really peaky 2.0L 4 cyl. I am not sure I want to go really steep on 1st gear. Plus I have to have a rev.

[brant]

the small clutch does have some effect
we run a 5inch clutch with the F first gear and its finicky to get rolling
we have zero torque at low rpm with our 2.0/6 race motor-big cams