Os Giken 5 Speed Vs Ppg Straight Cut/helical Cut Dog Gears Vs Sequentials

[Piggaz]

Right guys. It looks like I've busted my OS 5 speed in my GTR. It's currently making 470 rwkw and peak torque (according to the dyno so NFI is its accurate) is 762 NM at 5100 RPM IIRC. The 5 speed has been in the for the past 5 or so years. When I popped my engine last year I found two locating pads on the box drain plug, so it got rebuilt and it was all sweet. Last Tuesday rolled around and it looks like I have either bent or stripped a tooth in second gear. I know Gav has busted two of these things and also Tricstar one or too also.

I'm not one to flat change or jam it into gear, i'm pretty soft on the box like that as I don't want to bust another one.

So, whats the options?

Are the PPG dog boxes really that horrible on the street?

Is wear an issue with the dogs? Will it last 50,000 kms given some mech sympathy.

Is it going to be a case of people that have never driven a dog box before not being able to jump into the car and drive it?

I'm not interested in turning the car into a "track car only". That's not what the car is there for, however, i'm not too keen on busting boxes because I decided I want to get up it a tad.

I was thinking straight cut 1,2,3,4, helical 5th (for highway) but still synchro but PPG doesn't do that set. The Helical set is rated to 800 HP, so is the OS so that doesn't "really" fix the issue here.

The thought of the R34 6 speed came into my head but that would also need change in diff ratio's. The 6 speed with 4.11's would feel like an EVO and I quite like the tall ratio's of the OS box. It worked well with the broad curve. Another thing is, are they that strong? You don't hear a lot of them busting like the 5 speeds.

Sequential. Well, its a lot of cash and I think it goes from "street car" to "race car" with one of them in it, so that really is not an option.

[GTR_JOEY]

would also like to know this^^^

[NYTSKY]

Have a drive of some different cars that have different gear sets.

Dogs are not that bad for the street, it's just something you need to get use to.

[chez00]

The dogs do wear in street application but I'd say you could get 50k out of them with a good operator. They are annoying on the street but then again I find coil overs annoying on the street, haha!

I know it's a bit of a shameless plug but ISF treating dog gears definitely slows the wear down and improves shifts.

PPG should solve your breakage issues but check other things like case alignment (centre plate flex) as well as the usual shimming etc., because no gears will put up with being out of alignment regardless of how strong they are. Did you run a billet centre plate with the OS set? Are you confident that the box was assembled with the correct clearances and preloads? It's easy to say the gear set is no good but it can often be bad assembly that leads to gear failure, and stupid things like using the wrong (poor quality) bearing. Please do not read this as a stab at you or your mechanic (or whoever assembled your gearbox), just worthy of a little thought.

Before buying, definitely see if you can drive a dog around your local beat to see what you think if you haven't already, you might hate it too.

[Piggaz]

The dogs do wear in street application but I'd say you could get 50k out of them with a good operator. They are annoying on the street but then again I find coil overs annoying on the street, haha!

I know it's a bit of a shameless plug but ISF treating dog gears definitely slows the wear down and improves shifts.

PPG should solve your breakage issues but check other things like case alignment (centre plate flex) as well as the usual shimming etc., because no gears will put up with being out of alignment regardless of how strong they are. Did you run a billet centre plate with the OS set? Are you confident that the box was assembled with the correct clearances and preloads? It's easy to say the gear set is no good but it can often be bad assembly that leads to gear failure, and stupid things like using the wrong (poor quality) bearing. Please do not read this as a stab at you or your mechanic (or whoever assembled your gearbox), just worthy of a little thought.

Before buying, definitely see if you can drive a dog around your local beat to see what you think if you haven't already, you might hate it too.

Box did have the billet centre plate in it. You'd be crazy to build one without it. In regards to the box being built right, the guy that did it is arguably the best in Sydney.

Either way, need to pull it down to see what exactly failed but it looks like from what I've described to be a bent or broken tooth.

[sime1]

Box did have the billet centre plate in it. You'd be crazy to build one without it. In regards to the box being built right, the guy that did it is arguably the best in Sydney.

Either way, need to pull it down to see what exactly failed but it looks like from what I've described to be a bent or broken tooth.

Hey piggaz I'm waiting on my ppg gear box to arrive as we speak. there not so hard to drive on the road. Also check out this video on you tube. Type in how to drive a dog box and click the Pfitzner performance gearbox,

[Piggaz]

Seen that video a million times. Still, before I commit to something like that, I want to drive one to see and feel it for myself.

I'll know more in the new year, but I'm still pushing PPG to do the straight cut 1-4, helical 5th, synchro box. Hopefully they do it.

[GTR_JOEY]

Did someone say trip to Adelaide??? end up pulling the box out yet Paul?

or u just been sinking piss since I left

[Piggaz]

Did someone say trip to Adelaide??? end up pulling the box out yet Paul?

or u just been sinking piss since I left

Car has been parked Joey. I drove it around to get all the ethanol out of it but that was about a month ago. It's in it's naughty corner haha.

I was going to chuck Micks spare box in it, but its summer and Xmas - too hot, too many cops, not good to drink and drive.

As I said in the post above, is they do the box that we want I dare say we will just do that and be done with it. There will be a bit of a delay if that happens though. If they don't, I still want to drive that dog box, but like you, I'll end up with that helical set unless the dog really surprises me.

When are you back?

[GTR_JOEY]

I would be really pleased if they end up doing a syncro set. I do wonder though how the larger input shaft will effect the torque load on the clutch as its a bigger diameter. As our engines are going to be very torquie already I hope this doesn't cause the clutches to slip. Did you ask PPG about that?...or maybe PPG can up the pressure plate clamping force??

Its all good mate, if you decide you want to do the gearbox we can do it at the workshop when I get back. Wont take long, we've done it enough times now

Im back very soon mate, not allowed to say dates, but ask Ivi she can tell you

[GTR_JOEY]

Actually when I think about it, it shouldn't really effect the clutch that way

[Piggaz]

I'll speak to you about that when you get home.

It does mean pulling the clutch off and sending it away though.

[GTR_JOEY]

OH GOD... more $$$$ lol

[r32-25t]

Just go drive the dog box and then buy one, they don't make what you're after because it serves no benefit over what they already sell

[ranga]

Hey piggaz I'm waiting on my ppg gear box to arrive as we speak. there not so hard to drive on the road. Also check out this video on you tube. Type in how to drive a dog box and click the Pfitzner performance gearbox,

Got it in and going yet sime? its me tom!

[unique1]

I drove a str8 cut dog box around In a weekend street car previously and I find once you know how to shift without crunching it there is not a lot I didn't like. Only issue is the whining bloody 5th gear as mentioned. Annoying as he'll on the freeway.

Shifting down and up gears is actually really smooth if done right and you don't have to jam it in or thrash it to get it in at all. Just let the revs match properly on downshifts and it falls into gear with no issues. Up shifts are easy too.

I wouldn't have one in a full time daily driver but weekend fun car I would do it .

Once you have driving a dog box you will realise how slow shifts are in a synchro box. They are great fun when driving hard too.

[Piggaz]

I drove a str8 cut dog box around In a weekend street car previously and I find once you know how to shift without crunching it there is not a lot I didn't like. Only issue is the whining bloody 5th gear as mentioned. Annoying as he'll on the freeway.

Shifting down and up gears is actually really smooth if done right and you don't have to jam it in or thrash it to get it in at all. Just let the revs match properly on downshifts and it falls into gear with no issues. Up shifts are easy too.

I wouldn't have one in a full time daily driver but weekend fun car I would do it .

Once you have driving a dog box you will realise how slow shifts are in a synchro box. They are great fun when driving hard too.

That's handy to know.

After what feels like a million emails and a few very lengthy calls to Tom (PPG's sales bloke and the poster above), I have decided to take his advice and whack the same box as he has, which is the helical dog 1-4 with a larger spline. For the 5th gear, i'll be going on a hunt to find an OS 5th only, which is annoying because I had one when I purchased my OS set years ago but sold it off because I never thought I'd need it. Grr!

[tricstar]

Got one you can have. Pm me your address

[sime1]

I got the same box through tom top bloke and top box

[Piggaz]

How does it drive?

Fill us in!