I'm going to be rebuilding my transmission hopefully next week and want to pre-order as many parts as possible to minimize downtime and cost. I searched around a bit and have read several books, but haven't seen any definitive answers on what parts *should* be replaced in a full rebuild. Transmission is a M2U4 out of a '97 Prelude SH with 195xxx miles on it.

I want to replace all the parts that should be, but don't want to waste money on ones that don't. The two big questions I have are which bearings should (or shouldn't if that's easier) be replaced, and if people usually replace the shift forks or not.

Transmission has the typical 5th gear grind, so I will be replacing the 5th gear shift fork and synchro sleeve. Transmission doesn't have any symptoms otherwise, I just know it's time for a refresh and I'm going to have it out to do my clutch anyway. I'll be replacing all the synchros with Synchro-tech carbon synchros & also planning on picking up their bearing & seal rebuild kit. I noticed their rebuild kit only includes 5 bearings however, but according to the parts diagrams there are probably close to a dozen or so. It looks like it's mostly needle bearings that aren't included; do any of these need to be replaced under normal circumstances? There are also the two differential bearings; should these be replaced? Other than that I think it's mostly just oil seals and washers and then whatever else I find once I open it up.

Any help is greatly appreciated.

 

Typically you will not need to change the needle and diff bearings. Check them over well just to be safe and make sure they are still in good shape. Depending on what the trans looks like, it may be best to go with a Master rebuild kit which will include the 1-2 Sleeve, 3-4 Sleeve and 5-R sleeve as well. When you do place your order make sure that you specify that it is for the M2U4 since one of the seals will be different than the non-SH models.

 

Before rebuilding any unit you should perform a teardown inspection to determine the level of wear and the parts that are required.

The best transmission overhaul or rebuild component is a keen eye.