Modifications to the Datsun 1600 Roadster Chassis and Drivetrain by Joe Hauser, National SCCA Champion - G Production
Over the years I modified or replaced many items. Please find below a summary of the most effective modifications I carried out on my 1600 Roadsters:-
I replaced the stock items with higher spring rate springs from the Datsun Competition Department . One ring was collapsed in order to lower the front and increase the spring rate. This caused interference with the tie rods so they had to be modified (bent) in order to clear the frame.
Again, I replaced the rear springs with higher rate springs from Datsun. At first I used lowering blocks to lower the rear. Later, however, I fabricated adjustable rear spring shackles to enable easier adjustment of the wheel weights.
FRONT SWAY BAR
The stock front sway bar was replaced with a new bar fabricated from 1.0625 chrome moly bar stock. Bar connections were Heim joints attached to the lower 'A' arm. (The Heim joint is a spherical bearing embedded in a chrome-moly steel head to provide unhindered movement in any direction).
REAR SWAY BAR
I fabricated a rear sway bar from a front Datsun sway bar which was 0.625 diameter. I modified the bar by drilling adjustment holes. This enabled adjustment at race events depending on track conditions. Again, the bar was connected to the lower spring pad via Heim joints.
One end was fastened to the right frame member by way of a fabricated bracket with adjustment holes. The other end was fastened to the right side of the rear housing with a further bracket, again c/w adjustment holes. The Panhard rod could therefore be raised or lowered to slightly change the rear roll factor. It was bushed on the left and Heim jointed on the right. An anti rear windup shock absorber link was attached to the rear housing with a bracket extended above the housing and attached to the frame.
I tried many different shocks from: Koni, Carrera, Carlife, and even a pair that were made for a big Chrysler sedan. The Carreras worked as good as any.
The front spindle shaft was smoothed and polished after one broke.
Rear shock absorbers were competition Monroe as specified on some oval track American cars. These shocks were great and lasted the full time I had the car.
Front disk brake pads were Ferodo DS11 as long as they were available. I also tried various other ie Repco metalic and later Performance Friction.
Rear brake wheel cylinders were changed to a smaller 3/4inch spec., to reduce rear wheel braking. For a time I experimented with a pressure limiting valve but, on balance, I preferred the smaller cylinder arrangement. Rear linings were mostly Datsun Competition Linings known as 'green stuff'. I did try other compounds including metallic, but decided the Datsun shoes were as good as any.
DRIVETRAIN (See also the Engine pages for Joe's modifications to the 1600 engine)
I used both aluminum and cast iron flywheels. The cast flywheel was lightened and the alum ones were faced for wear. One aluminum flywheel had steel inserts attached with machine screws, the other had a groove milled in the face where the disk ran. The groove was filled by plasma spraying in a bronze alloy. It was then refaced. That process worked better than the inserts.
The clutch pressure plate was a stock Datsun 2000 plate. Clutch disks were competition plates from Datsun. I tried using a metallic disk but I did not like the positive lockup that it provided. I thought it put too much shock load on the drive train and would eventually cause more drive line failures. Besides, the competition clutch plate caused no problems.
Three 5 speed transmission ratios were available. ie stock, middle close, and so called ultra close. I never used the stock transmission in a race because the ratios were too wide for my peaky race engines. I did use the middle close for the first couple of years at which time I opted for the ultra close.
For the first couple of years I used 5th gear in the 5 speed. However, although I made a custom built adapter which enabled the use of a better spline, I found I was having trouble keeping the drive shaft in balance, which resulted in cracked rear transmission tailshaft housings. I finally decided to try reversing the drive shaft so that the splines would be near the differential. This cured most of the driveshaft problems. I also found that I really wasnt getting any benefit from 5th gear. In time I decided that if I selected the proper rear ratio for each track, the first 4 gears in the 5 speed were adequate. Because 5th gear in the 5 speed was 15% overdrive, the drive shaft was rotating over 9000 RPM at peak revs and this caused the drive shaft to vibrate if it was not in perfect balance. The above two items solved my tailshaft housing problem.
The rear differential housing was modified because the rear axles would break after a number of hard races. The housing was modified and converted to a full floating rear, ie the load was carried by stub axles, and the axle shafts only provided the motivation. This completely eliminated axle problems.
Rear drive ratios varied depending on the track. At various times I ran everything from a 5.125 at Bryar to a 3.9 at Charlotte. Besides these I also available to me were a 3.7, a 4.35, a 4.65, and a 4.87. I had a couple of limited slips but preferred the welded up differentials. Since the rear had been converted to a full floating arrangement it only took about 30 minutes to change rear ratios. This was often was done at the track after practice or qualifying, in order to improve lap times.
Click here for further information on Joe's differential modifications.
I had the privilege of going to the U S Airforce Officers Aircraft Maintenance school. It was a concentrated 10 month course oriented toward making us the best Aircraft Maintenance Officers in the world. It was an excellent course and, if it didnt teach us anything else, it taught us that there was only one way to do a job - that was to do it right. If you didnt get it right the first time you did it over until it was right. That was also the philosophy I used when I worked on my racecar.
I had a limited amount of funds and consequently my car was not always as state of the art as some of the other cars. However, it was put together in the best way that I knew how. I had a good feel for what would work and what would not and how much abuse it would take. (Rob - Joe's race finishing attests to this!). I always disliked exceeding any of my preset limits. However I did exceed these limits on rare occasions, if it meant winning or losing the race.
My advice to new race drivers, owners, or maintainers. Forget about the exotic - there is no mystery ingredient that will make you a winner. It is the hard work and attention to detail that helps make the so called LUCK.
Remember, you have to finish to win.
Col. Joe Hauser
These pages and images, unless otherwise stated, are copyright ©1999 & 2000, Joe Hauser, Rob Beddington & The Classic Fairlady Roadster Register. Do not redistribute in any form without the prior permission of the owners.