There are two transmissions in the car and both are M2Y4, sadly both have what seems like worn 1st and 2nd gears. Don't grind going into gear but when under load pops out of gear. Anyone have ideas on how to repair? I've looked for replacement gear sets and collars for at least 1st and second and was not able to find anything new. Any help is appreciated.
Trailer to storage

Trailer to storage

In storage

 

Popping out of gear suggests the transmissions have been run without fluid for a while now... OR your shift linkage is so rigid that the engine movement under load is yanking the transmissions out of gear.

Just an observation: Your front engine will NOT run correctly in closed loop with the O2 sensor mounted at the muffler tip... too much oxygen from the outside to corrupt the readings... your adaptation will be CRAZY. Move it to collector pipe in the header (between the 4-1 junction and the flex pipe).

 

^^ second.

Also cool build. Doesn't look like there's much Prelude left though lol.

 

Thanks for your reply! I've got enough brand new Honda fluid in the transmissions now, but who knows what the previous owner did with it, so excellent point! Next time I'm in storage, I will check the linkage movement by looking at the arm on the trans while under load to see if there is movement, if there's none I guess it means the little dog gears are worn inside? Since a new shift collar has engagement gears at a slight inward angle to pull the gears together but in my case they might be worn, which I didn't pay too close attention to when I had the trans apart.

Great point about the O2 sensor! What you're seeing is actually the downstream sensor with a modified spark plug defouler with a 1/16" diameter hole to trick the stock OBDII in thinking there is a catalytic converter. The upstream O2, the one that is used for AF ratio is just before the muffler, but it's behind the pipe so you can't see it in my photos. I have this trick on both engines done and they work flawlessly with no engine codes.

 

Thanks for your feedback! It is forcing me to learn quite a lot, and it's been quite fun so far. I was able to run it on the street once just down the block and couldn't really open up both engines or hit VTEC but with it being so lightweight it felt pretty amazing even at partial throttle. Put a huge grin on my face I'm really excited to get the transmission popping out of gear thing figured out and get the rest of the body panels mounted so I can register the thing and drive it on the streets like a normal stock looking Prelude!

Here is a link of me starting it up after months of sitting in storage:

 

If it doesn't grind going into gear it's possible the ball setting spring is bad and not holding it in gear.

https://www.hondaautomotiveparts.com...-mt-shift-fork

check synchrotech if you needs gears and synchros

https://synchrotech-transmissions.com/

 

You are able to replace the spring without pulling the tranny.

 

Thank you so much for your feedback and the links! I remember putting the detent springs back in and didn't consider them as the culprit since my understanding was that they are there to help keep it in gear but the main keeping together force was due to the slight angle in the mating engagement gears and collar but it's definitely worth replacing those since they are cheap and easy to put in!

 

The twin engine Honda Prelude is fixed and running good now! The front trans had a bad countershaft bearing, replaced that and problem was solved. The rear trans had a worn 2nd gear synchro, and a P2A8 with wrong ratios. I didn't pay close enough attention when I did the manual swap which is embarrassing to admit. Anyways, found a used M2Y4 at a junkyard and now the car rips! The AWD 400 Hp feels like a lot more since the car lost so much weight. The first time at full throttle was super exciting! Check out the video below

 

This is a sick build!!

 

Thanks for your positive comment