Finally got the kids to sort this out for me.
This is from the last Track Day that is run here in Christchurch. Really great event with a diverse range of cars from Porsches and SRT Dodge Challengers to Anglias and everything else in between.
The rules are pretty simple, no passing through corners or under brakes which keeps the risk factor under control yet provides a great opportunity for people with fast cars to really stretch their legs and see how good they really are.
This footage is from later on in the day on the short "club" track.
Excuse the 1st lap- rusty driver, finding neutral at the hairpin and cold tyres.
Anyway I would be interested in hearing a few informed opinions of how they think the car is handling. I just don't think that I have got it quite right yet and I suspect the culprit is a too soft rear which is throwing too much bias on the outside rear causing it to twist up and unload the inside front too much, which in turn is putting too much strain on the outside front ( our tracks are predominantly left hand corners so its the right front that really gets a hammering)
In the last 2 laps as the tyres are starting to get hot you can hear it squealing around the left hander onto the front straight and I seem to be on/ off it a bit too much for my liking.Also the high speed left hander leading onto the short straight to the hairpin.
I've had the rear spring pack beefed up slightly and I am going to get a larger, adjustable rear bar but it is very much a case of trial and error and I am very wary of taking too larger steps as the car generally feels pretty good.
Cheers
Dave
https://youtu.be/eil4ZEPUeiw

Good stuff Dave! Looks like a fun little track and the Datto goes well :)

It's hard to tell much about the car's handling without feeling it for yourself, but it does look to be setup pretty soft. There's a fair bit of body roll and it looks to me like it picks up the inside front a fair bit on that fast last turn. But it seems to carry good corner speed as it is... Stiffeneing it up a bit all round probably wouldn't hurt though.

Thanks Harry,
Yes, thinking about it afterwards it probably is a big ask for someone to judge exactly what is going on by that inside car footage.
Believe it or not it is pretty stiff at the front with 275lb springs and a 21mm adjustable bar.
Being what it is ( historic race car that is street legal, and I do tend to drive it to that particular track ) I don't really want to turn it into an oversprung go kart so one is always walking a fine line chasing optimum handling however even at this stage its a lot of fun to drive.
Cheers
Dave

Dave I'm with Harry in this one too; the car turns in well and carries good corner speed but I do notice a lot of mid corner throttle corrections especially in the transitions. Namely the S curves with the transition between track sections. The front does seem soft but as Harry said hard to tell form the video. It seems like you get a momentary push coming off the apex that turns into oversteer half way between the apex and exit curbing.

The motor sounds stout and the gearbox seems really nice as well and you were definitely giving the moderns an eye opener. Is that the 60 series box in your car?

There is one serious thing we need to address; why on earth are those Miata drivers going so slowly? I love driving my 1200 because they are such capable little cars but I also know that I'm 7-8 seconds a lap faster in a Spec Miata (110 whp, sway bars, shocks springs and spec tire). A couple of those looked to have quite a few mods. Really they should be made to serve some kind penence.

Hi Tom,
Miata drivers- love it! One of those was turboed as well.
Yes, that's the 60 series c/r box in it.
I guess going through those S curves between the track sections there is a lot of weight transition from one side to another and being in 2nd there is also a heap of torque going through the chassis that does make it tend to oversteer if one gets on it too hard.
Be interesting to see what, if any difference the slightly beefier spring pack will make.
Next meet August 13!
Cheers
Dave

Yeah, that's plenty stiff enough at the front for a street/track car with the light A series. Sounds like you're on the right track stiffening up the rear a bit.
Looking forward to more videos :)

Quote:
Hi Dave - I'm in Palmerston North and have a Coupe racecar. Often run in the same group as MX5/Miatas here too (Manfeild) - am generally 1-2 secs per lap faster than them but they have limited mods for their series (must say they do handle well even relatively stock although their power/weight lets them down).

I'm interested to learn about the gearbox you're running. I'm using a 60 series 4 speed with close ratios built/commissioned by Reg Cook "back in the day" (early 1980s I think). 'Rally' ratios with 1st gear ratio around 2.5:1. Straight cut gears - noisy! (Although I only notice it on warm up and cool down lap.)

The best ratio 'boxes I've had were two Ultra-close (2.169:1 1st gear) 56As but unfortunately each eventually broke, and I'm only running a mild 1300.

As far as I am aware Cook had Bettanies make 5 kits for 5 speed 60 series boxes.
2nd, 3rd and 4th are straight cut.
I know of 2 others down here in Chch, I believe there is also 1 somewhere in Australia.
Cook then did some cutting and welding of selector shafts to make it all work.
I'm not entirely sure whether he started with an 'A' series or an 'L' series box but the end results is a dogsleg 5 speed pattern.
I also had one of the ultra close 5 spd 56 series boxes but it was simply too fragile to handle the output of my engine. A beautiful wee box with absolutely magic ratios though.
This 60 series box is really about the 1st 4 gears with a bit of a gap between 4th and 5th- probably what I would describe as more of a good rally box. It certainly scampers off the mark though and I would love to run it through a quarter mile some time.
Cheers
Dave

Straight cut gears eliminate the sideways thrust of the helical gears, the downside is that the straight gears are weaker

Straight cut gears need no mod of the selectors, unless the gears are made to different dimensions. I wonder if he changed the synchro type or something?

To my knowledge there was no L-series 60-series gearbox. In any case the factory 60L was already a dogleg 5-speed, which can be converted to straight-cut gears by replacing the cluster and the individual gears. As a bonus, you can change to close-ratio or other gearsets at the same time. That may be why Cook did it

stock helical-cut gears (quiet)



custom straight-cut gears

Dave,

Bettany Gears just finished repairing the Mid-Close cluster gear for my 56 4 speed; I've enquired as to making/modding my 60 series either close up 2nd or remaking 1st & 2nd as those are one half of the cluster gear.

The 56 series C/R boxes are great but as many of us have found past a certain level they are just up to the power/torque outputs. Mine seemed fine until I get the motor above 80whp (100 at the crank?)

I broken 3 cluster gear (always 3rd); one was stock until pulled from a car where I know the driver beat the box (it made 5 laps) and only put in cause it was clean (pure lazy). The second was a mid-close that I was advised to go through but didn't and that made it 2 seasons. The third one went 4 to 5 seasons, the last two of which it was behind the A15.

OK back on topic; Dave I, as usual, went cheap on the struts and installed non adjustable KYBs. They work ok but the lack of adjustability is an issue; in a section with a 180 left into 60 right 120 double apex left, when I rapidly transition from 60 right to 120 left I'm steering into the left so rapidly and the left side of the car is still loaded up that the car will snap back right as if I've over corrected a slide. The situation gets worse on old tires, if I had a way to adjust the rebound damping on the front I could slow this down. Basically the car kind of trips over the left front then the suspension unloads back over to the right more rapidly then the tires can cope with. All of the other transitions are fine except this exact spot and only on tires near the end of their useful life. I need to stump up for Konis or the like.

Tom