|The MGA With An Attitude
REBOUND STRAPS, Form Follows Function -- RS-110
Rebound straps on the rear axle serve to limit downward motion of the axle. This is intended to catch the axle when the car goes airborne, or when it may encounter a sudden steering transition that causes excess body roll. The axle must not be allowed to drop so low as to hit end of travel of the shock absorbers or to land on the exhaust pipe.
Photo at right is compliments of David Brown in Hampshire, UK. This is his 1959 MGA with original issue rebound straps. This may be the only MGA in existence having original rebound straps that are still in serviceable condition 55 years on. Mine were in tatters after 20 years.
Below is another example of original rebound straps, removed from an MGA 1600 by Don Tremblay, Rutland, USA
Original rebound straps were made of thick woven cotton web strap, looped and heavily stitched at the ends. These were originally plenty strong to serve the purpose for many years, but they were also prone to rot with time and would ultimately break. Life expectancy of the original web straps was maybe 10 years if the car was driven regularly and parked outside. In those days cars were expected last perhaps 10 years before being retired, so the old technology was not so bad in its time. The ultimate failure could be either a break in the center or a split out at one end. Any MGA today either has already had these original straps replaced or needs to have them replaced.
For decades (at least since 1977) the replacement parts have been fabricated with similar web strap but also molded with a heavy rubber jacket for environmental protection and durability. I have a set of these on my car, installed in 1977, on the road since 1986, more than a quarter century and a quarter million miles with no problems. I extend congratulations to Moss Motors USA for supplying very good parts in 1977.
However, .... Some recent issue parts are much weaker. These are made with much thinner webbing, and the thick rubber cannot make up for the lost strength. For an extensive report on the long term continuation of such Faulty Parts, see article FT-023
Some of these recent straps stretch dramatically when loaded, and return to original length when unloaded, like a useless rubber band. Others may break immediately, as soon a the normal leaf spring load is applied with a suspended rear axle, or they may break within 24 hours sitting in the shop, or they may break during the first drive. All of this is of course entirely unacceptable. Many complaints have been sent to the suppliers in person or via various BBS, many faulty parts have been returned, but the faulty parts supply seems to continue regardless.
Until the suppliers can get this sorted out and produce rebound straps that actually work, there are not many alternatives. There is one supplier selling blue woven nylon web straps on eBay that look a bit like lawn chair parts, but people who have used them report that these parts actually work. I hate the idea, but in light of the current situation you might try these parts, as I currently have no reasonable suggestion for original style parts. - Sept 24, 2013.
Since form follows function, and beauty is in the eye of the beholder, I think they are just beautiful parts. My worry about this is that the standard Brit car parts suppliers might pick up on the trend and start selling the nylon web straps as regular replacement parts. Next thing you know, thousands of cars would be wearing these strange parts, there may be no alternative, it becomes the de facto standard, and folks with interest in originality are permanently out of luck. Come to think of it, seems like it has been that way for several years already.
Addendum, December 2013:
Moss Motors has recently had these parts remanufactured to their order. Parts in the following picture (from Moss Motors Ltd, UK) were selected for photo specifically because they have some of the webbing showing at the edges.
I don't have any test result information, and no field reports, but also no known complaints as yet. Fingers crossed, as this is the only source I know that may have serviceable rebound straps for MGA. The same parts should be available from Moss UK and Moss USA.
Addendum May-June-July 2016:
New rebound straps purchased October 2014, installed May 3, 2016. Photo here shows 30-year old replacement parts in relatively good serviceable condition, and the new replacement parts.
New straps are 8-3/4" center to center as original. Old straps are 9" center to center after 30 years and 330,000 miles in service. The original type parts are heavy web straps coated with thin rubber for environmental protection, and they do not scretch.
New leaf springs installed June 8, 2016. The replacement rebound straps installed a month earlier are worthless. When the axle was lowered the straps stretched like soft rubber bands from 9" to 10-1/2" long until shock absorbers hit end of travel. Bummer.
Installed freshly rebuilt rear shock absorbers June 18, 2016. Now the issue of bad reound straps just became critical and urgent. July 3 2016, installed new latest issue rebound straps from Moss Motors. When the axle was allowed to drop the straps stretched from 8-3/4" to 9-5/8" with almost 1 inch stretch. This is not even with dynamic bounce conditions, just gentle lowering of the floor jack. While this is not as bad as the prior issue straps, it is still unacceptable (and I suspect they will stretch more with use). So this is not the end of the story, as better parts must be found.
Addendum, July 26, 2016: Just 3500 miles of all paved roads, changed the straps again. The most current issue three week old straps from Moss Motors were badly stretched and broken at one end, so off to the dust bin.
This time some friends in New Zeland who make their own have sent me a pair of synthetic web straps. The eye ends are lined with truck air brake hose for the heavy bushings. They are indeed quite substantial, and look like they will handle the job nicely. It was a quick change.
See article RS-113 for more details on these new GOOD parts.