710 race car

[troyt]

Well, I sold the Race Wagon last year to fund the purchase of a Crossle Formula Ford. And while I'm enjoying the challenges of open-wheel racing, I do miss racing Datsuns with my B-Sedan buddies. So after owning and racing a Roadster, a 240Z, and a 510 Wagon, I thought it was time to continue my twisted little saga and go racing in a 710.

This 710 race car was originally owned and built by James Cole of Napa, CA back in the mid-80s. He raced it in SFR-SCCA GT-3 for a few years, then it sat for over twenty years. It was then rescued and rebuilt by Ermish Racing six years ago and sold to another NorCal racer, whom I recently purchased it from. It is a 1974 model, runnng a race-prepped L20b, a 280ZX trans (soon to get a CR 5-speed left over from the wagon), 13x7 Panasports, coil-over front with Wilwood calipers, and a live axle LSD rear with 510 drums.

It wasn't running when I bought it, but I worked on it for a few days and took it racing at Buttonwillow Raceway last weekend (a bit prematurely as it turned out). I replaced the head gasket and gave it a tune, but didn't expect the clutch and ignition problems that bedeviled me all wknd. Turned out to be a loose pressure plate (!) and a bad rev chip in the MSD. But after much midnight oil being burnt at the track, we finally got in a few fast laps on Sunday afternoon.

Many more stories to follow as we get the bugs worked out and start having some fun with this cool little race car.

 

 

 

 

[bonvo]

i saw this car in person at ermish's shop its a nice car man sad to hear you sold the goon though

[Bentaxlebob]

Excellent purchase.

[Eagle_Adam]

Need so many more pics !!

[Dats Crazy]

Very nice. I like!

[opalbeetle]

This is excellent. 710s crawling out of the woodwork everywhere. Beautiful car!

[troyt]

The Wagon went to a good home, and I'll probably even get to drive it on occasion as we share a pit most race weekends ;-)

I'm gonna leave the old 80's paint on the 710 for now, the patina is kinda cool. Got a few other things to worry about for now anyways.

More pictures as she gets more track time.

[Dirty Evo]

Yes, the 710 is pretty bitchin.  Great patina, i felt honored to be camped accross from it at the track.. have it showing up in the background of the family photos!

[troyt]

Ya know Dirty, this is a DATSUN forum right? Should I list my scooters too ;-)

Oh, by the way, your 510 Wagon is pretty bitchin too...

[izzo]

for the love of all things datsun, never paint that thing. its only original once.  Keep it like that! change the wheels, change the seat, hell change the oil.. but leave that paint alone!

[troyt]

Well I'm getting ready for the Portland Historics featuring Datsun, so I polished the paint today, it went from flat to matte, so maybe I'll leave it after all :thumbup:

Also rebuilt the rear brakes, changed a leaky axle seal, installed new brake master cylinders, switched from Weber 50s to Mikuni 44s, etc, etc.

[troyt]

I'm hunting for a 4.11 gear set for this car, a h165b type 1, they came in early 710 automatics. I've got a 4.62 and a 4.88 I'd trade if I had to. I'd take a R&P set, a diff, a reared, whatever, as long as it's a 4.11. My race car is currently set up with a 4.88 and a ZX 5 speed, but that isn't very optimal at all. I've got a .90 OD CR 5 speed I want to use, but need a 4.11 or 4.38 to make that work.

Thanks for any leads, new, used, OE, NOS, whatever...

[]2eDeYe]

Wow great looking car! Good to hear that the wagon will stay on the track as well. :thumbup:

[datzenmike]

'74 with L18 automatics had the 4.11. I have one in mine.

[troyt]

Thanks Mike, thats what Im looking for. If you know of one available, let me know. So far junkyards and parts guys are empty, the only one Ive found so far is with Pitroad in Japan..

[datzenmike]

I'm thinking of swapping my 3.90 (L20B) for my sedan's 4.11 for a bit more oomph.

 

A 4.375 would be killer with a 280zx close ratio box.  'Fraid a 4.624 is a bit much

[troyt]

Long time since an update, so here goes. The 710 needed quite a bit of work to get to my picky standards but it's coming along (plenty of info, pics, videos on my blog). I ended up buying a 4.11 and 4.38 R&P set from Pitroad in Japan. Money transfer to Japan was a bit of a pain but the deal finally went through. I installed the 4.38 in my h165 LSD, it pairs up great with my close-ratio 5-speed. I have another LSD I want to mount the 4.11 in but it has some broken parts so I gotta find another LSD (maybe a broken one) to finish up my Fontana diff. I now have a 4.62 and 4.88 R&P set and a welded diff in case anybody is going racing with a stock 5-speed. I've rebuilt the car's brakes, rebuilt/revalved the rear shocks, installed a new digital MSD, installed a Mallory distributor left over from the Wagon, and continue to fine tune things on the track.

I'm planning on getting the 710 out again for VARA's season finale at Willow Springs Raceway the first weekend of November.

[datzenmike]

Ahh, I just recently swapped in a 4.11 into my '76 L20B 710. The stock one is 3.70 so a 4.11 is a blast to drive.

[troyt]

About 10% better ;-) Suprising what a difference such a small change can make.

[datzenmike]

11.08% better. :lol:

 

I notice first gear is way shorter and the tach rips toward 6k!!! The 3.70 was a long long wait from 4 to 5k and it really wasn't accelerating much just screaming so I would shift it. Now it gets there so fast it caught me by surprise. I love it!

 

The plan is a zx 5 speed. This will reduce the over all first gear from 11% down by 8.4% (over all I still have a 2.6% increase) but the gears are closer together and the 25.% overdrive will eliminate the 4.11s in 5th gear only. Highway mileage should be the same as when I had the 3.70 diff but all other gears are lower.

[troyt]

Great choice, I tell everyone who will listen to use a ZX five speed for street cars. Close ratio 1st-4th for the streets, big OD fifth for the freeway, and plenty sturdy. I've used them in a couple race cars when I was just planning on using 4th as a top gear, worked fine.

[datzenmike]

The gears are closer together but this moves first closer to forth and harder to roll from a start. (not at all impossible... just slightly more work) Not so bad when 'racing' as you don't stop much, and you might actually be able to use first in a slow corner. For the street (and racing?) going to 4.11s or 4.375 or higher makes a lot of sense.

 

Most 71B 5 speeds are the 'mid ratio' with a 3.321 first which works well for stop and go and mileage on the highway. The later 'close ratio' zx 71B is a 3.062 first which is an 8.4% drop in RPMs... and yes the zx over drive is twice as high at 25.5% than the mid ratio 12%. 

 

I have a 3.321 first gear in my 710 and plan to swap a zx close ration 3.062 in maybe in the spring. In preparation for this I recently swapped in a 4.11 differential which lowers everything11%. My thinking is that I have basically removed the 5th over drive, and 5th will be revving at about where the old 4th gear was. The zx box will 'get back' 8% of the 11% in one through fourth gears. The 25.5% over drive will now work out to around the old mid ratio's 12%. Lower 1-4, closer ratio, but keep the 5th over drive about the same. 

[troyt]

The 710 had taken a back seat for the past year as I've been racing my Formula Ford. So it was time to finish it up for the "All Datsun" race with VARA in Pahrump, NV last wknd. I got it repainted last month, a fresh motor in last week, new seat in and brackets fabbed up, burned up some money and a lotta late nights. It was a great event with both Peter Brock (in photo below with me) and John Morton joining us for the event. The 710 ran great Friday and Saturday until I broke the teeth off the pinion shaft during Saturday's Qualifying race while I was running in third. Ah well, that's racing...

[docbainey]

Cool! What tire/wheel package you runing?

[INDY510]

What are you doing for rear leaf springs? Any shock mounting point mods? Is the LSD axle still a H-165? I want my 710 Coupe to handle more like a 510