Hi guys,

I'm in the process at the moment of bringing an Evo 4 back to life. And I'm planning to do a few autocross events and perhaps a few sprints. At the moment its got the AYC (its still working for now) and I'm looking down the track to do a RS conversion.

There is quite a bit of information on this forum and on the MLR forum and also spread across the net when you use Google, but I'm still a bit baffled. So it seems the best/easiest way would be to get an original Evo 4 Rs rear diff and do the swap, but they seem to be getting harder to get these days...

The other option is to keep the AYC case and swap out the open diff for a Cusco/Kaaz LSD and disable/remove the plumbing to the pump and so forth. But I haven't really found a solid lead describing the process accurately.... so that would be like a walking through the forest a bit blind.

Another option was to look at the diffs from the 5-9s but the reduction ratio is not the same... its 3.307 not the 3.312... and the propshafts are longer on the 5-9 then the ones on the 4.

I have also seen some companies offer conversion sets, but they look like RS diffs taken from the later models but again the reduction ratio issue comes to mind.

If someone could give some light onto this topic or perhaps even share some of their experience that would be greatly appreciated

 

I'm not quite sure what the question is here lol
But from someone with a 6 GSR, I can share what I've gathered at least.

Firstly, as far as diff ratios go, it seems that the consensus on MLR is that the ratio differences are negligible and that 5-9 diffs will work just fine on an e4.

What is your current power level and your expected future power level? The weakness in the AYC setup lies in the actual casing of the diff. There is a lot of potential to be had in mastering the handling of the AYC setup, and working with the car's ECUs as opposed to our natural inclination to work against it. With that said, I personally do not think there is any benefit to changing the AYC diff out to a kaaz or cusco unit. Your casing will split eventually, and if LSD is what you're after, an RS conversion is the better way to go. If not, and you're itching to upgrade, Evo 7-9 AYC rear diffs are said to be 30% stronger in terms of casing. Evo 8 and 9 AYC rear diffs reportedly work just fine with the 4-6 ECU and provide better handling because of the SAYC internals vs regular AYC (No proof on this).

RS diff conversions on the 4 are simply bolt up as far as 5-9 diff's go. HOWEVER, the e4 RS comes with shorter rear axles than the 5-9, therefore your wheel choices will be limited. Some have reported using 5-9 axles without a problem. I unfortunately can't shed any more light on this.

4-6 Prop shafts are all supposed to be the same length, GSR and RS are different with the RS being approx 20mm shorter (Don't quote me on that). GSR props work just fine for 4-6 RS conversions.


Dryden motorsports offers a RS Conversion kit to utilize an RS rear diff and axles. In my opinion it's a good product, but a complete waste of money as you are literally 2 (fairly common) bars away from a OEM setup for far less $.

I think that's it lol

 

Thanks for the informative reply

Sorry I was up pretty late writing the post. What I'm looking for is people's experience, opinions and thoughts to the conversion. I have been for the past month and a bit looking around for some solid information, its all a bit scattered.

Current power level is just under 300 hp (bit over a 1 bar boost) and there are no plans to lift the power (want to keep it reliable like a daily driver).

I saw that also on the MLR forum how some have done the conversion with a 5/6 rs diff and reported no problems. But I haven't seen any build threads where you can really say 'ok the conversion works'.

An evo 4 rs diff would be great but I have yet to find one for sale at the moment.. maybe I should jump on the MLR and make a post.

In regards to the propshafts here are the lengths for the 4 and 5.

Attachment 223672

The kit also looks solid from Dryden motorsports. Do you know anyone who has used this kit?

 

I have done the complete conversion to an Evo8 RS diff on an Evo IV. Despite the ratio differences, driveshaft differences and axle differences it all bolts up and works. You will need the diff mounts from the Evo 8 as well.

 

I don't think you're gonna get much feedback on the Dryden kit aside from a handful of people in Australia. It is far less hassle to do the conversion using oem parts.

And personally speaking, after witnessing the issues with the first bushur racing mustache bar, I don't trust anything tubular holding up my rear diff.

 

http://www.lancerregister.com/showthread.php?t=433750

this is how I converted mine

 

Yeah cool! would you have any pics of the completed conversion from underneath? how about the track width, since the propshafts stick a bit further out. I would guess the rear track would be a bit wider then?

 

That is a valid point there, the oem stuff is normally up to the scratch even though it is a bit heavier. I'll have a look on a few Australian forums see what they say.

 

That is awesome

But I'm not sure if I can find many vr4 bits here in Germany..

 

The track doesn't change, that's fixed by the diff location and hub location. The inner joint has enough in and out movement to allow it to work.

I don't have any pictures and the car was rear ended and then parted out.

 

Does the evo 8 carrier and moutasche bar also fit into the rear with little modification? And how about the propshafts?

 

Yes you have to use the Evo8 diff mounting bars. We used the Evo IV driveshaft (driveshaft = propshaft I think).

 

Ok so the mounting bars from the evo8 then fit and screw straight into the giving holes on the evo4?

Ya driveshaft in the sense of like this:

http://www.lastchanceautorepairs.com...infield-IL.jpg

ok so that means I can use my evo 4 gsr driveshafts and then just find a evo 8 rs diff with the carriers to do the conversion.

 

Just to be clear, the shaft running from the transfer to the diff (driveshaft) can be reused but the shafts from the diff to the hubs (axles) must also come from the 8.

The mounting locations for the support bars are the same.

 

Hey there,
i am looking at doing the same conversion into my evo 4 with a evo 8 rs diff. Will the 8 rs rear axles fit along with it?
Is there actually a difference in ratio and if so is that a big issue?
ive heard the tail/prop shaft has to be shortened also, around how much does it need to be shortened?