Throttle Jerk Fix

So my 42 year old car has always had a very jerky accelerator pedal, which is a common issue for early Datsun Z-Cars with the mechanical linkage.  After looking at my options, I decided to change over to a throttle cable (similar to modern cars) which should deliver a silky smooth pedal and acceleration.

First, I decided on a Mr. Gasket steel braided throttle cable kit from Amazon for  (#5657)  and an aluminum throttle arm from Speedway Motors for (## 91018400)

In addition, I needed to figure out a way to hold the cable housing at the carburetor.  For this I chose a hardened L bracket that I had laying around & mounted it to the exhaust manifold heat shield.  As there's not much pressure being put on this, it should hold up well.

 

I next had to modify the accelerator pedal, including bending it & then determining the best way to mount the cable end.  I chose to not drill it, rather use an "S" connector.  Longer term I may drill it out, but for now this works.

 

I think needed to hook everything up and adjust for the proper amount of slack.  I also greased the cable very well, although it probably could use some more.  Please note that I did change the L bracket that was used as I needed it to be in a better position over the carburetor linkage.  

 

Overall, I'm very satisfied with the outcome.  I'm now able to accelerate from a stop very smoothly!  The only downside that I've identified thus far is that I needed to replumb the breather from the valve cover as the throttle arm blocks the path of the original hose.  I also need to change the color of the linkage arm as they sent me a purple one...probably some sandpaper and it'll brush right off.

Here's some additional info that I've run across throughout my travels:

Miata Seats Installed

Last fall I was able to pick up a pair of early (NB) Mazda Miata seats, including sliding rails.  There is a little wear on the side bolster, but the seats are in much better condition than the 42 year old Datsun seats.  They also hold me in much better and resemble a similar look to the original seats.  Make sure to check out how to add speakers to the miata seats --> LINK

My goal was to not modify the body of the Datsun any more than I needed to but still allow me to sit comfortably.  Most people agree that using slider rails with the Miata seats raise the seat up several inches, and as I'm 6'2" my head was touching the ceiling in all comfortable positions of the seat.  I did not want to remove the seat mount on the floor of the body as many people do, so I opted to fabricate my own seat mounts from some steel stock and bolt them directly to the body.  This does not allow for forward/backward movement of the seat, but as there is no need to move the seats, I thought this was an acceptable compromise.

I did go through several iterations of how to mount the seats including:
  1. Using OEM Datsun slider rails
  2. Using Miata slider rails
  3. Custom mounts without sliders

1. OEM Datsun Rails
This was by far the 'easiest' approach, although it does require several spacers to be inserted in the back of the Miata seats to allow for them to fit as well as to drill a hole in the Datsun seat rail.  A good write up can be found here:  http://forums.hybridz.org/topic/91742-miata-seats-installed-with-instructions

2. Using Miata slider rails
This is a better option as the rails bolt nicely to the Miata seats, the rails are much more robust than the Datsun (as they lock on both sides), although there is still the height challenge.

      

3. Custom mounts without sliders
This is the best option, in my opinion.  The seats are at the perfect height and the position is comfortable.  I purchased several steel bar stock (3/16") as well as some square tube.  After some quick measurements I was able to cut two risers for the back of the seat bracket (to prevent the 'bucket' effect common when putting new seats in a Datsun) and welded them on.  I probably could have used washers or some other method of lifting the back of the seats up, but I thought I should get some practice welding.  The one thing that I'm not happy I had to do, but it makes everything a lot simpler is that I cut holes in the floor pan to allow for a deepwell socket fit through in order to bolt on the rear mount.  As the seats don't slide, I wasn't able to fit my hand underneath to bolt the mounts down once the seat was placed.  I did get some body plugs to cover the holes to prevent water and fumes from entering the cabin after I painted the freshly drilled floor pan.

 

Test fit on the driver's side

First mounted the mounts to the bottom of the seat

Another view of the custom mounts

Its been a long winter!

Well spring is finally in the air, although the temperatures are still not as warm as we'd all like here in Chicago.  The Z has been in hibernation for the long winter, but it started right up and performed great.  Over the winter I did perform a couple of projects which I'll speak to in future blog posts including: New Seats, Front Wheel Bearings, and a redesigned Throttle Cable.  Still on deck for this spring/summer will be Rear Wheel Bearings, New Exhaust, and repairing minor rust damage from the undercarriage.

Brake Booster

While out driving a couple weeks ago I noticed when I pressed the brake pedal that a loud "hissing" sound began as well as the engine RPM changing quite a bit.  After further diagnosis, it appeared that I had a major vacuum leak coming from the brake booster.  Most likely the 41+ year old rubber diaphragm just deteriorated.  Apparently in 1972 the brake booster changed mid-year.  Jan-Aug 1972 used a 1971 brake booster and the Sept - Dec 1972 (and all the way upto 1978) used the later brake booster.  The holes in the firewall are different and the older (which I have) booster is a 6" smaller diameter.

Original brake booster removed:

 

I was able to slide the brake booster out without having to disassemble the master cylinder

Remanufactured Cardone brake booster (compliments of Amazon.com).  I did need to change the engagement pin on the booster and I'm still in the process of adjusting it to ensure the brakes engage at the proper pedal pressure.  There are stories of the reaction disk (a small rubber spacer in the booster) slippping out, but I did confirm that mine is securely in its place.

 

While I had the accessibility, I swapped out the steering coupler for the rack & pinion steering.  The old hunk of rubber had certainly seen better days & the new one dramatically  improves the handling & responsiveness of the car.

Other useful bits I've found along my travels...

5spd transmission

Last weekend I acquired a 1977 5 speed transmission for a guy who was parting out the engine/drivetrain of his 280z.  Supposedly it drove great without noise and only has 80k miles on it.  I picked it up for $100 which I think was quite a great deal.  I've been seeing these go for $250-$300, and this one included an extra flywheel, clutch, and engine splash guard.

The transmission is a FS5W71B model, Serial # 7322759 meaning

•  7=1977
•  3=March
•  22579 = Sequential number of this transmission being produced (#22,579 for the month of March 1977)

This is an early "wide ratio" transmission which should improve the drive ability of the car, especially at highway speeds with the 0.864 overdrive gear.  Below are the drive ratios for the different transmissions available for the S30.  I started with a 1972 240z 4speed and will be installing a 1977 280z 5speed.

Before Pictures

 

First order of business was to powerwash and degrease the transmission.    I did cover up the output shaft with a plastic bag as well as the speedo gear to prevent water from entering the transmission.  I do plan on installing the transmission in the car prior to rebuilding it.  This will allow me the ability to see where its actually leaking from as well as if any gears or forks make funny noises.

After Degreasing & Powerwashing Pictures

 

Next comes jacking up the car and removing the old 4 speed transmission and installing this new 5 speed unit.

 Transmission pulled out through the rear and remaining clutch and flywheel (note that the engine must be supported when pulling the transmission!

All of the shuttering I noticed when engaging the clutch was due to two springs being broken on the friction disk.










240z & 280z pressure plates and release (throw out) bearing collars are different sizes.

 

The car is now back together & shifts much better than expected.  The clutch does engage very high up in the pedal stroke, which is different than before but it may be due to the different type of clutch pressure plates.

Here are some great reference pictures from the InterWeb...

 

Another great reference site is Blue's Tech Tips: http://atlanticz.ca/zclub/techtips/transmissionbreakdown/index.html

The Speedo gear in the transmission must match the differential, so I'm going to need to pull the one out of my 4speed transmission and insert it into the new 5 speed to keep the speedometer accurate...
YELLOW is the 16 tooth for the 3.36
BLACK is the 17 tooth for the 3.54
BLUE is the 18 tooth for the 3.70
WHITE is the 19 tooth for the 3.90
RED is the 20 tooth for the 4.11
PURPLE is the 21 tooth for the 4.38

Seatbelt upgrade

After too many passengers getting confused with the stock 3-point seatbelt harness (fixed length shoulder strap and all), I decided to upgrade to a set of Wesco seatbelts.  I believe they are either the same or very similar to the set that is available from Motorsports.  Wesco has a nice online system that allows the user to identify exactly which seatbelt combination to select based on the vehicle.

The setup I selected ended up being $173 out the door with shipping and tax.  See http://wescoperformance.stores.yahoo.net/

Here are some pictures of the before & after

Stock seatbelt system

Stock seatbelt on top, Wesco on the bottom

Wesco Seatblet connections (stock mounts)

Wesco receiver mount, stock location

Wesco shoulder harness, using the optional L-Bracket, stock mounting location