FAQ

A: While experienced DIY enthusiasts can install them (they’re direct bolt-on for most BMW M models), we strongly recommend professional installation by a qualified mechanic or BMW specialist. Torque specs provided must be followed—never use impact tools on discs and caliper brackets. Proper installation is critical for safety.

• Street/spirited driving: EBC Bluestuff or Ferodo DS2500—these offer excellent cold bite, low noise/dust, and good modulation without being too aggressive.
• Track/aggressive use: EBC RP-X/SR11, Ferodo DS1.11/DSUNO, Pagid RS29, or similar race compounds for consistent high-temperature performance and fade resistance.

We stock or can source pads matched to your caliper (CP9660, CP9668, or CP9449 pad shapes). Always match pads to your primary use—track pads will be noisy/dusty on the street.

A: Our kits are torque-matched to OEM specs for balanced bias. AP calipers will improve pedal feel due to the stiff design and anti-knockback springs. You get firmer, more consistent response with less fade. Proper bleeding and bedding are key for optimal feel.

A: Up to 15kg for our F8X front kit depending on your current setup. If coming from the standard blue calipers with 380x30mm discs, expect a weight saving of approximately 4.5kg. If you're currently running the 2NH 400x36mm setup, expect a saving of around 15kg.

A: Depending on region, AP Racing Pro 5000 R calipers my not be homologated for street use, however with street-friendly pads (e.g., Ferodo DS2500) they are perfectly suitable. They offer better modulation and heat tolerance than stock, but expect more dust/noise with aggressive compounds.

They will not be as quiet/low-maintenance as OEM for daily driving. We would always recommend using our anti-rattle clips (available here) to reduce pad knock/noise.

Pro 5000 R calipers also do not have dust boots so will require more maintenance if driven in harsh environments. When changing pads, always clean the pistons before pushing back in to avoid damage to the seals.

A: Genuine AP Racing Radi-CAL calipers use aerospace-grade materials, proper piston sizing and proven endurance designs. Cheaper kits often use mismatched or low-quality parts that fail with heat or offer poor modulation. We focus on safety, longevity and real performance gains—we offer premium kits without the premium price tag.

A: Yes, significantly for most drivers. Our AP Racing kits reduce unsprung weight (by up to 15kg per axle), provide better heat dissipation, stronger bite, and more consistent pedal feel under heavy use. This means less fade, better trail-braking and more confidence—often translating to much faster lap times depending on the car, driver skill and track.

A: Yes, we can ship worldwide from the UK. International customers are responsible for any import duties, VAT, or customs fees. Contact us for a shipping quote to your location. Over the next few months additional regions will be added for direct checkout.

A: Most UK orders ship within 1–3 business days (The majority of RennStop products are kept in stock) and arrive in 1–2 days via tracked courier. Made-to-order or custom items may take 7–14 days. We have added estimated chip dates to all items and aim to ship before the date given. Just get in touch if you need a more accurate date.

A: Please see our returns policy here. As some components are supplied/manufactured to order, we may charge a re-stocking fee. If you contact us before ordering, we can make sure that you order the correct parts/kit for your application.

A: Popular components are held in stock for fast shipping. Kits are assembled to order (typically with a 7–21 days lead time). Product pages indicate an estimated ship date, but feel free to email for current availability.

A: AP Racing dominates motorsport (F1, endurance racing) for lightweight design, fade resistance and pad/disc availability. Our custom kits for BMW M cars offer superior heat management and unsprung weight savings compared to many alternatives—perfect for serious track enthusiasts.

A: We’re proudly based in the beautiful Cotswolds, UK—right in the heart of some of the country’s best driving roads!

A: Absolutely. Every kit includes detailed installation instructions. We always recommend professional fitting, but we’re here for ongoing support—whether it’s troubleshooting, recommending spares, pads, or setup advice. Just email sales@rennstop.com or reach out via our contact form.

A:Yes, we can offer custom colours for all anodised parts with a 2-4 week lead time. We will also consider requests for new platforms or take on custom design / manufacturing projects. Just get in touch at sales@rennstop.com to discuss.

A: We don’t currently have a public showroom or walk-in facility, but we’re fully committed to customer support. Drop us a line at sales@rennstop.com with any questions—we respond quickly and love helping fellow BMW enthusiasts get the most from their AP Racing upgrades.