Our Mustang II springs come in rates from 275 thru 425 and in 13.5” free height/length. They will require cutting to the necessary length on the majority of applications. For the heavier vehicles such as full size pickup trucks and fat fendered cars the spring rate used will normally be in the 350-400 range. With Small Block and automatic a common rate is 375 to 400 and with the addition of A/C or a big block you will need to compensate for the additional weight and go to the next higher rate. Frame boxing and plating, accessories, and fuel tank size all play a part in selecting spring rate. When vehicle is sitting at ride height ready for test drive the lower control arms should be parallel with the ground or pointing down at a slight angle on the outer ends. The springs will settle some in the first couple of hundred miles so allowance for this should be made.
Use the following chart to select your rate:
Our Mustang II springs that we currently offer are all 13.5” long and require trimming to the length needed for each individual application. Weight rating changes as the spring is shortened. When installing in the vehicle the flat end goes up into the upper hat and the end with the “pigtail” goes down into the lower control arm. Spring is rotated when installing to position the pigtail properly. Springs TOO long will have a tendency to NOT sit properly on the lower arms and actually in some cases bow outward causing spring bind.
Specs Material Type Steel Sold in Quantity Pair Finish Powder Coated Color Black Coil Spring End (A) Square Coil Spring End (B) Pigtail Progressive Rate Spring No Free Height 13.5 Inside Diameter 3.5 Position Front Wire Diameter 0.56 Diameter Big End 4.6 Diameter Small End 4.6 Spring Rate 275 Spring Rate Range 200 - 299 lbs. MFG. Part # 917230-275 Reviews I would buy the 400 lb rated next time Rated by Dave on January 03, 2022Summary: Worked great in a 55 Chevy 2nd series truck with MII front. Next time I would do a 400lb for a softer ride. I hade to cut the spring a little to get the right ride height.
yes Rated by dave T Bucket on December 14, 2021Summary: did away with my coil over shocks, and went back to reg, shocks and springs. rides grate
Pros: worked grate
Yes, I recommend this product.
Great product Rated by Tracy Hunter on October 06, 2021Summary: Used them on s10 with mustang 11 front end
Cons: None
Yes, I recommend this product.
Would buy again Rated by Zeke on July 28, 2021Summary: I bought these to replace the lowered springs I installed years ago to hopefully improve the handling and ride. I cut the Max 2 inches of the coil and it gave my 38 Ford a nice stance. Waiting for springs to finish settling to see the final height.
Yes, I recommend this product.
Would buy again Rated by Hair Lip on July 15, 2021Summary: fit as promised
Yes, I recommend this product.
Related Items / Suggested Parts Speedway Mustang II Coil Spring Rubber Isolator Cushion Pro Shocks® SM400 Chrome Mustang II Replacement Shock Speedway Motors Mustang II Front Shocks Tech Support We're here to help before and after your purchase. If you have a question or need assistance with one of our products, please contact us through Messaging and a knowledgeable Speedway Motors team member will be happy to help. About Speedway Motors is America’s Oldest Speed Shop® and has been a trusted source for specialty rodding and racing products and friendly expert advice for more than 72 years. Founded in 1952 by “Speedy” Bill Smith – a racer and street rodder himself – Speedway has grown from a one-man operation to become the world’s largest manufacturer, distributor and retailer of street rod and racing products. Our industry-leading fast delivery is the result of same-day shipping from our state-of-the-art, centrally located 500,000 sq. ft. headquarters. Speedway’s size offers customers unmatched product selection and low pricing, while our excellent technical support and customer service have made us a recognized leader in the rodding and racing industries.