Why do the GR Supra A90 and BMW Z4 G29 share the same tie rod end part from SPL?

The Toyota GR Supra A90 and BMW Z4 G29 were jointly developed by Toyota and BMW and share the same front suspension architecture, including the tie rod end geometry at the outer knuckle. This shared platform means a single SPL part number covers both cars; the same pivot relocation correction applies to both, and the same OEM part numbers are referenced in each brand's own part catalog.

What does bumpsteer actually feel like from the driver's seat?

Bumpsteer is felt as a pull or twitch in the steering that the driver didn't input; the toe angle is changing as the suspension compresses, which changes the steering angle momentarily. Over a rough surface, this creates a slightly wandering feel at the steering wheel. Under hard braking with simultaneous cornering, it can feel like the front end is doing something unexpected. On a track with curbing, the steering input required to stay on line changes as the front suspension loads and unloads over the kerbs. Correcting bumpsteer removes that unpredictability; the steering responds only to what the driver asks of it.

Will these tie rod ends affect NVH on my street-driven Supra or Z4?

SPL specifically addresses this: these tie rod ends are not a significant NVH contributor. Replacing the factory rubber tie rod end with the SPL spherical bearing unit does not introduce meaningful road noise, harshness, or vibration under normal street conditions. SPL describes them as improving the driving experience by reducing bumpsteer, which is itself a positive change for daily driving as well as track use.

Why does the curved design of the turnbuckle matter on a significantly lowered car?

At significant ride height reductions, the angle between the tie rod and the knuckle at full suspension droop increases. A straight turnbuckle can run out of articulation range at full droop and bind; when that happens, the energy that should be absorbed through free pivot movement is instead transmitted into the inner tie rod as bending stress. Repeated full-droop events on track curbing can bend or break the inner tie rod under those conditions. The curved profile of the SPL turnbuckle is specifically engineered to maintain full articulation through the complete droop range, protecting the inner tie rod regardless of ride height.

What OEM parts do these replace on the Supra and Z4?

On the Toyota side, these replace part numbers 45046-WAA01, 45046-WAA02, 45047-WAA01, and 45047-WAA02. On the BMW side, they replace 32 10 6 887 402, 32 10 6 887 400, 32 10 5 A38 DE6, and 32 10 5 A38 DE8. Note that OEMs update part numbers regularly; this list reflects known numbers at time of publication and may not be complete.

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Description

SPL Parts Adjustable Bumpsteer Tie Rod Ends for G29 BMW Z4 and A90 Toyota GR Supra

The Toyota GR Supra A90 and BMW Z4 G29 share the same front suspension platform, and they share the same bumpsteer problem once the ride height changes. The factory tie rod end pivot point was designed to work with the factory suspension geometry; lower the car, and that relationship changes. As the suspension compresses through bumps, cornering, and braking, the arc of the front lower control arm and the arc described by the tie rod end no longer match. The toe angle changes dynamically as the suspension moves; that’s bumpsteer, and it shows up as unpredictable steering feel over rough roads, shoulder wear on front tires, and instability under hard braking. The SPL TRE G29 addresses that by allowing the tie rod end pivot to be relocated using the included 304 stainless steel 1/8-inch spacers. Moving the pivot corrects the mismatch between the tie rod arc and the suspension arc at the car’s actual ride height; less dynamic toe change through bump and rebound, more predictable steering response, and less front tire shoulder wear. The improvement is measurable in improved lap times and clearly felt on the road, particularly over rough surfaces and track curbing.

Features

Allows front tie rod end pivot relocation via included 304 stainless steel 1/8-inch spacers; corrects bumpsteer resulting from lowered ride height, modified caster, or front lower arm geometry changes
Custom CNC-machined 6061-T6 aluminum curved turnbuckles; curved profile maximizes articulation range and allows full suspension droop travel without binding; prevents inner tie rod bending or failure on significantly lowered cars
7% lighter than OEM at 1.41lbs (0.64 kg) per side; Ti-6Al-4V titanium hardware anodized in blue reduces mass further without compromising clamp strength
Maintenance-free PTFE-lined FK bearings made in the USA; chemically bonded liner; no grease required
304 stainless steel 1/8-inch spacers included for precise incremental pivot relocation
Not a significant NVH contributor; improves driving experience by reducing bumpsteer without introducing noise or harshness

Specifications

Body Material: Gun-drilled 2024-T351 aluminum
Shank: Heat-treated 4340 chromoly with electroless nickel plating
Heim Joint: PTFE-lined FK 3-piece rod end
Spacers: Multiple stainless steel thicknesses for pivot tuning
Origin: Made in the USA

Applications

Toyota GR Supra 2.0: A90 | 2020-present
Toyota GR Supra 3.0: A90, A91 | 2020-present
BMW Z4 sDrive20i: G29 | 2019-present
BMW Z4 sDrive30i: G29 | 2019-present
BMW Z4 M40i: G29 | 2019-present

Notes

Installation Instructions
Several OEM parts are replaced, please contact us with questions
SPL components are made-to-order in the USA; build time will be confirmed at the time of order.

Frequently Asked Questions

Why do the GR Supra A90 and BMW Z4 G29 share the same tie rod end part from SPL? The Toyota GR Supra A90 and BMW Z4 G29 were jointly developed by Toyota and BMW and share the same front suspension architecture, including the tie rod end geometry at the outer knuckle. This shared platform means a single SPL part number covers both cars; the same pivot relocation correction applies to both, and the same OEM part numbers are referenced in each brand’s own part catalog.
What does bumpsteer actually feel like from the driver’s seat? Bumpsteer is felt as a pull or twitch in the steering that the driver didn’t input; the toe angle is changing as the suspension compresses, which changes the steering angle momentarily. Over a rough surface, this creates a slightly wandering feel at the steering wheel. Under hard braking with simultaneous cornering, it can feel like the front end is doing something unexpected. On a track with curbing, the steering input required to stay on line changes as the front suspension loads and unloads over the kerbs. Correcting bumpsteer removes that unpredictability; the steering responds only to what the driver asks of it.
Will these tie rod ends affect NVH on my street-driven Supra or Z4? SPL specifically addresses this: these tie rod ends are not a significant NVH contributor. Replacing the factory rubber tie rod end with the SPL spherical bearing unit does not introduce meaningful road noise, harshness, or vibration under normal street conditions. SPL describes them as improving the driving experience by reducing bumpsteer, which is itself a positive change for daily driving as well as track use.
Why does the curved design of the turnbuckle matter on a significantly lowered car? At significant ride height reductions, the angle between the tie rod and the knuckle at full suspension droop increases. A straight turnbuckle can run out of articulation range at full droop and bind; when that happens, the energy that should be absorbed through free pivot movement is instead transmitted into the inner tie rod as bending stress. Repeated full-droop events on track curbing can bend or break the inner tie rod under those conditions. The curved profile of the SPL turnbuckle is specifically engineered to maintain full articulation through the complete droop range, protecting the inner tie rod regardless of ride height.
What OEM parts do these replace on the Supra and Z4? On the Toyota side, these replace part numbers 45046-WAA01, 45046-WAA02, 45047-WAA01, and 45047-WAA02. On the BMW side, they replace 32 10 6 887 402, 32 10 6 887 400, 32 10 5 A38 DE6, and 32 10 5 A38 DE8. Note that OEMs update part numbers regularly; this list reflects known numbers at time of publication and may not be complete.

About SPL Parts

SPL Parts is a USA-based manufacturer of high-performance suspension components engineered for both professional racing and demanding street applications. Built on the core principles of strength, lightweight construction, low friction, and precision, SPL Parts products deliver the adjustability and alignment performance required by top race teams and discerning enthusiasts alike. Every component is produced using USA-sourced, certified materials and machined by experienced local shops to exacting tolerances. Professional TIG welders ensure maximum weld integrity, while each part is hand-fitted and treated with anti-seize and 3M internal panel coating for lasting protection. SPL Parts conducts all research and development in-house, allowing the team to leverage firsthand product knowledge and deliver unmatched customer support. Their suspension components feature innovative adjuster designs for quicker, more precise alignments, and utilize spherical bearings with Teflon liners that are self-cleaning, self-lubricating, and built for long service life. From concept to assembly, SPL Parts is made with pride in the USA by skilled machinists and welders who are committed to quality, innovation, and performance.

Additional Information

The Bulletproof Automotive website contains many thousands of products purchased in multiple different currencies. All of the prices are entered manually and accurately at the time of entry. Due to the consistently fluctuating international exchange rates, at times prices may not be able to be honored at their original intended rate. We apologize for any inconvenience this may cause, unfortunately our website is unable to compensate dynamically for what can at times be volatile changes in the cost of items due to currency values fluctuating, changes in prices from suppliers, changes in shipping and import duties, and other factors. Rest assured that any order you place on line will be at zero risk to you in this area. If in the event your order cannot be fulfilled at the original intended website price we will offer you a 100% refund, no questions asked. We will continue to do our best to maintain updated prices and we will always continue to offer our price match guarantees as well to ensure our prices are always the best for you. In short, prices may change without notice. It is always advised to give us a call prior to placing your order online to confirm availability and to confirm current pricing.

Shipping Policy

Items that are in stock in the US, either at Bulletproof’s warehouse or at a supplier’s warehouse, are generally delivered within 7-10 days. Special order items from overseas take considerably longer. As a courtesy Bulletproof offers delivery estimates to our customers which take into consideration manufacturer availability and shipping schedule. These estimates represent our best guess based on previous orders from the manufacturer and do not in any way imply a guaranteed delivery window. Many manufacturers work in a “just in time” inventory system and often take 2-20+ weeks to produce an item once an order is submitted. All deliverable items are then sent to our Japanese warehouse. Bulletproof ships a minimum of one full ocean freight container every month from Japan, oftentimes more than one a month. Ocean freight takes an average of 4 weeks. Typically it breaks down to one week in Japan for paperwork and customs, two weeks by boat and one week in US customs/clearance. Due to the wide number of variables between manufacturer and shipping schedules, delivery estimates are simply just that – estimates. We attempt to estimate conservatively and we usually deliver faster than our estimates suggest. It is not Bulletproof’s policy to guarantee delivery time of any special order item, this is impossible for us to do. By ordering you acknowledge that there is no required delivery ETA and an order may not be canceled or altered due to manufacturing or shipping delays, all ETA’s are provided as a best guess only. Please review the full Terms & Conditions here.

BP Pricing Difference

We do pricing a little differently on our JDM brands and we believe in making things simple and clear. No hidden fees or surcharges. Every price you see includes the shipping cost to our office in Los Angeles, California and all the associated taxes/duties/fees for bringing the products into the US. The only shipping you ever pay is from our facility in the US to your location. Be wary of resellers that don’t include the cost of international shipping in their pricing on JDM parts. While we believe we’ll always have the lowest all-in price on JDM products, we offer a price match guarantee for all authentic parts purchased from authorized dealers as well. For many international customers, it’s much more affordable to ship from the USA than from Japan directly, as the air freight and ocean freight costs are typically much less. However, for customers looking to ship directly from Japan outside of North America, or domestically in Japan, we can provide pricing specifically for that scenario. Please do not hesitate to contact us with any pricing questions or concerns. Please email us at sales@bulletproofautomotive.com with any inquiries.

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SPL Parts Adjustable Bumpsteer Tie Rod Ends for G29 BMW Z4 and A90 Toyota GR Supra

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SPL Parts Adjustable Bumpsteer Tie Rod Ends for G29 BMW Z4 and A90 Toyota GR Supra

Features

Specifications

Applications

Notes

Frequently Asked Questions

About SPL Parts

Reviews