FF Front and Rear Track Then and Now

[rickd]

(Note: the numbers used in the following post are rough, very rough, approximates, I certainly don't have numbers for all the cars on period and I'm sure there are outliers on either end, so that said...)

Track lengths from the 70's into the early 80's were somewhat constant at 48-52'' with some pushing into 54''. I'm going to guess and say this was due to limits of mounting the rear shock outboard and no one wants to deal with the hassle of moving it inboard for what they saw as little gain.

Well, 1983 comes along, and, as they say, the rest is history. Dave Bruns and DB-1 is introduced, track #'s jump to 60'' and there was no looking back. Today from my little survey tracks are (approx) 62-64''.

So is that all it was? One man with the vision to follow through where others dithered.
Is there something about suspension design that made going out to 60'' difficult?

Just a crazy question that started nagging at me...anyone with any ideas?

[FVRacer21]

This is an interesting question considering the conversation in F1 over car width - especially at Monaco.

There is a max car now - I wonder when that came in. Since most cars came from England, maybe there was something in their rules?

The max now is 185cm (72.8.. inches) so I would assume you would build to the mad width today.

Of course there was the Crossle 40 and Lola 520 narrow track for Road Atlanta - did not work at most other tracks. Didn’t last long.

Rocker and pull rod were around for a while before the Swift so not sure the shock thing was the limiting factor. Crossle 50 Reynard and Van Diemen all moved shocks inboard by 1982.

The ADF is interesting - sort of a rocker front but outboard rear. Not sure that the inboard front brakes did as much as the rocker set up did. Did your survey include the track on that? If so, it might point to a Bruns effect.

Now - did this open rule at the time obsolete a lot of cars, and if FF had had a smaller max width earlier would it have kept the cost down? FV is restricted by design and same with most closed wheel classes - except for sports racers which seem to have also gotten wider. I seem to remember that CSR and DSR were relatively tiny things in the 80’s.

I wonder if Steve Lathrop can stop by as the Zink Z10 looks like it had a wider track compared to the English cars.

ChrisZ

[CARSHouston]

Unsure why the cars kept getting wider, however I've always used the idea of wider is better on cars I've built. If you noticed the ad for the Stohr FF Stohr FF for sale (apexspeed.com), it was one of the widest FF ever built and they had changed it to a narrow design to take advantage or better use the new radial FF tires. In talking to Steve Lathrop, he said that he had made new rockers for the Z10 that were 1" wider and the handling had improved. He told us he'd make some wider rockers for a Z16, but we've never gotten them, so I can't tell if it improved the handling of that car.

[BLS]

Doesn't wider equal flatter, less roll, such that the tires maintain maximum contact easier? Obviously there is a point of diminishing returns...

[Spengo]

I would also be curious to know why cars didn't go wide and long immediately as soon as inboard shocks made it easy. Even early pushrod cars are shorter and narrower than what people consider "modern" designs. I assumed it was due to tire construction or maybe class rules.

[CARSHouston]

I always considered long to be a bad thing, too short = too twitchy and too long = not responsive enough. Most all good FF are close to the 96-to-98-inch wheelbase range. I don't know what a Swift is, but 30 to 50 series Crossle are about 96.

[rickd]

I always considered long to be a bad thing, too short = too twitchy and too long = not responsive enough. Most all good FF are close to the 96-to-98-inch wheelbase range. I don't know what a Swift is, but 30 to 50 series Crossle are about 96.

Wheel base on the DB-1 was 96''.

Prior the DB-1 there were very few inboard rear shock cars(where there any?). I have to think the difficulty in packaging this setup limited it's use and therefore limited extended front tract for ''production'' cars where price was an issue, particularly for penny pinching brits.

[rickd]

I would also be curious to know why cars didn't go wide and long immediately as soon as inboard shocks made it easy. Even early pushrod cars are shorter and narrower than what people consider "modern" designs. I assumed it was due to tire construction or maybe class rules.

Could it be there are suspension design issues with inboard shocks particularly in the rear, specially locating the anti-roll bar. I'm not a design maven by any stretch, do roll centers get more complicated with wider trackers?

[tlracer]

Other than as a response to changing tire technology/design:

- Outboard suspension track was limited by the shock installation. Wide track would need either a very shallow incline for the shocks, giving a big bending moment on them so poor operation and increased wear

- Rockers allowed a track increase, but limited by the rigidity/weight of the rockers themselves, since a long rocker would become either very heavy or a 'spring' in its' own right

- The advent of pull/pushrods separated the spring/shock operation from the suspension as the bending moments from either outboard or rockers became tension/compression loads in the rods, allowing further increases in track

That said, Van Diemen always insisted their narrow-track RF83 (all inboard) was for reduced frontal area and hence better straight line speed...so maybe there's just a big element of trends and marketing in it!