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Leaf Springs

Plaza stocks Multi-Leaf Springs, Taper Leaf Springs, Extra Leaves, Spring Pins, Spring pin bushings, Shackle kits, Threaded Rod, U-Bolts, and other bolts and hardware. We can even customize or repair leaf springs for you in our repair shop.
 

Many of the springs stocked by Plaza are full taper springs.  They are used on heavy duty trucks as front springs and in a few tandem 4 spring suspensions. Taper springs will sag as they near the end of their usefl life or occasionally break one of the leaves. 

Volvo 35003-0036 Rear Leaf Spring

Mack Camelback Spring

 
The cracking of one leaf often means that the other leaves are also wearing out and so replacing the entire spring is sometimes more prudent then a temporary repair . However Plaza Fleet’s repair shop can quickly fix any broken multi-leaf or full taper spring.  Service recommendations for taper springs have been provided by Dayton Parts here.
 

 
Good Advice When Repairing Leaf Springs - Do Not Reuse U-Bolts

The purpose of the U-bolt may seem obvious, but there are a couple of maintenance points that are worth mentioning. Obviously, the U-bolt provides the force to clamp the leaf spring and other components together. More specifically, although you expect a leaf spring to be able to flex, the U-bolt is designed to eliminate ALL flexing in the area BETWEEN the two U-bolts. The issue is how to insure this.

Since the clamping force of a U-bolt cannot be measured directly, you use torque to indirectly measure clamping force. Now here is the interesting part.  The relationship between torque and clamping force can be expressed by the formula:  Clamping Force = Torque/(K x Diameter)  (Where K is a measure of the friction between the nut and u-bolt threads)

Looking closely at this formula you should see that friction is the enemy of clamping force. The more friction there is around the threads, the less will be the clamping force. For the same amount of torque, the higher the friction between the nut and threads, the less clamping force that is developed.  Used U-bolts simply offer too much friction. Used U-bolts will have rusted and damaged threads from the previous installation and previously torqued U-bolts will suffer from distorted threads.  The important service recommendation is therefore: 

Do not reuse U-bolts if you want to maintain the required clamping force.

You will find torque recommendations and the full explanation of clamping force and the importance of new U-bolts in this service recommendation by Dayton Parts.  (OK then, if you won't take our word for it, read here what automotive engineers have to say about reusing u-bolts.)

 
Below is a small sample of the many leaf springs that Plaza currently has in stock.

TRA-2728	TRA2728 SPRING LOW ARCH	Binkley SP0356 Hutch pn 356-00
43-434	43-434 SPRING	Ford F2HZ5310M F3HT5310HA 1970-95 52' springs 8,200 lb LN700 Aeromax
43-583	*SPRING T	Ford F2HZ5560C F2HT5560JA 1963-99 3' wide 10,500 lb
43-682	SPRING	Ford F6HZ5310ABA F6HT5310ABA Front 4' wide 8,200 capacity L series 1996-98
43-698	SPRING 18,000 NEW STERLING	Ford Sterling F6HZ5310ACA 54' Multileaf spring, front for Ford L series
46-122	SPRING	Freightliner A16-11812-000 Front 1984-2003 4' wide 6,000 lb FLA FLB FLC FLT FLL
TRA-699	TRA-699 SPRING	Fruehauf UXB000201 3' wide 14,000 lb 49' axle spacing F, FL, J, NF series
59-428	SPRING	Kenworth HK48110-1440 Front 4' wide 64' lg 6,000 lb T400, 450, 600, 660, 800
62-812	SPRING 2QK3333	Mack 2QK3333 Front 3.5' wide 55 1/2' lg 10,000 lb DM, RD8, FDM, LE(U), MR(U)
62-856	2QK3413AP2 SPRING	Mack 2QK3413AP2 Front 3.5' wide 55 1/2' lg 11,500 lb DM, RD8, FDM, LE(U), MR(U)
62-143	SPRING 4QK4004A	Mack 4QK4004A Rear 4' wide Camel Back 38-44,000 lb current production
62-147	SPRING 4QK4005A	Mack 4QK4005A Camelback Spring 4' wide 38-44,000 lb capacity
62-1287	SPRING	Mack 4QK4108M Rear 4' wide Camel Back Spring Suspension 50,000 lb
55-128	SPRING NAVISTAR	Navistar 1660853C91 Front 3' wide 50' lg 3,500 lb 1000, 2000, 4000, 7000, S series
55-154	1661476C91	Navistar 1661476C91 Leaf spring 9,000 Lb through 20,000 Lb axles
55-156	1667482C91 IH SPRING	Navistar 1667482C91 Front 4' wide 6,350 lb models 1000, 2000, 4000, 7000
55-870	55-870 SPRING	Navistar 472620C92  1979-82 Front 4' wide 7,050 lb 5370, 5870, Paystar 5000 series
55-041	SPRING	Navistar 492803C91 1987-09 S series rear single axle 3' wide 8,820 lb
75-178	SPRING	Peterbilt 02-01817 Front, 4' wide 64' lg cast eye 10,500 lb models 320(LCF), 325
83-109	83-109 SPRING	Reyco 08470-01 Truck Model 101 suspension 40,000 lb 50' axle spacing
TRA-2270	TRA-2270 SPRING	Reyco T3564 3' wide 11,000 lb models 21b, 25, 31, 41, 45, 73, 83, 90, 99, 102CC
46-1670	TAPER SPRING	Sterling A16-16405-000 4' wide 54' lg 6,000 lb capacity berlin eyes 1998-2004
96-147	VOLVO SPRING	Volvo 35003-0036 rear single axle 11,500 lb capacity models FE4, FE6, FE7
96-135	96-135 SPRING	Volvo 35003-3206 Rear single axle 3' wide 10,000 lb models FE4, FE6, FE7
96-952	SPRING 371010035	Volvo 37101-0035 1976-03 Autocar 2002-09 Front 4' w. 52 1/2' lg 9,500 lb Expeditor
96-982	TAPER SPRING	Volvo 37101-0058 1976-03 Autocar 2002-09 Front 4' w. 52 1/2' lg 9,500 lb Expeditor