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wanting new lsd, what to ratio to get???

3K views 19 replies 11 participants last post by  blueoval 
#1 ·
hey guys im thinking of buying another diff for my ea, my cars a 3 speed auto, i got told the diff ratios are shit on these (as are the transmissions) so i want to upgrade to make it a bit quicker, i dont care about top end speed all the much, i just want to be able to get off the line quicker and have a repectable 0-100 time. any one got any ideas??

what model e-series came with a shorter ratio diff??? I would like lsd too?? if any one has any suggustions and knows what model it came out on feel free to add your opinion.

also how much does a second hand diff cost from a wrecker???

thanks guys and girls.
 
#2 ·
EF/EL XR's and Ghia's scored a 3.45 LSD
i think there is a 3.23 aswell. any higher then that with the 3spd and it wouldn't be fun :)
 
#3 ·
Some EB XR8's came with 3.27's as standard like mine before I changed it. But you cant go past a 3.45 for drivability and performance. Problem is where to find one in good condition!

Beware of going too high in ratio as you torque will be used up too early as you accelerate.

Anything between a 3.23 to a 3.45, 3.7's maybe should be fine for your current setup.
 
#7 ·
puttin 4.11 in a 3 spd EA is not really the answer for an everyday street car. Drivability would be of concern imo.

I reckon you would get a pretty big kick in the pants putting a set of 3.45's on a 3spd EA coming from a 2.77 or whatever.
 
#8 ·
I have had my car with a 3 speed and 3.23 diff. It was a huge improvement over the 2.77 diff. At 100km/h it sat on 2700rpm. I would not suggest anything much higher then that.

If you are not concerned with driving the car on the freeway, and don't care about rpm.. a set of 3.9's or 4.11's with a few breathing mods like exhaust, intake (cam would be good) will have you a nice quick car!

Simon.
 
#9 ·
Ive got 3.08's (4speed Series 2 EA) and sit at arround 1700rpm at 100kmh, and still find it slow off the line, and as the 3 speed has the same 1/2/3 ratios as the 4speed i wouldnt go for 3.08's if your making a change. 3.23/3.45 would be the way to go.
 
#12 ·
Well my 3.08 read 1700 at 100, and the 3.45 reads 1900 at 100 or 2000 at 110.

Wierd, maybe your torque converter solenoid isn't locking up properly, they can start to slip after time.

Yes I changed the transducer gear over.

Rollin has a 5spd with a 3.9 and it reads 2250 at 100... 5th is shorter, plus shorter diff, I think something is wrong at your end...?
 
#13 ·
Mine runs at about 2000rpm in 5th at 100kph with a 3.08 diff.

Brent
 
#17 ·
Sorry to take this sort of off-topic but I fear that my rpm reading/speedo is slightly out.

History - I had the car dyno'd a while back when I had my 3.08:1 single spinner, and the speedo check showed that my speedo was out by 4%, at 100kmh on my speedo my actual speed was 104kmh.

Calcs - My current tyre set up 225/50 has a diameter of 610mm ( measured ) which at 100kmh turns at 870rpm.

The tailshaft then turns 3.45 times faster at 3000rpm to which the gear box converts 4th at 0.68 and the engine should be at 2050rpm.

Now the problem here is that I am showing 90 rpm slower at the same speed as 1950rpm at 100kmh. Which is 4%, now as far as I can tell, the dyno operator explained to me that my speedo was reading slow, but usually on a stock car it reads fast.

My car is now reading fast, so I've shifted my error by 8% in the wrong direction.

Two wierd things about this, 1) if I put the 3.08 gear back in by mistake then there would be no change, 2) the 3.45 gear should have changed the amount by 11.2%.

Now the only thing that makes sense is that the tyre size is 5% smaller than stock, in which case woul dmake the reado read ~5% fast, which would marry in with the fact that 1950rpm x 1.05 (adding 5%) equals ~2050rpm. The very rpm/speed combination I am after.

So in short, me speedo is still out by 4% or so and its got nothing to do with the ratio change, its just furked!
 
#19 ·
The fastest solution would be to put a 5 speed/3.45LSD in your car.
 
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