OS Giken 5 speed close ratio gears
01-13-18, 03:47 PM
#51
One of the cars that ran a PAR here, the mechanic ended up cutting a hole in the body to speed up "rectification" work on the shift mechanism that happened at virtually every session during each meeting. Ended up biting the bullet in frustration "putting" a Hollinger in the stock case eventually....where the case there just accommodated the input quill, which is about all it's good for. 
Reality is, stock cased gearsets are pretty much a joke if you're doing anything half-serious - track day warrior might just be ok, OS will eventually **** the bed too......but for other reasons.
Reality is, stock cased gearsets are pretty much a joke if you're doing anything half-serious - track day warrior might just be ok, OS will eventually **** the bed too......but for other reasons.I’m sorry, but respectfully disagree. A Hollinger is a whole other animal as any real racing trans. However there are some nice builts using both of these transmissions without issue. Sometimes the factory casings are weak and yeah that’s a different story. The 1sr generation Aisin craptastic vs much stronger top-loader 2nd generation RX8 6-spd boxes are one example. Any trans is going to wear out and break even. Sometimes it comes down to the driver and how hard they are on it too. I tend to break more than most because I’m not afraid to shift fast and hard ...
.
.
Last edited by TeamRX8; 01-13-18 at 03:50 PM.
01-13-18, 05:54 PM
#52
Well, transmissions fail for different reasons and its a balance to some degree (alternate gearbox designs withstanding).
Torque-
The Type R box (TII, FD 5 speed) shears 3rd gear as the main shaft and counter shaft flex away from each other.
One could machine a new 3 speed +1 gearset (custom ratios) that took 3rd gear out and replaced it with a cuff to hold the two shafts together while increasing the input shaft diameter and it would be a pretty damn strong gearbox in the stock case as far as torque handling.
Frictional forces-
The Type R gearbox fails early under high rpm use at the track (like behind a NA P-port) because it has a pretty robust high mass gear set. To counter these weaknesses you need component processing techniques like WPC, exact clearancing and/or alternate mesh machining (straight cut), and more advanced lubrication system.
Shifting-
Some boxes like the smoothcase Type M and the smoothcase S1 RX-8 gearbox have weak shift forks that like to break if you shift with too little mechanical empathy. Put heavier heavy duty shift forks in and you punish the synchos with too much mass behind the shift action and the synchros wear fast leading to poor high rpm shifting.
Another shifting issue is all Mazda boxes (in native chassis) after FD Type R have the power plant frame flexing to deal with. Under load the transmission rotates clockwise and as you lift throttle and pull the gear selector out of 2nd gear removing engine torque from the power plant fame the gearbox rotates back counter clockwise and where you though 3rd gear "gate" would be is 5th gear and *crunch* you force the shifter into 5th with too much speed differential damaging the 5th gear synchro. Miata and RX-8 don't usually have torque so this is less of a problem than with the FD.
It was the comment above comparing S1 RX-8 trans to the S2 trans that made me think of this because the S1 RX-8 trans has been proven to be strong behind the relative high torque of a turbo 3 rotor, you just have to be careful shifting. However, breaking while shifting is definitely still a weak point in the transmission when comparing various transmissions strengths.
Torque-
The Type R box (TII, FD 5 speed) shears 3rd gear as the main shaft and counter shaft flex away from each other.
One could machine a new 3 speed +1 gearset (custom ratios) that took 3rd gear out and replaced it with a cuff to hold the two shafts together while increasing the input shaft diameter and it would be a pretty damn strong gearbox in the stock case as far as torque handling.
Frictional forces-
The Type R gearbox fails early under high rpm use at the track (like behind a NA P-port) because it has a pretty robust high mass gear set. To counter these weaknesses you need component processing techniques like WPC, exact clearancing and/or alternate mesh machining (straight cut), and more advanced lubrication system.
Shifting-
Some boxes like the smoothcase Type M and the smoothcase S1 RX-8 gearbox have weak shift forks that like to break if you shift with too little mechanical empathy. Put heavier heavy duty shift forks in and you punish the synchos with too much mass behind the shift action and the synchros wear fast leading to poor high rpm shifting.
Another shifting issue is all Mazda boxes (in native chassis) after FD Type R have the power plant frame flexing to deal with. Under load the transmission rotates clockwise and as you lift throttle and pull the gear selector out of 2nd gear removing engine torque from the power plant fame the gearbox rotates back counter clockwise and where you though 3rd gear "gate" would be is 5th gear and *crunch* you force the shifter into 5th with too much speed differential damaging the 5th gear synchro. Miata and RX-8 don't usually have torque so this is less of a problem than with the FD.
It was the comment above comparing S1 RX-8 trans to the S2 trans that made me think of this because the S1 RX-8 trans has been proven to be strong behind the relative high torque of a turbo 3 rotor, you just have to be careful shifting. However, breaking while shifting is definitely still a weak point in the transmission when comparing various transmissions strengths.
01-13-18, 07:02 PM
#53
I believe ( but could be wrong) the Giken set uses stronger shafts and a shallower angle on the gear cut - so its getting towards a straight cut rather than helical. This would make it stronger than OEM to an extent wouldn't it?
I mainly chose it for the ratios than strength though.
I mainly chose it for the ratios than strength though.
01-13-18, 08:35 PM
#54
Well, transmissions fail for different reasons and its a balance to some degree (alternate gearbox designs withstanding).
Torque-
The Type R box (TII, FD 5 speed) shears 3rd gear as the main shaft and counter shaft flex away from each other.
One could machine a new 3 speed +1 gearset (custom ratios) that took 3rd gear out and replaced it with a cuff to hold the two shafts together while increasing the input shaft diameter and it would be a pretty damn strong gearbox in the stock case as far as torque handling.
Frictional forces-
The Type R gearbox fails early under high rpm use at the track (like behind a NA P-port) because it has a pretty robust high mass gear set. To counter these weaknesses you need component processing techniques like WPC, exact clearancing and/or alternate mesh machining (straight cut), and more advanced lubrication system.
Shifting-
Some boxes like the smoothcase Type M and the smoothcase S1 RX-8 gearbox have weak shift forks that like to break if you shift with too little mechanical empathy. Put heavier heavy duty shift forks in and you punish the synchos with too much mass behind the shift action and the synchros wear fast leading to poor high rpm shifting.
Another shifting issue is all Mazda boxes (in native chassis) after FD Type R have the power plant frame flexing to deal with. Under load the transmission rotates clockwise and as you lift throttle and pull the gear selector out of 2nd gear removing engine torque from the power plant fame the gearbox rotates back counter clockwise and where you though 3rd gear "gate" would be is 5th gear and *crunch* you force the shifter into 5th with too much speed differential damaging the 5th gear synchro. Miata and RX-8 don't usually have torque so this is less of a problem than with the FD.
It was the comment above comparing S1 RX-8 trans to the S2 trans that made me think of this because the S1 RX-8 trans has been proven to be strong behind the relative high torque of a turbo 3 rotor, you just have to be careful shifting. However, breaking while shifting is definitely still a weak point in the transmission when comparing various transmissions strengths.
Torque-
The Type R box (TII, FD 5 speed) shears 3rd gear as the main shaft and counter shaft flex away from each other.
One could machine a new 3 speed +1 gearset (custom ratios) that took 3rd gear out and replaced it with a cuff to hold the two shafts together while increasing the input shaft diameter and it would be a pretty damn strong gearbox in the stock case as far as torque handling.
Frictional forces-
The Type R gearbox fails early under high rpm use at the track (like behind a NA P-port) because it has a pretty robust high mass gear set. To counter these weaknesses you need component processing techniques like WPC, exact clearancing and/or alternate mesh machining (straight cut), and more advanced lubrication system.
Shifting-
Some boxes like the smoothcase Type M and the smoothcase S1 RX-8 gearbox have weak shift forks that like to break if you shift with too little mechanical empathy. Put heavier heavy duty shift forks in and you punish the synchos with too much mass behind the shift action and the synchros wear fast leading to poor high rpm shifting.
Another shifting issue is all Mazda boxes (in native chassis) after FD Type R have the power plant frame flexing to deal with. Under load the transmission rotates clockwise and as you lift throttle and pull the gear selector out of 2nd gear removing engine torque from the power plant fame the gearbox rotates back counter clockwise and where you though 3rd gear "gate" would be is 5th gear and *crunch* you force the shifter into 5th with too much speed differential damaging the 5th gear synchro. Miata and RX-8 don't usually have torque so this is less of a problem than with the FD.
It was the comment above comparing S1 RX-8 trans to the S2 trans that made me think of this because the S1 RX-8 trans has been proven to be strong behind the relative high torque of a turbo 3 rotor, you just have to be careful shifting. However, breaking while shifting is definitely still a weak point in the transmission when comparing various transmissions strengths.
The S2 RX8 box is way better strength wise and everyone says so/knows it, except Mazda really hosed ratios in their usual fashion; 1st is way too low & the 2nd-3rd gear ratio gap is too big for North American models. I don't know what their problem is with getting the right ratios in place? For road racing though with the 5.125 Motorsport rear gear you get a nice spread from 3rd - 5th/60 - 130 mph.
.
.
Last edited by TeamRX8; 01-13-18 at 08:54 PM.
01-14-18, 10:20 AM
#55
Moderator
iTrader: (3)
Join Date: Mar 2001
Location: https://www2.mazda.com/en/100th/
Posts: 30,792
Received 2,573 Likes
on
1,829 Posts
plus the ratios are terrible for a high revving car. the R box is much better suited to a low revving engine with torque, like the T2
the 5th gear thing is just a problem with that transmission design, our B2600 pickup had a broken 5th gear too
01-15-18, 02:25 AM
#56
Rotary Freak
I believe ( but could be wrong) the Giken set uses stronger shafts and a shallower angle on the gear cut - so its getting towards a straight cut rather than helical. This would make it stronger than OEM to an extent wouldn't it?
I mainly chose it for the ratios than strength though.
I mainly chose it for the ratios than strength though.
New race series over here for S1 Rx8s requires stock gearboxes, hopefully not rushing shifts or vainly hoping any syncro gearbag will cope with 8k+ abuse will let them live.
RX8 Cup Australia ? One-Make RX8 Rotary Racing
Oh yeah, there's a bloke arranging a group buy on s5/6/7/8 gearsets from Albins at the moment on fdrx7.
Last edited by billyboy; 01-15-18 at 02:27 AM.
01-15-18, 06:21 AM
#57
Yeah, shift easy, the right oil helps; my recommedation is Ford Motorcraft XT-M5-QS is you can get it down there. Best 90W manual trans oil on the market IMO, and it works the best in either RX8 box..
We also have an aftermarket company here in the US that sold an adjustable shift-blocking device that bolts-on at the top of the shifter called a Syncho-Saver. It has adjustable limiters that stop the shifter from pushing past the gear engagement point. This helps a lot on an S1 box because it's easy to push or pull past the engagement point if a lot of force is used for shifting, and then all kind of bad things start to happen. Kind of surprised they don't allow gearset changes though. Par has a nice gearset for both the S1 and S2 gearboxes that will greatly improve life. It's not a,performance enhancer, it just makes the box stronger and last longer between rebuilds. I guarantee you'll end up spending more buying replacement or rebuilding stock gearboxes than what the Par gearset cost.
We also have an aftermarket company here in the US that sold an adjustable shift-blocking device that bolts-on at the top of the shifter called a Syncho-Saver. It has adjustable limiters that stop the shifter from pushing past the gear engagement point. This helps a lot on an S1 box because it's easy to push or pull past the engagement point if a lot of force is used for shifting, and then all kind of bad things start to happen. Kind of surprised they don't allow gearset changes though. Par has a nice gearset for both the S1 and S2 gearboxes that will greatly improve life. It's not a,performance enhancer, it just makes the box stronger and last longer between rebuilds. I guarantee you'll end up spending more buying replacement or rebuilding stock gearboxes than what the Par gearset cost.
02-07-18, 01:02 AM
#58
Arrogant Wankeler
Sounds like getting a box out of PAR isn't any easier than waiting for OS to do a production run.
PAR gearsets
PAR gearsets
07-03-18, 08:42 PM
#60
Well it’s only fair for me to share my own experience. I’ll refrain from making any judgements and let each person decide on their own. At the end of last year I entered into an agreement with Par Engineering and direct deposited a $5,700 USD payment into their account based on an 8 - 12 week completion time.
Six months later (end of June, 2018); not one word or notice. So after being patient I contact them to see what the status may be. I was not informed about status, but told they had some kind of equipment failure. Despite one or two more emails other than being told that a refund is out of the question I still haven’t been told what the status of my order is or when I might expect it to be completed. Completely out of pocket and in the dark. Even after I politely, but openly stated such in my last reply there was no response.
Since I don’t do social websites it’s not possible for me to post my experience directly on their Business Page, but thought people should be aware of the situation for better or worse.
Six months later (end of June, 2018); not one word or notice. So after being patient I contact them to see what the status may be. I was not informed about status, but told they had some kind of equipment failure. Despite one or two more emails other than being told that a refund is out of the question I still haven’t been told what the status of my order is or when I might expect it to be completed. Completely out of pocket and in the dark. Even after I politely, but openly stated such in my last reply there was no response.
Since I don’t do social websites it’s not possible for me to post my experience directly on their Business Page, but thought people should be aware of the situation for better or worse.
Last edited by TeamRX8; 07-03-18 at 09:26 PM.
07-03-18, 09:43 PM
#61
Same story here. Paid in full for an os giken set through rhd japan 18 months ago. Eta kept getting pushed back and pushed back. Latest one was 29th of june. Literally just got an email off rhd japan that that eta has gone out the window and the fatory cant give them one.
at least they have kept me in the loop though.
about half the price of yours at about 2700aud.
maybe if a few more ppl put an order in the factory might decide to do a batch?
at least they have kept me in the loop though.
about half the price of yours at about 2700aud.
maybe if a few more ppl put an order in the factory might decide to do a batch?
07-03-18, 11:16 PM
#62
You two seem like you might be the most patient and understanding people I've ever heard of. I would probably have tried to find a translator and reached out to someone at Giken via linked in or something. That's so insane. Shame too, trying a set of these someday would be nice.
09-30-18, 12:51 AM
#63
Arrogant Wankeler
Wow that really sucks. Can't say I'm surprised with PAR though.
Looks like it would be a kit from Green bros or DIY tremec for any decent gearbox replacement from now on, the getrags aren't worth the $ for what they are.
Looks like it would be a kit from Green bros or DIY tremec for any decent gearbox replacement from now on, the getrags aren't worth the $ for what they are.
12-08-18, 12:28 AM
#64
Well it’s only fair for me to share my own experience. I’ll refrain from making any judgements and let each person decide on their own. At the end of last year I entered into an agreement with Par Engineering and direct deposited a $5,700 USD payment into their account based on an 8 - 12 week completion time.
Six months later (end of June, 2018); not one word or notice. So after being patient I contact them to see what the status may be. I was not informed about status, but told they had some kind of equipment failure. Despite one or two more emails other than being told that a refund is out of the question I still haven’t been told what the status of my order is or when I might expect it to be completed. Completely out of pocket and in the dark. Even after I politely, but openly stated such in my last reply there was no response.
Since I don’t do social websites it’s not possible for me to post my experience directly on their Business Page, but thought people should be aware of the situation for better or worse.
Six months later (end of June, 2018); not one word or notice. So after being patient I contact them to see what the status may be. I was not informed about status, but told they had some kind of equipment failure. Despite one or two more emails other than being told that a refund is out of the question I still haven’t been told what the status of my order is or when I might expect it to be completed. Completely out of pocket and in the dark. Even after I politely, but openly stated such in my last reply there was no response.
Since I don’t do social websites it’s not possible for me to post my experience directly on their Business Page, but thought people should be aware of the situation for better or worse.
yeah, so I get an email from Haysam @ PAR in September saying it’s finally ready to ship, we make up, no hard feelings, etc. ...
... and still nothing. Coming up on our 1 year anniversary in the next couple of weeks. It’d be nice if I could at least receive a card with some flowers or chocolates for being such a nice patsy.
Last edited by TeamRX8; 12-08-18 at 12:33 AM.
12-11-18, 10:12 PM
#66
Wow, that sounds so disappointing. 
Well I got a response about it being three months after him telling me it was finally completed and still nothing. To paraphrase:
“Yes, that’s right. Will organize shipping.”
I’m not sure if it’s just been sitting there unshipped or if it’s just more of the bs smoke, sigh ...
.
Well I got a response about it being three months after him telling me it was finally completed and still nothing. To paraphrase:
“Yes, that’s right. Will organize shipping.”
I’m not sure if it’s just been sitting there unshipped or if it’s just more of the bs smoke, sigh ...
.
12-11-18, 11:10 PM
#67
Sorry to hear that, Idk what it is man, I hate to generalize or put bad energy out, but this is the way it has been for me with everything other there. Alot of people seem to have had good luck, but in the past year of my build, its always been miscommunication, slow response, and mistakes for three major companies, that'd you never expect to drop the ball
12-30-18, 12:16 PM
#68
Yeah, not a single word since, but you’d think if it actually shipped he’d at least let me know. My guess is that the next reply to yet another inquiry is that it will just be more smoke blowing out his fecal pipe.
wish I could go back and edit out anything positive I said or suggested earlier in this thread. Simply cannot recommend doing business with a company that behaves this way, but will just leave it at that. Ranting and raving isn’t going to accomplish anything more than what’s already pretty much been a total fail. Probably not worth the effort, but I’m going to contact the Australian embassy and see if they have any recommendations on how the situation might be addressed. I can’t claim to have been blindly robbed, but clearly it’s bordering on that.
.
wish I could go back and edit out anything positive I said or suggested earlier in this thread. Simply cannot recommend doing business with a company that behaves this way, but will just leave it at that. Ranting and raving isn’t going to accomplish anything more than what’s already pretty much been a total fail. Probably not worth the effort, but I’m going to contact the Australian embassy and see if they have any recommendations on how the situation might be addressed. I can’t claim to have been blindly robbed, but clearly it’s bordering on that.
.
Last edited by TeamRX8; 12-30-18 at 01:12 PM.
12-30-18, 06:34 PM
#69
Yeah, not a single word since, but you’d think if it actually shipped he’d at least let me know. My guess is that the next reply to yet another inquiry is that it will just be more smoke blowing out his fecal pipe.
wish I could go back and edit out anything positive I said or suggested earlier in this thread. Simply cannot recommend doing business with a company that behaves this way, but will just leave it at that. Ranting and raving isn’t going to accomplish anything more than what’s already pretty much been a total fail. Probably not worth the effort, but I’m going to contact the Australian embassy and see if they have any recommendations on how the situation might be addressed. I can’t claim to have been blindly robbed, but clearly it’s bordering on that.
.
wish I could go back and edit out anything positive I said or suggested earlier in this thread. Simply cannot recommend doing business with a company that behaves this way, but will just leave it at that. Ranting and raving isn’t going to accomplish anything more than what’s already pretty much been a total fail. Probably not worth the effort, but I’m going to contact the Australian embassy and see if they have any recommendations on how the situation might be addressed. I can’t claim to have been blindly robbed, but clearly it’s bordering on that.
.
12-30-18, 08:47 PM
#70
I'd just like to put in that after 18 months RHD Japan refunded me in full for the OS gearset tno hassles the minute i requested it. They followed up progress every month or two for me the whole time but in the end i needed my money back. Not their fault. Allegedly the OS Giken factory was affected by earthquakes or some **** and never got their act together on the gearset production thereafter.
10-16-19, 11:19 PM
#72
Suppose I should update this. In the end PAR came through and despite all my b&m’ing I have to express satisfaction with them despite the wait. There were some unique situations that contributed to it all and it was just my luck on the timing. On top of that the RX8 turbo project fell through but may be revived again at some point. I need to get my autox DSP RX8 up and going for next year first before reconsidering it again; life happens pretty much sums it all up.
10-17-19, 08:25 AM
#73
Performance Veteran...
Suppose I should update this. In the end PAR came through and despite all my b&m’ing I have to express satisfaction with them despite the wait. There were some unique situations that contributed to it all and it was just my luck on the timing. On top of that the RX8 turbo project fell through but may be revived again at some point. I need to get my autox DSP RX8 up and going for next year first before reconsidering it again; life happens pretty much sums it all up.
Did anybody else have any luck with a OS Giken gearset finally being delivered or made? Maybe we could all do a group buy to get them to do a another production run? 🤷🏻*♂️