Castor angle on front suspension

[Nick]

Has anyone tried lower castor angles than the 2 deg +/- 0.5 deg in the manual ? I have found my steering to be very heavy when cornering sharp bends and I was wondering how much effect 2 degrees has on the steering load. I saw the following article in an E-type club newsletter from 2007. It mentions only 1/2 degree of castor. Does anyone have their suspension set this low ?

"In practice, the castor angle affects steering effort and centring. On E-types, a slightly positive angle is required for general road driving (about ??): this improves cornering and can actually enhance the effect of a negative camber. Race cars are frequently set up with higher positive castor angles; however, when driving on the road, too much castor can make the steering feel extremely heavy. "

I'm running with 185 Aquajets at 32psi with an unassisted rack and normal diameter steering wheel.

Thanks,

Nick

[Moeregaard]

Nick, in my experience, any deviation from the factory settings results in heavier-than-normal steering effort, especially at low speeds. You didn't mention whether or not you are running at the factory ride height, but if the suspension is lowered you may have inadvertently taken things "outside the box." You shouldn't have this problem with the tires and pressures you are running.

You can perform a crude check of the castor angle, using a carpenter's framing square set vertically in front of the suspension arms, and then measure the distance to the center marks visible on the threaded portions of the upper and lower ball joints. Trig this out and it'll give you a pretty good idea of the castor angle. Since camber is set using shims, it's usually not the culprit, so I would look first at ride height and then at castor.

[Nick]

Thanks Moe,

I think my ride height is pretty much as standard but yes it would be useful to check. Also I haven't yet checked to see what my current castor angle is - your 'crude' check method sounds straightforward. I just wanted to see first if there was a 'oh yes, we all set to less than the book' view out there in the community.

Nick

[Moeregaard]

You're very welcome, Nick. I'd expected others to chime in on this one. The guys who run E-Types competitively mess about with different suspension settings, but many of these modifications make for a pretty poor road car. In my view, Jaguar just got things right the first time around. I mentioned checking ride height, because E-Types are often seen with their "bums in the air" due to sagging front suspensions. On LHD cars, this is compounded by having the weight of the driver, battery and fuel all on the same side, which will lead to a "port list" over time. When I reassembled my '65 4.2 FHC, I set the front to the factory settings and removed the spacers from the rear Koni dampers, essentially bringing the car to 3.8 specs. Rear springs were slightly uprated from standard. With 185-15 Avons at 32 PSI, I had a very nice road car.

[jag68]

I'm one of those guys that raced an E Type for quite a number of years, and have played with castor a lot. If you think about the geometry of the front suspension you'll realize that positive castor has the effect of jacking up the inside wheel when you turn into a corner - this is why the steering gets heavier - you are slightly lifting the car on one side. Try racing a modern go cart, these things have massive amounts of positive castor. Having said all that I'd be really surprised if 2 degrees would have that significant an effect, especially since you run quite skinny tires. It doesn't hurt anything to run less castor - but it will decrease the self centering effect which will increase nibbling etc. Just don't go into negative castor. Have you checked the ball joints including the tie rod ends to ensure that you don't have binding when you turn the wheel?