Dealer Letter #109B (November 1967) - Trailer Towability

Johnson service bulletin archive / Dealer Letter #109B

Johnson Motors red Dealer Letter letterhead

November, 1967

Dealer Letter #109B

SUBJECT: TRAILER TOWABILITY

The problem of trailer towing characteristics is one that is plaguing not only the boat trailer manufacturers, but also the travel trailer industry.

In recent tests we found that there was nothing inherently wrong with the towing characteristics of our trailers provided a proper hitch of the correct rated capacity was used. However, when the hitch load was less than five or six percent of the gross trailer and boat weight, a swaying condition was evident along with excessive vertical motion at the hitch. The recommendations of automobile manufacturers and the Society of Automotive Engineers are that seven to ten percent of the gross trailer weight should be carried on the hitch. When this is done, the swaying condition is negligible.

Applying these recommendations to our boat and trailer rigs, the hitch weight should fall in the following categories if a weight distributing hitch is used:

1968 Johnson Surfer & trailer: 222# - 318#
1968 Johnson Reveler 155 & trailer with brakes: 182# - 260#
1968 Johnson Reveler 120 & trailer with brakes: 175# - 250#
1968 Johnson Caprice & trailer without brakes: 122# - 175#

NOTE: The hitch loads shown on the trailer capacity plates are somewhat less and are intended for use with heavy duty frame mounted hitches. They should be increased when a weight distributing hitch is used.

Particularly in the case of our 19 footer, 222# to 318# carried on a standard frame type hitch, over taxes the rear suspension of an average towing vehicle to a very unsatisfactory condition.

Now available on most current automobiles is an optional "Trailer Towing Package". Even though heavy duty springs and shock absorbers are part of this equipment and will greatly improve the ability of the vehicle to handle trailers satisfactorily, the rear suspension still receives most or all of the added weight of the trailer, unless a weight distribution type hitch is used.

Based on the above table of recommended hitch weights for various Johnson rigs, the proper hitch to be used can be ascertained from

PAGE 2 SERVICE BULLETIN DL-#109B
JOHNSON MOTORS, DIVISION OF OUTBOARD MARINE CORPORATION, WAUKEGAN, ILLINOIS 60085

the following table which was established by the Society of Automotive Engineers.

PERMISSABLE VERTICAL TONGUE LOAD WEIGHTS
CORRELATED WITH RECOMMENDED TYPES OF HITCHES

CLASS TRAILER	MAXIMUM GROSS TRAILER WEIGHT	MINIMUM TONGUE LOAD	MAXIMUM TONGUE LOAD	RECOMMENDED TYPE OF HITCH
1	UP TO 2000 LBS.	40	80	BUMPER HITCH
		50	200	FRAME HITCH
		150	300	WEIGHT DIST. HITCH
2	2000 TO 3500 LBS.	100	200	FRAME HITCH
		200	500	WEIGHT DIST. HITCH
3	3500 TO 5000 LBS.	210	700	WEIGHT DIST. HITCH
4	5000 TO 10,000 LBS.	6% GTW	12% GTW	WEIGHT DIST. HITCH

Using the Johnson Surfer & trailer as an example, the gross combined weight is approximately 3175# and the recommended hitch weight is 222# - 318#. Accordingly, the towing vehicle should be equipped with a weight distribution hitch.

The weight distribution hitch, although more costly than bumper or frame types, pays for itself in comfort of ride and assurance of safety. Reese Products, Inc. of Elkhart, Indiana, as an example, has recently introduced a single spring bar equalizing hitch for under $50.00. Approximate cost to install such a hitch is around $25.00. A small investment in this writer's opinion to insure the safety of a $6,000.00 rig plus your own safety and the well being of others on the highway.

In closing, it is appropriate to acknowledge the fact that several automobile manufacturers now stipulate in their new car warranty the necessity of utilizing proper hitch installations in order to maintain a valid warranty.

JOHNSON MOTORS

Carl Klawonn

Administrative Assistant

CK/krm