Author Topic: 1988 Turbo 'Vert Project  (Read 36890 times)

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Offline murz

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Re: 1988 Turbo 'Vert Project
« Reply #195 on: June 11, 2018, 10:18:02 AM »
Looking great! Really neat, I've wanted to do this to my silver car as well, one of these days.
1986 AS GXL Turbo swapped
1993 VR R1

Offline toplessFC3Sman

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Re: 1988 Turbo 'Vert Project
« Reply #196 on: June 18, 2018, 06:55:42 AM »
Everythings coming back together now - the controller and screen are all packaged up into the warning light cluster, the control knob and switches are packaged into the ash tray & all wires are run behind the dash, and it all is working as intended.


I had a bit of a logical error in reading the new sensors added in the intercooler and cooling systems, but eventually found it and re-did the input pull-up resistors and code to calculate everything correctly. The problem with making things so compact is that it's difficult to make any changes without screwing other things up, accidentally bridging pins with the soldering iron etc. Oh well - maybe I'll look into having a custom board printed next time.

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Beyond that, there was a bit more time spent making block-off panels for bits that have gone missing or to plug other holes in the radiator bulkhead to force more air through the heat exchanger and radiator. Also, since a bit of the interior had to come apart to fish all the wires through, I inevitably broke some of the very brittle plastics and had to do some gluing to re-assemble them. It seems that both the AFR gauge and the EGT gauge are having issues too - all the inputs seem to be there and correct, and they all worked when the car was parked, but now they don't. I'm leaning towards bad or broken solder joints at the connector, but we'll see when I open them up.

Overall, its getting very close to being back on the road!

Offline murz

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Re: 1988 Turbo 'Vert Project
« Reply #197 on: June 18, 2018, 09:09:18 AM »
Looking good!! We'll have to do an rx7 cruise when it's back on the road, or something.
1986 AS GXL Turbo swapped
1993 VR R1

Offline toplessFC3Sman

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Re: 1988 Turbo 'Vert Project
« Reply #198 on: July 07, 2018, 06:41:17 AM »
The last piece of the puzzle, at least from a mechanical side, is the ducting. This is critical to make sure that the air forced in the front bumper when the car is moving does not escape and go around the radiator and heat exchanger - its forced through it. Otherwise, you're going to be relying on the fan all the time to pull air through, which is going to be a huge drag on your electrical system, and it may not be able to keep up on the highway where electrically driving the fan can actually be detrimental to air flow.

Since we cut a hole on the driver's side of the radiator to make room for the fittings and pass hoses back and forth, this is the biggest place that we need to address with ducting and block-off panels. For some of the more complicated shapes, or where I wanted to have a more rigid panel after bending it, I cut the pieces out of a sheet of textured ABS plastic. Using a torch, its easy to heat up parts of the sheet and bend it into the shape you want, and when it cools off it will be nice and rigid in that new shape. It cuts nicely with shears, and drills nicely to put holes in for fasteners to hold it onto the panel. Speaking of these holes, I was just using some of the christmas-tree style push-in trim fasteners for this since they are cheap and all they need is a hole of a certain diameter to go into. Make sure to be careful drilling these holes so that you don't hit anything behind the panel that you're drilling, and plan ahead for access to these holes once the heat exchanger, pump etc are in place.

Anyway, this first panel is inside the engine bay right next to the battery. I cut up some extra length of the water hose, put a slit down the side, and wrapped it around the actual water hose to help protect it from rubbing and to better fill the hole. Then, this panel covers the "L" shaped section behind the headlight and onto the radiator support, with a small part bent out to hug the water hoses. There is also some window & door foam used here, like what you'd get at a hardware store for insulating the gap between doors or windows and their frames. This stuff is great since its very pliable, and comes with a strip of adhesive along one side so you can just stick it in place. I've used it before for filling small gaps between the radiator support or plastic panels and the radiator or oil cooler, and its done a good job.



Since this hole cuts through into the area underneath the driver's side headlight too (it makes it much easier to get the heat exchanger into place), that area needed to be blocked as well. This was a simpler panel, really just an "L" shaped piece trimmed to fit. This shot is looking right next to the headlight, along the metal panel that forms the driver's side wall running along the "frame rail" to the bumper support. This piece also has the window and door insulation between it and the metal since the surface was more irregular here.


Now, what is that blue and white panel to the left doing there? For larger sections, I used a yard sign for a local Greek festival, since the material is basically the plastic version of corrugated cardboard. It is two layers with lots of lines between them, it bends very easily along one axis, and free is the best kind of cheap! This is to replace one of the panels that directs air to the radiator in the center section of the car, next to the coolant overflow bottle, that went missing years ago. I had to make that panel in two pieces to get it into place and block off the side, but it also runs along the inside wall there to partially block the hole that we cut for the heat exchanger hoses.


For all your racing needs, go to St. Nicholas Speed Parts! I'm also going to use this stuff to make an air filter box to separate the filter from the rest of the hot engine bay.

Offline toplessFC3Sman

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Re: 1988 Turbo 'Vert Project
« Reply #199 on: July 07, 2018, 07:33:13 AM »
Unfortunately, all that ducting needed to be removed, as well as the heat exchanger, battery & tray, and some other parts in front of the radiator because... on the maiden voyage of the S.S. Savannah, she sprung an oil leak!

There was oil dribbling down the side of the oil cooler, and it was dripping once or twice a second when the engine was running. I hadn't noticed this before when the car was stationary and up on jack stands (thus why everything else got re-assembled around it), but this had to be addressed. I could see it was coming from the oil cooler thermostat fitting since the cooler hoses were all dry, but I at first assumed it was the crush washer. When I disassembled it and replaced the washer, it was gushing out in a constant stream instead of just dribbling a little bit... uh oh.



Yep, the bung itself is cracked. Maybe from overtightening when I reassembled it? I would have expected the aluminum threads to strip first, since its not a tapered hole, and I was not tightening it to a huge torque, but who knows...


So, now Savannah sits like this, waiting for this to get welded up or a replacement oil cooler, we'll see which route works out in the end.

Offline toplessFC3Sman

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Re: 1988 Turbo 'Vert Project
« Reply #200 on: July 20, 2018, 09:32:56 PM »
I was thinking about how prone the intercooler would be to heat soak and getting warm from the engine & air coming off the radiator, and since the system was already drained to get access to the oil cooler, I decided to try to do something about it. Since I had plenty of the corrugated plastic signs, and they already have all these little air pockets inside of them, I figured they would work very well as insulation as long as the open edges of the corrugation was sealed off. So, I did some tracing, made a pattern, and figured out how to run a bunch of zip-ties to hold it all on to the intercooler in a removable way.

More St. Nick's Speed Parts!

Then, once I had the pattern down, I took some reflective aluminum foil tape and covered the outside of the sheet with it, and wrapped it around the edges to seal off and trap the air pockets inside the corrugation channels for insulation. I went with reflective tape mostly for the look - it would theoretically help with reflecting radiant heat, but thats only a concern if the piece has a direct line-of-sight to something really hot, like over 500 C, since radiation levels are proportional to temperature^4. Things at 90 - 100C, like the coolant, radiator, and outside of the engine (except the exhaust & turbine housing) have no appreciable radiant heat transfer, its all convection through the air or to the coolant.

I did cut holes in the sheet for the mounting pads to stick through, and one on the underside over the alternator since the clearance there was already very tight (I bent the end tank inwards to give more room for swinging the alternator up to tension the belts). I'm not too concerned about this part, since this is the hot side of the intercooler anyway - when the turbo is really working & making boost, the gas coming out of it could be 150C or more, at which point insulation would only be keeping heat in, not out.




Its not the prettiest, but its a lot better than the sign alone would be. The tape was a lot more stiff than I anticipated too, so getting each strip nice and straight was very important. Now, here it is, installed in the car. The second picture also shows the cut-away needed in one of the hood supports so that the hood closes properly without hitting.



Offline toplessFC3Sman

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Re: 1988 Turbo 'Vert Project
« Reply #201 on: July 30, 2018, 09:58:52 AM »
So, while driving Savannah to work for the second day, as I was getting off the highway the diff whine when coasting was very severe, and was accompanied by a gravelly crunching sort of noise at low speeds. The noise went away completely when I was accelerating or was positively sending torque through the diff, so it was only when it was unloaded.

Thinking that possibly the diff had drained over the two years that the car was parked, I went to a parts store to try to refill it during lunch. Unfortunately, I couldn't get the car high enough in the air to get enough leverage to open the drain plug, but fluid did come out the fill plug... so it was definitely not empty, and while the fluid seemed a little thin, it wasn't terribly bad. Either way, that didn't seem to be the root cause. I coaxed her home that evening by waiting for traffic to be light, and by driving with my foot on the gas slightly while braking to keep everything properly loaded.

Then, on Saturday morning when I had some time, I was dropping the rear subframe to get to the diff, and the driver's side stud snapped clean off, flush with the bottom of the nut! Shit!


I'm still thinking of how to go about repairing this, since the documented way on RX7club (get at the top of it where it is welded into the chassis, cut away the welds, get a new stud and weld it in) really is prohibitive with all the extra chassis reinforcement that would need to be cut away right over this spot in the convertible. Anyway, still considering other options here...

Back to the diff problems, it came out of the car the rest of the way without protest, and I could get it mounted up on the engine stand by drilling an extra hole in the base plate for one of the three front mount studs, making it a lot easier to work on than last time.


Removing the cover to look at the carnage, and.... there doesn't appear to be any?


There is a little bit of darkening on the inside edge of the ring gear teeth, but I don't really know what that means. It is not really in a spot where the teeth should normally be transferring force either. Other than that, there is no chipping, apparent pitting, or other inconsistencies that I've noticed in the teeth.

Removing the torsen LSD & ring gear didn't yield any other surprises - very little end-to-end play, but definitely more gear lash between the ring & pinion than I would expect. The bearings on either end of the diff were also in good shape, with the only irregularity being a slight discoloring spaced evenly with the rollers in a few spots - I'm guessing there was maybe some slight corrosion when things were sitting? Manually turning the race on the rollers feels very smooth, and the discolored spots don't seem to protrude or feel any different than the rest of the surface.

However, after flipping it over to get at the pinion bolt, I found that this bolt was not even finger-tight, and the drive flange was loose in the end! Either the nut loosened up in service, or the bearings around the pinion shaft wore down enough to allow it to loosen up? All those parts looked almost immaculate, including the bearing outer races that I could see, and the bearing pins... so it was just loose? I find it hard to imagine that it would wear down that much and leave no sign of it on the bearings.


Anyhow, I plan on just re-assembling and snugging up that front nut (well, getting another one, as the locking portion of it is suspect now) and then looking at the mesh patterns on the ring & pinion with marking compound to determine if it looks like it will work or not.

Offline ~Groll69~

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Re: 1988 Turbo 'Vert Project
« Reply #202 on: August 01, 2018, 11:58:04 AM »
i hope that was the only issue with it.  Unfortunately you broke that bolt for the rear sub frame.
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Offline toplessFC3Sman

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Re: 1988 Turbo 'Vert Project
« Reply #203 on: August 14, 2018, 02:11:55 PM »
I got some time to work on Savannah again this weekend, and the first thing to tackle was the broken subframe stud. I've been thinking about the best way to go about this, since the convertible has considerable structure built up above it that would need to be cut away, and then re-welded to preserve the additional convertible structure. If possible, I'd like to salvage the current stud, especially since as far as I can tell, the threaded end and portion that broke only serves to clamp the subframe to the unibody - the base of the stud has a bump-out that locates the inner bushing within the subframe mount so there will hopefully be lower loads on the bolt itself.

Anyhow, since the original threads were M14 x 1.5, I wanted to use the same size in a high 10.9 grade to try to keep comparable strength and a relatively wide cross-section in case there were bending loads too. This requires cutting down the stud a bit to get enough of a cross-section for threading. I wanted about a 2mm thick wall all the way around at a minimum, which meant cutting it at the point where the taper brought it out to 18mm.



There was about 30mm of the stud remaining (originally it had been about 75mm of un-threaded taper, with another 25mm or so of threading on the end), with an end diameter of just under 18mm. Drilling the stud precisely down the middle was very important so that the threading doesn't poke through the side, to keep a constant cross-section in the stud, and to allow threading the bolt once the subframe tube is around the remains of the stud. Since all of this was still on the car with the rear up on jack stands, I needed to get creative in making a setup that would keep the drill aligned properly, while still allowing a number of different drill sizes to work up to the final 1/2" bit (12.7mm, while M14 x 1.5 wants a 12.5mm initial hole). So... here's a pretty janky solution that worked surprisingly well...



First, I cut an "X" in the surface of the stud, with the center of the X being the center of the stud. This was to keep the tip of the bit located at the proper spot. In the above image, I had already done a little initial drilling with a smaller bit, and had come back with a larger bit which unfortunately wandered a bit off-center - this had to be cleaned up with a dremel grinding tool to make it sit concentrically again.



However, locating the tip is only part of the problem... to control the angle of the drill, you need to fix the other end of the drill bit in space too, which brings us to the jankier bit...



Yes, a 17mm 12-point deep socket, pounded over the end of the stud, and a series of spacers to locate the end of the drill bit within the driver square at the far end of it. Each bit required its own spacer or spacers depending on the bit length and diameter, so I ended up with a small pile of little tubes made out of lighting rod, aluminum tube, brake line etc. So, now all I need to do is put the right bit in the drill, slide the spacer over it to fit in the drive square, spray it all down with WD40 as cutting fluid and to lubricate this spacer, slide it up into the socket and feel around for where the tip falls into the hole in the center of the stud, and then keep pressing this heavy ass drill into the underside of the car for 15 - 30 seconds at a time, then remove it, clean out the chips, spray it again, and reinsert until I get to the right depth. Also, to get up to a 1/2" drill bit going deep enough into the stud, I needed to do this with I think 6 different sized bits, periodically sharpening the bits as necessary. My arms and upper body were in no shape to be doing all this lifting and pressing, so now its time for the jankiest part of the whole thing (just when you thought it wouldn't get any worse...)



Yes, a jack to apply pressure to the back of the drill to do the cutting. Through all of this, trying to keep the stud cool was important, so I was spraying that with WD-40 too to try to prevent it from work-hardening... This worked pretty well up until the 1/2" bit, which got hot extremely quickly and actually burst one of the two bits in that size I had. The other one I was eventually able to make work by drilling out the center of that 17mm deep socket to make it large enough to put the remaining bit through, by frequently re-sharpening it, and through a lot of persistence. In the end, I had a properly sized hole about 40mm deep to the shoulder of the angle at the tip of the bit, looking pretty close to centered & concentric.



The bad news is that all of this took around 4 hours, and that trying to tap it is an absolute bear - it took about 40 minutes to even get the tap started, and another 2 hours to get 3 full threads cut into it since I suspect that it did work-harden and kept grabbing the tap, forcing me to go very slowly. I ordered a harder cobalt-steel tap and a bottoming tap to try again, hoping that the quality of my harbor-freight-grade current tap is just not cutting it (heheh), but we'll see when they arrive.

In other news, I finally got around to painting the diff teeth with marking compound and checking the engagement. By the looks of it, the coast-side pattern is indicating that the pinion is too far away from the ring gear (too shallow), which would be consistent with bearing wear and the looseness of the pinion nut. I think I'm resigned to ordering a few shims and a new crush collar from Mazda to try to get it set up properly since I don't want to have to go through all of this again.


The drive side, shown below, is also off and really biased towards the toe, although this may be a consequence of adjusting the ring offset to get the backlash correct. Either way, we'll see when I get the new shims (need to measure what the current one is first)

Offline murz

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Re: 1988 Turbo 'Vert Project
« Reply #204 on: August 14, 2018, 03:24:26 PM »
Wow, that's definitely janky, and only got worse with the jack! I see where you're going with it though, hopefully the new tap will speed things up. Yikes!
1986 AS GXL Turbo swapped
1993 VR R1

Offline ITSWILL

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Re: 1988 Turbo 'Vert Project
« Reply #205 on: August 15, 2018, 01:29:03 PM »
should work nicely. I'm sure you already thought of this but, when you are done tapping it make sure to smooth out the end of the stud.
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88 TII 20B T70 turbo

Offline toplessFC3Sman

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Re: 1988 Turbo 'Vert Project
« Reply #206 on: August 18, 2018, 08:31:47 PM »
So, in the end, after cleaning up the end of the stud, the rear subframe and differential seemed to just slide into place as if nothing was wrong, and the 80mm bolt threaded in with no issues. I had also gotten a 90mm bolt, just in case, but it bottomed out in the threading before tightening onto the subframe, which tells me that the 80mm is engaging just about all the threads in the stud that it can for maximum strength.


Now we'll see how it handles the driving loads placed on it...

Anyhow, onto the diff itself: The assortment of spacers, new crush-tube, and a new pinion seal came from Mazdatrix today. I was hoping that they'd arrive yesterday so that I could get everything together to make an appearance at the Woodward meet, but due to an issue that they had getting one of the spacers, things didn't ship in time. Oh well... they came around noon today, and I got to work shortly thereafter.

Since the engagement pattern showed that I needed to space the pinion closer to the ring gear since the bearings had worn and allowed it to move further away, I needed a thicker spacer to be inserted between the pinion and the closest thrust bearing. This required the thrust bearing inner race be pressed off of the shaft, the existing spacer had to be replaced with a thicker one, and the inner race then be pressed back onto the shaft. I didn't have a press, and my assortment of hammers was nowhere near big enough (although I tried...), but fortunately the local hardware store had one back in their shop (Carpenter Brothers in Ann Arbor, at the intersection of Plymouth & Nixon Rd - you saved me again!). Support your local stores!!! Stepping up only 0.14mm to the 3.29mm thick spacer seemed to place the wear patterns in the middle of the teeth, at least from the base of the tooth out to the tip. They were roughly centered (about as well as I think they could get, given the spacer thicknesses that I had to work with), and I was more worried about the coasting side, since after my noise problem was under coasting, and a lot of reading confirmed that it was the more troublesome side with used gears. The contact patterns had a bit of a strange, pointy shape to them, which seemed to be contact at the tip of the shape staying constant, while the rest of the pinion tooth sort of dragged around that tip as it slid along the ring gear tooth. Ultimately, the contact spots look like they're in the best location that I can get them, but the shape is a bit odd. We'll see how they sound, and hopefully they don't require another adjustment anytime soon.

Drive Side


Coast Side

Since I got a lock nut for the pinion shaft from a general hardware store, it ended up being a bit too long to fit in the recess in the driveshaft and the edges needed to be ground down a bit. Not really a big deal, but if I were to do it again I'd just get the proper lock-nut from Mazdatrix as well.

Offline toplessFC3Sman

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Re: 1988 Turbo 'Vert Project
« Reply #207 on: August 25, 2018, 07:17:34 PM »
Its been about 600 miles since the engine rebuild, and 400 since the diff rebuild and subframe repair. Time to change the oil and filter, and in 600 miles to change the diff fluid. The engine is still feeling strong, and I just got the boost dialed up to the same 12 psi that it had been running at prior to the rebuild. The diff is making a little bit of noise on deceleration, but it is soft enough that I think its just about normal, given the mazdaspeed stiffer diff mounts on all 3 corners. Oil change tomorrow, then some more miles to continue breaking everything in

Offline murz

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Re: 1988 Turbo 'Vert Project
« Reply #208 on: August 26, 2018, 06:48:21 PM »
Good to hear it's been good so far! You should take a picture of the vert, it's been so long since i've seen her haha.
1986 AS GXL Turbo swapped
1993 VR R1

Offline toplessFC3Sman

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Re: 1988 Turbo 'Vert Project
« Reply #209 on: August 28, 2018, 10:09:23 AM »
Oil looks good with no metal flaking that I can tell, the coolant level hasn't budged, and the only concern is a little bit of oil smoke, especially on over-run at 6-7000 RPM - I don't know if this is due to having the oil slightly overfilled, some weak seals in the turbo, problems in the PCV & breather system, or what. The catch can was also very full, leading me to think I might have hooked up something wrong with the PCV