practice

Observations on leaf spring repairs

The most often needed spring repairs that we have seen in our shop in the past fifteen years are to the three inch wide rear springs found on Ford "F" series pickup trucks. The two stage leaf spring assembly is prone to breaking the second and third leaves, counting top down, but not the main nor the heavy secondary plate. Due to the low replacement cost of the assembly we find it easier, and better by far, to sell a complete replacement of both rear springs instead of just the broken plates. This approach will insure the truck owner of a balanced end result at not too high a cost.

Since the models came out in 1988, K and C series Chevrolet pickups using the increased length two and a half inch steel springs on the rear have had a high incidence of failure in the intermediate leaves. This spring is repaired more often than replaced due to high cost. Our shop fits the repair leaves properly in arch and thickness, and makes sure tip insulators and bolt style clips are used in the job. Often an additional leaf is recommended to be inserted in the assembly once the loading of the truck is found out and this too is prepared correctly. Now this sort of care is commonly overlooked by facilities not in the business of leaf spring work and unpleasant results will come about, noises and shortened repair life to name two.

Toyota Tacoma models of both 2WD and 4WD starting at the beginning of this line have had a lightly designed rear leaf spring assembly most likely for ride characteristic that has shocked some owners when given a moderate load to carry. An additional leaf will cure the sagging vehicle although in some cases two leaves are better. Metric dimension tempered plate is used in the original spring of course but standard width, usually 2-1/4", plate can be used without adverse result. Here again proper fitting for arch and the use of tip insulators give the best performance. We are just beginning to have repeat customers who had their Tacoma vehicles reinforced when new back for repairs after six or seven years of service and they report a satisfactory load carrying history.

Having beat the subject to death on other pages, I'll kick it one more time here. U-Bolt selection and installation is critical in spring repair. Namby-pamby tightening with an open end wrench just won't cut it. Don't undertighten a U-Bolt. Check out our chart for tightening torques and reef 'em.

Here in Vermont we have encountered another unusual problem which may or may not happen anywhere else that results from undercoating vehicles with lube oil to prevent rust. Road salt will rust out a rig in five years if no undercoating is applied and lube oil is the cheapest by far. You have to reapply each year though! The problem comes from the oil sprayed on the springs and axle. If there is any looseness whatsoever at the U-bolt/axle junction before the oil goes on, afterwards everything just slips apart! We have had many customers come in after an oil undercoating job with their axle just floating around, the centerbolt broken and the spring leaves splayed out. The cure is a new centerbolt and new, fully tightened, U-bolts. The oil won't hurt the springs and will keep them from rusting too.

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