Diff Ratios

[Gavclassic]

The 4:1 ratio in my KE17 is way to short. Looking for a bolt in replacement thats about a 3:7. Otherwise what ratios can yoy get for a KE30/55 rear. Any advise would :) be greatly appreciated!

[Taz_Rx]

Pretty sure 55 diffs are 3.9 for manuals and the autos are 4.something

[corolla_nut]

There were 3.

In a borgwarner there was 3.89:1 a 4.1:1 and a 4.3:1. Never seen a 3.89:1 though. I don't know what you can or can't get in a jap diff, have a funny feeling that the autos have the taller ratio.

[corolla_nut]

Also, the reason why you have such a short ratio is that you have a very small rubber band for an engine and it doesn't have the torque to pull you along at higher speeds that you would get out of a nice tall differential. Ideally you'd need a bigger engine to run a taller diff. I'm under the impression a ke17 was designed to be a snappy little car and you lose that snappiness with a smaller diff. I'd be happy with the 4:1.

[KE70-from-mt-panorama]

Gavclassic has a 7k in his ke17, so i don't think power at high speeds will be a drama. (from memory he is going to be using it for circuit work)

 

correct me if I'm wrong though

 

cheers

[13BT_KE20]

you might find a 3.7 to be a bit long.........

 

I ran a 3.6 in my old S2 RX7 for a while (before changing back to 3.9), but it was waaaaaaaaaaayyyyyy to long. I'm talking 80 in first, 120 in second, 3rd was...............

 

i think a 3.9 would be better if your looking for a taller ratio, altho i don't know why you really want to change it. I loved the 4.1 in my RX7.

 

IMO 4.1 is perfect for an NA car

[Felix]

He needs a taller diff ratio because he is making peak power at 6200rpm. Going from a 4.1:1 to a 3.7:1 would drop the cruise revs at 100kays by about 300rpm, plus boost the top end speed by around 20km/h at peak power rpm.

 

Gav if you are running the Borg Warner diff, Datsun 120Y's share the same diff style (BW68) but have 3.9:1 gears. I'd also look at 2L sigmas, as apparently some had the smaller Borg Warner diff in them. Also maybe look at datsun 200B's... My ACL gasket catalogue tells me that some share the same diff gasket as ke55's.

Edited June 18, 2008 by Felix

[Gavclassic]

Thanks guys! At the moment my KE17 runs the original Jap dif, 4:1 is standard, 4:3 is what comes out of the KE18 wagons. My other option is to cut down and RX 7 S2 or S3 disc rear end. If i'm going to go down the Mazda option i need to make sure i can get an LSD for it with at least a 3:9 ratio. :lolcry: I'll also be using the front brakes of the Mazda just to keep it all balanced.

[Jono]

the ke55 bw auto is 4.33:1. which sucks for the freeway.

[Taz_Rx]

I can help now!! :lolcry:

 

S1 (s1 has drum rear) & S2 rx7's are 4x110 as you know, but s3's are actually 4x114.3! ;)

 

S3 factory race lsd's aren't too hard to find, but you don't want that stud pattern.

 

Best bet for a s2 lsd is a guru centre (looking at about $1000 with no gears.

Then, here's the bit you'll like - the S2 centre being mazdas "medium sized diff" came in many many cars throughout the years, hence giving you HEAPS of ratios to choose from.....

 

1500 wagon – 4.675:1 ratio

1500 sedan – 4.11:1

R100 – 3.7:1 or 3.63:1

Capella – 3.9:1

RX-2 auto and late 3.9:1

RX-2 early manual 3.7:1

RX-3 – 3.7:1

1600cc 808 – 3.7:1

929 – 3.9:1 (later cars had 3.909:1)

12A RX-4 – 3.9:1

121 – 4.11:1

626 – 3.9:1

929L – 3.7:1

E1300 – 4.875:1

E1400 –4.44:1

E1600 – 4.1

E1800 / 2000 – 3.9

Most Diesel vans were around 3.9:1

1st Generation RX-7 – 3.9:1

 

For more info on Mazda diffs, there's not much that isn't covered in this thread......

 

http://ausrotary.com/viewtopic.php?f=16&t=2695

[13BT_KE20]

I can help now!! :lolcry:

 

S1 (s1 has drum rear) & S2 rx7's are 4x110 as you know, but s3's are actually 4x114.3! ;)

 

S3 factory race lsd's aren't too hard to find, but you don't want that stud pattern.

 

Best bet for a s2 lsd is a guru centre (looking at about $1000 with no gears.

Then, here's the bit you'll like - the S2 centre being mazdas "medium sized diff" came in many many cars throughout the years, hence giving you HEAPS of ratios to choose from.....

 

1500 wagon – 4.675:1 ratio

1500 sedan – 4.11:1

R100 – 3.7:1 or 3.63:1

Capella – 3.9:1

RX-2 auto and late 3.9:1

RX-2 early manual 3.7:1

RX-3 – 3.7:1

1600cc 808 – 3.7:1

929 – 3.9:1 (later cars had 3.909:1)

12A RX-4 – 3.9:1

121 – 4.11:1

626 – 3.9:1

929L – 3.7:1

E1300 – 4.875:1

E1400 –4.44:1

E1600 – 4.1

E1800 / 2000 – 3.9

Most Diesel vans were around 3.9:1

1st Generation RX-7 – 3.9:1

 

For more info on Mazda diffs, there's not much that isn't covered in this thread......

 

http://ausrotary.com/viewtopic.php?f=16&t=2695

sumed it up very nicely there Taz

 

Just thought id add that S1/2 are 24 spline axles and S3 are 26 spline axles. Therefore S3 diff/axles are a fair bit stronger. If you plan on running wide rubber/slick you may find the S2 to be a bit weak. you may find your twisting/snapping axles. Bit your not running a great deal of power so a S1/2 way hold up.

[Felix]

I'm not sure about the ke17's, but the ke15 sprinters had a 4.22:1 diff standard. The ke16 wagon had a 4.44:1 diff standard.

 

Pretty sure the ke70's with jap diffs had 3.9:1 ratios. They are not very common though.

[Gavclassic]

I can help now!! :lolcry:

 

S1 (s1 has drum rear) & S2 rx7's are 4x110 as you know, but s3's are actually 4x114.3! ;)

 

S3 factory race lsd's aren't too hard to find, but you don't want that stud pattern.

 

Best bet for a s2 lsd is a guru centre (looking at about $1000 with no gears.

Then, here's the bit you'll like - the S2 centre being mazdas "medium sized diff" came in many many cars throughout the years, hence giving you HEAPS of ratios to choose from.....

 

1500 wagon – 4.675:1 ratio

1500 sedan – 4.11:1

R100 – 3.7:1 or 3.63:1

Capella – 3.9:1

RX-2 auto and late 3.9:1

RX-2 early manual 3.7:1

RX-3 – 3.7:1

1600cc 808 – 3.7:1

929 – 3.9:1 (later cars had 3.909:1)

12A RX-4 – 3.9:1

121 – 4.11:1

626 – 3.9:1

929L – 3.7:1

E1300 – 4.875:1

E1400 –4.44:1

E1600 – 4.1

E1800 / 2000 – 3.9

Most Diesel vans were around 3.9:1

1st Generation RX-7 – 3.9:1

 

For more info on Mazda diffs, there's not much that isn't covered in this thread......

 

http://ausrotary.com/viewtopic.php?f=16&t=2695

Thanks heaps! I've actually got a S3 RX 7 thats basically a rolling shell that i bought for the disc rear end. If i was going to use it i also intended to use the front brakes as well, then front and rear would have the 4 x 114.3 stud pattern which is a bit easier to find 14" alloys in. My S3 RX 7 is an auto, but i don't know the ratio yet. If i could find a S2 disc rear and front brakes and struts for reasonably money i'd consider using them instead.

[lappy]

3.7 that fits in to a 30/55 housing is a 3.7 rear diff from an AL25 Tercel. Half of the speedway guys I race against run them so the source is very reliable.

[camerondownunder88]

Hi,

I will back up Felix statment about KE1X ratios.

 

I got more sprinter manuals in mail today and the KE15,17 had 4.22:1 ratio diff. The later KE2X car had 4.1:1 ratio as it advertises the fact in my manuals that the KE2X has higher top speed lower revs yada yada.

 

Also KE1X wagons have 4.44:1 also as Felix said.

 

So Gav if your KE17 is a 4.1:1 is it the original diff still?

 

Cameron