Renault 21 Saloon & Estate Brake Wheel Cylinder, Left Side – 7701032318

CM246

Item	Detail
Application	Renault 21 (B48_), Renault 21 Estate (K48_), Renault 21 Saloon (L48_)
Side	Left
OE No.	77 01 032 318, 77 01 067 936
Other Reference	CR.618 I
Bore Diameter	22.22mm
Mounting Size	Φ31.8/25/2-M6x1
Port/Connecting Size	M10 x 1.0, M7 x 1
Matching Right-Side Part	XUI2828A-R (OE 77 01 032 319 / 77 01 067 937)
Packaging	Neutral box or custom OEM/ODM branding
Certifications	ISO 9001, IATF 16949, VDA6

Left and Right: Why This Part Comes as a Pair
Drum brake systems use two separate wheel cylinders per axle — one mounted on each side — and on the Renault 21, these are mirror-image parts rather than identical interchangeable units. The XUI2828A-L is the left-side wheel cylinder; its counterpart, the XUI2828A-R, is the right-side unit. The two share identical specifications (22.22mm bore, Φ31.8/25/2-M6x1 mounting, dual M10x1.0/M7x1 ports) but are built as mirrored components so the bleed valve, piston travel and mounting orientation match the brake shoe geometry on their respective side of the axle. Installing a left-side cylinder on the right side, or vice versa, will not seat correctly against the brake shoes even though the bore and thread specifications are identical.
This is reflected directly in the OE numbering: 77 01 032 318 (left) sits one digit apart from 032319 (right), and 77 01 067 936 (left) sits one digit from 067937 (right) — Renault assigned sequential part numbers to the left/right pair, which is common practice across most OE catalogs for mirrored brake components. The CR.618 I aftermarket reference follows the same left-designation logic as CR.618 D does for the right side.

Ordering the Correct Side
For workshops and distributors, the practical takeaway is that a full rear drum brake service on the Renault 21 normally requires both the XUI2828A-L and XUI2828A-R — not one or the other. Distributors stocking this part should carry both references together rather than assuming a single SKU covers the full repair, since a customer replacing a leaking or seized wheel cylinder on one side will frequently need the matching side replaced shortly after due to similar wear patterns and fluid contamination risk across the shared brake circuit.

Same Platform Logic as the Right-Side Part
As with its right-side counterpart, this wheel cylinder fits the Renault 21 saloon (L48_), estate (K48_) and the B48_ chassis code spanning 1986 to 1997 production — a vehicle line that has had no factory parts supply for roughly three decades, making aftermarket manufacturing the only ongoing source for this component.

Who Stocks This Part
Buyers are the same specialist suppliers and classic Renault parts distributors who stock the right-side equivalent — typically operating in pairs rather than as a standalone line item. Distributors building a Renault 21 brake parts range should list the left and right cylinders as a matched set in their catalog, since most workshop orders for this vehicle request both sides together for a complete rear brake service rather than a single-side repair.
OEM/ODM private label packaging available for distributors building a matched left/right brake parts catalog.

Confirming Left vs Right Before Ordering
Side designation on drum brake wheel cylinders is determined from the driver's perspective sitting in the vehicle, which can vary by labeling convention between suppliers. If a customer's existing part is unmarked or the side is unclear, the safest method is to confirm against the OE number stamped on the original cylinder rather than relying on "left" or "right" terminology alone, since conventions occasionally differ between European and other regional catalog systems.

Q1: Can I order just the left-side XUI2828A-L, or do I need both sides?
A full rear brake service on the Renault 21 typically requires both the left (XUI2828A-L) and right (XUI2828A-R) cylinders. Ordering only one side is uncommon and usually only appropriate when the matching side was replaced recently.

Q2: What is actually different between the left and right wheel cylinder if the bore and mounting size are identical?
The bore diameter and thread specifications are the same, but the two parts are mirrored — bleed valve position and mounting orientation are reversed to match the brake shoe layout on each side of the axle. They are not interchangeable despite sharing the same core dimensions.

Q3: How do I know if my existing wheel cylinder is left or right if it isn't labeled?
Confirm against the OE number stamped on the original part: 77 01 032 318 or 77 01 067 936 indicates left side, while 77 01 032 319 or 77 01 067 937 indicates right side.

Q4: Why are the OE numbers so close together — 318 and 319, 936 and 937?
Renault assigned sequential part numbers to left/right mirrored pairs, a common numbering convention across most OE catalogs for symmetrical brake components.

Q5: Can this be supplied under our own brand packaging as a matched left/right set?
Yes. Custom packaging, label printing and logo branding are available for OEM/ODM bulk orders, including matched-pair packaging.