After doing everything in the previous post, I put the Civic back on the ground to move it as we were doing a bbq for my partners birthday earlier in the month. I had rushed to get the Civic back together with the hope of going back to the track to confirm the intermediate shaft bearing wasn't the issue and it was most likely something gearbox related. After the birthday weekend, I had been trying to find 1 last day/night event at SMSP but everyone said it's all booked out.

With being a wee bit disappointed I didn't get to do much track work this year as I had originally planned, it meant I just had to do it next year. I need to use the Christmas/New Years break to get the Civic ready. I've replaced everything that could have been the noise, hoping it wouldn't be gearbox related, but it's apparent it is.

With the Civic back up in the air, within 20-30 minutes the gearbox was on the ground. Lets pull this puppy apart.

FYI, there is a video at the end of this post showing the in car noise | opened case old bearing noise | opened case new bearing noise.

My friend Tony is quite handy fixing things and has pulled apart a few B series gearboxes before, and was happy to take a look at mine. I loaded it up in the Mazda and headed to his. The plan is to pull it apart and replace whatever we find broken. Boy are we in for a surprise..

Fixing the gearbox

The gearbox dismantling, fixing and reassembling was over two consecutive Saturdays as we first had to pull it apart to find what was wrong, then order the parts, fix it and put it back together.

I was playing apprentice for these two days. I know everything for the Civic, except rebuilding an engine & gearbox, but was excited to learn.

Inside of the case was looking good, no signs of damage or metal shavings.

Initial look over the gearset, nothing looks too suss. Tony noted something straight away here, that his never seen a tapered diff bearing on these before. More context on this later, quite depressing actually.

Wait, it's a early model 4.4FD gearbox!?

When we pulled the case off, Tony pointed out straight away that the tapered differential bearing is unusual as his only ever seen ball bearing ones before, and he said oh this might be a early model gearbox, oh ohh. I was about to learn something I've had no idea about for the past 8yrs..

Turns out the JDM spec Type R S80 gearbox had 2 different variants for the 96-97 & 98-00 models.

• Early model: 4.4FD | B16 4th & 5th (shorter) | tapered differential bearings
• Late model: 4.7FD | B18C 4th & 5th (longer) | ball bearing differential bearings

I have always assumed there was only 1 Type R spec gearbox, which was the late model configuration. When I bought it, we did various comparisons between speed, rpm, gears to confirm it wasn't a GSR box and it looked to be true. Testing it against my mates CRX which has an upgraded Type R box with the 4.9FD and B16 4th/5th, it would be even 1st to 3rd, then he'd jump ahead in 4th & 5th. It's always hammered on track, keeping up with a lot of higher powered turbo cars on the straights..

I kept thinking.. "It feels like I've just found out a girlfriend has cheated on me for the past 8 years.."

So even though it has the shorter 4th/5th, the 4.4FD slows everything down so much and we could see this on the gearing comparison charts. This would back up how I've always said 5th feels so short on the straight at SMSP. And sometimes I'd watch the footage back and felt 4th is a smidge slow. Interesting.

What to do now? The plan was always to do a B16 4th/5th + MFactory 1.5 way differential. It might be a tad hard to find a OEM 4.7FD, and new aftermarket is more than I wanna spend. I've recently been shown the money I'd spend to work the gearbox + my B swap package could fund a K swap in parts and it would be way quicker and more reliable.

With that, I decided I'd go with what I originally said to myself and only replace whats broken, the differential bearings. Don't get me wrong, the 4.7FD would be awesome, but it's hard to think about spending the money on this with what I said above for the K swap. If I wish to work this box in the future, I can easily remove. It really isn't a big job.

I was very confused & conflicted driving home that night and for a few days afterwards on this discovery. Pros are I've achieved what I have with essentially a shitter ratio which I had no idea about. "So a 4.7FD would mean I'd be better". Cons are theres less $ value to it now, and pricey to make it what to me it "should" be. hmmmmm

Differential bearings

Anyways, back to it. Quite quickly Tony felt the cause of the loud noise was definitely the differential bearings. A lot of score marks on the rollers, and the ring itself as seen below. A few others whom I showed a in car video to of the noise said it seems like differential bearings. Nothing else looks that out of the ordinary, so it has to be this surely.

With the differential out, we decided to pull it apart to inspect for any further damage inside. Luckily no damage inside the diff, which was made the dollar signs disappear.

To confirm the differential bearings would most likely be the cause, Tony dug out some used but still good ball bearings for this differential. We fitted them to the diff, put it in the case by itself, put it back together and spun which instantly removed the noise.

Gearset

Gearset report, all gears look good.

• 3rd & 4th syncro + syncro selector sleeve? had a fair amount of damage
• 2nd syncro does have a bit of wear and tear but nothing to be concerned about. Don't have any photos.
• Reverse does have a bit of wear and tear but that's ok, in car it's never had any issues.

3rd & 4th, both syncro's had a lot of damage. You can see on the photos below, the burring on the teeth, also the points of the teeth were worn down and off centred. We actually replaced this set with spares Tony had, they were in a lot better condition, and the grip section on the inside of the syncro still had some good grip to it, mine were smooth to the finger feel.

Reverse:

The magnet has done it's job!

New bearings + reassembly

I went ahead with acquiring a ball bearing conversion kit as this comes with the shims my box doesn't have. The manual says to use a press to fit them, but we went with the ol heat trick using the gas torch. Once the bearings were fitted, we reassembled in the box and checked the clearances, everything was within spec!

With the bearings fitted, the only thing left to do was reinstall everything. Actually not too much of a bad process!

If you've watched any of my track video's, you'd be aware of how much play there is in the shifter. We checked the clearances of everything on the shift mechanism inside the box but everything was within spec. The only thing out were these springs which hold a ball in. Tbh I can't remember what they did, but they should be 30mm so we did the ol stretch-a-roonie.. Easy peasy

All back together, and ready to thrash! Thank you Tony for doing this and teaching me along the way. I'd be tempted to try it myself next time with the manual by my side!

Reinstall gearbox

Once home that afternoon, I went about reinstalling the gearbox. I usually bench press it in, it's a somewhat painful method but I find it gives good control over positioning the box. This time I had already decided prior to try using the engine crane. Not too bad, just had to strop the box correctly so I wouldn't have to stuff around too much aligning it. Bolted it up to the engine and the mounts, will need to refit everything else + torque everything another day.

With it reinstalled, I topped up the oil. The following morning I found a small puddle under the car.. of course. The seal for the shifter mechanism was leaking. Replaced.

Old:

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