tr7triumph.com

The AC system on my 76 FHC weights 55 pounds. I weighed each component before installing it. I expected to see a huge difference in handling qualities with all that extra weight in the nose. But I can't discern any. Mind you, I'm not track testing this car but I am driving aggressively through corners at speeds up to 60 mph. Logic tells me I should have a bunch more oversteer but I don't see it. What do you think Hasbeen or others who can be considered experts in handling qualities.

[img][IMG]http://i615.photobucket.com/albums/tt234/nickmi/TR7%201975/Yellow.jpg[/img]
nick
'79 TR7 DHC
'76 TR7 FHC

Of that 55lbs most of it will either be almost directly over the front axle line or behind it, so I wouldn't think it'd make all that much difference.

"Keep calm, relax, focus on the problem & PULL THE BLOODY TRIGGER"

80'Triumph TR7, 73'Land Rover (Ford 351. V8),
'89 Ford Fairlane
'98 MG-F, 69'Ford F250.

Nick with all due respect, you are probably not getting close enough to the limit for the cars natural handling to show.

Using the tenths system properly, 10.000001 tenths is the speed at which the car, with the perfect driver flies off the track. I always discount any narrative where people talk about 11 tenths as garbage.

Now I have set more than a few lap records, including one Bathurst F2 record I still hold 40 years later, & I would not have exceeded 9 tenths setting it. Most of the races I won I would have been driving at about 8.5 tenth. Very few people can drive even that close to the limit for more than a lap or 2 without making a mistake which is at least time costly, if not disastrous. Good drivers always practice quicker than they race.

So having established what I mean when talking 10Ths I reckon my racing was usually at about 7.5 to 8.5, with the occasional effort at 8.5 to 9.5 in the first couple of laps after the start, passing manoeuvres, & perhaps the last few laps in a tight finish. My hard road driving is at 5 to 6 tenths. Even with pace notes I doubt I ever got to 7 tenths on the road, except by accident.

In my younger days, in cars with much lower limits, MG TC, Singer 9 Simca Around & other such on cross ply tyres I probably drove at 7 tenths regularly.

It is only at above 6.5 tenths that a cars natural handling characteristics appear. Up to that most drivers are using the slow in, fast out, where a car with adequate power will power slide the rear, & those with less power will push the front out in understeer.

Much as we would like to believe we can feel all these things, we would often make changes greater than your weight distribution change, & I subjectively could not tell if it were an improvement or not. It was only when we looked at the stop watch we could tell if the car was quicker.

There were times when a chance made the car nicer to drive, & I thought improved, but the lap times were slower. This is why I separate handling from grip & corner speed. For road driving, handling is more important than cornering speed for an enjoyable drive.

In my blog I mention driving Mike Champion's Brabham for him in the last round of the Oz drivers championship in 67. The car was so badly set up that in the wet first practice session, I brought it in as I could not drive it at the low speeds. In the second dry practice despite being only a little better set up, I drove it at proper racing speeds. The natural handling character of the Brabham came through, & the car was quick. I made second fastest time, then won it's class the next day.

Even with it very wrong, it still had it's Brabham characteristics. This is the same with our cars. The 7 & the 8 are quite differently modified, & "improved". However, even blindfolded you could not fail to tell they are very much blood brothers.

Don't beat your self up over not being able to feel a few extra pounds over the front axle, very few, if any of us could, particularly on the public road.

Hasbeen

What Hasbeen says makes so much sense.

I'm not a race driver. I dispelled that thought in my early twenties when taking my Triumph Trophy over a motocross track (taking a road bike over a motocross track, who does that) I realized in the red mist of racing I could not distinguish the limits and would do what ever it took to pass whatever was in front. Not a situation that implies a long and healthy life so I put all thoughts of racing away.

How ever, I have noticed this with my Spider (with A/C stuff intact).
On slow tight turns (small traffic circles) it does seem to have some under steer. On taking it to the limit on the a tight windy road where I live where the tires are just starting to break away, it does so equally front and rear for a perfectly balanced handling characteristic (all Kumho tires in the 32 psi range). I couldn't wish it to be better. It doesn't have the bumper weights in. I don't know if it would change if I did or if it would change if I didn't have the compressor in. I just don't want to change anything. Handling may be different if braking (not much any ways) for a corner or accelerating (not much any ways) out of a corner but I don't drive that way so I don't know.

- - -TR7 Spider - - - 1978 Spitfire- - - - 1976 Spitfire - - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra - Yellow TCT

Hasbeen has it covered, but 55lbs probably will not be noticed with the poorly tuned butt-o-meter.

It might be noticed on track compared with similarly prepared cars, but not likely with just wheeling around local roads.

http://jp-motorsports.com

Gasoline weighs about 6 lbs a US gallon. with the 14.6 gal tank the change over the rear axle is 87 lbs so depending on the fuel load the "extra" AC weight is readily counter balanced.

Edward Hamer
Petaluma CA

I noticed my 25kg bullbar on my landy. Obviously it was positioned as far forward as anything could possibly go on a softly sprung, high centre of gravity vehicle with tyres around a meter tall to exaggerate it. On removing it i found the delay in 'turn in' had virtually disappeared on twisty country lanes at 60mph (ish) and it was more chuckable, rather than any noticable difference in oversteer. The car normally had terrible understeer anyway... I didn't notice it at all on sweeping bends, it was more on tight S bends where the car had to quickly change direction. Basically the steering felt more direct.

I'm not sure how relevant my comment is but in my mind, if you can remove unneccesary weight for free without compromising on safety then it can only be a good thing. If you can add weight, gain aircon but not notice it then that's a good thing too

Rob.