Dear Friends,

What’s your opinion on changing the original AYC rear diff to a plated LSD diff for street use ?

What will be the driving characteristics with such a change ?

if done, would you advise for torque biassing type front diff as well ?

 

For street use, you wouldn't notice a difference, other than not having to fix a broken AYC system anymore. Racers prefer the plated diffs because they are more predictable, and more reliable with increased power. Front & rear Cusco RS diffs without AYC is a really tough combo to beat all-around.

 

Thank you very much.
Are both Cuscos front and rear plated ?
Would it make the car too aggressive handling wise or will not feel the difference until the car is driven hard?

 

The Cuscos are plated, yes. The RS has springs for preload and has very good road manners; it may show more signs of lockup in low-speed situations like parking lots, but wouldn't be unpleasant at all. You would need to convert the rear to the RS-style diff housing, which I understand is quite expensive overseas.

 

I am familiar with the RS diffs as we have been rallying with Evo8-9s. We were using Ralliart LSDs in them back then.
But never had a road car. My son has a X with auto box
Now, my friend’s Makinen VI has a problem with AYC diff. It seized one of the shafts and the bearing on the planetary gear system. I have found a used one and repairing it but I am wondering ultimately should I convince him to switch non AYC. He is a docile street driver with standard engine.

 

For what it's worth, I use a Ralliart Evo X LSD in my Evo I and it's just fine for street use. For the TME, I might suggest keeping the AYC. Originality is the most important thing for those these days, it's almost sacrilegious to modify one now.

 

I highly recommend you get an AYC diff complete from Evo 8/9 - it is stronger than Evo 6/6.5 TME AYC, and AYC is magic on the road.
I have TME RS2, and 2 other Evos with Plated Diffs, and plated rear diff typically induces some understeer, some resistance to turn in. Especially since TME has VCU, and not ACD that totally "opens" front to rear torque lock up.

I run Evo X AYC rear, and I could "feel" the added torque split capability the later AYC diff has over original TME.

X AYC has different flange/CV on left side (inner) and is a real project to get adapted to TME half-shaft, having to build CV joint half X and half 6-7-8-9. So just get Evo 9 AYC and enjoy the awesome torque vectoring and increased reliability over standard TME AYC.

 

Regarding the originality concern, you are absolutely right but our car is not fully original due to evo9 engine block evo8 head. The original block might be restored but currently is not in the car. Rest of the car pretty much original and accident free.

Interesting to know, X AYC is a doable upgrade. Thank you very much.

 

Thank you very much. Interesting to know the X AYC can be used in the earlier Evos. And I didn’t realize that the Evo 9 AYC could be used in the TME.

Did you keep the original AYC pump etc, or all that hardware has to be taken from the X incl pump if it was the X AYC conversion?
And the same question goes for the AYC pump for the Evo 9 conversion.

Where did you get your halfshafts adapted for the X conversion?

Regarding the Evo 9 conversion into TME, most probably the Cwp ratio will not match the front and the TME’s Cwp has to be fitted to the Evo 9 AYC diff unit. Am I correct ?

I generally find the TME’s overall ratio rather slow, it feels like it needs a longer CWP or 6 speed box.

 

Evo X and Evo 9 AYC fits straight into TME, no issues with CW or anything.
Original pump works fine, the pumps are all pretty much the same, so no issue.

The CV joint was "adapted" by professionals who used hardened steel pins (machinist tools) of right diameter to manage the issue with CV joint ***** not being same on X and 5-9 CV joints.

I think that you can just fit an Evo 9 AYC and be done, as its virtually identical - except this output flange - to the Evo X.
And E9 is direct fit.

Make life easier..I just knew who could sort me and in US we don't have Evo 9 AYC, but we have Evo X AYC - so it was practical solution.

 

I may be wrong but I have seen a Evo9 AYC the other day, apparently the CWP ratio was different than our TME’s CWP ratio.
Then I thought it will not fit to our car.
is not it true that I can not alter only the rear CWP and I have to change the front diff CWP as well ?
Am I missing out something?

Is there a source that I can see all the OE diff ratios of all Evo cars ?

 

My TME works great, so its proof it works.
You can check online the specs, but I have zero concern.

 

First, I am going to find out what “ratios” we have got in the rear AYC diff, front transfer case ( which I miss called front diff above ) and the Final Drive in the gearbox to see if there is a ratios miss match between the “ transfer case “ and the “ rear diff “.

If I am not wrong NO miss match ratios are allowed between these two ( TC and Rear Diff ). And if there are different ratios ( even slightly different), this is no good and eventually will damage something. Am I correct??

Once that confirmed, I will also confirm the Final Drive ratio of the car/gearbox. FD determines the gearspeeds and therefore the top speed for a given RPM. Our car has 5sp box and once the gearbox is open I will confirm the gear ratios. Then we can judge if it is the original TME box or swapped at some point during the previous ownerships. By the way, I think our FD is a kind of short ratio and the car wants a slightly longer FD.

 

Hi again,

Today, we have dismantled everything and I have all the ratios. I am going to start a new thread now asking for the confirmation that our TME has the original ratios. I would be thankful if you could contribute to my new thread as well.

Many thanks

 

I saw your post, but the trans ratios are online, you do not need a thread.
If you trend on line you will confirm. TME RS2 and Evo 6 GSR have same ratios, and Evo 9 SE in USA has similar ratios (closer stacked 5 speed).
https://www.lancerregister.com/threads/gear-ratios.795/

See the link.

You are overly concerned with details, I am not the first one to swap X AYC into an earlier chassis. Even if minor difference, the VCU will dampen it. The very reason to have differential is to dampen wheel-speed difference, and each time you make a turn your inner and outer wheels travel at different speeds. Same applies with center diff.


Just drop in 9 AYC and enjoy.