Fees, Assembly and Repair

Diff Lab provides competitive pricing on assembly. Often the cost of assembling a differential plus freight to and from Diff Lab in Brisbane is equal to the cost to build a differential locally. As it usually won't cost you any more, there is no reason why you can't have the very best differential assembly for your vehicle.

Work Priority

Diff Lab exists primarily to serve the amateur and semi-professional motor racing community. These customers have priority over customers seeking repairs for road vehicle driveline components. Road vehicle differentials will be moved down the queue if there are upcoming motor racing events and differentials are needed for these events. Diff Lab can service and upgrade components for road vehicles when time permits. Delivery times can be guaranteed for race events. Delivery times for road vehicles cannot be guaranteed.

Regarding quotes:

Diff Lab does not disassemble differentials and provide free quotes on repairs. Due to a heavy workload Diff Lab can provide a rebuild of the differential only. Diff Lab can only work on differentials as a paid job, and never to quote on repairs. A complete rebuild is the only service available for a damaged or noisy differential. Partial rebuilds, and quotes on repairs are not available. The owner of the differential understands that if a differential is sent to Diff Lab, a fully repaired differential will be provided in return and priced accordingly as per the customer's requirements. The customer has access to all of Diff Lab's pricing online, and work will proceed. Customers who are receiving a full rebuild are aware of this before sending in the differential. All items in need of remedy are remedied to the highest standard. Work will not be performed any other way. Customers should not send in a differential if they do not want it repaired. Customers seeking to send in a diff and receive a quote only, should go elsewhere. Diff Lab will quote on a complete job only, and will have to make certain assumptions about the condition of the differential. Generally there are no surprises and the amount charged is the same as the quoted price. If there is a major discrepancy between the quoted rebuild price and the estimated final cost (for example, the differential has a broken carrier, or broken gears), the customer will be notified. In rare situations like this, where the customer has received bad news that the differential rebuild is not possible, or will be cost prohibitive, Diff Lab may opt to waive all costs and dispose of the differential.

Regarding exchange differentials:

Diff Lab performs all work on the original differential, or on exchange. Exchange differentials are provided at Diff Lab's discretion. If the original differential cannot be repaired, an exchange differential may be supplied. The broken differential is not returned to the customer. There will never be a scenario whereby a customer orders differential repairs, and receives two differentials back. The customer will receive an exchange or repaired differential only, and not the broken differential, or the remnants of a broken differential. The customer is aware of this before sending a differential to Diff Lab, and has no rights to receive two differentials back when they supplied only one. If a used differential is supplied, the broken differential is not returned to the customer. This is common practice and should not come as a surprise.

Exchange differentials are to be returned within 14 days from the date on the invoice pertaining to that exchange unit, with strictly no exceptions. After 30 days, the customer now owns the differential, and Diff Lab does not need it back. The customer's deposit will be used to replace the differential which was not returned in a timely manner. If the customer returns the differential after 30 days, it will sit in storage until it is claimed by the customer, up to 60 days, then discarded. There will be no core refund given in this instance, because the customer has forced Diff Lab to replace it, to ensure business continuity, versus taking civil legal action against the customer for loss of income and productivity from failing to return an exchange unit which is needed for the business's ongoing operations. We trust that the customer understands the importance of returning exchange units in a timely manner. The customer has the privilege of exchange units because others have done the right thing. If all customers failed to return them, there would be no exchange units available.

Diff Lab does not pay for freight for exchange differentials. The customers is responsible for all freight costs on exchange differentials. Diff Lab can organise freight.

Fully refundable deposits for exchange diffs are as follows:

E30/E36 188mm: $700

E36/E39 M3/M5 210mm $3000

E46 M3 $1000

E46 188K: $300

E90 168/188LW: $500

E90 215LW 135i/335i/140i $1000

E90 M3 / E60 M5 $1500

F-series non-M: $500

F-series M: $1500

There are no deposits payable for exchange differentials supplied to partner workshops. If a workshop is known to Diff Lab and a relationship exists, Diff lab may waive the exchange deposit for other workshops which are not official partners. Home addresses and customer's businesses are not partners, nor known to Diff Lab and will attract an exchange deposit. 100% of the deposit is returned if the exchange unit is returned within 14 days.

Exchange Diff Procedure:

  1. Drain the old differential thoroughly while it is still installed in the vehicle.
  2. Remove the old differential, soak in degreaser and pressure wash.
  3. (Finned differentials only) Remove the rear cover and install onto new differential with Loctite grey or blue sealant.
  4. Install new differential and fill with Diff Lab's supplied or recommended oil (most units use 75W140 limited slip). Tighten both plugs.
  5. Completely drain the old differential by placing it upside down, and spray inside with brake cleaner. Allow to dry.
  6. Place old differential into the box supplied, and strap to the pallet supplied. You must return the pallet or you will be charged to replace it.
  7. Return the old differential by TNT only, within 14 days. You can book in online without an account.

Fees for labour are as follows:

Standard Differential Assembly - $499

Differential Assembly with Race Contact Pattern - $599

Differential Assembly where customer supplies 25%-100% of parts - $699

Differential Assembly where a person has already tried their best to DIY, but has fallen hard on their buttocks instead - $ who knows?

Standard Ball Bearing Differential Assembly - $599

Ball Bearing Differential Assembly with Race Contact Pattern $699

LSD Installation only (LSD purchased from Diff Lab) - $199

LSD Installation only (LSD not purchased from Diff Lab) - $399

Differential Ring and Pinion Lapping (takes 1 week) - $199

Rust Removal Acid Wash - $99 (not guaranteed to remove 100% of rust.)

Differential Oil Drain and Disposal - $69

Differential Cleaning - $129

Differential Cleaning of a disgusting mess of filth and horror - At least $129

Differential Disassembly and Disposal - $49

Re-Stocking Fee - 15% of item's listed value

Call out to any location for immediate assistance - at least $199

Differentials which are dirty, oily or greasy will attract a cleaning fee. Differentials which are not drained will attract an oil disposal fee. Differentials which are too rusty to work on require a 24 hour rust removal bath and will attract a fee. If you require the removal of a ring and pinion from a differential this will attract a small disassembly fee. The disassembly fee includes disposal of the case and other items which are unused. Items which are special-ordered at your request and are no longer wanted will attract a 15% re-stocking fee. If you attend the workshop to deliver a differential when I am not present, and demand I attend to hold a discussion, there will be a call out fee. I am not always at the workshop and there are no unplanned visits from customers. Deliveries can be made at any time during business hours whether I am there or not.

Diff Lab offers free packaging for freight, with no handling charges. Differentials are plastic wrapped, bubbled wrapped, with protective foam added on the cooling fins, all free of charge. Diff Lab can organise courier pickups of differentials at no extra charge on top of the freight cost.

Assembly Time:

Custom differentials which require CNC machine work take longer than standard differential builds which don't require CNC machine work. These are 135i Manual, 235i Manual, 335i Manual and 435i Manual. Any other differentials with welded crown gears also have longer lead times. Often these are available on exchange for immediate change-over. If they aren't, they are processed in batches and may take 3-4 weeks before the batch is complete. Diff Lab generally keeps the 188L and 215K sized differentials fitted with Superlock LSDs in stock for immediate exchange. You will be informed up-front if there is no exchange diff available. Once work has begun on your differential, there is no way to re-assemble the unit after the ring gear has been cut off the carrier. Work must proceed with the LSD fitment in order to make the differential functional again. There is no financial compensation available if you decide that you cannot wait for the CNC work to be completed, and your differential is finished.

Noisy Differentials:

Diff Lab's focus is the assembly of racing differentials with custom and aftermarket limited slip units. Diff Lab can repair blown and noisy differentials also, but there is risk carried by the customer in doing so. 168/188/L/LW differentials fitted to 1-series, 2-series and 3-series BMWs may suffer from premature bearing failure, ring and pinion failure, and spider gear failure. Diff Lab can replace the bearings in these units with new OEM parts. The differential may fail again. If the ring and pinion is badly worn, the metal contamination may spoil the new bearings. This is not a manufacturing defect in the bearings. Diff Lab takes no responsibility if the differential suffers bearing failure again. The customer has been warned up-front of the issue, and accepts responsibility for the differential. 188L/LW differentials suffer from premature ball bearing failure, and excessive ring and pinion wear, though not as frequently as the 168L/LW units. It is possible to strengthen only the carrier bearings in these 188LW units with upgraded taper bearings. The problematic pinion ball bearings remain and these are not covered by any kind of warranty if the heavily worn ring and pinion is contaminating the oil. The customer is warned up-front about differentials fitted with ball bearings.

The way to know whether or not a differential has accepted a rebuild (and gear lapping) is to drive the vehicle. It is not possible to test the ring and pinion to determine whether it is going to contaminate the oil again. If a differential has had gear lapping, and becomes noisy again, it may have to be considered not repairable. Diff Lab can offer another rebuild, but it is rarely advised.

At Diff Lab there is no provision for working on vehicles. For diagnosis of noisy differentials it is best to attend one of Diff Lab's partner workshops. Diff Lab accepts responsibility for diagnosis only when performed by a partner workshop.