V6 Accord 6MT Transmission Rebuild

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We were recently brought a very rare vehicle, a 2006 Accord EX 4 door with a 6 speed manual transmission. This vehicle was due for a clutch replacement as well as having a 3rd gear grind that had plagued the vehicle for several years. The owner had taken it to the local Honda dealer but the dealer, after twice removing, tearing down, and inspecting the transmission, could not find the source of the issue.

We began by removing the transmission, which is no easy job on this generation Accord. If you have been quoted in excess of $2000 by a dealer to change the clutch on this vehicle, there is good reason. To do this job, 3 of 4 engine mounts been to be removed, the engine must be suspended from above, and the lower front suspension and subframe removed completely. This is just to provide access to the transmission – once that is complete, then it is a fairly straightforward process, much like other front-wheel drive Hondas.

After removing the transmission and opening it up, we were able to identify a fair amount of debris on the internal magnet (considering it had been recently torn down and inspected) as well as in the internal pump filter and inside the case. Typically, when there is an issue with gear grinds during shifting, the issue will be worn synchro sliders or damaged synchronizer rings. Less common are issues with the shifter forks and bearings. All of these items were inspected, and the only issue that could be found was minor wear to the synchronizer ring coated surfaces (this transmission actually uses carbon-coated synchronizer rings, from the factory). This is the sort of item that a factory tech could easily miss, especially given that factory technicians may have never even seen the inside of this transmission type before, given its rarity. This is, however, the sort of thing that Marcucci Motorsports is very familiar with, and we have much experience with.

The transmission components were thoroughly cleaned, all clearances and bearings checked, and reassembled with a new 3rd gear OEM Honda gearset (which includes a new 3rd gear, synchro hub, synchro slider, and synchro rings. Typically, new bearings would be installed, but after inspecting them it was determined that all were well within their original design tolerance and they were safe to reuse. The reassembled transmission was then reinstalled, with a new OEM clutch disc, pressure plate, and release bearing, and the grinding issue was resolved.

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