NB Miata Built 5 Speed Transmission
NB Miata Built 5 Speed Transmission
Sale Sold out
Regular price $1,298.00 USD
Regular priceUnit price per
Current lead time is 8 weeks on all built transmissions. Please note that lead time is the approximate time that we will start on your order regardless of the time that your order is placed or when your transmission you shipped to us arrives. The lead time for your transmission begins when the order has been placed.
The 5 Speed is a popular option for racers, as it allows a higher speed in each gear, and less shifting. Until recently, the 5 speed transmission was only an option for low power builds that don't include power adders, and would start to fail around 220-250hp. We've addressed these issues, and built 5 speed transmissions that are handling 300+ hp! Now you can enjoy taller ratios and higher speed per gear on your higher power builds, and race cars. NOTE: We originally developed these boxes to handle the abuse of road racing on slicks and have successfully done that and only recently have been testing the power capacities. 300-320hp are what our high horsepower testers are putting down in their cars with stage 2 boxes. We are still working on actual claim numbers, but want more testing done to verify claims. We will update this info as soon as we get some results.
Currently, we provide three options for the NB 5 Speed transmission builds. Prices listed include a useable core exchange or rebuilding your current transmission. A core charge of $600 is applied in addition if no core is provided.
NOTE: DUE TO THE WEAKER GEAR SET AND OTHER INTERNALS OF THE 1.6 TRANS, 1.6 CORES WILL NOT BE ACCEPTED FOR REBUILD. If you currently have a 1.6 core, you must select no core, and pay the core charge, and you will receive an updated transmission built with a 1.8 core. For more information, see our article on the differences. You can identify if you have an older 1.6 transmission case by the iron input shaft cover. At this time we cannot offer any core credit for 1.6 Transmissions.
Stock Rebuild - $1298 plus shipping
Stage 1 - $1455 plus shipping
Stage 2 - $1905 plus shipping
Stage 3- $ 3250 Plus shipping
Option - Carbon/Moly Synchros Add $200
Stock Rebuild: Rebuilt and blueprinted to our spec to increase cooling, efficiency, and improved longevity over building to stock specs.
Stage 1: Includes everything in the stock rebuild, but built using hardened case studs for increased clamping force that helps maintain gear stack settings.
Stage 2: Highly recommended for racing/track applications using an aftermarket limited slip and or using slicks, for higher powered applications, and for applications using a lightweight flywheel and/or and unsprung clutch disk. Note: We do not recommend the use of lightweight flywheels and unsprung clutch disks. Both severely increase shock loads on the gear train with little to no measurable increases in performance.
-Gearboxes are completely torn down, go through an extremely detailed qualification process, cleaned, and rebuilt, replacing seals, synchros, any failing gears/parts and are built with upgraded bearings.
-Modifications are done to improve oiling and cooling of problem areas.
-Machining is done to gear engagement teeth to improve gear engagement feel. Most race boxes get different engagement teeth timing to improve ability to shift for specific gears, so racing style and applications are important to disclose prior to rebuilds.
-Gear tooth machining to reduce temps, noise, and improve oil evacuation.
-Shift-bias modification for better shift feel and help to ensure proper gear engagement.
-Upgraded bearings to handle higher performance and higher speed applications.
-Gearboxes are built using hardened studs versus bolts. This provides a stronger and more reliable clamping force of the transmission case which results in maintained gear alignment and dynamics creating a stronger, higher power capacity transmission that will last longer.
-Cryo treated gears for up to double the gear strength. Not to be confused with double the horsepower capacity of the box itself, but in general, gear steel itself can have its strength almost doubled with cryogenic treatment depending on initial gear steel quality according to cryo machine manufactures and metallurgists.
-Partial break in on a bench dyno for verification.
Stage 3: Highly recommended for endurance racing, sprint racing, and boosted applications.
Includes everything from stage 2.
-Mazda Motorsports custom gearset that replaces the following:
5th Gear Pair
Splined countershaft reinforcement collar
5th gear thrust washer
The gearset has been designed to increase oiling throughout the transmission and to handle higher shock loads. The gearset is made from higher strength steel alloy than the stock gears.
Upgrade with Carbon/moly synchros will last longer than brass, shift faster than brass, and are compatible with many more types of fluid.
Please note these transmissions are built to order, and as such, they come with a lead time of about 1 month. If you will not be providing a working transmission to be rebuilt, please select the 'no core' option when purchasing. If you are providing a core, you will be responsible for shipping or delivering the transmission to our shop before we will ship the built transmission out. If you would like to receive a transmission before you ship your existing transmission, you will have to select the 'no core' option. Once the new transmission is installed, please contact us to arrange a core charge refund. We reserve the right to adjust the core price depending on condition of transmission. While most transmissions that are replaced in working condition will receive the full core refund, transmissions with sheared teeth, or other catastrophic damage will be refunded at a reduce value.
We recommend using Motorcraft XT-M5-QS Transmission fluid, and running the fluid for 1000 miles before flushing it and replacing the fluid. Transmission holds 1.9 Quarts of fluid, so the 4 quarts is enough to preform both initial break in, and refill after 1000 miles.
PLEASE NOTE: Transmissions must be drained of fluid before sending in for repair or core charge. A $25 clean up fee will be charged if the transmission arrives full of fluid. Core return must arrive at Walter Motorsports no longer than 30 days after shipment of built transmission to be eligible for core charge refund. Cores received later than 30 days after shipment of built transmission will not be eligible for core charge refunds. Please reach out to us directly with any questions about this policy.
In order to ensure the best results, please follow our Transmission Break in Best Practices
Note: All transmissions are shipped in an igloo cooler which is charged to the customer. This is the most secure method we have found to ship transmissions without damage. Please keep the cooler to send the transmission back for refreshes or rebuild in the future.