When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
Well...looks like custom motor mounts are in the cards for me any way. Moving the engine back 3" and toward the driver's side 1" puts the mounting holes in a fairly inconvenient location. There's no way to get the FC motor mounts in there, or really any other mount. Looks like I need to get the steering rack in to check if I need to move the engine up at all, then I can weld up some mounts.
Driver's side is way too close to the crossmember and there's no more flange left to mount too:
Passenger's side is a bit better, but would still need a spacer under the mount to clear the crossmember:
I think we have a winner here. Moving the engine back 3", to the driver's side .5" and up .5" seems to be workable.
Firewall clearance is close, but good.
Lots of room for the starter
Inside there's a good mount of room. Should be able to fit all the HVAC components back without issue.
would have needed to make clearance the slave cylinder, but I probably didn't need to trim as aggressively as I did everywhere else.
Oil filter will still need to be relocated, but I may be able to fit an off the shelf relocation kit now. I'll likely just machine my own for fun still.
without moving the engine up .5" the oil pickup tube is nearly on top of the steering rack. Certainly no room for the oil pan.
Lifting it up .5" gives room for the pickup tube. The oil pan will certainly need to be modified though.
the shifter will need to be brought forward around 2.5" to be centered. I'd considered using an RX8 5 speed (and I haven't completely ruled it out yet), but the sifter is just under 4" shorter than the FC/FD trans. As it happens the shifter would sit just about exactly where that little cylindrical nubbin is on the tail shaft, and would sit a little farther forward than I may like. That said, the RX8 trans has provisions for the PPF already. No idea if it has a port for the speed sensor though. The FC trans may be easier to deal with once I have a solution for mounting the PPF.
And much to some peoples dismay the twins fit as well.
A little close, but the turbos weren't fully seated down either, but clearance is clearance!
Great progress, a little disappointing on the quality of that subframe though!
I have a Rx8 5 speed in one of my FB's if you wanted see one in person - I think we are only a few hours apart. It does not have any provisions for the speedo gear/sensor though - at least not on the housing itself. I believe the grooves are already there on the output shaft for the c-clips/gear but have not had it apart to confirm.
In Miata land most swap guys delete the PPF and add a mount for the front of the diff. Have you considered doing that here to simplify the trans portion of the swap?
Great progress, a little disappointing on the quality of that subframe though!
I have a Rx8 5 speed in one of my FB's if you wanted see one in person - I think we are only a few hours apart. It does not have any provisions for the speedo gear/sensor though - at least not on the housing itself. I believe the grooves are already there on the output shaft for the c-clips/gear but have not had it apart to confirm.
In Miata land most swap guys delete the PPF and add a mount for the front of the diff. Have you considered doing that here to simplify the trans portion of the swap?
I believe you are correct in that the rx8 trans already has provisions for the speedo gear. Probably becasue the center portion of the gearbox is shared with the FC/FD. I think the syncros are a little different, but past that I believe they are the same gearbox. the picture below is stole from this thread. RX8 on the left, FD on the right.
Thanks for the offer. I may take you up on that. There's a 5 speed for sale in Queens that I might go snag this weekend, but we'll see. Good to know for sure there's no provision for the speed sensor. From the pictures it looks like there isn't, but i have yet to find a good picture. I was hoping the boss was at least there so I could machine in the holes.
I have considered just making a mount for the diff. It would likely be easier than trying to make the speed sensor on the rx8 trans work.
And for those following, I did receive the bumpsteer kit from them.
on the note of the diff mount, looks like Banzai Racing make a diff brace, that would serve well. I may just copy that design, or get super lazy and just buy one.
Yeah I was in the same boat with the Miata subframes I'm working on putting in an FB. I ended up buying a pre-made ppf delete, one less thing to fab out of a list that is already miles long.
Also, can confirm the Rx8 5 speed shifts smooth as silk - triple cone syncros ftw!
And much to some peoples dismay the twins fit as well.
dismay is the wrong word, its just that out of all the options you have the stock turbos are least good.
its just that the best thing about the 20B is the noise it makes and the turbos make a great muffler
dismay is the wrong word, its just that out of all the options you have the stock turbos are least good.
its just that the best thing about the 20B is the noise it makes and the turbos make a great muffler
a fair statement. If I were.to crack the engine open again id seriously consider putting some high compression rotors in it and running it NA. The twins are likely a short term solution anyways, but it'll help me get up and running faster and I'm anxious to drive this beast already.
Started working on the motor mounts. "it's not stupid if it works" is the theme here. I started by making a little jig to hold the 20B motor mount. there a single bolt up top that holds it to a right angle plate, and an adjustable parallel to level the mounting surface to the table.
the remaining mounting holes are marked on the tape with transfer punches.
the new bracket is then mounted up with the holes aligned. Again using the transfer punches. you can see the original mounting locations here fairly well.
Made the offsets I wanted. Again that's 3" back and .5" over. For the height offsets I'm thinking it's smarter just to shim the motor mounts up a bit. That's a lot easier (and adjustable) than trying to alter the motor mounts.
I then machined a little centering device from some scraps I had kicking around. The large piece is machined to the same thickness as the stock mount. The little piece is a tight fit on the bracket, as well as the larger piece so it keeps everything centered on the mounting hole. The screw then clamps everything down tight.
then it's just a matter of clocking the piece so it's (roughly) parallel to the other bracket. Honestly it's not critical at all, if it's off it just meants the motor mount has to rotate slightly.
Too lazy to bring the MIG welder in from the garage so I took the opportunity to work on my TIG welds. I'll never clam to be a welder so be kind, haha.
Need to reinforce, but that's pretty much it. Here it is compared to the stock mount.
motor mounts are done! and powder coated! I used the same method as the above for the passengers side mount, but it was significantly more awkward as the pad that the motor mount sits on is almost in line with the pad that bolts to the engine.
I didn't take tons of pictures along the way, but here's what I ended up with. Massive overkill on the drivers mount, I know, but I was having fun so I kept adding pieces. haha
Drivers side mounted. You can still access the drain plug and the lower bolt without issue.
Passenger's side mounted up. It's a bit trickier as it has to fit around the exhaust manifold but be out of the way of the rear turbo drain tube.
Also made my spacers to get the .5" of vertical lift I need. Decided to make .25" spacers to go above and below the engine mount so I didn't run out of threads on either side of the mount. The FC motor mount also has little raised keys to clock them, so I have to drill holes for the spacer to clear them.
And it looks like my fixturing worked pretty good. Its sits right where I wanted it! And as a bonus the stock R1 strut bar will now fit, which I really wanted to keep.
Next issue is the oil pan. I know for sure the pan needs to be trimmed by the steering rack, so that's where I'll start. If you haven't noticed by now I like jenky fixtures to get things done, so this was my approach. I needed to find how high the pick-up tube sits so I know where to trim the oil pan. so I bolted the pick-up tube to my work bench and used a laser level to find the high spot.
I bolted my laser level onto my metal shaper and used the table to raise and lower it so I could easily find the high spot on the pick-up tube. "it's not stupid if it works"....right?
Once I knew where the high spot was I could transfer that to the oil pan.
All trimmed and ready for test fitting
But then I ran into a bigger issue. Having moved the engine back 3", the rear end of the oil pan is now hitting the rear bar of the subframe. This is what custom projects are all about...solving problems....IF I were to trim the oil pan to clearance the subframe, this is how much I'd have to take out. The good news is that I could extend the pan sump about 3" forward to keep the volume, and maybe even increase it a little.
The other option, is to modify the subframe. Not sure I'm crazy about this idea as it'll reduce the rigidity of the subframe, but maybe it wouldn't even matter if I were to reinforce it enough....
Or, I could just make a custom oil pan....I feel like I'm close to doing that if I keep modifying the stock pan. Thoughts or recommendations?
On one hand, the subframe is already an aftermarket part so I think it makes sense to modify that.
But if you are already needing to modify the oil pan, I've seen people claim that a stiffer aftermarket oil pan can help avoid the engine twisting. https://www.pineappleracing.com/oilp...02rx7race.aspx is one example, also Bacon Rotorsports Racing on facebook. I think there are others, but those are the ones I'm familiar with.
On one hand, the subframe is already an aftermarket part so I think it makes sense to modify that.
But if you are already needing to modify the oil pan, I've seen people claim that a stiffer aftermarket oil pan can help avoid the engine twisting. https://www.pineappleracing.com/oilp...02rx7race.aspx is one example, also Bacon Rotorsports Racing on facebook. I think there are others, but those are the ones I'm familiar with.
that is the factory way to stiffen the engine, if you look at the R26B the dry sump plate is thicker than it needs to be, and then there is a CF brace on top.
Supernow offers a 10mm thick plate and 10mm shorter engine mounts, https://www.rhdjapan.com/super-now-e...anel-fc3s.html
That's a great looking oil pan. My machines are certainly not large enough to make a billet oil pan out of one piece I'm afraid, but I'm still considering getting some parts laser cut and welding it up. Superfastmatt has a pretty inspiring video on making one, but I do like the idea of making the base much thicker.
While I figure out what I'm doing with the oil pan, I decided once and for all to just use the T2 transmission and ditch the PPF. So I broke down and got the banzai diff brace and made an aluminum spacer to simulate the thickness of the PPF. In case anyone is wondering, the PPF is just about 5/8" thick where it bolts to the diff.
Installed, but one of the nuts inside the frame let loose so i'll need to fix that at some point, but it's in and holding the diff where it needs to be. This whole area is going to need some TLC at some point, but i did clean up and powder coat the braces right next to the banzai brace.
Moving onto the transmission, the shifter needs to get relocated forward 2.5", but first lest address something that has been bothering me for a while. The new slave cylinder never quite fit the stock rubber boot for the extension rod, so I decided to re-machine the end to match the stock slave cylinder. It's always fun trying to fixture a weird casting but I got it. The boot fits like a glove now and isn't over stretching it
Ok, now onto the good stuff. The tail housing, and shift rod all need to shrink by 2.5", so first thing is first, I needed a way to hold the tail housing so I made this little plate to hold it while everything happens
Unfortunately there's no meat for me to drill a new mounting hole so some extra material needed to be added.
ready for welding
all welded up, don't judge the welds too much, this cast aluminum was super dirty
Bottom welds machined flush with the mounting pads
adding the new holes!
holes added, and spot faced for the bolt heads to sit flush
I didn't get a picture of chopping 2.5" off, but I'm sure you can imagine that. The tail housing was (for fun admittedly) machined to recreate the taper cut.
Still not done. There are 2 alignment pins that hold the tail housing in place. One pin is right in-between the two new mounting holes, so a little plate had to be welded in and then the fixture plate was used to transfer the dowel locations.
the rear locating pin had to be remade as the hole is a bit farther up in the housing. Had i thought about this I could have welded up the area the pin goes and used the stock pin, but no worries a new longer one was made
All the parts including the shortened shifter tube
and all put together with the left over bits
And the last piece of this puzzle was the shorten and drill the actual shift rod
Onlt one more thing before the transmission can go back together. The FD uses an electronic speedometer and the drive gear is quite different, so that has to be swapped over from the FD trans. FD on the left, FC on the right.
The FD gear spins the sensor the opposite direction!
It also has more teeth than the FC gear
Next up is all the transmission sensors, so stayed tuned, it's not a straightforward as anyone would like....haha.
Back to work, I wanted to get the speedometer sensor installed. At first glance there are a few difference between the FD sensor and the FC cable drive. Besides the obvious size difference and the difference in gears, they look fairly similar. FD on the left, FC on the right.
What was not so obvious is that on the FD, the centerline of the gear and the centerline of the oring boss are offset effectively creating a cam. As you rotate the sensor to get the mounting bolt lined up it pushes the gear into the output shaft in the transmission. With the sensor installed so the bolt holes line up, it physically pushes the output shaft so it's no longer concentric with the rear seal. Not great...
A few hours later and 2 revisions 3D printed later and I designed a little adjustment bracket and ultimately machined from aluminum.
I also made a little T nut and centering washer to clamp the sensor all together.
Installed and no longer displacing the output shaft!
The other sensors needed are the reverse sensor and the neutral switch. I probably don't NEED the neutral switch as I'll be running a standalone, but I have the sensor already. Of course nothing is ever straightforward on parts that are 30 years old. Both sensors had broken wires like this. There should be 4 wires here, and even the ones that are attached are hanging on for dear life.
I won't get into the nitty gritty of it all but basically I'm cheap and didn't want to spend hundreds of dollars buying new sensors, just to have to hack up the wiring anyways. So I removed all the potting from both switches exposing the actual sensor terminals inside the sensor.
Soldered on fresh wires and repotted the backsides
I can trim the wires to length once the transmission is reinstalled and I know where the mating connectors are, but at this point it's just a matter of installing new connectors.
Next topic...I could use some insight. After the shifter relocation getting the transmission into reverse gear is nearly impossible. I have to slam it back to get it into gear. It looks like this little pin is blocking the control lever end from moving far enough over to get into gear.
Not sure if I drilled the pin slightly off angle, but does anyone know what this little guy actually does? The FSM doesn't mention it, and to me it just looks like a guide to help the shifter get into the correct location. When it's removed I can get it into gear just fine. Anyone know what it's for? I'm thinking I can just regrind the angle on here to provide a little more clearance.
thoughts, or does anyone know if there's a deeper function for this guy?
Took a look at mine for you, but the only one that is easily accessible for pics right now is a T2 trans that has a modded FB shift tower on it (in this case moved forward quite a bit for a K24 swap that hasn't happened...) It looks like the FB tower is a bit different in that the pin you reference is round, there is no bevel like the one you show. In either case, when in reverse the little ear on the shift mechanism actually slides under that pin. Near impossible to get a good pic so I just marked the ear I'm talking about with red using the finest photo editor around, MS Paint...
Either way, the FC should operate the same way, tab slides under that pin. Given the level of detail you've been giving this I wouldn't think you got the angle of the hold wrong, buy it's possible??
Thanks for taking the time to get me that photo. Yes, it's possible I messed something up, but I took quite a bit of care to align the machine to the existing hole and drill the new one 2.5" from that. I was able to snake a scope inside the speedometer hole and everything looks like it lines up inside the trans.
1st and 2nd:
3rd and 4th:
5th and Rev:
In 5th:
in reverse, with that pin removed
I know the pictures aren't great, but everything seems smooth and looks to be lined up. I think for now i'm going to stick this pin in that I made (mine is on the right). Everything seems to work good with this one installed.
Also, while I had the trans off I decided to swap out the clutch. After more review and actually talking with the folks at clutchmasters, I think the 725 kit is not going to be a good option for driving on the street. Got a decent deal on a fairly fresh Exedy twin disk which seems to be fairly popular among FD owners. the disks are sprung so it'll cerainly be easier to drive.
11-16-23, 02:19 PM
Maybe one day!
