3rd gear crunch - advice

[EG30]

hey EG30

Thanks for your advice dude! i was lookin at synchro tech and i saw these:

http://shop.synchrotech-transmission...BSK-SYN101.htm

is that what i need or do i need more lol?

Your car is a dc2r right?

If it is and your box is only 10 odd years old and not 20+ years old from the early B series, it's not likely the side seals and shift rod boot would need replacing. In an ideal world with plenty of budget you would want to replace all consumables inside box.

In my case I didn't replace the bearings or seals in the above kit, but I did replace the differential side bearings which isnt part of the above kit. My orig bearings were still in pretty good shape but I decided to replace them while the box was apart since they werent $$$ and they are one of the most important bearings within the box.

I bought the complete carbon synchro set 1-5 gear with the synchro springs which were crucial as they also wear out gradually and start the process of crunching at the 1st place, and worn synchro rings+sleeve/hub assys are the end result over time.

[EG30]

I am also curious about this and hopefully you can clarify EG30, if a box grinds on a particular shift no matter the revs can a simple replacement of the synchro rings fix the issue or is wear of the synchro sleeve itself more often the issue? Or is pulling the box apart to look the only option?

I'll post a pic of my used 3rd/4th sleeve/hub set soon, you'll see they werent that badly flogged out at all and yet caused me occasional crunches at moderate revs ie 4-5k rpm and definate crunches under competition conditions at events with 8800rpm upshifts. Highly unlikely it's only your sync rings worn and yet the sleeves and hubs are still in good cond.

If yours does it all the time, more than likely it's flogged out lot worse than mine at that particular gear. If there are issues with the clutch/hydraulics and fluid type/conditions it would happen in all/most gears and not just one gear.

Opening up the box is the only way to find out the root of the problems. Doing the box yourself and able to have the car off the road for a period of time allows you to order the parts as you needed. Whereas at a mechanic's workshop they would want to finish the job within a day or two to free space for other jobs in line.

Your car is a K series right? K series box is notoriously problematic in gear crunches and even factory carbon lined syncs in FN2s and FD2s crunches quite early in their service lifes. Will be helping a friend to strip his FN2 box later this year and replace worn parts with synchro tech replacements; will post any interesting findings.

[DakDak]

^ Hat off to you sir!

[RtN]

do you have a short shifter? I used to have a BC short shifter in the car, it crunched (I think its a crunch lol) in high revs only on 3rd gear. I changed it out after it happened 3 or so times.. overhauled the shifter set up. Everything OEM: New shifter, shifter bushings, change rod bushings, shifter washers etc, lubed it all up, solved it for me.

[hello]

I am also curious about this and hopefully you can clarify EG30, if a box grinds on a particular shift no matter the revs can a simple replacement of the synchro rings fix the issue or is wear of the synchro sleeve itself more often the issue? Or is pulling the box apart to look the only option?

pulling apart the outer transmission case is the only way.

3 things can wear:
- teeth on gear itself
- synchros.
- synchro sleeve.

the synchro hub doesnt really have teeth.

as for rebuilding gearbox, i think you need:
- accurate digital vernier caliper (0.0001")
- feeler gauge set
- press + suitable piping to press gear in
- hondabond/permatex
- mainshaft holder & base to measure mainshaft thrust clearance
- bearing separator
- plenty of degreaser too. canned ones works best. $2.20 a can.
- vice grips to hold countershaft when bolting/unbolting top nut.
- snap ring pliers

either way, replacement is expensive as you cant get synchros by themselves from honda. only aftermarket like synchrotech sells separately.

honda sells per gearset (gear, synchros, ring, sleeve and hub).
theres a thread in k20a.org for separate gears in K gboxes.
only for 2nd gear though.

[ChargeR]

Thanks EG30 and hello (appreciate the list of tools too!), the box I am referring to is the Y1 in my CR-X, and I am considering rebuilding it. Looks like I will just take the box out and disassemble it before I order anything.

I haven't had much to do with gearboxes before, if you could post a picture of what your worn synchros looked like EG30 that would be appreciated. Would be good to see your experiences rebuilding the K series box too .

[EG30]

Pics of my old 3-4 synchro sleeve & hub

3-4 gear synchro hub:

3-4 gear synchro sleeve:



As you can see the dog teeth of both 3rd and 4th gear sides of the sleeve got pretty badly galled and the 3rd gear side is worn worse than the 4th gear side. Bit surprised with the significant wear on the 4th gear side I hardly get crunches changing up to 4th gear at 8800rpm.

The hub wasnt too badly worn compared to the sleeve, I bought the Honda set that came only as complete set ie 3-4 sleeve/hub/springs/synchro rings so a new one is installed. If budget was tight one could consider replacing the sleeve only by buying it on its own from sychro tech online. My 1-2 sleeve is also galled though not as bad as the 3-4 sleeve so I intend to replace it on its own next time I open up my box again and take the chance of not replacing the hub and save some $. Bear in mind Honda specifies the synchro sleeve and hub are to be replaced together.

sleeve/hub on mainshaft along with the gears:


Apart from the dog teeth that wears away, the valley on the outside of the synchro sleeve acutally wears away with time, along with the selector fork. Worse case scenario where both sleeve valley-groove and selector fork are worn outside specification; the trans can jump out of gear since the gear isnt fully slotted in place even though you have slotted the gearlever as far as it could go. If you have the habit of resting your hand with some pressure on the gearknob the selector fork will rub against the sleeve groove at the speed of the mainshaft rotation and gradually wears themselves down as a result.

In my case the sleeve groove isnt too bad, about 0.1-0.15mm wider than the brand new item, and you can see some visual signs of wear inside the groove in the above pic.

[EG30]

Thanks EG30 and hello (appreciate the list of tools too!), the box I am referring to is the Y1 in my CR-X, and I am considering rebuilding it. Looks like I will just take the box out and disassemble it before I order anything.

I haven't had much to do with gearboxes before, if you could post a picture of what your worn synchros looked like EG30 that would be appreciated. Would be good to see your experiences rebuilding the K series box too .

Oh dear the Y1 cable box.....

I have the same in my ED9 b16a converted CRX too, it's costly to rebuild and you are likely to need most of its internals replaced ie on top of the usual synchros rings and sleeves, but also almost all of the bearings and seals with its age, and the selector forks were aluminium instead of the more robust steel items in the later hydro boxes. Havent seen any cable box selector forks for sale new online, and if you could source from Honda new they wont be less than $250-300 each and there are 3 qty of them.

It would be a much better bet to source a YS1 box from the DA9, which has the larger casing that would accomodate the internals from a hydro box. That way you get to upgrade to much stronger selector forks and get rid of the gay ratios at the same time. Might take a while to find a reasonably priced DA9 box at a wrecker and say a hydro box with a damaged casing from a frontal collision eg2/dc2/ek4/em1 but it's well worth it. If there happens to be an EK4 box with the good ratios, along with a 4.785 or 4.9 FD you'll have one very sweet setup in that crx of yours.

[ahmiie]

eg30 expect a pm for some advice on monday morning

[tinkerbell]

when you changed the gearbox oil ahmiie, what condition was it in?

[ahmiie]

getting it done at the end of this week.

when i bought it off the guy, hed told me hed changed the oil but i never actually asked him which oil and what condition.

so ill get that done and who knows, might fix the issue?

[ChargeR]

Oh dear the Y1 cable box.....

I have the same in my ED9 b16a converted CRX too, it's costly to rebuild and you are likely to need most of its internals replaced ie on top of the usual synchros rings and sleeves, but also almost all of the bearings and seals with its age, and the selector forks were aluminium instead of the more robust steel items in the later hydro boxes. Havent seen any cable box selector forks for sale new online, and if you could source from Honda new they wont be less than $250-300 each and there are 3 qty of them.

It would be a much better bet to source a YS1 box from the DA9, which has the larger casing that would accomodate the internals from a hydro box. That way you get to upgrade to much stronger selector forks and get rid of the gay ratios at the same time. Might take a while to find a reasonably priced DA9 box at a wrecker and say a hydro box with a damaged casing from a frontal collision eg2/dc2/ek4/em1 but it's well worth it. If there happens to be an EK4 box with the good ratios, along with a 4.785 or 4.9 FD you'll have one very sweet setup in that crx of yours.

Thanks for the explanation and the pictures! After your comments I am thinking I might just take it apart and have a look, and if it isn't salvageable without changing a heap of parts then I will just continue to double clutch it into fourth and see how far I get. Not too keen on wasting much more money on this B series driveline than I already have. If it was just a matter of replacing the basic stuff along with the 3-4 sleeve/hub then I might rebuild but from the sounds of things it could be a lot worse.

[tinkerbell]

so ill get that done and who knows, might fix the issue?

that is correct.

[Bodgy Racing Developments]

pm sent re clutch

[ahmiie]

cheers shak