Honcho's Long Road to Imola Type-S Zero

[Honcho]

Transmission Refresh 14

Differential, NSX-R Final, etc.

Completed the differential. Only slight issue was in the torque sequence of the cover bolts. The NSX-R ring gear is just a touch larger than the 4.06 and rubs against it during the torque sequence. I found that the cover ended up tilted after a few passes because the cver was hanging on the ring gear. I had to take care to torque evenly and very slowly while watching the cover go down, making sure it was even all the way around.

Rather than tapping with a hammer, I found that using the cover bolts in a criss-cross pattern worked well to seat the ring gear on the diff cover.

Using the press and a long slotted screwdriver to release the snap ring for the clutch preload spring. The old race from the countershaft bearing came in handy here.

The old spring plate.

The new components. The NSX-R preload uses two spring plates and a thinner holder to keep the overall distance within the clutch pack the same. You can re-use one of the old spring plates if you want, but I chose to replace it after 75,000 miles of good service.

New spring plates and holder installed with fresh MTF (marked "J" for convenience).

Cleaned the central gear and clutch plates and applied fresh MTF.

Carrier assembly cleaned with fresh MTF.

Carrier and clutch pack cleaned and installed with fresh MTF.

All back together.

Next, I tackle the countershaft.

 

[Honcho]

Transmission Refresh 15

Countershaft

Managed to disassemble the old countershaft, clean and get through 2nd gear. From the state of the brass synchros on this and the mainshaft (they appear new and nearly identical to the brand new synchros), I believe this transmission had a synchro replacement service recently. Interestingly, it seems that the brass rings were replaced, but not the hubs, which are showing typical wear for ~75,000 miles. Consiering the prices of the brass synchro components, I'm glad I have a spare set. However, you probably won't see me speed shifting at the track like I used to. I know Dori Dori says it's faster, but the NSX transmission is becoming something of an antique- we need to preserve it!!

My clever (ish) holder solution: I split a piece of 2x2 in half with my chop saw and then used a wood rasp to scrape out a semi-circle on each side. It worked quite well! Though, a 6 or 8 inch vise would have been better.

I broke my screwdriver doing this- problem is I can't find a cold chisel small enough to fit in the slot. Even though it wasn't bent all the way out, I was hoping my "big beast" 3/4" drive impact gun would just blast it off.

Yep. Chugga-chugga- ZIIIP! It didn't even slow it down.

The service manual has a rather complicated method of disassembly involving different pullers and a press. After studying the parts diagram for a bit, I thought why not just press the shaft out of the entire stack? Much easier.

After that, I arranged the components. As noted earlier, the synchro rings and bearings look new.

 

[Honcho]

Transmission Refresh 16

Countershaft, Short Gears

With the countershaft taken down, it was time to install the NSX-R shaft and short gear stack. Like the other parts, these were caked in dried packing grease. Some time was needed to clean with acetone and a microfiber.

The NSX-R countershaft. -J00 designation.

The NSX-R shaft on the right. Old shaft on the left.

Note that the gear cuts go deeper than on the standard shaft. Improved oiling? Seems odd, since reverse gear sits here.

Reverse and first gear fitted with the new bearing and old thrust shim. Synchro teeth on 1st look very nice for 75k miles. Checked the clearance and the .04 mm kind of fit, but felt tight. Though, given the way the gears fit on the shim, I'm not sure I was measuring it right. The diagram in the manual doesn't quite match the actual gears. Also, maybe I need to have it all pressed together before checking clearance?

1-2 first blocking ring installed with new spring. So nice to have new parts with clean oil.

New 1-2 hub and select sleeve.

Upper 1-2 synchro blocking ring and cone set. The only double-cone synchro in the 5-speed.

Synchro rings installed with a new bearing.

The first "short gear". 2nd.

Tested the operation of the hub sleeve and it selects quite smoothly.

 

[Honcho]

Transmission Refresh 17

While most of the old gears looked pristine, I have concerns about the countershaft 5th. This is the bottom of 5th gear, which sits against the top of 4th. The gear teeth are chipped on the bottom edge, but the top edge is fine. The chips appear to cluster around 120 degrees apart. It's hard to understand what might be causing this other than perhaps shifting too quickly into 5th? Or possible skip-shifting from 2 or 3 into 5th. In both cases, the mainshaft 5th engages before the synchro has a chance to spin it up to the correct speed, causing the teeth to smash against each other. I'm checking with Japan to see if a new 5th is available. If it's not, I will try to file off the sharp edges of the chips in the hopes of preventing further deterioration.

 

[NSXnZ]

Wow, one of the best car porn threads ever. Took me a month to read through most of it. Lol. What a cool project!

 

[RYU]

5th gear to me isn't really a power gear (at least for me) so if you can't a new replacement perhaps consider deburring it like you said and send to get WPC coated or something? Or some other kind of hardening type of coating?

While most of the old gears looked pristine, I have concerns about the countershaft 5th. This is the bottom of 5th gear, which sits against the top of 4th. The gear teeth are chipped on the bottom edge, but the top edge is fine. The chips appear to cluster around 120 degrees apart. It's hard to understand what might be causing this other than perhaps shifting too quickly into 5th? Or possible skip-shifting from 2 or 3 into 5th. In both cases, the mainshaft 5th engages before the synchro has a chance to spin it up to the correct speed, causing the teeth to smash against each other. I'm checking with Japan to see if a new 5th is available. If it's not, I will try to file off the sharp edges of the chips in the hopes of preventing further deterioration.

 

[Honcho]

[MENTION=20915]RYU[/MENTION] good news is that Honda Japan has one, so I will just replace with a new gear. I have to give credit to [MENTION=33247]MotorMouth93[/MENTION], who cleverly pointed out that, based on the locations of the chips, someone tried to use a 3-jaw gear puller and chipped the teeth. In fact, we're pretty sure this was a snap ring repair from back in the mists of time- more on that in a later post. I'm going to try and do the thrust shim clearance tonight so that I can add any needed shims to the Amayama gear order.

 

[RYU]

Speaking of shims... If I ever get that LSD in my hands I need to do the same measurements and order the same parts. If you can wait a week or two perhaps we can join forces for that Amayama order. No biggie though.

 

[Honcho]

Transmission Refresh 18

Countershaft 3rd and 4th Gear

Hit a snag.

The 3rd gear pressed on without issue. It was stiff, but it ultimately went on. 4th gear- not so much. My press can get it to about 10 mm from seated before it just stops. Admittedly, I have a small 12-ton press, so something larger is required. IIRC, LarryB used a 20-ton and now I know why. I was going to try heating the gear first, but before I go that route, I'm going to see if my local transmission shop will just press it on for me.

**EDIT**

My local transmission shop's press was also a "12-ton" except it was about 3 times larger than my garage press LOL. It took them longer to find the right sleeve/socket combo than it did to press the gear.

 

[Honcho]

Transmission Refresh 19

Mainshaft Thrust Clearance

Time to check the thrust clearance so I can order shims if needed and also my new 5th gear. First, let's see what is in there.

1.01 mm or Shim K (1.00 mm)

0.73 mm or Shim F (0.75mm)

Hey, wait a minute...didn't Tyler's 5-speed have the exact same shims in it? [MENTION=35590]Big McLargeHuge[/MENTION]? What are the odds? Anyway, here is the new transmission case next to the old one, which we now suspect is itself a replacement case from an old snap ring repair.

Mainshaft installed in the clutch case.

Shims and oil control plate installed in the new case.

Aaaaand... Wait. That's not right...

I think what is happening is we have a brand new cut case and a brand new top bearing. Unlike a used transmission, where these parts have been fitted and moving against each other for thousands of miles in a bath of hot oil, it's a "rough" dry fit. Tonight, I will place the mainshaft in the case first and then carefully tip the whole thing into the clutch case. Should solve it.

 

[Honcho]

Transmission Refresh 20

Mainshaft Thrust Clearance

I'm glad I measured this clearance. There is no way my existing shims were going to work. To review, my transmission came with the following shims: Shim K (1.00 mm) and Shim F (0.75 mm) for a total shim thickness of 1.75 mm.

As shown below, the measured thrust clearance with the shims installed, but without the spring washer is .025" or 0.635 mm
Adding back the thickness of the spring washer (0.84 mm), we get a final thrust clearance of (0.635 - 0.84) = -0.205 mm

Since the thrust clearance can't be negative (the mainshaft would not fully seat!), we need thinner shims. If I use the existing 0.75 mm shim, I have two options:

Using Shim C (0.60 mm), we get a total shim thickness of (0.75 + 0.60) = 1.35 mm
Starting with our too-thick -.205 mm clearance, we remove the old shims to get (-.205 + 1.75 mm) = 1.545 mm
Adding our new shims (Shim C and Shim F), we get a final measured thrust clearance of (1.545 - 1.35) = 0.195 mm

Using Shim D (0.65 mm), we get a total shim thickness of (0.75 + 0.65) = 1.40 mm
Starting with our too-thick -.205 mm clearance, we remove the old shims to get (-.205 + 1.75 mm) = 1.545 mm
Adding our new shims (Shim D and Shim F), we get a final measured thrust clearance of (1.545 - 1.40) = 0.145 mm

A "perfect" shim for this transmission would be 1.375 mm, but it is not available. So I have to choose between the two. The specified acceptable range is 0.14 mm to 0.21 mm. Using Shim C puts me only 0.005 mm away from the minimum allowable clearance. Using Shim D puts me in a looser, but safer range with .015 mm away from the max clearance.

So this begs the question- on the NSX 5-speed, is it better to be tight or loose on the mainshaft clearance? I recall [MENTION=12356]Mac Attack[/MENTION] mentioning that he was a hair tight beyond the minimum (less than 0.14 mm) and he had some notchy shifting. This has me thinking looser is better- thoughts?

Setting up the gauge. I used a landscaping bolt and one of my pressing plates to fix the base.

Making sure it is zeroed.

Lifting the mainshaft up. Reading 0.025" I checked a few more times- making sure to seat the mainshaft all the way down and pull all the way up. The reading did not change.

 

[Big McLargeHuge]

Shim brothers! Lol. This part is what added a few weeks to my rebuild because even calculating the correct range of shim sizes and ordering the ones I thought I needed couldn't get me to the right tolerances at first, so I ended up ordering new shims twice over (same for the diff preload). They were hard to find in the US (Tim @ OEMAcuraParts helped me out here) and I'd order several sizes more if I were you. You can always sell the ones you don't use like I did. It might save you a few weeks.

I'm not an expert but personally I'd choose shims on the looser side of the tolerance range for the reason you listed. My clearance was also negative like yours with the original shims.

 

[Honcho]

Shim brothers! Lol. This part is what added a few weeks to my rebuild because even calculating the correct range of shim sizes and ordering the ones I thought I needed couldn't get me to the right tolerances at first, so I ended up ordering new shims twice over (same for the diff preload). They were hard to find in the US (Tim @ OEMAcuraParts helped me out here) and I'd order several sizes more if I were you. You can always sell the ones you don't use like I did. It might save you a few weeks.

I'm not an expert but personally I'd choose shims on the looser side of the tolerance range for the reason you listed. My clearance was also negative like yours with the original shims.

Shim Brothers!

I ordered 1 size thinner and thicker than these two (4 shims total) just in case something changes with the clearance (can't imagine it will, but still.) I agree and I think I'll go with the looser range.

 

[Honcho]

General

Progress Report

Not much actual work happening this week, as I am investing some time in tidying up the workshop. I like a clean workspace and there are piles of materials, parts and tools everywhere due to all of the work over the past couple months on the various things. Now that the new 5th gear and proper shims are ordered, I have some time to pivot to other tasks while i wait for the mail from Japan:

"Small" Tasks, i.e. Things That Can be Done in One Evening

• Finish the ABS custom S2K harness and install it
• Assemble the blower with new foam and install
• Install the new heater hoses and brackets
• Install the center tunnel hard and soft coolant hoses
• Pre-install coolant hoses on the engine
• Rebuild alternator and install it with a new belt
• Rebuild starter
• Install gas tank
• Finish painting the console trim pieces (they're nearly done, but no pics )
• Complete the interior wiring so I can get the carpets and interior trim back in

"Big" Jobs, i.e., Things That Need A Weekend and Probably a Friend to Help

• Install front subframe
• Cut and cast new motor mounts
• Transfer engine to wood block stand and install clutch, transmission
• Install transaxle into rear subframe
• Install hood
• Install rear subframe

Also, we need to remove the driver B-pillar so that I can fit the quarter panel better to the door- the door sticks out about 2 mm. I need to put some spacers behind the side scoop and at the B-pillar to make it flush. Similarly, I just realized that the headlights I worked hard to fit properly need to come back out! The front subframe has 4 bolts that sit under the light. Grrr. In a nice development, the shop that pressed on my countershaft 4th gear (for free) said they would be happy to press out my suspension bushings. So, rather than struggle in the garage, I'm just going to take it to them. I have the tools to install the poly though. Still on the fence about anti-seize versus the PTFE silicone grease. I'm leaning anti-seize...

Also, I have to rebuild both driveshafts, which will be a few nights each. I was hoping to get this car started before Christmas, but it might be 2022 before we see the crankshaft turning under its own power. I know I'm losing a week with all this cleaning, but a clean workshop makes everything move faster. It's a good tradeoff I think. I'm hopeful that the Thanksgiving break will give me some extra time to knock out some of the above.

 

[Honcho]

Anti-Lock Brakes

AP1 "Honcho Harness"

Quick update- Amayama sent the transmission parts, so I hope to close up the transmission case once the mail comes. Probably next week since it is EMS.

Meanwhile, time to pivot back to the front bay, which has been neglected during the past few months. The holdup is the completion of my custom AP1 ABS harness, which must be installed before the other front bay components can go in. Had some free time last night, so I decided to get to it already!

As this ABS modulator unit is from a AP1 S2000, there is no TCS functionality. There is a great thread on NSXCB where Kaz and Britlude (I think) went in really deep on whether one can get the AP1 module to work with the NSX TCS system. The verdict was no. In my case however, it's a moot point because I deleted the ancient TCS system from the car. This means the AP1 harness is a bit easier to make, since you don't have to wire the 18-pin plug at all. It just uses the 20-pin Tyco/AMP Multilock 070.

The harness itself contains four main "branches" coming off the tree: (1) Wheel Speed Sensor and Data feed, (2) Main Power feed, (3) Ground Loop, and (4) SCS Terminal feed.

[HOLD]

Taking a cue from T3TEC, I ran the sensor and data wires into three smaller connectors so that they can be easily passed through the firewall grommet.

[HOLD]

Test-fitting the completed front bay harness section. I will remove it and tweak a few times until I get it running just right.

Here, I'm working on wiring up the solid-state relay and vehicle-side 20-pin plug, which contains the reciprocal small connectors. They don't need to be weatherproof because they are inside the car. I will use a HD 090 4-pin connector to make the relay connection easier. Just need to figure out where to place the relay.

My Astro ratcheting crimper doesn't really work on the smaller wires. I needed to use my manual crimper. I found, for these small 20-22 AWG wires on the AMP 070 pins, using Set "E" for the wire crimp and Set "C" for the insulation crimp yielded good results.

 

[Honcho]

Anti-Lock Brakes 2

Harness adapter, solid state relay, etc.

Working on the 20-pin adapter for the NSX wire-side plug. This is a Tyco/AMP Multi-Lock 070 connector. I doubled up the wires in the IG2 pin and they fit well.

The completed interior harness adaptor. The AP1 module uses a different WALP signal because of the digital dash on the S2000. Our NSX uses an ancient incandescent light bulb, so you must use a solid state relay to get the "ANTI-LOCK" warning light to work correctly on the dash. I chose to wire the relay to a HD 090 4-pin connector to make a cleaner installation.

A closer look at the interior connectors.

My circuit diagram. I have to express my gratitude to Kaz, who patiently walked me through all of this last year. I would never have been able to get this to work without his helpful guidance. I decided on the 090 connector for the relay after making this, but it doesn't really change anything.

 

[Honcho]

Anti-Lock Brakes 3

AP1 Harness Routing

The exterior harness is routed. Now, I can resume installation of all the front bay components, including the hood!

Main lines routed cleanly.

Grounded to the ABS bracket.

The SCS check terminal. I need to find a way to make this a clean access point. Maybe zip tie to an existing harness?

I follow the T3TEC method and use the FR brake hard line as an anchor point.

Routing into the main cabin through the firewall grommet. I did not seal this on my 91 (using the KSP harness) and never had an issue. Still, I might put some black RTV on there. Note the main power leads running toward the fuse box. You can also see the new washer hose. It's now clear pink instead of black.

Main power leads routed to the fused power side of Fuse No. 30.

Main leads in the passenger footwell.

 

[Honcho]

Re-Assembly 41

AT Neutral Safety Bypass

While I had my wiring tools out for the ABS harness, I did a quick side-job on the AT neutral safety bypass. On the AT NSX, this switch replaces what the clutch safety switch does on the MT cars- prevents starting unless the circuit is complete (i.e., shifter is in "Park"). I rigged a bypass loop using what I thought was the proper harness plug. Turns out it didn't fit, so I just made a wire loop with heatshrink and some 3M Termiflex tape.

 

[Honcho]

Interior

Center Console, Trim Pieces, etc.

Throughout all of these other projects, I've been slowly re-finishing my interior trim. For the early cars, I use Duplicolor Honda Graphite Grey. I find that, combined with the gray self-etching primer and a clear coat, the color is really close to the OEM finish. It's a bit more "gunmetal," which is actually perfect for my S Zero concept.

Center Console

My original plan was to glue my original console back together. But, I realized getting it to be the perfect angle will be tough. Besides, it's not in the best shape from being hacked up over the years for aftermarket stereo installs. So, I pivoted and found this really nice OEM console for a good deal. Like most of the early cars, this one was bubbling around the top corners.

Because the rest of the console was in perfect shape, I decided to channel the spirits of our old-school Prime interior guys, [MENTION=5957]D'Ecosse[/MENTION] and [MENTION=9919]Malibu Rapper[/MENTION] and repair just the bubbles rather than melt the foil off the entire thing. The reason the foil lifts in these sections is that it is stretched at 4 angles over a sharp corner. If you remove the foil in these sections and relieve the stress, the rest of the film should last a long time.

First, using a sharp razor, cut peel lines around the area you want to lift. Then, use the razor to lift the foil and peel the sections ​off.

Next, fill the sections with Bondo Glazing Putty. The idea is you want a smooth transition over the lines you cut, so there is no "shelf".

Finally, sand down the putty until you have a flush surface. I used a 300 grit foam block. This took several tries to get right.

Self-etch primer going on. 3 light coats.

Color coats applied. This looks so good just by itself- however the sun and heat will affect this paint. It needs a clear coat.

I use Eastwood 2K catalyzed clear coat. This is a highly volatile paint, so I chose to paint outside to protect my lungs. Even then, I wore a respirator. You don't want to mess with this stuff.

Here is the clear going down on the other parts. Now, I can assemble the door panels and get them on the car.

 

[Honcho]

Re-Assembly 42

Center tunnel coolant hoses

Not many pictures due to the struggle, but I attached all of the center tunnel hoses and the coolant hard lines running into the front bay. Note for other members- attach the top large (S-shaped) hose first before connecting the heater hose. Otherwise, you will have a tough time.

Mistake- I should have connected the big hose next to this one first...

Got it connected. I noticed that the new S-shaped hose was slightly shorter than the original hose. Thankfully, I was able to get enough hose on each end past the bulge for full clamp engagement.

 

[Honcho]

Re-Assembly 43

Shift Cables

While I was under the car doing the hoses, I took a minute to shore up the dodgy shift cable hanger with a couple zip ties. Probably overkill, but I don't want the cable dropping...

 

[Honcho]

Re-Assembly 44

Heater hoses, bleeder, etc.

Installed the updated heater hose bleeder pipe and hoses. I realized I will have to check and possibly reset the air mix motor cable and doors. This means probably removing the motor from the bottom of the HVAC unit. Grrrr...

 

[Big McLargeHuge]

AP1 "Honcho Harness"

Funny that you're finishing up the ABS work now, I just happened to do the same thing this past weekend . Thanks again for the help and wiring diagrams.

Good idea using spade terminals for the relay, I just left them as flying leads which isn't as neat. I like using Weatherpack connectors in general since they're easy to work with and the terminal pins are easy to install/remove, but they're just so bulky compared to the Sumitomo HD style.

I zip-tied the SCS terminal to the same bracket as the old NA1 orange solenoid connectors but you probably don't have that. Maybe you could make a small bracket (or recycle an OEM one) to clip the Weatherpack onto and bolt onto the Nissin bracket ground?

Nice job on the center console. Stripping all the foil off really sucks no matter what method you use.

The water valve is pretty impressive when you think about it even though it's annoying to work around in the car. 30+ year old plastic w/hot coolant and the ends haven't broken off yet. What forbidden knowledge does Honda have?

 

[Honcho]

Funny that you're finishing up the ABS work now, I just happened to do the same thing this past weekend . Thanks again for the help and wiring diagrams.

Good idea using spade terminals for the relay, I just left them as flying leads which isn't as neat. I like using Weatherpack connectors in general since they're easy to work with and the terminal pins are easy to install/remove, but they're just so bulky compared to the Sumitomo HD style.

I'm becoming more and more of a fan of the HD and HW 090 connectors. They're so easy to work with and so versatile. I've used them for virtually all of the wiring changes I'm doing. Even the ECU plugs are giant HD 090's.

I zip-tied the SCS terminal to the same bracket as the old NA1 orange solenoid connectors but you probably don't have that. Maybe you could make a small bracket (or recycle an OEM one) to clip the Weatherpack onto and bolt onto the Nissin bracket ground?

I'm going down this rabbit hole lol. I have some spare 090 brackets from various part removals and I'm seeing if anything will fit and look OEM in that area. I'd like to secure the connector itself rather than the wire for durability...which is making me lean toward re-pinning it with a HW 090. I have a spare bracket (from the old ABS) that will snap on the 090 connector and hold it in place....

The water valve is pretty impressive when you think about it even though it's annoying to work around in the car. 30+ year old plastic w/hot coolant and the ends haven't broken off yet. What forbidden knowledge does Honda have?

The same forbidden knowledge that makes the factory-assembled short block virtually indestructible, but any rebuild just falls apart or never runs quite right. They must have had some kind of fire-demon (Onibi?) trapped in the basement of Tochigi and they used its power to assemble the engines. That's my theory anyway...

 

[Honcho]

Re-Assembly 45

Radiator Hoses

All front and center area coolant hoses are installed. These are the main hoses for the radiator. Note for other owners- the white dot on the hoses goes toward the radiator. Noticed a quality control issue from Honda- the radiator top hose was cut at a slight angle on the bottom fitting. Cosmetic issue, though- will not affect running.

[Hold for heater hoses.]