Hi all, I own a Datsun 200B fitted with an L20B and a five speed which I believe to be out of a Bluebird. Fifth gear is more like a gear 4.5, and it's revving at over 3,000rpm at 100km/h. This is a bit higher than I'd like it to be revving, so I was wondering if anyone could suggest a five speed that will mate up to my motor and allow it to rev a bit lower?

My old ED wagon revved at about 2,100 at 100km/h in fifth gear, and my current RX-7 revs at just over 3,000rpm, having said that it is a rotary. Just some comparisons.

I had a series 3 Bluebird once, and it seemed to rev a bit lower at 100km/h in fifth. I still have the five speed, so if I swapped the bell housings over, would that be any better? Does anyone know if there is a difference between the ratios in both boxes?

All help or suggestions appreciated

_________________
green200b - aka Alistair

The fleet:
'80 200B GX - the green200b - hibernating indefinitiely
'81 RX-7 - 12A extend port, 4.375 LSD - daily (currently hibernating)
'74 RX-2 - 13B bridgeport, 4.444 LSD - cruiser (also hibernating)

My L18 powered 510 used a 5speed stanza box with an r180 diff, cant remember the diff ratio, but it would rev at 3200rpm at 100kph.

I was going to try and find something a bit better suited to freeway driving as i travel an hour a day to and from work costing me a fortune in fuel, my L18 blew up before i had a chance to do much research , a few people told me that a 260z 5speed would be a good match.

As for the bluebird boxes im not to sure.

_________________
My names Travis and I have a Datsun problem.

easier to change diff ratio...?

Probably. That said, a diff change lowers the ratios in all gears, but there may be a box with similar or identical 1-4 and a biggr overdrive on 5th. Maybe

There's a few pages out there that will tell you the Gear ratios of all the various boxes, the info I have thus far says...Live with it.

The 240K box I believe has the same ratios as the early Bluebirds, 5th —> 0.864. The 260Z is the steel synchro box, but is better only in the spread in the first four gears and only marginally at that, 5th —> 0.864
Then you move onto the R31's and the such, 5th —> 0.838, slightly better, maybe enough to make it worth while. 2nd Gear is shorter (slower) and the rest are the same.

These engines were designed to rev. 4spd box with 1:1 top gear and to overtake someone you'd knock it back to third and feed it to it. Of course that's with a 3.9:1 diff ratio. Sounds like you might have something a bit shorter in there.

_________________
Happiness is watching the race.... in your rearview mirror

had a look in a folder of mine tonight and found written down:

1982 onwards 280zx has 0.752 fifth.


I cant guarantee its correct but try searching for this perhaps if a diff change is out and let us know how you go.

ca18 is good.

_________________
I am a Troll.

Check the ratio's in this table. http://zhome.com/ZCMnL/tech/GearRatios.html
For a dato that does a fair amount of highway work I have found the R180 3.545 diff works best with any g/box combo. Think from memory 100kph in a 4 speed with 1:1 4th was 3000rpm so in 5th would be around 2800 ish.

_________________
Original 77' 260Z 2+2

Nice gearbox is the R30 skyline alloy box.
5th gear is a true overdrive so great for cruising.
Don't know the ratios off the top of my head though.

_________________
1972 Datsun 1600, S14 SR20DET Engineered (204rwkW @ 17psi.)
viewtopic.php?t=6579
#SR20Datsun @SR20Datsun

Thanks for all of the replies!

I had considered changing my diff ratio, but I thought I would see if there was a better gearbox to use first. How about a 720 five speed? The website that sbthomo suggested I look at said that they had a longer fifth.

Or would I be better doing a gearbox rebuild and putting different ratios in?

_________________
green200b - aka Alistair

The fleet:
'80 200B GX - the green200b - hibernating indefinitiely
'81 RX-7 - 12A extend port, 4.375 LSD - daily (currently hibernating)
'74 RX-2 - 13B bridgeport, 4.444 LSD - cruiser (also hibernating)

As the bluebird 5 speed ratio's are .864 overdrive , it's not the gearbox that is the problem. Getting your gearbox rebuilt with a custom gearset from ALBINS in ballarat will cost $2000. Changing the diff ratio to something like 3.5 would be cheaper as long as you can find one to suit.

Less than a minute with google http://www.gracieland.org/cars/techtalk/gearing2.html

The 720 has a taller 5th, but then they also have a different cluster ratio, you'd need to find out what that gear ratio with the cluster ratio from your box would be. I think the 720 has a shorter cluster set, so could be by the time you throw the 5th gear set in there you'll end up with a stupid o/drive and the car will stuggle to push it up a decent grade in 5th. Also the websote only lists the post '80 720 Boxes, the earlier boxes would have a different ratio I think as the diesels and petrols had different diff ratios.

_________________
Happiness is watching the race.... in your rearview mirror