Popping out of 5th after LSD install

1033 Views 34 Replies 6 Participants Last post by rgm_93si, 1 d ago

rgm_93si

Discussion Starter · 1 mo ago

2

I installed an MFactory LSD, a Synchrotech carbon synchro kit as well as various OEM bearings and any items that were not included in the kit in my 93 Si hatch with a D16Z6. I referenced the service manual and several videos. The installation went smooth as well as the first test drive where I went through all the gears keeping it under 50mph. However, on the highway it pops out of 5th between 55 and 65mph. The transmission was not making any noises or grinding and shifted smoothly. I drained the fluid and checked to make sure the snap ring was on the counter shaft bearing which it was. I pulled the transmission again and opened it up and there is no sign of an issue. The car has new Hasport motor mounts, energy suspension bushings on the shift rods and a K-tuned shifter. I’ve had no prior issues with the transmission which has less than 150k miles.
The first thought was that 5th gear may be bad so I am attaching some pictures. To me it looks fine, but maybe there is an expert out there that can verify. At this point I am stumped, the only other thing I can think of is to take it to a tranny shop and have them look for any issue. If anyone knows of anything else I should be checking, I would appreciate their input.

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drtalon123

· #2 · 1 mo ago

Have you tried bench shifting the assembly with the outer case off to make sure the 5th gear slider is fully engaging the synchro and gear?

Also, what does the shift fork on 5th look like? If its worn out, it may not be pulling the slider all the way down to the gear.

What about your detent balls? Are all of the detents in place? If you're missing any, the slider could be trying to wiggle its way back to neutral when its running.

rgm_93si

Discussion Starter · #3 · 1 mo ago

3

drtalon123 said:
Have you tried bench shifting the assembly with the outer case off to make sure the 5th gear slider is fully engaging the synchro and gear?

Also, what does the shift fork on 5th look like? If its worn out, it may not be pulling the slider all the way down to the gear.

What about your detent balls? Are all of the detents in place? If you're missing any, the slider could be trying to wiggle its way back to neutral when its running.

Yes, I manually shifted through the gears and 5th looked good. The 93 Si doesn't have dentent balls in the housing like 96's and up. (It's a S20 B000.)
The new slider appears to be fully engaged. I did notice when I removed the main shaft from the shift fork that the 5th gear slider seemed to move a lot easier over the gear than the other gears.
One thing I am confused about is the honda parts shift fork diagram shows springs and balls, #8 and #13 in the diagram. Are these between the shift fork and the shaft where you can't see them?
Right now I have the main shaft disassembled. Once I have everything put back together, I will try everything manually again.

Thanks for your help

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slo_eg8

· #4 · 1 mo ago

give it a minute and a wild bone may appear

Reactions: 2

dfb399

· #5 · 1 mo ago

slo_eg8 said:
give it a minute and a wild bone may appear

That's what she said.

Wait....
ew.

mattliston

· #6 · 1 mo ago

I highly suggest having a buddy get into the car while you are underneath (jacked up and supported, of course) and look closely at the bottom of the shifter when you get 5th gear engaged.

It is too easy to have something slightly off.

Being these are bar shifter cars, you can have perfect everything except one gear being a bitch.

If the engine moutns are new, loosen all the bolts holding them (ALL of them), fire the engine up, rev it a few times to get it to move, and while idling, tighten as many botls as you can reach without danger of dropping a tool somewhere where sparks or moving shit might be.

drtalon123

· #7 · 1 mo ago

rgm_93si said:
Yes, I manually shifted through the gears and 5th looked good. The 93 Si doesn't have dentent balls in the housing like 96's and up. (It's a S20 B000.)
The new slider appears to be fully engaged. I did notice when I removed the main shaft from the shift fork that the 5th gear slider seemed to move a lot easier over the gear than the other gears.
One thing I am confused about is the honda parts shift fork diagram shows springs and balls, #8 and #13 in the diagram. Are these between the shift fork and the shaft where you can't see them?
Right now I have the main shaft disassembled. Once I have everything put back together, I will try everything manually again.

Thanks for your help
View attachment 144835 View attachment 144836 View attachment 144837

What does the face of the 5th gear selector fork look like? This guy:

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If its worn out, it wont push/pull properly/fully

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rgm_93si

Discussion Starter · #8 · 1 mo ago

3

Pics of 5th gear shift fork and with slider

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transzex

· #9 · 1 mo ago

drive that tiny roll pin in on the shift shaft and slowly slide it out, covering the shaft opening and the ball opening as parts will go flying.

Reverse side of the 88-91 5th fork has some wear, but nothing to worry about, also I see you have it right side (Beveled) up.

4th gear side of 3-4 fork is showing some wear on one tip....would have to see the three others.

PS. I love the wrong answers posted that the OP had to correct people on.

Reactions: 1

rgm_93si

Discussion Starter · #10 · 1 mo ago

3

transez I really appreciate your input. I was hoping you would show mercy and respond. Here are pics of 1rst/2nd forks and mainshaft. If you think the shift forks are acceptable maybe I should put the transmission back in and look for a shifter issue. Thanks

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transzex

· #11 · 1 mo ago

second pic of the 1-2 fork, the left (short) side has noticeable wear., like 6.25mm-6.30mm, new is 6.50mm and 6.45mm is as thin as I've tried and documented.

generally popping out of 5th is lack of lube via the shafts, which is why I say to always cleaned them out.

slo_eg8

· #12 · 1 mo ago

I love watching bone work

transzex

· #13 · 1 mo ago

slo_eg8 said:
I love watching bone work

Careful, I might drop in some time. DIL's BFF who I walked with in Son's wedding, now lives near Busch Gardens and working for city of Tampa.

Reactions: 1

slo_eg8

· #14 · 1 mo ago

let me know if youre ever in town, buy ya a root beer

Im 7 miles from busch gardens lol

rgm_93si

Discussion Starter · #15 · 19 d ago

I disassembled the shift fork assembly - cleaned and lubricated. Took apart the main and countershaft and reassembled. Shifted through the gears before installing. The installation itself went smoothly. Also removed the k-tuned shifter and didn't see any issues. Just took it out for a test drive and it shifted smoothly through the gears, no grinding or whining. Again 5th gear pops out when I hit 50. Since the transmission had zero issues before putting in the Synchrotech carbon synchros, maybe it is the synchros? At his point I give up. I plan on pulling the tranny for the 3rd time (which never gets old) and taking it to a shop and have them go through it. Possibly put the original synchros back in. Worst Mother's Day Ever!

transzex

· #16 · 19 d ago

how did the roller bearings and oil ports in the mainshaft look?

mattliston

· #17 · 19 d ago

detent springs? condition, age, etc..

rgm_93si

Discussion Starter · #18 · 19 d ago

I cleaned and blew out the oil ports and used a minimum amount of sealant when putting case back together to avoid potentially plugging the holes. All the bearings on both shafts are new. The springs and balls in the shift fork looked good. (Verified when the springs flung the balls across the room.) I just drove the car again. It will stay in 5th as long as I stay under 50. Over 50 it pops out and I can't put it back in 5th. I can downshift to 4th and when the speed is lower, I can then put it back into 5th. Staying under 50 with a 350hp d16 is depressing.

mattliston

· #19 · 19 d ago

I am assuming, no noises? no grinding, either by noise or by feel?

When it pops out, does it behave like it lost tension and kicks to nuetral, or does it feel like it "socketed" itself out (initial resistance)

I ask, because Im trying to figure out in my head if there is anything at say, 45mph, or 48mph, that slowly climbs up, then pops.

Is your exhaust extremely bass sounding? Maybe there is a perfect pitch that does something.

Im spit balling here

One thing I might try in your shoes, if EVERYTHING looks and feels good, is to loosen each and every one of your mounts and associated bolts/nuts. Just enough to let it move or rock around. Then have someone while it is idling, engage 5th several times in and out while you look under the hood.

Even if it only happens at speed, I wonder if the shift linkage is doing something. Maybe a big burr in the shifter ball?

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rgm_93si

Discussion Starter · #20 · 19 d ago

No noise or grinding while driving, when it pops it's a hard kick to neutral. All motor mounts are new Hasports. The transmission stopper bracket mount is also new. This time when I installed the transmission, I used an engine hoist and loosened all the mounts. Everything lined up perfectly and was torqued to specs. As stated earlier I dropped the k-tuned shifter to check for any type of obstruction. I even put in a new set of energy suspension shift bushings even though the old ones were less than a year old. There's a couple of transmission shops close by, I think that is my best bet. I don't have the stamina to go through another trial and error event. Thanks

Here's a link to my build: 93 Civic Si Project | Honda D Series Forum (d-series.org)

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