almost made a wordy pointless thread heres the summarized version auto -> manual swap related
whats the rpms at 70-80 mph in 5th.

 

im curious how much better my car would be on the highway. atm most of my drive is at 70mph sometimes 80 if im keeping up with traffic. with the 4spd auto it has me sitting around 3k. i want to do the swap eventually anyway but if it can keep my rpms lower for cruising and ill save that much mpg wise maybe ill push the swap up on the priority list.

 

you do realize there's like 15 different transmission codes you can have all with different ratios? I mean I may be exaggerating with 15, but there's definitely a few.

 

ya id imagine there several different versions. probably ranging differences between them about 500-1000 rpms based on my question. so if one runs at 2k at 70 another 2500 and another at 1500 so if we have 3 people willing to post an answer regarding my que it would give me a general idea of rpm ranges. it would give me an idea rather than just assuming 5 speeds rather than 4 so 5 gears slightly closer together with 5th ending 500 rpms less than my current 4th gear. 500 rpms isnt a huge mpg difference as ive tried being the granny for a week and didnt see enough difference to move the swap up on priority. if we are talking 1000rpms typical difference that would put me in a more ideal modern rpm vs speed.

 

si transmission probably 70 at 4k rpm, cx transmission, could be 1800.... I'm guesstimating and everything else will be in between. I do believe the ratios are out there, but I'm at work again and have no real ability to look for it.

 

ya i couldn't find much when i looked besides reference to using 3rd or 4th for a dyno pull. but thats why i was hoping a few members who might still have a 6th gen 5spd might chime in.

 

Stolen from HT

1st-----3.250
2nd-----1.900
3rd-----1.250
4th-----0.909
5th-----0.750 for Si HB and Del sol Si
or------0.702 for 2 dr or 4 dr sedan
Final Drive---4.250

The transmission that has tall gears is from an HX, not a CX. My memory failed me. I'll look for those ratios later, however you can try and find them yourself for transmission code S40. S20 will also work. There are a couple of variaitons.

 

thx
i know its a little pointless to really look into this stuff for what im doing but when it comes to my vehicles i try to do as much digging before i move ahead with anything. get my ducks in order and know exactly what im going after. i like the 5th and 6th gen civics but i see far too many that are just patchwork junk that barely functions because it wasn't done right. or its just ricey junk you wish the engine would blow up so you dont have to hear it anymore. ive actually got whole walkthrough threads on various more technical swaps and mods either saved or straight printed out. the only thing i haven't been able to locate either wrong search criteria or just looking in the wrong spots is information on the manual transmissions. partly the reason why i haven't already scooped up a donar scrap car for most of the parts i need. if you have a good resource for that could you just send it my way and ill do my own reading.

 

ok so the s40 and s20 all have about the same gear ratio ending with 5th either 702 or 750. final drive mostly is 4 something to 3.75. i found a article that lists all 5th to 7th gen transmissions. i cant find anything relating to the automatic which doesn't matter much as im getting the idea between the gearing and relative suggested rpms. 5th gen cx/vx or something had an option to have a 3.25 final drive. could be wrong as i dont mess with gearing almost ever but the lower ratio for the final drive will suck some of my power but it should help lower my rpms for highway use. so if i get an s20 i would want the bearings and everything checked anyway so while its apart i can have the 3.25 final drive gear put in. just to clear it up im aware while i only have some bolt ons my power still sucks so it could even make 5th gear almost unusable unless im going down a hill or flat roads. but it would probably put 4th gear in the same area my automatics 4th gear is now. any suggestions or opinions on this idea. i like my civic and i do plan on getting more power down the road but i also enjoy driving my civic so keeping the power and drivetrain in a usable level is where id like to be.

 

so question... if you're doing an auto to manual, why not just do a full swap including the engine? A lot of drop in options that are proven options for like two decades...