My EVO 4 Build thread.... it will be slow....

[Slowboi]

Evo parts Ireland on Facebook is the company I went through. They have a ton of parts for jdm cars. The guy who runs it was very good at getting back to me.

[jdmvip]

Sorry if I missed this or if for some reason it's not possible but can't you take the matching axles from the EVO 8/9 or will they not fit for some reason? This is what Subaru people do when changing the diff or transmission (they get the matching axles for the actual ratio of the current diff and/or transmission).

A few things I found out about the rear diff in the evo 4's:

The rear diff has an early version of ayc which doesn't work very well and can fail under higher hp applications. For this reason I'm going to convert to a mechanical diff.

I then researched different options for that, there are a few. Cusco and Kaaz make mechanical duffs that will go in the stock case. However this doesn't solve the problem of the ayc case being weak. Under higher hp apps. The case will crack (ayc case)

The next option is using the rs diff from an evo 4. I have to say, good luck finding one. They are rare. I did manage to find one in the uk but the going price for these set ups is 1600 pounds shipped to canada.... So $2800.

A cheaper way of addressing this is buying an evo 8/9 non ayc diff. Lucky for us all usa/canada market evo 8/9's came with the rs diff stock. Mr111746 is the part number stamped on the case.

2 issues with this, one the ratio is slightly different, two the axels are slightly longer.

I have spoken to a couple shops about the difference in ratio.... It is very small. So small that none of the shops think it will cause a failure or put any undue stress on the drive train.

The axels being 20mm longer is not a problem if you keep stock ride height. If you lower the car it will become a problem since the ends if the axels will bottom out. To correct this you can use '98 (8th gen) vr4 axels. They are the same length as the evo 4 rs axels.

[Slowboi]

If I had an Evo 5 or higher that would probably work but from ver 4 to 5 they widened the track of the car. There are other differences as to how they achieved a wider track but most of it comes from them moving the hubs out and using longer axels. So basically all the axels from ver 5 on are about 20 mm too long.

[jdmvip]

Oh I see .... the growing pains of evolution I guess
But seriously your post made me think would the hub from the 5+ fit and would that solve the 20MM gap?

[Slowboi]

It would probably fit, but then the track would move out and then I would have to deal with the wheel being 20mm closer to the fender. If I was doing a wide body conversion this might be an idea, but I don't want to go too crazy. All Im trying to do is duplicate the Evo 4 Rs set up with easier to get parts. Right now the 4 rs stuff is very rare and expensive.

[jdmvip]

I see what you mean, I just wish there was an easier way to solve your diff axle issue. Would 20MM closer cause rubbing on the inner fender? I guess if you did go this route worse case is that you could do a roll but I know you're a collector and may not want to (I wouldn't roll mine either lol).

I guess you could just take your time and look in Japan for a IV RS diff which are rare as you say. The ideal solution would be to get an Exporter to buy and hold the diff and then buy another car and ship it by container so you get free shipping on the diff.

[Slowboi]

[Slowboi]

4 rs/cm5a rear diff case on its way
UKDM Evo 9 rs centre section
cm5a 1.8 turbo gsr axels (same length as evo 4 rs)
And the mustache bar and brackets to make it work!

Ill be looking into custom axels eventually but they are not necessary on stock power. Next ill be shopping for coil overs ....

[Rygar]

Evo parts Ireland on Facebook is the company I went through. They have a ton of parts for jdm cars. The guy who runs it was very good at getting back to me.

Thanks for the info!

[Slowboi]

I should have updated this a while ago, but here we go. So I ended up getting all my parts through evo parts Ireland. All the diff parts above to my door in three days from Ireland..... Blew my mind. I ended up shipping through TNT. Those European couriers don't mess around.

So my next step is to clean the case and paint it, then I need to start looking into coilovers as well. I'm watching a cheap set of ohlins on yahoo auctions.