Torque Rating Requirements for Installing Leaf Springs on a 7000 lb Tandem Axle Trailer
Question:
What is the torque requirements for all bolts related to the leaf spring on a 7,000 # tandem trailer. U-bolts, shackle bolts, attachment bolts to the frame? Thanks
asked by: Terry B
Expert Reply:
The torque requirements for leaf spring u-bolts depend on the diameter of the u-bolts that are being used. If the gross weight of your tandem axle trailer is 7,000 lbs, then you likely have two 3,500 lb axles. Typically 1/2 inch diameter u-bolts are used with leaf springs for 3,500 lb axles and they have a torque rating of 45 ft/lbs to 70 ft/lbs.
The shackle bolts do not require a specific torque rating because tightening the shackle bolts too much will squeeze the shackle straps against the leaf springs and the whole suspension system will bind and cause problems. The best thing to do when tightening down shackle bolts is to use lock nuts and tighten them until they are snug and then backed off 1/4 turn. Lock nuts should be used because they resist loosening with vibration or torque.
Finally, I strongly recommend welding your leaf spring hangers to your trailer frame. Mounting the hangers with a bolt only will not provide a secure connection between the trailer frame and suspension, even if the bolt is torqued down properly. There are some hangers that come with bolt holes on top, but they should be welded as well as bolted. If you want to use a bolt as well as welding your leaf spring hangers, then you can follow the same torque specs as the leaf spring u-bolts.
A 1/2 inch diameter bolts should be torqued between 45 ft/lbs and 70 ft/lbs. A 9/16 inch diameter bolt should be torqued between 65 ft/lbs and 95 ft/lbs and a 5/8 inch diameter bolt should be torqued between 100 ft/lbs and 120 ft/lbs. I have attached two FAQ articles on trailer suspension for you to check out.
Product Page this Question was Asked From
4-Leaf Double-Eye Spring for 5,000-lb Trailer Axles - 25-1/4" Long
- Trailer Leaf Springs
- Double Eye Springs
- 5000 lbs
- 1-3/4 Inch Wide
- 4 Leaf
- 25-1/4 Inch Long
- Painted
- etrailer
more information >
Continue Researching
- Q&A: Upgraded Equalizer and Replacement Leaf Springs for 2020 Grand Design Transcend 27BHS
- Shop: Suspension Kit for Tandem-Axle Trailers - 1-3/4" Wide Double Eye Springs - 2-1/4" Links
- Shop: Dexter Heavy-Duty Suspension Kit for Tandem-Axle Trailers - 1-3/4" Wide Double Eye Springs
- Q&A: What Are the Torque Specs for Trailer Suspension Parts
- Article: Double-Eye Trailer Suspension System Review
- Shop: Replacement Shackle Strap - 2-5/8" Long
- Shop: Replacement Flange Nut for Dexter Trailer Suspension Kits
- Article: How to Accurately Measure Trailer Leaf Springs
- Shop: Dexter Bronze Bushings - Qty 4
- Article: 5 Tell-Tale Signs It’s Time to Replace Your Trailer’s Leaf Springs
- Shop: Shackle Bolt with Locknut for Double-Eye Springs - 3" Long
- Video: etrailer Trailer Suspension - Leaf Spring Suspension - AP233 Review
- Shop: Curved Equalizer for 1-3/4" Wide Double-Eye Spring - 14-3/4" Long - 9/16" Center Hole
- Q&A: Torque Spec for Tightening Trailer Brake Assemblies to Trailer Spindle
- Article: How to Replace Trailer Leaf Springs in 5 Steps
- Video: etrailer Trailer Axle 4-Leaf Double-Eye Spring Installation - Boat Trailer
- Video: etrailer Electric Trailer Brake Kit Installation
- Video: Review of etrailer Trailer Tie Downs - Recessed D-Ring with Square Holes - RRING-Q6000
- Video: Review of etrailer Trailer Tie Downs - Recessed D-Ring with Round Holes - RRING-R6000
- Q&A: How Often Should Dexter EZ-Flex Equalizers Get Greased
- Search Results: 3500 bearing kit
- Search Results: tandem axle equalizer
- Q&A: Determining Correct Shackle Strap Size for Top Brand Tandem Axle Trailer
- Q&A: Determining If Equa-Flex Equalizers LC314336 Will Fit 2020 Coachmen Freedom Express 257 BHS
- Q&A: Upgrade for Dexter Curved Equalizer 13-142
- Search Results: dexter suspension kits
- Video: Review of Dexter Axle Trailer Leaf Spring Suspension - Equalizers - K13-142-02
- Video: Review of Lippert Replacement 7/16 Inch-20 Flange Nut - LC122103
- Search Results: shackles
- Search Results: bushings trailer leaf spring suspension