Im after a few tips with crusing speed on the main freeways. I have a 1200 ute with an A14 Turbo that revs its ares off when crusing on the freeway @100km/h. Yes i only have a 4 speed box and i did price a celica 5 speed with Dellow conversion kit. but i dont have a lazy $3000 sitting around at the moment. So i was thinking of changing the diff centre. i have the 4.11 diff at the moment with 15inch rims.

Any suggestions or experiences with this conversion would be great. Ive gone through Wiki and it tells me how to install etc but not what results i would get out of different ratio's

your most available option is 3.9, and a bit harder to get is 3.7

there is calculators on the net you can enter your speed/tyre size/diff ratio/gear ratio and it will tell you the rpm, then you can enter with a different diff ratio and see the new rpm. best to use that maths than someones "experience" anyway

you will obviously be cutting acceleration, and it is noticable, but if you have a nice wide power range with your turbo it may not be such a problem

looking for a series 1,2 bluebird with h165 diff is where you need to start looking. 3.7 diff is what you need. My 180rwkw ca18det 1200 has a 3.45 diff and its no fun on acceleration but is good on the freeway.

try here its what i use
http://www.wallaceracing.com/
cheers

simple to work out. You're interested in revs at 100 or 110kph? Take your revs at that speed, divide by 4.11 and multiply by your intended ratio.

eg if you're doing 3700rpm at 100kph and thinking about a 3.9 diff:
3700/4.11*3.9=3500rpm

$3K for a celica box ?? One just sold here recently for $1050. D: mite have a 3.7 for sale

What profile tire are the 15's??

If you have option of going to a different aspect ratio...............from 50 to 60 series etc that would drop the revs 300-400 Rpm's

Also define revving its arse off.........an A-series motor will spin 5K all day, it might be loud in the car but otherwise it isn't an issue.

Tom

Amen to that, Tom.

Thanks guys, if I can reduce my revs by 500 to 1000 rpm then ill be happy till the 5speed comes along. To me driving on the freeway at 5000rpm is not cruising. And for long periods of time forget it. ill do a few calcs and see what I get. Cheers, also the tyre profile is a good one, I have 50 series profile now I might try 60 next.

From what I've read. Ill need the shim to use the bluebird diff, but my axles and tailshaft should be fine from the 1980 1200 ute.
Is that correct?

3.7 would be the go, 3.454 would be the best with a 4 speed and 60 profile up from your 50
Cant believe Dellows prices them that high now. Its cheaper to cut and shut a 71C box