63 series 5 speeds confirm ratios and front case swap.

[Tom1200]

So in my quest to get around paying $3000 for stronger close ratio box for my A15 powered 1200 coupe I've been delving into various options.

 

The latest thing I noticed is the Z20 powered cars (HL510 & 200SX) 5 speeds have a 1.9 2nd gear (according to Datsun1200.com) but I noticed On Jason Grey's list this may not be so.

 

If the 63 series for the Z20 does have a 1.9 2nd gear does anyone know if all front case/bellhousings are interchangeable?

 

If so my plan would be to use the Z20 5 speed and swap cases with the B210 63 series case/bell, I have a 4.38 ring & pinion in the car as well as a 4.62 and I use very short 20.6 tall Hooiser tires so,the overdrive tranny isn't a big issue. 8000 rpms in 4th is 110 mph.

[flatcat19]

L and Z series 63A transmission will not work for your A.

 

 

The only common note they have is reverse over first and a 63mm bearing.

Cases will not swap directly.

[datzenmike]

Jason's list only shows the '77-'79 S10 200sx (L series). It doesn't list the A10 (HL510) at all with L or Z series engines.

 

The A series dogleg, the S10 dogleg and the optional A10 with L series engine all have the same gear ratios.

3.382

2.013 ... 40.5%

1.312 ... 34.8%

1.000 ... 23.8%

0.854 ... 14.6%

 

The '80-'82 A10 with Z20 engine gas the (slightly) closer gear set.... very subtle.

3.170

1.921 ... 39.4%

1.312 ... 31.7%

1.000 ... 23.8%

0.854 ... 14.6%

 

Yes the Z series front case can be swapped for the L series. You could also put an A series front case on them but I think the input shaft clutch spline count for the A series is different. You would have to swap that too. They all share the same adapter plate, tail housing, input and tapered counter bearings..

[Tom1200]

Mike there is a clutch disc that works. As for the percentages as odd as it seems that 1% is just enough to keep the motor above 4500 RPMs. My 56 series mid close box has the same ratio for 2nd gear.

 

Tom

[Stoffregen Motorsports]

Yes, there is a clutch disc that works, but I can't remember if it's a F10 or Sentra (E16) disc.

[datzenmike]

Well the front case has to come off to swap the guts anyway. Just change the input spline and you can run all your A series stuff.

[Tom1200]

Mike I've had the tranny out and apart enough over the last 12 months that it's a slam dunk.

 

Last October my 56 mid close 4 speed shredded 3rd in Friday practice (I was fastest overall, doh!) I then bought and installed a ultra close, it worked great but I didn't like how it operated as it had a slight bearing growl and the syncros didn't feel quite right, so I took it out to put new bearings in and changed 2nd & 3rd syncros. I've found that even though the syncros are within tolerances that once they wear more than about 20% they start working against you if rev matching the way I do. In the meantime I sent the damaged mid close cluster to Bettany gear in NZ to have it repaired and I will be putting that gearbox back together in the next month or so.

 

Pulling the gearbox on my car is a bit of a pain as the motor is pushed back 1 1/2" so the process involves undoing the motor mounts, lifting the engine and moving it forward (resting) on the original mounting location so you can get to the bellhousing bolts. I used to be able to swap trannys in under an hour with hand tools now it takes two hours as even with moving the motor the clearance is not great.

 

I just took 40lbs out of the car so naturally the 63 series will put almost all of that back but one of the goals of the car is that it doesn't need to be wrenched on constantly like the single seat race cars I've owned over the years. Up until around 2005 I raced the car with the stock 4 speeds, the mid close 56 box was spaced well for my home track. A 63 series mid close would have those same ratios and more than enough strength behind my prepped A15. Fingers crossed I'll manage to source everything I need, I've got a line on a 63 series B210 5 speed tranny for the front case as well as a z20 63 series 5 speed.

 

Tom

[datzenmike]

This may be silly but could you cut strategic openings in the floor/fire wall to get at these bolts? Something that has a secure screw on cover or plug? 

[Tom1200]

I thought of that as well but the join of the tunnel and firewall is where the torsional rigidity in the shell comes from. As long as your not pulling out gearboxes regularly it's fine.

 

For the most part when I did the A15 upgrade I shot myself in the foot; I installed the H190 because it was at the time the cheapest larger rear end I found. That required a shorter driveshaft which I got cheap from Dave Patten, my measurement skills where lacking and the shaft needed to be about an 3/4 inch longer, well I just moved the motor back as far as it would go since that would help the weight distribution. My wife does remind me that all the upgrades have resulted in the car going from 10-12th overall to consistently running top 5. It's easier on the ego as well, people compliment the car and how well I'm driving it, I've always been driving the wheels it but no one seems to take notice when you're 12th overall. So despite my whining about finding a solution for busting 56 series gearboxes every 3-4 years shaving 12 seconds a lap has been worth it.

 

Tom

[datzenmike]

No kidding.

[Stoffregen Motorsports]

12 seconds a lap?

 

I remember when 12 seconds was the entire field at the checkered flag. Our top 5 would all be within a second of each other.

[Tom1200]

I should clarify on the 12 seconds on a couple of fronts; when the car was sporting 50-55whp I was running 3:06, after porting and flat slide carbs and sporting 73whp it was down to 3:02, when I put in the A15 105whp or so and widened the front track to match the H190 rear axle I was down to 2:54s. I've made some minor tweaks that will probably shave another second and half or so and I'll possible crack the top 3.

 

The group I'm in at vintage races is really diverse; everything from 1958 to 1975 sports and production cars to Formula Vee and Sports racers. So you have drivers in 750cc H-mods sporting 45hp to 1300lb sports racers with 190hp. The gap between the front runners to the last place car can be 30 seconds per lap. There are generally 5-7 classes with total anywhere between 20 to 30 cars. The driver skill level varies wildly as well; some former runoffs winners to first timers ranging in age from 17 to 80.

 

The gearbox isn't worth as much per lap as one would think because I can do most of the track in 3rd and 4th. There are only two corners where I use 2nd and only for about 100-150ft. While its worth probably a second a lap the problem is the cars ahead of me are 1.5 to 2 seconds faster and the cars behind me are 2-3 seconds slower.

 

Now a 5 speed dog box box that would allow me left foot brake and go up and down through the book without the clutch like imd Min single seaters that's a different story...............my wallet isn't ready for that.

 

Tom

[Valvebounce]

To do a bell housing Swap you'd need an A series 63A front casing to start with. 

I can confirm that the OD of an L series /etc 63 series input shaft is bigger than the OD of the A series spigot bush. They're longer too. 

It's a trick to machine them down, as you have to hold the input shaft by the tapered synchro ring journal. Not impossible, but it takes a bit of skill. 

 

I'd have your flywheel remachined to accept a 200mm LD20 pressure plate. The diesel ones are quite heavily sprung. And then I just ran standard 200mm L series clutch disc. 

A 56/60 series bellhousing wont fit a 63. but I'm sure you knew that already.

I always found the 2-3 jump to be shorter on a 56, than on a 60. my A15 was supercharged, so the extra weight didn't matter when I fitted the 63.

[Tom1200]

I have a good machinist that can turn down the input shaft to fit the pilot bearing / spigot bush.

 

The true solution is for me to bite the bullet and buy a proper box; naturally I'm a bit reluctant to drop 3-4k on this. Qauife makes a really nice 4 speed sequential with drop gears (quick change in effect final drive) but it's 4K.

 

Tom

[rusty12ver]

luk 06011 on rock auto for the clutch disc

http://www.rockauto.com/m/mobilecatalog.php

Not sure if the link will work. For the 190mm clutch and 1" shaft.

[Dime Dave]

I've had a 63 series dogleg in my 1200 racecar for years. The OD 5th works fine with stump puller gears. 

 

The B210 / A / 63 series 5 speed has the same splines as the L & Z transmissions, but the pilot bushing diameter is smaller on the A trans. 

 

To do the L/Z to A case swap you will need to either swap the input shaft with the front case to get the correct A series pilot bushing size or have the L/Z input shaft machined down to the correct diameter. Also double check the gear count (input & lay shaft) before assuming an input shaft swap will work. 

 

To use the A series 180mm flywheel/clutch cover you'll need to use the B210 5 speed clutch disc. It is the correct 180mm diameter with the larger L/Z series input spline. 

 

At VIR, my 1200 would pull 8400 in 5th down the back straight. That is over 9800 rpm at the drive shaft, so you need to have some good quality parts in there to keep things together with an OD 5th transmission.

[Valvebounce]

With 3.9 gears mine would do 6000 in fifth. Which is 7000+ at the driveshaft. Mine was shortened "in the shed" and not even balanced. I always meant to fit driveshaft hoops.

But that's on a street car, so it wasn't seeing those speeds every day.

[datzenmike]

The dogleg over drive is 14.6%  or 0.854

[Tom1200]

Well I used the 60 series 5 speed at a track day this past Saturday and it worked OK, dropping from the 4.38 to the 4.62 would solve the main issue with the street box. The 4 speed ultra close is perfect but again it will not hold up even behind my semi built A15.

 

I've resolved myself to biting the bullet; I'll be selling off my mid close and ultra close 4 speeds as well as various other bits I have in the garage to go towards a gearbox. I could buy a proper gearbox now but I do not dip into the non race bank account to pay for race parts. I'm leaning towards a Ford T9 with Quaife synchro clubman gear set. Note I haven an auto bellhousing for an adapter. The idiot driver in me wants one of those QBM1M 4 speed sequential boxes (a mere 4K) but I'm not expecting to raise more than $2500 for my various bits in the garage.