Page 1 of 1
2.78 ratio opinions
Posted: Sun Aug 12, 2012 5:14 pm
by PAYNEY05
Hi Guys,
I have to change the diff as the 3.36 has called it quits. To get the car back on the road i have a 2.78 to put in.
Can anyone tell me the good and bad about using this ratio? I am running a 138 RED motor(stock) with HR 3 speed gearbox. Wheels are 15 inch.
Most of the driving i do is freeway or not too hilly,
Thanks,
Payney
Re: 2.78 ratio opinions
Posted: Sun Aug 12, 2012 6:20 pm
by choppedfan
PAYNEY05 wrote:Hi Guys,
I have to change the diff as the 3.36 has called it quits. To get the car back on the road i have a 2.78 to put in.
Can anyone tell me the good and bad about using this ratio? I am running a 138 RED motor(stock) with HR 3 speed gearbox. Wheels are 15 inch.
Most of the driving i do is freeway or not too hilly,
Thanks,
Payney
You'll end up pulling it back out, it will make car too sluggish.
Save yourself the hassle and wait for another 3.36
Mick
Re: 2.78 ratio opinions
Posted: Mon Aug 13, 2012 10:20 am
by choppedfan
Use this gear/speed calculator Payney and you'll be able to see what the "performance "will be like, even the profile and width of your 15" tyres will affect the outcome
http://www.kabamus.com/garage/gears.html
Mick
Re: 2.78 ratio opinions
Posted: Mon Aug 13, 2012 6:43 pm
by Mick
yeah i think it will end up being a problem could be ok once up to speed on the freeway but you'll probly find you'll feel the slightest hill
Re: 2.78 ratio opinions
Posted: Mon Aug 13, 2012 6:47 pm
by muza
choppedfan wrote:Use this gear/speed calculator Payney and you'll be able to see what the "performance "will be like, even the profile and width of your 15" tyres will affect the outcome
http://www.kabamus.com/garage/gears.html
Mick
Thats a ripper!!
Re: 2.78 ratio opinions
Posted: Mon Aug 13, 2012 7:29 pm
by rosco
A pretty hefty challenge for a red 138 - not so bad if you're running an auto.... but a manua - and especially without synchro on 1st.... hmmmm... you'll struggle - and, believe it or not - you'll probably use more fuel.... revs will be lower - but the load on your engine for most of the time will be with the power valve open....
You might have got away with it with a HG onwards 3 speed - with synchro on 1st and a lower 2nd gear.... but if you had that - you'd have to open up the transmission tunnel - why then wouldn't you fit a 4 speed or a Jap box with overdrive.......
Drop back to 3:36 and you'll enjoy good economy, reasonable power - and avoid a lot of grief.... and won't need any engineering....
Just for those who do not know - be very careful when playing with diffs..... if you are running the early red diffs - or the grey - you'll need the "coarse spline" axles..... some of the latter diffs are "fine splined"..... one won't go into the other.....
frats,
Rosco