AST 4100 String Theory Signature Series Coilover Suspension Kit Toyota GR Yaris Mk1

AST 4100 String Theory Signature Series Height Adjustable Coilover Suspension Kit for Toyota GR Yaris Mk1

Elevate your driving experience with our AST 4100 Signature Series Coilover Suspension Kit, developed in collaboration between ourselves and AST Suspension. 

We've worked closely with AST Suspension NL to hone in on the ultimate no compromise suspension kit for the GR Yaris, providing more bump travel for road use, vastly improved damping performance and a useful range of damper adjustment to allow both comfortable, refined road use and focused on track performance.

The AST 4100 1-way adjustable kit very specifically features non-inverted dampers for maximum reliability and longevity, the goal with our bespoke GR Yaris kit was to create a pure upgrade for GR Yaris without any reduction of reliability or usability. The reliable non-inverted monotube design offers an incredibly long service life, while still being fully serviceable. The dampers maintain factory wheel travel but with 20mm shorter bodies, providing the maximum possible bump travel. This allows the car to conform to the road in a way unlike any other coilover kit on the market. Sensible spring rates allow stunning British B road performance while offering excellent support on track. For more focused applications, these spring rates used in combination with a set of uprated anti-roll bars offers a proper Porsche GT-car like experience. Whether you're taking your GR flat out around the Green Hell, heading off to the Welsh countryside on a blast, or touring Europe with your family, this kit fits the bill.

The AST 4100 Series shock absorbers use monotube technology, offering enhanced performance over conventional twin-tube designs. The floating piston design effectively separates gas pressure, eliminating cavitation and ensuring a consistently smooth ride, even in the most demanding conditions.

With easily accessible single-adjustable dampers, fine-tuning your suspension setup has never been easier. 2-way or 3-way adjustable kits are all very well and good, but 99% of end users never adjust them or get lost and confused by the multiple possibilities. These top tier single adjustable dampers provide all the range of adjustment most people could ever desire without any confusion. 12 positions from soft to stiff, they work perfectly at full soft and at full stiff, simply adjust to your preference and drive!

Technical specifications:

• 50n/mm front springs, 60n/mm rear springs in stock location (OEM Toyota is 35n/mm front and rear, String Theory Spring kit is 40n/mm front, 44n/mm rear)
• Developed for ride height range between -15mm to -45mm from stock.
• Single adjustable damper with simple 12 position adjustment, softer for road use, stiffer for track! Easily accessible from the engine bay and under the car on the rear.
• 22mm shaft diameter non-inverted front strut / 14mm shaft diameter upside-down rear shock. 20mm shorter bodies than OEM Toyota, same travel as OEM Toyota.
• Fully rebuildable and serviceable.

Professional Fitting Services:

We offer full fitting with ride-height, corner balancing, and geometry setup. To schedule your appointment, select the fitting option from the drop-down menu and choose “Collection/Fitting from String Theory” as your delivery method at checkout. We’ll be in touch to finalise your booking.

We take pride in our partnership with AST Suspension. If you are unable to locate the specific AST product you’re looking for, please don’t hesitate to get in touch. We are happy to supply any product from the AST or Moton range along with bespoke solutions for most applications.