AgresvEvo

Ok guys I need your help. A slight backstory, I bought my 06 Evo IX SE a few months ago and can't figure this issue out. After I bought the car I took it out and it would spin the front tires when I would get on it and even just rolling into it on the interstate. So I drained the rear diff and the drain plug was covered in shavings, so I purchased a good rear diff and installed this past week. The clutch the previous owner installed is an unsprung quartermaster twin disk clutch and is very grabby on take off and normal driving. This morning I took it on the interstate expecting this thing to put me back in the seat and I roll on the throttle and as soon as it starts making boost, the rpms F*^%@ing go to redline and I'm not going any faster. So I'm like dam, now the clutch is slipping. I downshift getting off the interstate and roll on it a little and get wheel spin. So idk wtf it is. I don't want to play a guessing game on the drivetrain if I can help it, because that will add up real quick. It's just weird because the clutch still grabs hard driving normal, and sometimes wheel hops under acceleration so the rear diff still isn't engaging. Maybe the t-case it going bad. Does this sound more like the clutch going out or the t-case? It doesn't knock or drive bad or make any weird noises ever, just this issue. Thanks again.

CaptainSquirts

iTrader: (3)

If your rear diff isn't working, I would stop driving it. You're going to make things worse. Did the car behave like this when your purchased it? Also get rid of the unsprung clutch disc, that thing is just going to cause you a lot of problems down the road. I think your best bet is to drain all drivetrain fluids and look at the ring and pinion itself in the transfercase to see if the teeth are all still in tact. But sounds like you're not sure what to do so I would take it to a shop that knows these cars. GL

hutch959

iTrader: (18)

do yo have any ACD lights on?

AgresvEvo

I have on the standard one light in tarmac but that's all. No other lights on.

Biggiesacks

Without knowing your setup I would guess by your description that your clutch is slipping. In lower gears its easier to light up the tires so there is less demand of the clutch, not so much at higher speeds.

AgresvEvo

Biggie that makes sense. I have been speaking to the shop that is familiar with the car and tuned it, and he said it could possibly be the acd pump.. idk but I like thought of 350 for the pump instead of 4k for a t-case from stm.

hutch959

iTrader: (18)

i would put it up on a rack.. or jack stands and put in 1st gear... and just let it idle.
apply the emergency brake slowly and see if it kills the motor of if it stops the rear wheels and the front keep turning

LetsGetThisDone

iTrader: (1)

That won't work on an ACD car. It'll just keep spinning fronts even if everything is as it should be.

gqcode

iTrader: (14)

I hate to said this but the same thing happen to me at the 1/4 mile track. I launch the evo and when I went to second gear the RPM when straight to red line and I wasn't moving any faster. Anyway for me I simply destroyed second, third and fourth gears. Transmission broke down and I just had a new clutch installed. It burn the clutch and I was able to see the hot spot on the flywheel. My T-case was fine but driving back transmission felt very notchy.

hutch959

iTrader: (18)

yea... i forget about how the acd works.
thanks for correcting

AgresvEvo

Yea I hate putting up stuff like this because it could be numerous things but I appreciate you guys helping out best you can. I'm thinking that I'm just going to start with the least expensive thing and work towards the tcase. The Diff is good to go for now, next I'm gunna replace the acd pump then tcase I guess. As I'm sitting here typing this, lol, would it make more sense to replace the tcase first with a non acd t case? I don't want to buy a new pump if I'm just going to replace the case with a non acd shortly after. I don't know how in depth that is yet though or if its the same as doing a stock replacement.

LetsGetThisDone

iTrader: (1)

This really doesn't sound like an ACD issue.

Evo9isLife

If the ACD pump was the issue then you would have all 3 acd lights lit up together. Sounds like clutch slip. Worst case its a tcase issue if in fact you are not getting power to the rear wheels. Did you ever put it up on jacks and put in gear and let it idle or move wheels by hand?

heel2toe

iTrader: (41)

Im reading this entire thing as a slipping clutch. Hooks in lower gears but slips in higher gears. Getting wheel hop doesnt mean your rear diff is going bad. And think about what happens when you step on the gas. Its all about weight transfer so the weight is shifted to the back wheels and lightens up the front which makes it easier to spin the fronts vs the rears.

AgresvEvo

Evo9islife - It has never had all three on at once. I wasn't sure if it would act like this and not throw the lights if the acd was going out and not completely out yet. like it was just working enough to keep it from turning all lights on. I did put the car in the air with the original (bad) diff and started the car, put it in 1st and all four spun even with the bad diff. I did not spin them by hand though. I will try this will new diff in and get back to you.
heel2toe - once it did the slip in 5th gear with very light throttle I thought that also, but I still have a lot of reading to do to completely understand the acd and how it works so I wasn't sure. What threw me off with the clutch slipping theory was in 1-3rd it will spin the front tires and wheel hop sometimes, but as you said the weight transfer would make it easier to spin tires and not the clutch. Also the clutch still grabs hard when taking off in normal stop and go conditions.

So general consensus it seems is to replace the clutch then move towards the acd/t-case? Either way the clutch was getting replaced because the unsprung Quartermaster twin disk is not enjoyable to drive. any Suggestions on a clutch kit? I'm going to buy one that is a bit overkill for room for future upgrades. twin/triple disk, sprung -vs- unsprung, full disk vs- plates? (if the clutch kit questions have been answered then disregard) I will drive the car mainly on weekends with spirited driving but plan to also take it to drag strip and auto x. If the harsh on/off clutch is the only way to hold the power then fine but if I could get one that's a little less on/off that would be preferred.

Thank you guys again!