last weekend, I enjoyed a prewar race car meeting at black forest germany. It was amazing to see how good the car (terry tuned engine) works in small hills - I was able to compete with much stronger cars like a BNC 527...
Although the car is a pleasure to dive, I'm a bit unhappy with the 1st gear. Usually I start in 2nd, even on not too steep hills. When using 1st to start, the wheels sometimes spin and top speed is below 10miles.
Back axle ratio 5.25 (42/8 teeth)
Gearbox is a 4-speed twin-synchromesh (constant 21-30 / 3rd 1.49 / 2nd 2.36 / 1st 3.89)
15inch wheels
Looking the the Bill Williams book - a change to 4.9 at back axle combined with 19inch wheels might be a good idea. Any suggestions what could be a better ratio for my car ?
14-06-2021, 01:07 PM (This post was last modified: 14-06-2021, 01:09 PM by Chris KC.)
Those are Nippy ratios. You could perhaps make the intermediate gears more useful with a "Super Accessories" set (1.27 : 2.01 : 3.32). Andrew Bird can do this (and possibly others).
Have to admit I’m a bit confused as to what you are wanting — you say your car went well at a recent meeting which suggests it’s relatively low geared — 15” wheels, and with brisk acceleration which is what you want.
I don’t quite see why you would want to change back axle ratio and use 19” wheels which will make your car too highly geared and possibly kill the sporty performance.
As for first gear, just use it occasionally when required. I’m not clever enough, looking at your intermediate gears to tell if it’s a close ratio box. If it isn’t you might like to consider getting one as that will make a big difference.
I run a special with a similar set up to your car so speak from some experience — hope this is helpful.
Gear ratio chart for hill climbs we generally use the intermediate ratio 22/29 in a lightweight car, for a heaver car or one with less power use the Nippy ratio. The other option is the Super Acc: 23/28 but 3rd gear is a bit to high for steep hill climbs such as Shelsley Walsh.
Terry.
thanks for your feedback! Of course, I would like to have both - top end speed and much acceleration :-)
I thought, as the car has so much power in 1st/2nd, I could change the gearing so that I use 1st gear for speeding up and will reach a higher top speed without loosing the overall sportive characteristics.
Stick to acceleration and top speed will look after itself. How you get to top speed is important which is why a close ration gearbox is important — you will appreciate changing from third to top at around 4000 rpm.
