Any Differences in gear ratios?

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Any Differences in gear ratios?

Postby bboytou » Tue Oct 12, 2004 6:33 pm

Hi! I'm in the process of putting my st185 jdm engine into my car. It's from a 91 gt-fourA. So I was thinking if I should use my USDM tranny or go with my JDM tranny. Anybody knows if the gear ratios will change if i put the jdm tranny in? What would you guys suggest?
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Postby CMS-GT4 » Tue Oct 12, 2004 7:51 pm

Depends on the year and model of the gt4.
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Postby beej » Wed Oct 13, 2004 2:35 am

if its a group A u have different ratios in the gearbox, which is alot stronger, has a dual cone synchro on second and a tripple cone on third....plus ur final drive is slightly different to a standard GT4.
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Postby beej » Wed Oct 13, 2004 2:37 am

oh yer i heard some of u didnt score a torsen LSD in teh rear.....if thats group A ur guaranteed to have it as the rear, as far as front and middle diffs i dont know if there'd be a difference
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Postby CMS-GT4 » Wed Oct 13, 2004 12:20 pm

The gears in the GA are not stronger. They share the same part number as gears in other gt4 boxes. They first and second ratio are lower, and 2nd and 3rd are the only ones with special syncros. IMHO I do not like the box. I have one and for autox the 2nd gear is too low, and 3rd is too high. Stick with a standard gt4 box. I would like to have a GT4 Rally even though 5th gear is of no use. It has a very close ratio to 4th.
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92 st185 (205 swap) | 03 350Z Track (sold) | 13 Pilot | 17 Mazda3
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Postby CMS-GT4 » Wed Oct 13, 2004 3:04 pm

I just noticed the 185A in your post.

The final drive is higher, and the first tow gears are lower.

I prefer the us 185 myself.
Coldiron
92 st185 (205 swap) | 03 350Z Track (sold) | 13 Pilot | 17 Mazda3
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Postby bboytou » Thu Oct 14, 2004 6:18 am

So what you guys are saying that if i put the jdm tranny in then I will be limited on my top speed,... right? Like for 4th gear in my usdm I can go about 119 mph and for fith gear I can go maybe even higher( that's because I've never gone faster then 119mph). So I guess for the jdm fith gear is like the usdm 4th, right? Geez! if it is, then that sucks. Do you guys think it'll kill more gas too?
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Postby CMS-GT4 » Thu Oct 14, 2004 2:07 pm

No, it is not. The final drive is higher, as in a higher gear ratio. Better fuel econ. They made the 1st two gears lower so they would compare to the older ones, but the other ratios are the same. It moved the 2nd further from third, which I do not like. You would raise you top speed with this box.
Coldiron
92 st185 (205 swap) | 03 350Z Track (sold) | 13 Pilot | 17 Mazda3
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Postby nosboy » Sat Oct 16, 2004 10:44 am

to the gt4 gurus,

I have a jdm185 gt4 RC (no hoodscoop, just an air vent) front clip, I plan on putting the tranny of the gt4 RC on my normal st185gt4, if I do so should I also install the rear diff of the gt4 RC to my car....or will it still be ok with the normal stock diff? My problem is the gt4 RC front clip did not come with the rear diff.
Next question, is the 1st to 2nd closer with the RC gearbox as compared to the standard gt4 tranny?....does the 2nd gear and third gear have double syncros? Is the 3rd gear ratio the same as that of the standard gt4?
Regarding the engine the RC comes with WTA intercooler right? Is the head and camshaft profile the same as the standard GT4? Does the GT4RC have buket over shim cam followers? Is there still a TVIS in the GT4RC?

All you experts please give me an answer...thanks
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Postby CMS-GT4 » Sat Oct 16, 2004 1:10 pm

nosboy wrote:to the gt4 gurus,

I have a jdm185 gt4 RC (no hoodscoop, just an air vent) front clip, I plan on putting the tranny of the gt4 RC on my normal st185gt4, if I do so should I also install the rear diff of the gt4 RC to my car....or will it still be ok with the normal stock diff? My problem is the gt4 RC front clip did not come with the rear diff.
Next question, is the 1st to 2nd closer with the RC gearbox as compared to the standard gt4 tranny?....does the 2nd gear and third gear have double syncros? Is the 3rd gear ratio the same as that of the standard gt4?
Regarding the engine the RC comes with WTA intercooler right? Is the head and camshaft profile the same as the standard GT4? Does the GT4RC have buket over shim cam followers? Is there still a TVIS in the GT4RC?

All you experts please give me an answer...thanks



The rear diff ratios are all the same in all g4s. So switching out is not nessesary. As from a handlng perspective the rear torsen from an RC is better then the stock open diff. You can always get a clutch type lsd down the road if that mattered to you.
As I said in my other post, the 2nd and 3rd gears are the only ones with special syncros, and the third gear thru 5th are the same. zThe final drive is also higher.
The RC engine only has a wta ic. as for the engine specs i'd ask the folks at gt4oc.com The only detail I know of are the head is designed to disipate heat more. Other then that the engine should be close to a normal 185 engine.

cheers,
Coldiron
92 st185 (205 swap) | 03 350Z Track (sold) | 13 Pilot | 17 Mazda3
www.noritoy.com | noritoy.deviantart.com | http://www.alltrac.net/phpBB2/viewtopic.php?f=44&t=19891
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Postby nosboy » Sun Oct 17, 2004 12:00 am

rear diff ratio the same on all but final drive higher on RC...i dont understand..isnt final drive the ratio on the rear diff? Hope to get more info from you.
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Postby CMS-GT4 » Sun Oct 17, 2004 1:06 am

The final drive is in the box itself before being split front and rear.

Rwd is known for changin the gear in the rearend and calling that the final drive.
Coldiron
92 st185 (205 swap) | 03 350Z Track (sold) | 13 Pilot | 17 Mazda3
www.noritoy.com | noritoy.deviantart.com | http://www.alltrac.net/phpBB2/viewtopic.php?f=44&t=19891
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Postby nosboy » Sun Oct 17, 2004 8:43 am

got it. thanks
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Postby nosboy » Sun Oct 17, 2004 8:44 am

BTW wats the advantage of double syncros on 2nd and 3rd..is it easier/softer to shift?
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Postby CMS-GT4 » Sun Oct 17, 2004 3:22 pm

I didn't feel much of a difference, but I had a 92 box the start with which was rumored to have the same syncro treatment.
Coldiron
92 st185 (205 swap) | 03 350Z Track (sold) | 13 Pilot | 17 Mazda3
www.noritoy.com | noritoy.deviantart.com | http://www.alltrac.net/phpBB2/viewtopic.php?f=44&t=19891
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