magnumP5's RX-7 Build Thread

[Signal 2]

Glad you got the parts on the way.
But why would NASA require a working speedometer? Seems like I've seen purpose-built cars without any speedometer at all. Presumably just using the tach. And practically speaking, how would they check that at tech a inspection anyway? Drive or ride in the car around the paddock or lot?

 

[magnumP5]

I just looked at the exploded view of the transmission for your car and it looks like you just need to pull a 10mm bolt and remove the sleeve and remove the gear. It looks like you need a new oring, oil seal, and gear. I see a pin but I don't know what it slides thru. I pulled it up on the mazdaspeedmotorsports web site under "manual trans. case" I don't think you need to drop the trans for that unless you need to take the trans apart to remove the pin, Which would be stupid but I've seen dumber things.

According to the FSM the extension housing has to come off to gain access to the mainshaft. Of course the FSM says to remove the transmission to do this, but it may be possible to just unbolt the transmission mounts and lower the transmission some to gain access to everything. I believe the pin you're referring to holds the selector rod (or whatever it's called) in place. It's located behind a blind plate, which is bolted to the side of the extension housing. Again, may not be necessary but the FSM says to remove that and a couple other things (like the 5th/reverse lock-out assembly) before removing the extension housing itself. I don't think removing the transmission would be too difficult, maybe with the lack of space (only using jackstands, etc.), it's getting everything to line up when reinstalling is what has me worried now.

Glad you got the parts on the way.
But why would NASA require a working speedometer? Seems like I've seen purpose-built cars without any speedometer at all. Presumably just using the tach. And practically speaking, how would they check that at tech a inspection anyway? Drive or ride in the car around the paddock or lot?

I wouldn't think so for all-out track cars for TT or the Spec classes, but because my car is a street car in HPDE, who knows.

I drove around a bit yesterday to make sure everything worked fine (no noises or anything). I was using my wife's GPS for a speedometer and that seemed to work just fine even if it it seemd to be reading a little high. The car feels weird without a rear swaybar...

There is one other thing I'm current worried about. Since Tuesday night I have found 6 tiny steel balls (think ball bearings). 5 are the same diameter, 1 is slightly larger. I found the first one in the driveway on Tuesday when I removed the driver gear sleeve after first noticing the speedometer didn't work. I'm 99% positive it fell out of the transmission because when I look in the FSM it shows a little steel ball under the driven gear, and now that it's broken there was nothing holding the steel ball back. Now yesterday when I was playing with the rear suspension after a drive I found the other 5 in the garage. I did not notice these in the garage before the drive (the car wasn't even in the garage) and the transmission is sealed again so I have no idea where these came from. I'm hoping they're from something unrelated (like the castors on my creeper) because the car seems to drive and shift just fine. I don't know where else on the car they could have come from. Exhaust bearings maybe...

 

[Perro del Sol]

LOL, math FTW. Knowing gear ratios, final drive ratio and engine speed allows me to back-calculate speed pretty easily - it's just not something I want to do during multi-hour trips.

Will a non-functioning speedometer not pass Tech at a NASA event? I would think not, but you never know...

You'd pass tech at the event

 

[magnumP5]

You'd pass tech at the event

I figured, but you know I worry about everything.

I had the car checked out for free at a transmission shop to see if they could offer any insight. They complained that it was "hard" to get into reverse, LOL. They ended up saying they weren't accepting manual transmission rebuilds, but I wasn't asking for one so I gave up. They did offer to help with the removal/install for $450 - ha, no thanks! I'm going to try to pick up a spare transmission today, swap all the new speedo parts in when they arrive next week, then bring that to the BBQ to install. I'll keep the current transmission for the Miata gear swap/rebuild in the future.

Having been able to drive the car for a few days I'm a little disappointed. I still appear to be getting a lot of drivetrain movement even with all the stiffer Mazda Competition mounts and the solid subframe mounts. What I'm referring to is the jerking/bouncing/etc. when transitioning on/off/on throttle. There's even a little more noise coming from the rear end that I HOPE is due to the solid mounts and not to the backlash being improperly set in the differential.

 

[THE Phen]

I'd guess it was the bushings doing it myself. I've ridden in a few Miatas with the upgraded diff bushings and it's a lot more noise coming from them. The movement though... that has me puzzled. You should see less movement with those bushings.

 

[magnumP5]

I'd guess it was the bushings doing it myself. I've ridden in a few Miatas with the upgraded diff bushings and it's a lot more noise coming from them. The movement though... that has me puzzled. You should see less movement with those bushings.

Good to know about the noise. I did replace a lot of hardware during the swap so maybe something has come loose a bit in the cold(er) weather. I'm going to pick up a new (used) transmission with 103k miles (mine has 105k) and then maybe I'll get the car up to check things out.

 

[magnumP5]

Well I'm pretty sure the noise is a result of excessive backlash in the differential. I checked out everything this past weekend and while there's a little play in the drivetrain the majority comes from the differential. With the wheels off the ground and the car in neutral I can rotate the rear wheels a decent amount before hitting some resistance. Time to go have a talk with the shop that "set" the backlash...

In other news I picked up a spare transmission this weekend - needs to be cleaned badly. As it turns out the driver gear in the transmission appears to be unique only to turbo/non-turbo models so I may not have to break the spare apart - just verify the new sleeve and gear fit and spin properly and everything should be good. I may still tear it down for the learning experience though. Either way, nice to have a spare to rebuild with Miata gears in the future...

In other other news the new swaybar mounts came in on Friday, but when I went to install everything I could not find the u-brackets. I must have thrown them away with the busted stock brackets assuming the bushing kit came with replacements like they did for the front bar - NOPE. So now those are on order and should be in no later than Thursday. After those are installed it's off to get a new alignment and then hopefully off to the BBQ!

 

[magnumP5]

More useless updates:

Spent a good few hours cleaning the new transmission yesterday. Came to the conclusion there had to be a leak somewhere due to all the crap in there. More parts ordered: throw-out bearing, front/rear oil seals and front cover gasket. Assuming everything internal to the transmission is good this is actually turning out to be quite the little rebuild. I'll be sure to take pictures of the transmission because you guys like pictures, right?

 

[THE Phen]

But of course we like pictures!

 

[magnumP5]

But of course we like pictures!

And ye shall receive...

Played with the transmission last night. Here it is cleaned up (as much as I cared to) with all the sensors and plugs removed:

Next, I removed the front cover and extension housing. Front cover off, exposing front bearings:

Here's the extension housing. I've cleaned it up a bit since this picture.

What lies inside the extension housing. The little white gear is what I'm certain I broke in my current transmission.

Lastly, here are some comparison shots of the speedometer driver gear sleeve. The new (required) one is on the left and the old is on the right. Can you spot the differences (ignore the dowel pin partially sticking out of the new sleeve)? Believe it or not they are different enough to cause one gear to fit/not fit with another.

That's as far as I got last night. Today the new front and rear oil seals should come in as well as the new front cover gasket. The goal is to have everything installed and sealed up tonight so it will be ready for installation on Saturday.

The rear swaybar brackets should also be in today as well. Once those go on the car it's off to drop it off at the alignment place so hopefully everything will be done tomorrow afternoon.

 

[Sport23]

That's not much of an offset. I would have missed it if I wasn't looking for differences.

 

[magnumP5]

That's not much of an offset. I would have missed it if I wasn't looking for differences.

LOL, this is exactly what happened to me!

Many thanks to Marc (eprx799) for letting me use his lift and just in general helping out with the transmission install. There's no way I could have done this myself.

So the new transmission is in and it made the 200+ miles back home. Unfortunately we were about halfway through before I even remembered to take pictures and at that point my phone was dead On the way home I noticed the shifting was a little stiff during the last 10 minutes or so, so I took a look underneath when I got home. Ended up finding transmission fluid everywhere! The two bolts on the "cap and spring" assembly had come loose basically draining all the fluid from the shift tower (this is separate from the main transmission body and therefore is filled separately as well) and this fell directly onto the u-joint, which then flung it all over the underside of the car. It's a miracle the bolts didn't fall out altogether. Tightened the bolts and refilled the tower and no more leaks - yay. Shifting is still seems stiffer than I think it should be so I'm going to check the fluid today after work. I'm thinking I may have to drain/refill the fluid a few times to clean out the crap in there (who knows how long this transmission sat). This slightly annoys me, but I guess that's my fault for putting Redline Fluid in there right after a rebuild. Will likely fill it up with some generic AP GL-4 fluid, run that for a few days then switch back to redline to insure everything's cleaned out. I know everyone I met this weekend heard me say this like 5 times but AT LEAST I HAVE A SPEEDOMETER NOW!

HP+ brake pad install to occur next...

 

[THE Phen]

Glad to hear you made it home man. Sucks to read about your issues though.

 

[magnumP5]

Glad to hear you made it home man. Sucks to read about your issues though.

Issues aren't really too bad. I've fixed the leak but shifting is still quite stiff, but only with the car on. I've verified the fluid is at the proper level and it still looks clean. Does anyone know what would cause shifting to be difficult only when the car is running (otherwise it feels fine)? I've read a few places online that seem to hint to improper clutch disengagement but we didn't touch that at all. The pedal feels fine.

 

[bbrich57]

It's got to be engagement problems if it only happens when running.
A bad bleed out. A change in clutch or TOB. A bad master or slave cyl.

 

[magnumP5]

It's got to be engagement problems if it only happens when running.
A bad bleed out. A change in clutch or TOB. A bad master or slave cyl.

The clutch was not touched during the transmission swap and I replaced the throw-out bearing with a new one. I replaced the fluid and bled the clutch master last night - no noticeable difference. The stock line is pretty cracked and dry-rotted, but not leaking, so I may try to replace that with a SS one and see what happens. If that doesn't work I suppose it's time to try a new slave cylinder and master. If THAT doesn't work then I guess I'll just have to live with it until I replace the clutch down the road. It's not unbearable to drive - just noticeably stiffer than before.

 

[bbrich57]

Then I would have to say that the replacement TOB is shorter... too short for the app.
What else would cause hard shifting while running under the conditions you've described?

BTW: It wouldn't have been a SPEC TOB would it?

 

[magnumP5]

Then I would have to say that the replacement TOB is shorter... too short for the app.
What else would cause hard shifting while running under the conditions you've described?

BTW: It wouldn't have been a SPEC TOB would it?

Nope, Mazda OEM part. There were some noticeable differences between the new throw-out bearing and the old. The P/N I had from the Parts Catalog had been superceded so I just assumed there had been a design change. If there is a difference in the throw-out bearing's height, perhaps there is an updated clutch fork, or maybe mine it bent - who knows. I'm not going to be removing THAT any time soon.

EDIT: Nope, clutch fork P/N is the same so perhaps mine is bent???

 

[magnumP5]

Just finished bedding in the brakes (I hope). While I was waiting for the brakes to cool off I snapped some crappy cell phone photos of the car as it sits now:

All the OH guys already know this but believe it or not the rears are all the way up.

 

[magnumP5]

Did my first full HPDE event this past weekend. Had a blast but unfortunately the car wouldn't let me do all 8 runs. On the 7th run the low coolant buzzer came on the the car quickly started to overheat. By the time I made it to the paddock the water temperature gauge was pegged at "H". Over the next hour or so we added water and bled the system repeatedly but the low coolant buzzer would still intermittently come on. I made the entire 2.5 hour drive home with no overheating issues, but the buzzer would go on/off when I got off the highway. I added a little more water and got a few more bubbles out of the system last night after everything cooled off. I decided to drive it to work today to see how it would start after sitting all night and if the buzzer would come on. It started right up, but was a little rough until warmed up. The buzzer did not come on at all this morning but the engine does sound a little "weird" to me when it's decelerating in neutral - almost a hissing. Still not sure if anything serious is wrong, but I'll continue to drive it this week to see if any symptoms come back.