finally in need for a c64 gear box rebuild? :(

[Kenshin X]

Ok. I'll try and make it simple. I've asked a few people already but I've decided to post this online to get other people's opinions.

2-3 weeks ago while on the freeway at 80km/hr decide to do a power shift from 6th to 2nd, CRUNCH*

now happens most of the time if I'm travelling anywhere from 60-80km/hr from any gear. seems to like it better coming from 3rd gear though.

normal driving, gears are smooth. up shifting in lift not a problem.

had castrol syntrax + nulon g70 additive since Sept 2011 and has seen one track day and no more than 30,000km.

today bought red line mt90 and threw that in but still crunching. although SLIGHTLY better. Does it need to be run in?

In need for a gearbox rebuild? If this is the case I'd rather do it once and do it right. rebuild ut from the ground up and throw in better and stronger gears so I know the box will outlast the life of the car. quailfe lsd will be chucked in too...

opinion guys? thanks.

[jeffy]

stop hitting lift you hoon :P !

[david.]

stop hitting lift you hoon :P !

If your car had lift, you wouldn't be saying that ;)

[jeffy]

stop hitting lift you hoon :P !

If your car had lift, you wouldn't be saying that ;)

LOL !! touché ! :D

[123R-Prozak]

You must have dollars!

You didn't come to me for advise :P

[stock]

Stoppp hitting lift you Hoon!! lol

let me know how it goes.. i wanna get an LSD too

[Kenshin X]

You must have dollars!

You didn't come to me for advise :P

i was pming you but ur fking inbox is FULL

would be good considering u went though 2 boxes and didnt even have f/I LAWL :D

[123R-Prozak]

Oh my bad cuz.. Yeh my rolla has a gearbox feaver lol

[Kenshin X]

ok, i brought it to a specialist yesterday. During the test drive it didn't crunch until right at the VERY end of the test drive. I think he did go from 3rd to 2nd then. He concluded synchros but he added they weren't that bad enough to be replaced now. maybe the MT90 needed a bit of "running in" before it starts to work well?

then i took it to my mechanic the evening. He drove it and he drove it HARD. No crunching whatsoever but it ONLY did it when he skipped a gear from 4th to 2nd (which is the cause of my crunching) at 70km/hr. He said this would be "normal" because in reality, you are not supposed to skip any gears when downshifting as it causes unneccesary strain on the box. That didn't make sense to me. however i do realise that everytime i track my car, i ALWAYS go through the gears 4 > 3 > 2 but the main reason i do is engine braking and heel toe cuz it looks cool :P

i did some googling research and i found this on a supra forum...

syncros help out with small rev changes, but you will eat them up if you are making LARGE rev changes without double clutching. I recommend that anyone interested in this go to www.howstuffworks.com and read their article on manual transmissions.

Trust me, there are occasions where you need to double clutch just to ease the strain on your synchros. The reason F&F mentions it is because that movie is Hondabatized. I used to own and drive a 2001 6spd Celica GT-S, so I understand the need. The Celica's entire power band lies above 6k RPM, which is when the engine switches to the aggressive cam profile. So you are cruising down the highway at 65mph which was about 3200 RPM in the Celica. So fag does a ricer fly-by and you want to catch up (as much as a 4-cyl can) so you want to hit your powerband right off. Well, in order to do so you need to go from 6th gear down to THIRD GEAR!!! Yeah, I know, it's weird. Anyways, thats a difference of more then 3000 RPM and by just rev matching your fly wheel and dropping the clutch you are seriously straining the section of the transmission from the clutch plate to the gear ratios (part where the two gears mesh to create the ratio of what gear you have selected), not to mention your syncros.

The idea of double clutching is to get the WHOLE drive train matched up in speed so that when you engage into the lower gear the meshing between the drive shaft gear and idler gear is as smooth as possible. This is usually taken car of by the synchros, but if they are having to accelerate the idler shaft by huge amounts too often, they will eventually break.

so, in reality, you really shouldn't "skip" gears as it causes unneccesary strain on the box. This makes sense when the tranny specialist was driving it never crunched until the very end of the test drive. but even then the crunch wasn't that bad compared to what i experienced. but even that when it started to grind, i didn't force it into gear: i just clutched in and out and it slipped into 2nd no problem. so in a way that was "double clutching". no more noob shifting from me anymore. i want my box to last more than 160,000kms lol. hope the 10-20 times grinding/crunching didn't cause that much damage to my box :( well... at least i got the MT90 in there now. which would help with worn synchros. :)

coming from a 4spd carby to a 6pd fuel injection i'm still learning even now lol. one of my first threads on this forum was "a strange bouncing sound at high rpm" this was limiter -_-

[Mellow]

Any car with syncros (i.e pretty much every car these days) shouldn't need any of that double clutching nonsense.

[jeffy]

You almost had me? You never had me - you never had your car... Granny shiftin' not double clutchin' like you should. You're lucky that hundred shot of NOS didn't blow the welds on the intake! You almost had me?

[fillit]

Any car with syncros (i.e pretty much every car these days) shouldn't need any of that double clutching nonsense.

It still helps prolong the use of the gearbox, such as warming the car up before flogging it (as most new cars don't need to be "warmed up").

[Kenshin X]

Any car with syncros (i.e pretty much every car these days) shouldn't need any of that double clutching nonsense.

It still helps prolong the use of the gearbox, such as warming the car up before flogging it (as most new cars don't need to be "warmed up").

This.

[david.]

And synchros, like anything else wears out over time. I need to double clutch & rev match every time when shifting from 3rd to 2nd (bad 2nd gear synchro), and instead of forgetting to do it sometimes i just do it every time i downshift in any gear. No crunching & it actually feels a lot lighter on the gearbox.

[123R-Prozak]

I drive normal and no crunching :o

Lol

[Kenshin X]

-_-

[4ABHGE]

C-series gearboxes are pretty sensitive to quick changes and skipping gears thanks to pi$$ weak synchros...

My old AE102 crunched every time into 2nd and 5th lol

[4ABHGE]

C-series gearboxes are pretty sensitive to quick changes and skipping gears thanks to pi$$ weak synchros...

My old AE102 crunched every time into 2nd and 5th lol

Get an E58 if you want it to be bulletproof...