ITS/E Production SCCA RX-7

In reply to dannyp84 :

IIRC the qualifying rule is 120% of the fastest qualifier for the event, not the lap record. Also, that can be waived by the race director or SOM.

You can absolutely get a tin top FC to minimum weight!

In reply to jgrewe :

The EP minimum listed on the side of my car by the previous owner says 2363, so I wonder if it was given a percentage weight penalty due to some modification he didn't mention to me. I know some guys did Miata gearsets in the FC transmission case. I also have a 5.12 diff, but if I understand the rulebook correctly, there's no penalty for that.

dannyp84 said:

In reply to sevenracer :

I'm going to check via corner scales this weekend, but based on what the logbook says, minus the weight difference between me and the previous owner, and minus the 50 lbs of ballast I just took out of the passenger floor, I should be at 2533 roughly. My rulebook says my minimum weight for EP is 2170 or thereabouts. I probably don't have time to source a lexan hatch, but I could pull one of the headlights and throw in my lithium battery from my street car, it weighs 4 lbs vs whatever the big optima currently in the car weighs. 
I'm trying not to worry too much, though, I need to qualify within 115% of the lap record at Mid Ohio, which is 1:36, so I need to do a 1:50. I already did a 1:48 on club course which is longer, and that was my first time ever driving the car. So I'm cautiously optimistic.

According to the supps, the "club course" will be used for the entire weekend.  

In reply to grafmiata :

Ah you're right, good catch. Will you be there racing as well?

In reply to dannyp84 :

I'll be there crewing on my buddy's GT-3 rotary Miata, and Alliance Autosport may have 1 or 2 GT-2 cars enter, so I'll be helping on those as well.

In reply to grafmiata :

I'll keep an eye out for the rotary Miata and say hello, sounds like a cool car.

Definitely stop by!  Not sure where we'll be paddocked yet.  There are actually 2 rotary Miatas entered. This is ours ---

In reply to grafmiata :

Love the side exit exhaust, also those wheels are wild looking.

In reply to dannyp84 :

The wheels are just typical "wide-5" stock-car type stuff, but they work.

So last week I rebuilt one of the rear calipers after accidentally pushing it out too far with the caliper unbolted from the rotor. I also went through the wheel bearings to make sure everything felt tight and smooth, which required replacing the rears. This weekend I have lots to do once my parts arrive. Replace rear pads and rotors, bleed the brakes with new fluid because the old stuff looks kinda gross, new plug wires, find an old socket to shave down so I can actually pull the spark plugs and see how they look - I guess the plugs used for racing are a larger socket size and they barely fit in the recess of the housing, a regular socket won't slide into place. I didn't realize the white panels behind my race numbers were separate of the numbers themselves, so I need to stop at the local vinyl shop and grab some white backgrounds. My fire suppression system is just a fire bottle mounted on the passenger floor, so if I understand the rule book I need to run nozzles to the engine bay and the cabin, I'm not sure how that passed tech in 2022, but it seems that certain car classes just require the bottle to be present. I've also got some Hoosier R7s on the way, I talked to someone at Hoosier who verified that the S75 slicks I ran at the track day last year are now almost 8 years old.

If possible, once I get everything on the car sorted, it'd be nice to find a track day before the race weekend, so that I don't have to blow my practice session just bedding in new brake pads. I went out to Mid Ohio last Sunday to watch my friend Logan beat his old personal record in time trial, and being back at the track had me jittery to get back out there. The racing off season here in the rust belt is just too long.

In reply to grafmiata :

Nice to meet you at the track!

Had a roller coaster weekend for my first couple of races with the car. I managed to get rain tires last minute for the Friday practice, but I could tell my rear toe angle got knocked out of alignment because the car was doing really spooky stuff on the back straight on a wet track. Borrowed some toe plates that night and got it as close as I could and managed to qualify Saturday morning. Then on the pace lap of the Saturday afternoon race, I had an electrical issue that wiped out my dash, wideband and cooling fan. I did one green flag lap before returning to the pit for a DNF. Many hours later with the help of some fellow racers who were complete strangers a few days before, I found the source of the electrical short, a loose cool suit switch wire that shared a distribution block with a bunch of other components. I pulled the fuse for the cool suit and kept my fingers crossed before the Sunday race.

At the beginning of the weekend we had 5 cars in EP, but by Sunday two had dropped out. I didn't have nearly the pace of the front-running pair of Datsuns, but one spun out halfway through the race, so I went from 25th overall to 13th, and ended up on the podium in 2nd. I also beat my old personal best lap by about 2.6 seconds, and had a great battle in the last half of the race with an FP CRX. Wild weekend, if I ever figure out where the race photos got posted I'll upload a few.

In reply to dannyp84 :

Ah the joys of aged race car wiring! Glad you got it sorted enough to race on Sunday. Always fun to work your way up through the field.

Here's my dash of my FC at the Runoff's last fall. Wound up being a loose connection, but it took a good long while to find it:

In reply to sevenracer :

Mercy that's a lot of wiring. We have the same pedals btw.

Not too sure where to look for event coverage photos since I'm not on FB, but so far I found this and one other. Going to give the car a once over this weekend to determine whether I race Nelson Ledges at the end of the month. 

A bit late in updating this, but I made it to the Nelson Ledges divisional race at the end of June, though my schedule would only allow for the Saturday race, which took place right after the sky unloaded buckets of rain on us.. I was the only ITS car in my race group, but I managed 2nd overall, and had a pretty exciting battle with the STL FC RX7 driver who finished third. Halfway through the race though, the entire car was shuddering anytime I went to 5th gear, so I pulled the transmission once I got home. There was metal beyond just some synchro brass flake in the fluid, so I'm going to fit one of my spare transmissions, and look for someone to rebuild the original. 
I'm deciding between Pitt Race (close to home) and Waterford Hills (looks like fun and cheaper entry) toward the end of this month, and I'll have a couple of opportunities to race Mid Ohio and Nelson again before the end of the season. I'm having a brilliant time with the on-track battles, and meeting some genuinely great people in the paddock.

I'm going to say your tail shaft bushing has been hogged out. Running the 5.12 you can get to some pretty crazy driveshaft speeds.

I had a friend that had that happen at Daytona. The trans eventually spit enough oil out the rear seal that it wouldn't shift. He spun it at the kink in the infield when he couldn't load the tires properly. All the oil that was flung around by the driveshaft quickly ignited on the exhaust, ended up doing about $10K damage to the car.

Shuddering in 5th can be the tailshaft bushing (which also can take out the driveshaft yoke) or it can be excessive endplay on the mainshaft, which happens mainly due to two reasons: wear of the end play spacer retainer C clips, and the bolts that hold the main bearing retainer like to back off.

Usually all three.

My smoothcase rebuild adventure starts on this page.

This transmission is currently in my '81 and I can report that it is entirely shudder free in 5th.  Before the rebuild it would develop a nasty shudder under coast/cruise that would only go away with some acceleration to reset things.

I should mention that actual chunks of metal came out of the transmission when I loosened up the bolts that connect bellhousing, gearbox and tailshaft, but that's interesting about the tailshaft bushing. This transmission also had some pretty bad grinding in certain gears. Are you guys referring to the rubber bushing on a crossmember support roughly underneath where the shifter is located?

In reply to dannyp84 :

No, inside the case there is a bronze bushing that the driveshaft slip joint rides in.

Chunks could be the detent springs in the synchro barrels. Last I was building one Jesse Prather had some good springs to solve the little tab breaking off. Without the tab, they can rotate and let a piece that I can't remember the name of get tilted in its slot.

It's the brass/bronze bushing in the tailhousing that the driveshaft yoke spins in.

If you had metallic gear oil, for certain the bushing is trashed. Metallic oil destroys the bushing.  Usually the driveshaft yoke, too.

Every time I would break a gear in the trans, the metal in the oil would destroy the bushing and the driveshaft.  Now's a good time to upgrade to a repairable driveshaft so you can replace just the yoke the next time this happens.  One can't just pick up a used Mazda driveshaft for $50 anymore, need to plan forward.

I'm curious what Pete used for fluid, but racing we had great success with idemitsu.  That's what mazdatrix used on their rx7 trans.

We went from rebuilding every 2nd or 3rd endurance race to once every 3 years (12 to 16 races). It worked so well for us, tht we basically just used our spare junkyard transmissions and put the fluid in and ran for a few years.

No overheating.  No shifting issues.  No issues whatsoever after changing to the idemitsu.

Good luck! 

Whatever was cheapest per gallon, usually Coastal. Played with Shockproof to no real advantage.

I was killing them from shock stress, not endurance heat.  Different failure modes.

Has anyone bothered building a heat shield between the header and the transmission to protect it from exhaust heat ? I grabbed some heat shield material out of the exhaust tunnel of a fwd junkyard car to see if it makes any difference.

dannyp84 said:

Has anyone bothered building a heat shield between the header and the transmission to protect it from exhaust heat ? I grabbed some heat shield material out of the exhaust tunnel of a fwd junkyard car to see if it makes any difference.

It certainly can't hurt. Flyin Miata offers this to accomplish similar

 https://flyinmiata.com/products/dei-titanium-heat-shield

I'm probably going to do something similar alongside the transmission and differential. I already did this to the transmission tunnel 

In reply to RX8racer :

The heat shield is a very good idea to protect from the red/orange glowing exhaust running right next to the trans!

I always fantasized about running a small pump to take fluid from the drain plug (it's 18x1.5mm like a lot of things) run it through a small cooler and then reinject it to a manifold that sprayed it onto the gears and most importantly at the trough that runs fluid to the rear bushing.

When Mazda raced these in IMSA they had a setup that replaced the bushing with a roller bearing.  It required that you build up the tailhousing with weld, bore it to a larger diameter, and use a special hardened yoke.  This is beyond most of our abilities and requires NLA parts, so we have to improvise.