magnumP5's RX-7 Build Thread

[magnumP5]

Your updated build thread is the only thing I have to look forward to on Mondays. (2thumbs)

I've been trying to do a little work during the week now after Ian goes to bed. I realized I just wasn't getting enough done only working on weekends. Hopefully this means more updates during the week.

If you plan to drive te car on the road I think that a dual exhaust would be best. Loud is not always better for making power and loud exhaust gets old fast on the highway.

"fix me" that's funny. Evan needs that on his windshield too.

LOL, it also says "and wash me too" on the side. Sadly that note's been there for like six months. It's kind of sad when a build's been going on for so long the car has it's own layer of dust.

I'm still torn on the exhaust. Both will weight about the same with the dual being maybe a bit heavier due to more pipe. I'm pretty sure the single will make more power as it's less restrictive. The biggest factor is appearance. I've never really liked dual exhausts and a single with a turndown is pretty sweet, but it's kind of lame having a bumper cutout with no tip sitting there. I'm actually toying with the idea of getting an E-Production rear bumper cover from AWR that does away with the exhaust cutouts altogether. Maybe I'll run a hybrid setup with a valve at the split that let's me switch between dual/single outlet for city/track driving, haha!

 

[magnumP5]

As promised yesterday, my bearing "driver" tool:

and in its longer form:

Made it past a major hurdle last night. Started with this:

I ended up disassembling the reverse idler gear in the bearing plate so I could secure the countershaft bearing. With the help of my wife I was able to install the input shaft/4th gear assembly and pound the countershaft home:

It actually went into place MUCH easier than I feared. I lined up the teeth as best I could. 1st is a little offset because I really wanted to make sure 2nd, 3rd, and 4th (track gears) are as centered as possible. Fortunately, everything turns smoothly. I ended up calling it quits after I installed the reverse pinion and bearings.

Tonight's goal is to finish up this assembly (5th gear and rear bearings) and maybe even get the intermediate housing installed.

 

[hat1018]

The bumper has dual tip openings? Single inlet, dual outlet muffler, problem solved.

 

[magnumP5]

The bumper has dual tip openings? Single inlet, dual outlet muffler, problem solved.

I'm not sure how much that would supress the exhaust. I was told at least two mufflers are needed but the split should also cut down on the sound some. Since the manifold will exit on the passenger's side of the car it's going to be hard to achieve equal lengths of pipe after the split.

 

[magnumP5]

Naturally I didn't get as much done as I wanted. It's hard to make progress when you only have ~1 hour to work and you get stuck on something. The 5th/reverse clutch hub went on easily enough:

The 4X mm nut that goes behind the hub gave me issued. The FSM says to shift the assembly int 1st and reverse simultaneously to keep the mainshaft from rotating but because the reverse pinion on the countershaft is helical and unsecured it pops out of position allowing the mainshaft to spin. Eventually my wife came up with a solution to use a small wormgear hose clamp to hold the reverse pinion in place. Tightening the nut:

Torqued to ~140 ft-lb (FSM calls for 94-174 ft-lb) and staked in place:

With the delays due to the mainshaft nut I was only able to install 5th gear and the thrust washer behind it:

All that's left on the mainshaft are a couple of c-washers and their retainers, a bearing, and a c-clip. After that a spacer, the 5th gear pinion, rear bearing, and nut are installed on the countershaft and this part of the assembly is complete and I can start installing the shift rods and clutch forks, which still need to be cleaned.

 

[eprx799]

Nice work Jon. How much different would it be just to replace some sincros(2 and 3) as opposed to doing the swap that you are doing?

 

[magnumP5]

Nice work Jon. How much different would it be just to replace some sincros(2 and 3) as opposed to doing the swap that you are doing?

Unfortunately the level of diassembly is going to be the same. 2nd and 3rd gears are in front of the bearing support plate so everything has to come apart. The good news is synchros don't affect the assembly spacing so you should just be able to reuse all the spacing washers and shims. What year transmission are you working on? I've read the synchro design was much improved by Mazda in later years. I've got two whole spare assemblies if you need anything or want to swap gear ratios

I got the second assembly completed last night. Rear bearings installed:

Every now and then I find small errors in the FSM. For example, the FSM says the mainshaft rear bearing is installed before the 5th gear pinion on the countershaft. From the picture above you can see the pinion diameter is large enough to interfere with the bearing so it has to be installed first. Not really a big deal but it's slightly annoying to repeat steps. The clearance check/specs between the final thrust washer and c-washers doesn't make sense either. Mine is currently 4X the limit (.012" versus .004") but the only way to reduce that would be to get a thicker thrust washer or rear c-clip, neither of which come in thicker sizes. The FSM says to get thicker c-washers but that would help in this situation. Anyway, here's the final assembly:

I started cleaning parts for the next level so hopefully assembly will resume tonight.

 

[2.0t03speed]

man you have come a long way since the old days of wrenching on the p5. Send me a pm or a text next time before you come to visit.

 

[magnumP5]

man you have come a long way since the old days of wrenching on the p5. Send me a pm or a text next time before you come to visit.

I was thinking about this the other day. For as quick as the P5 was everything was basically "bolt-on." I stopped right before engine/transmission work was the next step. Not sure when I'm going to be in VB. I'll be in Blacksburg in May for my sister's graduation but that's as far as I'll make it.

No pictures today. I spent the evening mowing the lawn and cleaning up. All the parts for the next level of assembly are clean. The next steps are reinstalling the shift forks, rods, and selector ends. It's almost time to get the intermediate housing on.

 

[eprx799]

my trans is in good shape so far. but I guess if I need help with a rebuild I will just ship the trans to you and have you do it or you could help me and make it a learning experience.

 

[magnumP5]

my trans is in good shape so far. but I guess if I need help with a rebuild I will just ship the trans to you and have you do it or you could help me and make it a learning experience.

I think my wife would kill me if I did another transmission rebuild in the garage. She's already complaining about the smell (gear oil). I've no problem helping out it's just this isn't really a one-day job. With things somewhat resembling the OEM SST's it still took me ~2 days to pull everything apart and the organizing, cleaning, and inspection took much longer than that.

Random question for you though, have you ever gotten your Miata or RX-7 stuck in reverse (see below)?

Long post ahead. I made a lot of progress this weekend and then took half a step back in the end. Starting from where I left off...

Getting everything ready for the next level of assembly:

I'm obviously skipping a few steps here. Shift rods, clutch forks, etc. installed. Ready to install the intermediate housing:

Intermediate housing on, shift rod ends installed, and speedo drive gear in place. Note the change in lighting. I had to take breaks to let the silicone cure between housings. Ready to install bell and extension housings.

Bell and extension housings assembled. I think I went a bit overboard with the silicone...

Front bearings installed. The little snap ring on the input shaft was a PITA to install. I had to "modify" it slightly so my snap ring pliers could get a grip.

Front cover installed with gasket and bearing shim. There was another one of those "the EM is wrong" moments here. You have to set the front bearing "play" to 0-.004 inches but the way the EM has you measured the clearance is incorrect. Fortunately I figured it out and between the leftover shims I have from the original RX-7 and Miata transmissions I had exactly what I needed.

All finished...

...or so I thought. After the silicone cured I decided to slap on a stock shift lever and test out the gears. A quick row from 1-5 to neutral and everything checked out. Went to test reverse I found I couldn't get it to engage! I checked the other gears again and all were locked out! A quick spin of the input shaft told me it was already in reverse (boom05) In a frenzy I quickly pulled the extension housing and all it's pieces off, which were only recently installed, and discovered somehow I managed to shift into reverse while going from 5th to neutral. This morning a quick internet search showed this is quite common in Miatas and RX-7's although I'd never heard about it. Apparently this spring:

on the front of the 5th/reverse shift rod puts a good amount of force in the reverse direction. Shifting too quickly from 5th into neutral or too slowly from reverse into neutral seems to be the primary causes although some have reported this is worse with worn shifter bushings. I'm guessing what happened to me was when I released 5th gear into reverse (didn't 'guide' it) the force of the spring boosted the forward momentum of the rod, which somehow carried it into reverse at the precise moment I moved the selector rod into neutral. It probably didn't help that I had only 1/2 the shifter bushings installed and that the transmission was vertical so gravity was acting in reverse's favor. What's most annoying is there is a fix that can be done without removing the extension housing involving a screwdriver through the reverse switch port. Had I waited a few hours I would have discovered this and not had to remove the extension housing and associated pieces. Now I get to scrape off all the silicone and go through that process again. Either way, the transmission is essentially done so it'll be time to move onto the next task soon.

 

[eprx799]

The short answer to your question is NO. I have never had either of the car stuck in reverse. And I hope I never do.

 

[magnumP5]

The short answer to your question is NO. I have never had either of the car stuck in reverse. And I hope I never do.

Internet searches make everything seem like common place. I never had this issue with my RX-7 either so I thought it was strange it happened on the first try with the Miata transmission. I still find it hard to believe it's the result of some precise order of events but then again I couldn't find anything wrong with my reassembly other than the lower shift lever bushings not being installed. Knowing there's a fix now I'll give it another try with all the bushings installed and the transmission laid down when I get everything back together again. This is definitely something I don't want to happen downshifting from 5th-4th on the highway!

 

[magnumP5]

Reinstalled the extension housing and everything else except the "service cover." I realized I'm missing a small bushing that fits around the lower pivot ball of the shifter. Without this bushing the ball is really loose in the control rod "carrier" so it makes the shifter really sloppy. Other than that it moves into and out of 1-4 gears really smoothly. I've ordered a delrin replacement for the lower bushing and I'm not touching 5th or reverse until that goes in. While I was at it I also ordered some delrin engine and transmission mounts.

I managed to sell the stock fenders yesterday for some extra cash but I'm probably going to take a break from the RX-7 for a little while.

 

[magnumP5]

Haven't touched the car. I plan on taking off the Enkei's tonight and bringing them inside for storage until the car's done. The transmission will also be coming inside as well to free up some space in the garage. There's still a whole list of things to do. Still waiting on my exhaust manifold and 929 master cylinder...

 

[magnumP5]

Finally got a 929 MC! It's a little different than I expected (resevoir is angled, different casting, different color, etc.) but I guess I should have known with it being an aftermarket part (Raybestos). I would've loved to pick up a Beck Arnley (OEM) but it was over twice the cost. Oh well, as long as it works who cares how it looks. Seriously, who judges a MC?

Sooo wanting to get back to work on the RX-7 but life is in the way for pretty much the next two weeks. I think my next task is going to be the fiberglass fan shroud.

 

[magnumP5]

Not dead, just busy. Got a few things in the mail (but no exhaust manifold >.<).

Cancelled my order for the 929 MC and went through RockAuto for a different one:

The casting is a little different than the original but I don't think that matters too much. What concerns me is the reservoir is tilted forward and I'm pretty sure the original wasn't (thrown away). I'm concerned this could lead to issues with the fluid level sensor. I need to call RockAuto and see if they know what's up.

Finally got the delrin engine mounts (right), transmission mounts (left), and lower shifter busing (center):

The lower shifter bushing sits in the shift rod control end around the lower pivot ball on the shifter like so:

That's it for now. Really hoping to get back to work this week/weekend.

 

[magnumP5]

About the only progress I've made since the last post is getting the delrin lower shift busing installed:

I ended up having to shave it down from a little over 19 mm to a little under 17 mm to clear the return spring.

I got a text from Defined Autoworks saying I would have my exhaust manifold no later than today. I'm not too optimistic but hopefully that means it's at least in the mail. If it does arrive today I'll have lots of work to do. Too many things to list now. I've got yard/garden work to do tonight and tomorrow but hopefully with the long weekend I'll get some work into the RX-7.

 

[magnumP5]

THIS arrived:

This is a real "header." Overall length is >4 feet, equal-length 2 in. primaries to a merge and megaphone to 2.5 in. Two oxygen sensor bungs to monitor both rotors separately. Of course I couldn't leave well enough alone so I decided to mock it up with the intake manifold (you'll see why in a second).

Trailing rotor runner looks awfully close to the intake manifold, doesn't it?

Yeah. The clearance is something like 1/16 in. and the intake manifold has to be installed first. With EGT's expected to be in the 1800 deg F range I'm now looking into exhaust coatings. Swaintech seems to have the best reputation and I like that their TBC is .015 in. thick. I still may try to make a heat shield but I don't like the idea of it rubbing against the exhaust manifold and/or intake manifold. Worst case: I mill 1/8 in. or so off the intake manifold flange.

On Sunday I got the exhaust manifold on the car.

This also proved to be a bit of a PITA. Since this is all in preparation to get a full exhaust made I swapped in the new delrin engine and transmission mounts to insure everything would be in its final position. The manifold is close to the body of the car. So close the stock heat shield has to come out. Definitely need that TBC coating. I didn't take any pictures of the underside but the manifold exits near the end of the transmission under the driveshaft pointing toward the driver's side rear. I won't know for sure until I take some measurements but it looks like two mufflers in series should be feasible. Maybe even a small resonator.

With a little ADD I switched my attention to the brakes. It wasn't too much work to get the stock MC and booster off. Stocker booster next to the 929 one:

I spent the majority of Monday modifying the brake proportioning valve bracket and brake lines so they'd work with the new setup. The final product:

I still need to paint the BPV bracket and bench bleed the MC but everything's basically in place. When the brakes are done I plan on wrapping up some lingering small jobs (transmission wiring, remaining heater hose hole in the firewall, oxygen sensor harness) while I figure out how to get an exhaust made.

 

[magnumP5]

No love? Damn, tough crowd, and after all the hype surrounding this exhaust manifold...

Anyone have any experience with Borla XR-1 mufflers? The shop that build my exhaust manifold recommended them but they're pricey. For 2/3 the cost I can get similar cans from Racing Beat that are slightly larger and rotary specific.