4G54 to RX7 gearbox without fabrication??

[Sean]

Just been doing a little research for on of my scorpions (which needs a new Jap 5speed desperately) and come across some interesting info out of the states...

According to the transmission section of "Project Zero G" an RX7 gearbox can be mated up to a 4G63 wideblock using the bellhousing from a Mazda B2600 truck using "Starion" clutch which I take to mean a 4G54? clutch being US based.

Apparently the good old 4G54 was used by Mazda to power its small pickup trucks in the late 80's (as a G54B) and my googling has led me to beleive they were used here in Australia in Mazda Bravo's and Ford Couriers from about 87-90. They were then replaced by Mazda's own 2.6 known as a "G6" On the transmission side of the bellhousing they mate up with the RX7 trans.

So the RX7 box is meant to be pretty good from what I hear, there are plenty of old Bravo's and Couriers out there. Am I better off going down this route than just banging in another Jap 5speed box??

[A112H]

I have a Ford Raider (aka Courier, Mazda Bravo, B2600) and it uses the G6 Mazda engine. Basically a G6 is a 4G54 block fitted with a 12 valve EFI Mazda head. Mine is 4x4 so the box wouldn't be any good but I don't see why this engine from a Courier or B2600 2wd ute wouldn't bolt straight in or the box would work on your Scorpion.
You would have the same issue as a Triton or L200 box, it would be shitty ratios for a car.
Thats a bit off topic, lol
I guess that if my car uses a Mazda bellhousing designed to suit the 4g block then it might work with a RX7 box?

[webby]

Edit: actually read the above post lol
afaik most rwd Mazda gearboxes have the same bellhousing patterns but use different bells depending on the engine

[Sean]

Well Ebay tells me that a low KM jap import RX7 turbo gearbox (from an FD) will set me back around $500. A bit of a poke through some Mazda boards leads me to beleive the boxes are good for a few more horsepower than a Jap 5speed.

So, if I can stick a decent Mazda box in, recycling the clutch that I have that's only done about 5k km's and a bellhousing off a ford courier to mate the 2 together, I think I'm on a winner.

I might pay a visit to city dismantlers, they've probably got an astron motor, a courier bell housing, and an RX7 box for me to compare...

Home on thursday for a months break from working away, this will be interesting.....

[A112H]

City Dismantlers at Gepps Cross? If you are in Adelaide let me know if you need a hand to line them up, I am on annual leave this week and bored, lol

[Sean]

Yeah mate thats the one, saves visiting a Mazda wrecker and a Mitsubishi one, and possibly a Ford one!!

Not guaranteeing I'll spend my cash there unless they're cost competitive tho...



For anyone who's interested, a photo comparing the different bell housings....

To my eye it looks like ZeroG are on a winner here, the Mazda 54G bellhousing seems to match the Mitsubishi 4G54 exactly, and the bolts on the inside that match the bellhousing to the gearbox on the Mazda 54G box seem to my eye to match the Mazda RX7 pattern

A full writeup here, if it's working for them I'm happy to stump up the cash to try it here, only risk is shifter position, but the Scorp has the shifter further back than a Sigma doesn't it?? Might be OK...

http://projectzerog.com/rx7transmissions.shtml

[dang]

I've been researching this as well. There is a Starion on trademe.com with this conversion and Albins do close ratio gears and dogbox conversions for the RX7 boxes. It seems like a decent avenue to persue in terms of a close ratio box for the 4g54. The gearbox options seem to be the weakest link with the mitsi combos. I'm keen to see how the research goes, goodluck.

Dan

[Sean]

Well, home thursday, hopefull the 5speed has enough life left in her to get from Edwardstown (workshop it's sitting at) up to my new place, otherwise I'll get some value out of my RAA membership ;)

Not intending to big note myself, but I'm cashed up, have a new shed to play in, and the Mrs and I both have daily drivers for while the scopions (his and hers) are off the road. Pity she insists on keeping the auto in hers... I'll keep you fellas informed of my findings once I've had a trip to the wreckers!

Whats the chances of them selling me just the bellhousing off a bravo/courier and not the whole box? I'd assume most people looking to replace their bravo box could reuse the bellhousing they have.... Shouldn't be a deal breaker to the wrecker?

Sean

[A112H]

Pretty sure there is a 2wd courier at u-pull-it north if ya keen to get under it. They don't care what parts you strip out, I saw a guy there before xmas who was stripping the gears out of a gearbox as he only needed the 1st gear shaft, he just shoved all the rest under the car

[Cottees]

I remember reading the info about the 4G54 attaching to an RX7 gear box. The only problem with it was that the transmission ends up tilting to the side. Someone fixed this issue by mounting the engine on a slant so the transmission was level.

Edit: My bad, the slanty engine was in an RX7 I saw in the article. But there is still a slant in the transmission, but looks to be not too much of a problem, except for when trying to make a cross member for it.

[Sean]

I'd rather make a funny cross member up than try and adapt a bell housing!

Just bought a Cigweld mig for $50, time to fire her up!

[pistorf]

Just a quicky as to the strength of an RX7 box. One of the young guys that I worked with had a series 4 RX7 that was putting 375hp to the ground (mild port 13B,Hi flow T04,Haltech,etc.) Never broke a box.
Any NSW Central Coast members may remember it. (MRS13B)

[amgis_obrut]

I know of an S1 rx7 running a 20b putting out about 700hp and its running a modded RX7 box, seems to be holding up ok

[A112H]

With respect to the people we sold the cars to, all I am going to say is back in my shadey days I have seriously hammered S5, S6 RX7's and have broken diff mounts long before anything has gone wrong with gearboxes.

[turbogj260]

just on that photo have u thought about the clutch fork? Its on the opposite side and to me that means u need to go hydraulic... Just a thought..

[A112H]

I think the idea is to use the B2600 G54B bell housing on a RX7 box. In that combo the starter motor and clutch fork will be in the same positions as the Starion G54B box

[turbogj260]

yeah and the starion has the clutch fork on the passenger side witch uses a hydraulic master and slave cyl.

[Cottees]

Does anyone know if the B2600's engine was a wide or narrow block?

[webby]

I'd assume it's wide, as I've seen a few DOHC-headed Starions running RX7 boxes

[DanTurboLancer]

How did you go with this Webby?

The only thing i was thinking is arent the RX7 gearboxes pretty long?
Will the hole for the Gear shifter be back between the seats?

[webby]

I wasn't doing it

[DanTurboLancer]

HAHA oops sorry mate, it was Sean i meant to say

[Sean]

Still on the cards, just been flat out earning money, need to find time to spend it...

Sean

[Redzone]

I've done this conversion myself, it's easy as pie..

use the B26 carby 4G54 type bellhousing, clutch fork, throwout bearing, pivot ball, clutch slave cyl etc, and the FC RX7 box, shifter etc. the shifter housing on the box is EASILY moved wherever you need it to sit, or you can use an extension housing from a B2600 2wd ute to bring it forward. fabricate a rear mount and a tailshaft and work out a speedo drive gear appropriate for your diff ratio and you're set.

heaps of info on www.austarion.com...