close ratio trans

[rioredstang]

Has anybody used a OS GIKEN close ratio gear set? Will they fit stock shafts? What else is available for a KA.

[a250gpguy]

I was under the impression that many different granny will hook up with the right bellhousing. Since you mentioned the OS Giken kit another expensive option would be the Nismo 6 speed unit...

Cheers,
Ch
Sent from my NookColor using Tapatalk

[KA240SX808]

OS kit will fit the stock shaft. They just offer a stronger one for those making alot of power.

The Nismo 6-Speed is only for SR's so you'll need an adapter or custom housing.

[Tower240sx]

for the KA the RB25 trans is a close enough fit some people are willing to get away with bolting it up directly,

The problem with the stock trans is as much one of case and shaft strength as it is a gearset issue, it is much cheaper to change transmissions than to try and address the short comings of the stock unit

[CodyAce]

Find a 4.9 out of an Xterra front diff and slap it in.

[240sxTTC]

I use the 4.9 FD and it's great for my higher reving KA. 3rd and 4th gears are just about perfect for Mid-OH but 5th gear in the KA trans still sucks; way too tall.

[Matt93SE]

A 4.9?!?! Fawk.. the 4.6 is already too short for what I need. I was considering going to a 3.9 or a 3.6 and running a gear lower...
If you go to a dog box, VERY few run an overdrive in them, so I need to set up my diff gearing to work with a 1:1 top gear.
Either that or find the proper $$$$$ 5 spd dog box w/ overdrive.

You can also do it with a Jerico 4 spd by flipping the shift lever for 3rd and 4th.. then 3rd gear becomes the straight-thru 1:1 and 4th can be an overdrive. But that gives you almost nothing down low. 1st gear would have to be a track gear taller than 2nd to get any benefit out of it.

For you guys still running KA trannies, you can also use the 5th gear from a HArdbody truck. it's shorter than the S-chassis 5th gear and is much better for racing.

[240sxTTC]

A 4.9?!?! Fawk.. the 4.6 is already too short for what I need. I was considering going to a 3.9 or a 3.6 and running a gear lower...
If you go to a dog box, VERY few run an overdrive in them, so I need to set up my diff gearing to work with a 1:1 top gear.
Either that or find the proper $$$$$ 5 spd dog box w/ overdrive.

You can also do it with a Jerico 4 spd by flipping the shift lever for 3rd and 4th.. then 3rd gear becomes the straight-thru 1:1 and 4th can be an overdrive. But that gives you almost nothing down low. 1st gear would have to be a track gear taller than 2nd to get any benefit out of it.

For you guys still running KA trannies, you can also use the 5th gear from a HArdbody truck. it's shorter than the S-chassis 5th gear and is much better for racing.

I think the Hardbody is the same fifth gear ratio (0.838) as the SR20DET??

The KA is 0.759....booooo!

The vehicle speed for the 0.759 ratio at 7500rpm with a 24.50" diameter tire is 147.0mph and with the 0.838 is 133mph, which is perfect for Mid-OH but may be an issue for higher speed tracks like Road America. For those instances I would switch to my 4.63 FD, which increase top speed to 141mph.

[Matt93SE]

Yeah, the D21 has a 0.838 5th gear.

The problem with the 4.6 and stock ratio .759 is that I redline 4th with my 4.08 at the end of the straights at MSR-Houston. When I go to the 4.6, I have to shift into 5th about halfway down the straight.

.759 * 4.6 = 3.51 overall
1.000 * 4.08 = 4.08 overall

I lose 15% more torque by using the 4.6 in 5th gear than I do by keeping the 4.08 and staying in 4th gear.

I come off the corner in the meat of 3rd gear, but I'm still getting pulled at the end of the straights by Miatae. doh.

Cost me 3 sec/lap going to the 4.6!!

[KA240SX808]

IIRC for the HB/Frontier
4x4 = .821
2wd = .838

[240sxTTC]

Yeah, the D21 has a 0.838 5th gear.

The problem with the 4.6 and stock ratio .759 is that I redline 4th with my 4.08 at the end of the straights at MSR-Houston. When I go to the 4.6, I have to shift into 5th about halfway down the straight.

.759 * 4.6 = 3.51 overall
1.000 * 4.08 = 4.08 overall

I lose 15% more torque by using the 4.6 in 5th gear than I do by keeping the 4.08 and staying in 4th gear.

I come off the corner in the meat of 3rd gear, but I'm still getting pulled at the end of the straights by Miatae. doh.

Cost me 3 sec/lap going to the 4.6!!

I agree......the KA 5th gear ratio is a dog. I shift into fifth and the car feels like it stops accelerating. If you rev'd your KA higher the shorter FD's would actually help compared to the 4.08 with the stock trans. So what FD are you going to use and what trans or are you still figuring?

[Matt93SE]

Hmm.. it lost my last post..
I'm still looking for a Saenz 840 dog box. Maybe a G Force or Jerico 5 spd as well. Almost all of the 4 spds are a 1:1 4th gear, which would require me to have a tall final drive and finding those for an R200 is pretty fun.

If I run an overdrive 5 spd, I can use the drop gear to keep the car in its happy place vs. changing out rear diffs.

Changing a drop gear takes quite a bit less time, but you still have to pull the driveshaft and some other stuff off to get to it.

[Tower240sx]

which tranny are you looking at that has a drop gear setup already?

[CodyAce]

I agree......the KA 5th gear ratio is a dog. I shift into fifth and the car feels like it stops accelerating. If you rev'd your KA higher the shorter FD's would actually help compared to the 4.08 with the stock trans. So what FD are you going to use and what trans or are you still figuring?

Haha it's like 5th gear in a stock VE FWDer....you plop it into 5th and it just kinda 'stays there'....frutrating to say the least.

[Matt93SE]

which tranny are you looking at that has a drop gear setup already?

Almost all of them I'm looking at have a drop gear...