Hey Ken,
Thanks for doing the experiment. I hate to put you out like that ;-)
Now I am wondering if the car is pulling to the left under acceleration.
When I notice this is under hard acceleration, on the 2-3 gearshift ~5000 RPM
(mostly).
When I get off of the gas I have to steer to the left. So it is not on trailing
throttle, or engine braking, the clutch is depressed.
Well, I guess I'll have to experiment some more, not today though. It's 65 and
major thunderstorms here in northern IL. 8-(
On Apr 30, 6:16pm, Ken Streeter wrote:
> Subject: Re: Rear Steer?
> Tom Tweed wrote:
>
> > I'm just wondering if maybe the reaction you feel upon sudden
> > deceleration isn't just normal for a Roadster (front engine,
> > rear drive, `normal' diff) car lay-out.
>
> Well, I've never noticed it in my car, but I don't recall
> ever looking for it to happen, either. Thus, seeing as
> how today is the first 70+F day in NH this year, I figure
> I'll use this excuse to go out to the parking lot, start
> 'er up, and take a 30 minute break from work to test this
> one out... (Be back in a few minutes...)
>
> OK, I'm back. Wow! It is nice out there! What a perfect
> ride -- I even got to wave to a maroon Triumph Spitfire!
>
> Anyway, the experiment: I tried accelerating hard in 3rd gear
> up to about 4000 RPM, to induce some mild rear end "squat"
> and then suddenly let off the gas. The weight rapidly
> shifted from the rear suspension onto the front, as
> expected, but I didn't notice a tendency of the car to
> "dive right" (or left, for that matter.) I then repeated
> the test with my hands off the steering wheel, and the
> TR did want to go very slightly to the right. It certainly
> did nothing that would be considered a "dive right."
>
> I would account for the slight tendency to go right off to
> the fact that the front suspension on that car is in sore
> need of new bushings, and my front left ball joint has some
> play in it.
>
> Then again, maybe my worn suspension is masking
> the behavior you are seeing. The reason I say this
> is that under very hard acceleration, or under very
> strong engine braking, a behavior like the above
> may be happening as a result of "torque steer". I
> don't know if this is the cause of the symptoms
> you're seeing. Essentially, the rotational torque
> of the engine causes the car to be "heavier" on one
> side than the other under hard acceleration or hard
> engine braking. Since I can't recall which way the
> driveshaft (and engine) spin, I can't figure out in
> which direction the torque steer would tend to point
> the car.
>
> With any luck, the Triumph engineers designed it so
> that the torque steer is cancelled out by the driver's
> weight when no passenger is in the car -- but then,
> the question is whether they designed it for the
> US or UK? :-) :-)
>
> --ken
> '70/'74 TR6 Daily Drivers
>
> PS: Thanks for the excuse to get out and drive!
>
> --
> Kenneth B. Streeter | EMAIL: streeter@sanders.com
> Sanders, PTP2-A001 |
> PO Box 868 | Voice: (603) 885-9604
> Nashua, NH 03061 | Fax: (603) 885-0631
>-- End of excerpt from Ken Streeter
|