drove it to work today as a quick check for this weekend's hillclimb - all good. She's running like a gem :)
I'll only be competing on Sunday. Saturday afternoon you only get a couple of runs and it's just too far to go for bugger-all running. The weather forecast isn't good for Saturday anyway, so it would be a total waste of time if the predicted showers and storm affect those runs. Sunday is supposed to be fine and clear, and it's a full day of competition - makes the hour's drive each way worthwhile. And the mighty Datsun will be driving there and back - true street car style. No trailer queen bullshit :P

There's a decent number of cars in my class too - should be a bit of fun!
Mod Prod, Road Reg. 2001cc & over
Mazda RX-7 2340cc Turbo
Mazda RX-2 2340cc
BMW 325 2700cc
Ford Falcon XR6T 3998cc Turbo
Holden Commodore 5700cc
Mazda RX-7 2340cc Turbo
Suzuki Swift GTi 1298c Turbo
and my Datsun 120Y 1950cc Turbo - it's gotta be the underdog in that field!

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Good luck mate you still selling or decided to keep her now?

Thanks, it should be good fun.
I'm still selling it. No need for 2 toy cars. It did put a smile on my face driving it to work this morning though - it's a fun little car! I'll have a for sale sign on it this weekend and advertise it more widely after this hillclimb - didn't want it to sell before I took it back to Mt Cotton!

Awesome fun. Not quite as quick as I wanted to go, but it wasn't a fast day - too cold. We only got 5 runs over the day, and ended up with a best of 50.9 on the last run. 4th in class so not too bad. Still learning the best way to get it off the line and a couple of other places - it's a pretty wild machine! Definitely turns it on for the photographers ;)

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Too soft in the front still ?? That's a fair bit of weight transfer going on there

Wow you are microns away from having the wrong side up.

Stiffer front corners looks like its a must. WOW.

It's got me scratching my head a little to be honest. Front end is definitely stiff enough - it's not compressing the outside front too much. The front spring rate is the same as my old 1200 coupe, and it has a stiffer 23mm front swaybar vs the 20mm bar the 1200 had. It's got to be roll centres making the car pivot around a point that's too high, but the front roll centre should be similar to my old 1200 too, so I'm a bit confused...

The rear end is substantially different to my old 1200 - no rear swaybar on the 120Y, but stiffer springs. It definitely needs a rear sway bar - the following photo demonstrates that clearly, but I can't believe that will keep the car on the deck over lover's leap where the previous photos were taken. So I think I need to lower the roll centres further as well. I can do that by lowering the car, but it will need shorter rear shocks to avoid bottoming out.

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probably start with a rear swaybar and see what happens... they do have a diagonal effect, keeping more weight on the inside front wheel. And I'm not sure I want to totally stop it from 2 wheeling - it's pretty speccy! lol

I love this stuff. There is no right and wrong answer, just cause and effect. Do you have data logging to compare results? I have found it invaluable when making changes to my race car.

Interesting problems. On the surface I agree the last photo is indicative of too soft rear roll stiffness. If you had understeer at this point it would be a worthwhile change.
I always like soft springs and stiff bars on these old leaf spring cars.

Interestingly the other issue (Lifting both inside wheels) may be a problem with the cars track width and CoG height (Load transfer in roll is a function of track, CoG Height, sprung weight and lateral G - As you know suspension tuning is about maximising the use of this transferred load to give the best available grip - I always like to remind myself, you can't stop weight transfer)

It may also be a problem of the circuit design and lateral grip you are generating at that point (A good thing right), "fixes" may actually reduce the overall grip level and make the car slower through that section. I guess that is the fun of tuning suspension, educated adjustment backed by testing.
I also suspect it looks worse because the road drops away on the inside. Relative to the corner entry ground level the car doesn't appear to be rolling any more then the last pic.
Did it feel like it was going to rollover?

I remember seeing an IPRA Suzuki swift almost roll at wakefield fishhook turn a few years ago, flat road but the A050s generate such good lateral grip, high CoG cars with narrow track can be problematic. Unfortunatly there is a limit to the lateral grip each car has before it will roll over, although I doubt this was close to rolling.

I doubt roll centre height would have contributed to the problem, changing the heigh may fix the issue but will probably do so by reducing the overall lateral grip. Give it a try and see what the sector times look like.

Best of luck, please keep us posted.

Bryan

All those factors you mention are going to be very similar between my old 1200 and this 120Y. Both had cross-members notched to sit the engine low. Both had similar ride heights. 120Y actually has lower tyre diameter. So CoG height will be similar. 120Y probably slightly wider track if anything. 120Y weighs a total of 40kg more. There's not much in it either way.

I think you underplay the importance of roll centres here - it is the only thing that determines the point at which the body pivots. The higher the RC, the more you lift the inside of the car with each degree of body roll. A RC at ground level will barely lift the inside at all, whereas a RC at CoG will want to lift the inside as much as it compresses the outside.

I started refreshing on weight transfer theory and roll centres and stuff this morning but it hurt my head, so I decided on the KISS approach - more roll resistance can't hurt! And the last photo clearly shows it needs more rear roll resistance, so add a rear swaybar like the old 1200 coupe that didn't do this. I can adjust the front bar stiffer to balance it out if needed.