Slavery wasn't the only issue. Here is something from Jefferson Davis's speech to the Confederate Congress on April 29, 1861. It's an 1861 item, not one from 1860, but it indicates that tariffs and the protection they provided Northern interests at the expense of the South were a serious concern as well as slavery. Italics below were as in the documented version of the speech; bold items were my emphasis.
Strange, indeed, must it appear to the impartial observer, but it is none the less true, that all these carefully worded clauses proved unavailing to prevent the rise and growth in the Northern States of a political school which has persistently claimed that the government thus formed was not a compact between States, but was in effect a national government, set up above and over the States. An organization created by the States to secure the blessings of liberty and independence against foreign aggression has been gradually perverted into a machine for their control in their domestic affairs; the creature has been exalted above its creators; the principals have been made subordinate to the agent appointed by themselves.
The people of the Southern States, whose almost exclusive occupation was agriculture, early perceived a tendency in the Northern States to render the common Government subservient to their own purposes by imposing burthens [rustbucket note: that's the way the document spelled it] on commerce as a protection to their manufacturing and shipping interests. Long and angry controversy grew out of these attempts, often successful, to benefit one section of the country at the expense of the other. And the danger of disruption arising from this cause was enhanced by the fact that the Northern population was increasing by immigration and other causes in a greater ratio than the population of the South. ...
And in the next paragraph Davis mentions slavery.
In addition to the long-continued and deep-seated resentment felt by the Southern States at the persistent abuse of the powers they had delegated to the Congress, for the purpose of enriching the manufacturing and shipping classes of the North at the expense of the South, there has existed for nearly half a century another subject of discord [rustbucket note: i.e., slavery] involving interests of such transcendent magnitude as at all times to create the apprehension in the minds of many devoted lovers of the Union that its permanence was impossible.
When the several States delegated certain powers to the United States Congress, a large portion of the laboring population consisted of African slaves imported into the colonies by the mother country. In twelve out of the thirteen States negro slavery existed and the right of property in slaves was protected by law. This property was recognized in the Constitution, and provision was made against its loss by the escape of the slave. ...
And Davis then went on talking about slavery.
I've posted the following before, but perhaps you haven't seen it. It is from the New Orleans Daily Picayne published after Louisiana seceeded, IIRC.
Some months ago [i.e., prior to Louisiana seceding] we said to the Northern party, "You sought sectional aggrandizement, and had no scruples as to the means and agencies by which to attain your unhallowed purposes. You paid no heed to the possible consequences of your insane conduct." ... The South was to be fleeced that the North might be enriched.
Sounds like they were a little ticked off about the sectional aggrandizement that the tariff resulted in.
I think tariff issues had the same relation to the secession crisis as high gas prices have today with relations with Hugo Chavez.
They may have missed the point. It was always aggrandizement of the business class and its interests that were the object of Hamiltonian concentration and amalgamation of powers.
The Northern faction were simply continuing Hamilton's agitation of 1787 for royalism without the king, and for access capitalism protected and enlarged by the royal favor.
And no backtalk from the gomers, the subjects if you will, out in Stickland.