Chronos

2 seconds is a huge gain...you talked me into it, I'm gonna have to get one now

btw, do you know if it was a DOG tranny or synchro type?

MikeC

A few years ago I threw out most of my old magazines so unfortunately I can't look it up but I imagine it would have been a dog box.

Van Sema

iTrader: (1)

There's a guy here locally that is getting a 6 spd dog box for his FD ... In fact, I believe he has it and is just waiting to install it. I can't wait to see this thing in action!

GoodfellaFD3S

iTrader: (213)

Hmmm. Please give me details, Sprayin' Ray

Rhode_Dog

dang i didn't know HKS had one in the works too, i swear i read a while back that the GREX one is a dog box.

SpiritR

RE-Amemiya doesnt sell any trannies, they buy theirs from somewhere else.

HKS makes a 6-speed dog and 6-speed standard.

Trust/Grex only makes the 6-speed Standard and it fits in your original transmission case. Minor alterations.

Chronos

if you plan on installing a DOG box, don't plan on ever driving on the street, it's about the most un-streetable mod you can ever get!

OzFeTt

i think it should be made clear that dog engagement rings don't make gearboxes noisy, except if you fumble shifts. The noise you guys are talking about comes from the straight cut gears. (road cars have helical gears).

Dog rings make slow shifting a PITA but fast shifting absolute, seamless bliss. Straight cut gears sound cool for about 5 minutes before they give you a headache.

SPOautos

The stock gears stay in the powerband great. As a matter of fact they are pretty much perfect unless you have some crazy *** port job that lends to a peaky powerband.

The only reason I see for changing to a 6 speed is for a more usefull 5th gear HOWEVER, you can order a lower 5th gear ratio from Pettit, cant remember what it is but I think it still allows for a 170ish top speed. Unless you want to have a low 5th AND go over 170mph I dont see a reason for having a 6th gear.....especially not with a price tag like that.

Course as always, to each thier own lol

STEPHEN

GarageBoy

Anyone watch Two Lane Blacktop? The Big Block Chevy is backed by a M22 Muncie gearbox. Those are the straightest cut standard gears I've ever seen. Whines like it's supposed to!

MikeC

But every engine has a peak and more gears allows you to stay closer to that peak.

David Beale

As I recall, the lower 5th gear for the stock tranny is from the MPV. I'm pretty sure I saw the details posted on Steve C's site. For me, the extra gear would be nice on the highway. 5th gives too low RPMs at 50-60 mph and 4th runs a little high for long trip cruising. Course I don't actually go 50-60 MPH but that would be telling! ;-)

SPOautos

The powerband for a streetported 3rd gen very wide, usually around 1500rpms which is also how far the rpms fall when you change gears. Of course like I said some of the crazy port jobs make real peaky power but even still a 6th gear with real close ratios probably wont help that much. I'd imagine any small amout you'll gain from your rpms falling 1100rpms versus 1500rpms would be lost by having to change gears an extra time.

Your car would have to be up to TRUE race car status for a 6th gear with close ratios to be worth $7K. There are SOOOOO many things you can spend 7K on that would be MUCH more benificial than having a 6th gear thats not really going to do much.

Honestly most cars with a 6speed dont have ANYTHING on our trans. All they have is 2 overdrives. Look at a Vette, its 5th gear ratio is .74, our 5th gear ratio is .719 there really isnt that much difference there. The only difference is the Vette has a 6th gear of .50 so it gets decent gas mileage on the hwy

I know whith a custom trans you can pick all your gears but unless you use super close and low gears I dont think you'd benifit much. Plus when you use the super close gears your either going to kill your top or bottom end depending on how you gear it.

STEPHEN

David Beale

The vette is a peculiar car to compare to. They lowered the diff. ratio to keep the torque down in the transmission and drive shaft. It was breaking things like the drive shaft (not the half shafts - no change in torque to them) and the body couldn't restrain the torque. With the diff. ratio being so low they used extreme "overdrive" gears in fifth and sixth.

jimlab

I'm sorry David, but that's all absolutely untrue.

The 6-speed Camaro/Firebird and the Corvette (non-Z06) both have/had the same transmission gear ratios (2.66, 1.78, 1.30, 1.00, 0.74, 0.50) and both have/had 3.42 differentials because the LS1 makes enough low end power and has a wide enough powerband that the cars don't require a shorter (higher numerically) differential ratio. Even the '94-'97 LT1 6-speed F-bodys came with the same combination of gearing. The Z06 Corvette received different transmission ratios (2.97, 2.07, 1.43, 1.00, 0.80, 0.62), but still came with the standard 3.42:1 differential.

The real reason these cars have such deep double-overdrive (6th) gear ratios is to avoid a gas guzzler premium. 6th gear is not a pulling gear on any of these cars in stock form. It's a low rpm cruising gear for highway speeds.

Many F-body and Y-body owners upgrade to 3.73 and 4.10 differential ratios without any adverse affects besides gas mileage. The only people breaking drivelines, transmissions, output shafts, or differentials/axles are launching at higher rpm on slicks, and that's hard on the car no matter what the ratios are, particularly with a manual transmission.

pedro kim

hi, this email was sent nov 20 2001 hope it helps.

Kim.

A complete 1st thru 5th gear sets for your Mazda Turbo gearbox is priced at $5500.00 USD. We will require your gearbox unit for assembly.

This includes straight cut spur gears. a muli-piece layshaft (gears are stacked on a master spline) and racing ratios as sugested by us our to your requirements.

We have done this job previously, therefore we have experience with this application.

If you have any further questions, please contact me at 519 652-3030 EST.

Regards.

Jamie Houseman.

Jamie Houseman" <jamie@housemanautosport.com>

ForceFed

According to the GREX site, the 6 speed tranny has the following ratios:
2.823
1.941
1.513
.958
.760

pedro kim

this one was sent on march 2002

PEDRO,
SORRY FOR THE DELAY IN GETTING BACK TO YOU.ASSUMING THAT YOU STAY WITH THE
SAME LAYOUT, FRONT ENGINE,TRANS/REAR DRIVE, THE TRANSMISSION THAT WE WOULD
RECOMMEND WOULD BE THE "SGTS" THIS IS A SIX SPEED SEQUENTIAL WITH REVERSE AND
WOULD HANDLE THE POWER THAT YOU WOULD BE PRODUCING WITHOUT DIFFICULTY. PRICE
WOULD BE APPROX $15,000.00 F.O.B. CHICAGO DEPENDING ON CURRENCY FLUCTUATIONS.
IF YOU WOULD LIKE TO PROCEED, PLEASE DON'T HESITATE TO CONTACT ME AT
847-634-8200.
REGARDS,
SKIP

haasauto@aol.com

www.hewland.com/svga/usa.htm

as you can see this quote is for a Hewland transmission made in uk

ForceFed

To continue to the above post (forum crashed on me, big surprise!), i was also going to say that those ratios seem fairly reasonable to me since i plan to build a FD that will hang with some moderately high power MKIV Supras, and even on the highway.

Here's what i'm looking at: I'd like a 425-475hp FD that could hang with or pull on a maxed out stock twin or small single turbo MKIV Supra putting out approximately 450-580RWHP. If i can do that, i'd be extremely happy.

With the ratios of the GREX 6 speed, i feel this is the best way to accomplish the above set task. Previously i was looking into the GT35/40 mainly because of it's ball bearing center section and neglible lag, however if i can get away with something larger like a T88 or comparable turbo i will. Perhaps the 6 speed tranny is the way to go with a big turbo, and still keep it somewhat streetable. I'd like to keep the car streetable, so any transmission that may be notchy under normal, everyday driving conditions is no good.

I'm not stuck on the GREX box either. I'm very open and if someone can show me something comparable to the GREX box in terms of ratios and with perhaps a lower cost, i'm game. This seems like a very positive thread and i'd like to keep it that way if possible. There is some good information being tossed out

Also, Jimlab if you have anything to add regarding the GREX 6 speed and turbo combination i mentioned above i encourage you to add to the discussion Thanks everyone!

Darril

pedro kim

this one was sent on march 2002

PEDRO,
SORRY FOR THE DELAY IN GETTING BACK TO YOU.ASSUMING THAT YOU STAY WITH THE
SAME LAYOUT, FRONT ENGINE,TRANS/REAR DRIVE, THE TRANSMISSION THAT WE WOULD
RECOMMEND WOULD BE THE "SGTS" THIS IS A SIX SPEED SEQUENTIAL WITH REVERSE AND
WOULD HANDLE THE POWER THAT YOU WOULD BE PRODUCING WITHOUT DIFFICULTY. PRICE
WOULD BE APPROX $15,000.00 F.O.B. CHICAGO DEPENDING ON CURRENCY FLUCTUATIONS.
IF YOU WOULD LIKE TO PROCEED, PLEASE DON'T HESITATE TO CONTACT ME AT
847-634-8200.
REGARDS,
SKIP

haasauto@aol.com

www.hewland.com/svga/usa.htm

as you can see this quote is for a Hewland transmission made in uk

Kento

My $0.02:

First, it appears that the GREX uses straight-cut gears. If it does, the noise (gear whine) while driving on the street will drive you nuts, guaranteed.

Second, I agree that a six-speed will gain you little to nothing in a quarter-mile sprint. Forced-induction motors have the huge and relatively flat torque spread (unless you've got some insane porting like Stephen said, and that would kill streetability) that can pull gearing a normally-aspirated motor can't. This means you can avoid the shifts that cost time in a sprint. Normally-aspirated motors don't have the torque spread, so you need to keep them "closer to that peak" by giving them a torque advantage over inertia with lower and closer gearing. Also, forced-induction motors don't reap the same benefits from shorter gearing because they're a strange animal: they actually become more efficient the more load you put on them (up to a point, of course). Ever wonder why top fuel and funny cars run automatic transmissions with only one or two gears? Why not just equip them with a six-speed transmission for "better acceleration"? Because (besides the obvious less shifts) having one or two gears allows them to apply as heavy a load on the motor as possible without spinning the tires. The top turbo dragbikes run far taller gearing than any of the normally-aspirated ones; why don't they run shorter gearing that theoretically would make them accelerate quicker?

"Then why do turbo cars like the Porsche 911 have six-speeds" you ask? Because they were made to go around corners as well, so having an extra ratio can help eliminate a situation where you may be "caught between gears", and offer max acceleration off the corner. Actually, it may also be more of a marketing gimmick than we think; the earlier five-speed Porsche turbos never seemed to have a problem.

I don't think that a six-speed will help a huge single turbo be "more streetable"; the lag will always be there, and if anything, a downshift to a wider-spaced gear (i.e., stock) will help get the rpms up faster to build boost quicker.

Chronos

I also plan on running relatively high power: 450rwhp max on the road and 550rwhp max on the track (road racing) using a GT35/40, waterinjection, race gas, and slicks. I wonder if going for the 6speed would be a realiability issue if anything else...does anyone know how the stock tranny holds up at those power levels?

Great info on this thread btw!

jimlab

Perhaps where rotary and smaller displacement piston engines are concerned. Most V8s do, and my naturally aspirated 396 makes more torque at idle than most modified twin turbo 13B-REWs do at peak. From 2,000 to 8,000 rpm, it never falls below 400 lb-ft.

Actually, NHRA Top Fuel dragsters and funny cars use a direct drive (1:1) coupling from the flywheel/clutch to the differential. The clutches are multi-plate adjustable setups which lock up progressively over the course of the quarter mile. They transfer only about 16-17% of the available power to the tires at the starting line and rarely lock up fully by the end of the run. If they do lock up too soon, you'll usually see the tires go up in smoke mid-track, and they'll have to "take some clutch out" for the next pass.

Kento

I was referring to engines of equal displacement. Imagine a turbo or supercharged 396 compared to your naturally aspirated version. I'd say there'd be a difference in torque spread (maybe not wider, but certainly much, much higher), and the forced-induction version would surely be able to pull taller gearing than yours to garner an equal ET.

Not to get into a pissing contest with details here , but in concept, it's an "automatic" transmission. Everything is preset, the driver basically just punches the throttle and steers, no shifting necessary by the driver. But that's the reason they use only one (apologies, I was thinking of top fuel motorcycles, which have a two-speed transmission) "gear": to put as much load on the engine without spinning the tires. The engine actually runs better and cranks out more torque the more load is put on it.

TTBullet

does jason has website or contac #?