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chew*'s 01 Neon Mtx Project

Posted: Thu Nov 17, 2011 6:43 pm
by chew*
I should probably introduce myself.

I'm 36, from providence R.I. and been a mechanic or the more decriptive term for me would be Advanced automotive diagnostic tech since a mechanic is such a loosly based term ( parts replacer comes to mind )

Anyway my specialty is engine performance.

A few years ago i had a ground up 92 pointiac bonneville done up, it was Ok, I personally liked my 88 better....unfortunately some ass tboned my 92 and after 2 years the case finally settled....meanwhile i was driving some POS i paid 200 for before i bought a maxima with radiator support frame rot and welded a new one in with the car totaling at 800 with my labor.

That got stolen about 6 months ago.

4 months ago I picked up a 2001 neon mtx, I started reading up on everything you can do to them and caught the bug....

My first mod was a CAI.....after pricing them I said screw that. I went to a friends shop that does custom exhausts grabbed some stainless and mandrel bent my own. tossed some paint on it and a k&n and called it a day.

Now i've been reading and reading and reading alot.......for the passed 3 months..........during which time I have beat the snot out of my car and dragged it late nights not to be an asshole but to find the weakest links.

I'm not about to throw more power into the car when certain components can't handle near stock....I do things a little backwards, make things reliable then add power.

That leads me to the topic of weakness and strengths i found with my car.

Keep in mind all that is in car is a AFX, custom catch can and custom CAI ( drops out fender but very high to avoid locking up motor when going through RI "puddles" ) and AC delete.


First off you can rev piss out of it, even with 110K i have yet to hurt the engine.

Second revving piss out of it 7000+ is pointless stock. cam is useless after 5500, intake is useless after 6200 but the point was to see if valve train failed.


The power steering pump sucks.....evertime i pass 7K it goes airbound and sounds like i have a supercharger.......

The transmission is junk......I'm on my third now which I rebuilt this time....

For naysayers here's some shots of internals and the diagnosis.

Trans 1 110K.



I almost rebuilt this one till i found this out.....



And here's how it all started......

There's a set pin that goes in there......


Here's what's left of it. The missing part is what chunked the gears and trans.....


The above pin snaps, this pin spins, wipes out spider gears....eventually pin gets worn, slides out of diff, ejects set pin, boom.....


Maybe it's a fluke right?

Trans 2 32k orig 1 week of hard driving.




Looks like theres a pattern.....maybe we should install an LSD and that would solve everything....I tend to doubt it though, stress will go to driveline or backwards further into trans wiping out other parts, of course thats just my opinion.....

I could go on about the internals, the shift forks have like nylon wear pads......the central located bearing retainer has a nylon/plastic housing......

Lets face it it's not made to handle the stress of launching.

here's # 3........I just rebuilt this one with a slight mod to dif, the pin is welded in place on both ends to keep it from spinning....sure the diff will wipe out but hoping to keep the rest intact for now. It's a bandaid at best.....




Car is back up and running for now, on the fence about ordering and lsd for it though......I know the current diff won't last to long.

Here's an alternative that I may proceed with.




Aside from what I believe will need to be a custom bracket to hold intermediate shaft and all the parts to make it work such as the following.

intermediate shaft
starter 2.4
bell housing shim 2.4
clutch 2.4
flywheel 2.4

just to name a few.....

Might as well post a pic of my car to.......

For most of the time I have had it this is how it has looked......jacked up with a tranny removed :roll:


Anyway once we get some reliability issues worked out such as maybe going to a manual rack and straighten out some trans issues we can start adding some power....

I already purchased and entire R/T no title parts car 99% complete so we are off to a good start as far as that goes.

Posted: Thu Nov 17, 2011 8:26 pm
by a23dranger
when you do your trans. remember. 10w40 high milage mobil 1 oil in it, adjust your cross over cable on the shifter. have some sort of rod brake or shift stop so you dont over shift the trans. ie hurst or maddog. most trans failures are do to lack of lube and heat. atf is not the right thing to put in the trans and do not add friction modifier.

This is right from mr. ed peters himself.

Posted: Thu Nov 17, 2011 9:24 pm
by chew*
Been running penzoil syncromesh.

I highly doubt fluid is the cause of this pin snapping and the gears binding. The diff sits in the valley or res as well as final drive gear, it's constantly submeresed in fluid, now if it was syncros being the oiling system is passive I would agree fluid could be an issue......

Not to mention as you can see nothing has been subject to heat in my just snaps, grinds and tranny goes to hell.

The trans place I ordered my parts from identified my differential as I walked in door, said ehh you must have neon or a pt cruiser problems.......

The failures i'm seeing is in drag strip conditions.

Launch a few times, diff blows. Replace diff with a lsd, i'm guessing other crap will blow just based on what I know from having it apart.

I've had the t-850 apart, it built quite a bit stronger.

Posted: Fri Nov 18, 2011 10:39 am
by Danteneon
Peg-leg launch = blown diff pin. It's a fact.

Posted: Fri Nov 18, 2011 4:10 pm
by a23dranger
Yeah I'm just saying for the next one to follow those guidelines. They are some key factors to the trans itself having issues. Your dif pin deal I know is a different story but it all helps in the end with all of the componets .

Posted: Fri Nov 18, 2011 5:20 pm
by chew*
a23dranger wrote:Yeah I'm just saying for the next one to follow those guidelines. They are some key factors to the trans itself having issues. Your dif pin deal I know is a different story but it all helps in the end with all of the componets .
I can go over those if some people would like. There are numerous wear points to look for.

These t-350's are a pita to get back together though, I wouldn't suggest rebuilding one for a first timer. Getting the input shaft and counter shaft pressed back in right is a pita.

Posted: Fri Nov 18, 2011 8:41 pm
by a23dranger
Go ahead and let us know. Would be nice to compare and share with ed peters, drakito's transmission info. also what year and gearing are the trans you've had the issues with.

Posted: Fri Nov 18, 2011 9:25 pm
by chew*
So far I've had 3 3.55's apart.

From what i can see as far as diff issue goes, even a phantom grip won't help.

The issue is the gears start binding on the diff pin first and then it domino effects from there.

The diff I just tossed in was just starting to show signs of this, I should have snapped a shot when i had it apart.

Welding the pin + a phantom won't help much either, nothing will fall apart but eventually the pin will get sheared so much there will likely be 1 of 2 things that happen, main pin will snap or the more likely situation, all the metal from pin will eventually screw the syncs.

I will see if i can grab a better camera to show the spring wear I have noted for the syncs, among other things.

I'm trying a 3.94 next mostly to compare ETA's though that I have logged with 3.55's

After that I have to do this. ... 040169.jpg

Then compare ETA's again....

Sorry no time slips, newengland drag is a long ride home with a blown trans, so my buddies stopwatch and mignight + street dragging has to do for now since it's 1/2 mile from my house every friday ;)

Posted: Fri Nov 18, 2011 9:25 pm
by occasional demons
Dif pin tabs will at least save your transaxle case. The diff pin has been welded in place by some folks also.

Some '03 and '04 up came from the factory with diff pin tabs. They are dirt cheap insurance.

But if you are still smoking one tire constantly, any diff is going to fail eventually. The spider gears get poor lubrication with only one tire spinning. Once they weld to the diff pin, it is game over.

Posted: Fri Nov 18, 2011 9:45 pm
by chew*
occasional demons wrote:Dif pin tabs will at least save your transaxle case. The diff pin has been welded in place by some folks also.

Some '03 and '04 up came from the factory with diff pin tabs. They are dirt cheap insurance.

But if you are still smoking one tire constantly, any diff is going to fail eventually. The spider gears get poor lubrication with only one tire spinning. Once they weld to the diff pin, it is game over.
Exactly what I have seen and found out, I would think though that they would still get lubed, they are submereged in this trans. The fill/level check pint is above the axles.

I think the issue is i'm not smoking tires, I'm hooking ang gone.

It's taking maxximas till I am halfway into 4th to catch me and i'm still practically stock.

This one I did weld, it's a catch 22.

Don't weld pin, spins in diff, ruins diff. So i said screw it and welded it.

Doesn't stop metal shavings though.

Posted: Sat Nov 19, 2011 4:27 am
by D-Railed_Neon
damn bro, keep us up. Very helpful thread as I am starting to think my 127k 3.55 doesn't have too much life yet. Anyone got a 3.94 they wanna send my way? :wink:

Keep us updated brother :thumbup:

Posted: Sat Nov 19, 2011 2:23 pm
by a23dranger
3.94 is not much different. Only thing would be hd vs non hd. The gear teeth count on diff gear in the hd 3.94 vs 3.94 non hd are different. Found that out when I did the hd swap in my coupe. Same might go for the 3.55 hd and non hd setups.

Posted: Sat Nov 19, 2011 2:36 pm
by chew*
Agreed, only reason I am testing one is ETA's.

One of the things that I noticed that could improve this trans is the center shaft bearing.

On the t850 it's huge and sits in a normal race unlike our t350's

I can understand why NVG used it because as is assembly is a bitch....secondly this case splits unlike the t850, however i can't help but wonder if there was a bearing there with less tendency to flex if some of the issues would "go away"

I may play around and see if I can size a bearing to it.

A little trick for removing that race without a special tool btw.

I used my kerosene heater in my garage to warm the front case, applied a liberal amount of vaseline to bottom of housing that race sits in, poured liquid nitrogen into the race housing, the vaseline impedes the effectiveness of the ln2 on case allowing the race to get cold much faster than the housing. As it gets cold it shrinks, pops right out.

This race :)


Posted: Sat Nov 19, 2011 4:57 pm
by chew*
I thought I might post up some interesting info. Info that is pertinent to me and what I plan on doing providing the stars are all in alignment for me.

Some that has been a topic of debate regarding the R/T 2.0

Here's some facts/specs that some may or may not know.

All 1995-1997 connecting rods are made from HS150.

All 1997-2005 DOHC (except SRT) and standard SOHC rods are made from HS160.

All 2001-05 Magnum SOHC and SRT are made from HS170. (The 6.1 SRT Hemi also has HS170 rods)

The 01-05 Magnums have the strongest available rods available for a 2.0 engine.

Traditional drop forging HS150 HS160 HS170
Ultimate tensile strength 1.0% 6.6% 11.6%
Yield strength 18.3% 19.9% 24.7%
Compressive yield strength 12.2% 13.5% 21.3%
Shear strength 3.7% 9.7% 16.6%

So basically you can in your basic rebuild make a normal 2.0 bottom end stronger with factory parts. You can also get away with a little more power in an R/T.

Posted: Wed Nov 23, 2011 2:14 am
by chew*
Finalized a deal with owner of my donor R/T ( no title ) car, going up tommorow, might take a crappy cell phone pic of it, start a complete teardown of it after holidays.

I wanted to get started so I could rip it apart over holiday weekend but I got an M3 bimmer tying up my garage right now.

Sploofed the CAT 02's on that with defoulers, fixed the window transmission on drivers side, changed the tumblers from his broken door latch to a new one and now i'm chasing down a low coolant issue.....Owner is in denial it's a head gasket so I tossed some dye in it, gonna check the exhaust with UV tommorow. I supsect it's on compression/exhaust since it seems to be building pressure in radiator. Not looking forward to that job.......

Got some other projects lined up for the neon besides go fast /reliable parts so stay tuned.

Anyone with info as to where I might find a srt-4 parts car close to Providence R.I. ( 1-2 hours driving distance ) with the driveline still in it please let me know, striking out so far finding parts I need for the T850.

Posted: Wed Nov 23, 2011 12:59 pm
by LilSparkPlug
There's a guy on the MA/NH border, he's not a member here he's on SRTForums and he has a ton of transmissions and parts. Here's a link to his profile, you will probably need to become a member to view it:

BTW...welcome fellow Rhode Islander :)

Posted: Wed Nov 23, 2011 4:11 pm
by chew*
LilSparkPlug wrote:There's a guy on the MA/NH border, he's not a member here he's on SRTForums and he has a ton of transmissions and parts. Here's a link to his profile, you will probably need to become a member to view it:

BTW...welcome fellow Rhode Islander :)
Thx for the welcome and appreciate the info.

Posted: Wed Nov 23, 2011 5:22 pm
by LilSparkPlug
Anytime, last I heard he had 6 or 7 T-850s hanging around.

Posted: Fri Nov 25, 2011 10:52 pm
by chew*
Long day, I was down in PA for work, Had to leave the family at 8pm turkey dayto be somewhere at 6am......

On my way back I found Carlisle or close to it.....


Somehow found the energy to shoot over to my parts car which is 1 hour away from home around 2:30.

Took time to inspect the car a little better, before i just verified wiring, pcm, intake, head and header were intact.

This time i found some extra goodies, front and rear vibrant truss bars, short shifter, aftermaket tails, remote start which upon further investigation netted me a skim key for the car :rockon:. Red springs, guessing eibach and not engine mods persay other than a missing CAI that i can see......just the magnum part to an AEM was left. No UDP so likely stock internals.....

I pulled the lights, tossed on my car, they just need a good buff, no cracks.


Found a leak in my trunk so gutted it and tossed everything away, I know where a fresh trunk interior is. Pulled rear seat, will leave it like this till it rains so I can find source of leak.


Installed rear truss bar, maybe placebo effect but it feels like it handles much better now. Didn't bother with front, seems like it would be more for show......

It could use a paint job but for now I will settle with function over form.

Out with old

In with new, brake light pops up after a minute......have to figure that out.

Mileage almost identical to my car.

Some more parts I pulled while there......mostly to make pulling engine easier, it was hit preety good in front so I pulled intake and PCM and also took the antitheft.

Checked secondaries, they move freely luckily.....

If all goes well engine/trans/driveline and entire supsension tommorow, interior, steering column and wiring last.....the seats are dogged....the roof is good though as well as some other R/T ammenities.

Worst case if i don't need it i'm sure someone else does......

Also I have access to a 2002 manual swap donor, I already have wiring and PCM non skim.....the only thing it lacks is a trans.......

Posted: Sat Nov 26, 2011 12:27 am
by occasional demons
Trunk leak is most likely a need for new tail light gaskets. They are cheap from the dealer.

The fix for the brake light is too much of a PITA to bother with; pull the bulb. There are some micro printed cricuits in the cluster that need cut and re wired to fix the brake light issue on R/T and SRT clusters. IIRC there is a how to, but the pics are missing. They were pretty blurry when they did work.

Post 8, there is a better link.

Posted: Sat Nov 26, 2011 1:02 am
by chew*
Thx for link.

Looks simple enough compared to some of the stuff I do with computer parts.


Your probably right about the trunk leak, It looked like the passenger side was leaking from housing but that doesn't explain the small amount of water I found under rear seat.

Hopefully when I do the roof clip and reinstall windows any leaks in cabin will go away.

Posted: Sat Nov 26, 2011 1:58 pm
by chew*
occasional demons,

In your sig it says 01 MTX ES with 02 R/T pcm.

How did you go about using it, a full wire harness swap along with steering column?

Also is it possible to flash a second 02 R/T pcm?

I'm thinking of 2 sets of computers and engine control harness's installed one labeled MS, one OEM using MS on one and swapping all the connectors over come inspection time to the OEM setup.

Posted: Sat Nov 26, 2011 2:53 pm
by occasional demons
The cluster should be right up your alley then. :)

The '02 PCM, I got lucky on. It is a SKIM pcm, but my car does not have SKIM. There is a fault code for the SKIM that is likely what is letting it operate.

To get the MTV relay to function, I would need to wire the PCM socket to the relay using JY parts from another harness, or get an '01/'02 R/T engine bay harness. I am currently using a ghetto blaster IM, so it isn't an issue.

I didn't flash the VIN either, just plugged it in, and it worked. I took a risk buying it, and it payed off. With non SKIM, the VIN does not need flashed. The codes related to the MTV circuit, and SKIM communication do not set a CEL. (They don't affect emissions)

I believe installing MS into a PCM box and soldering in the OEM connector to the MS unit has been done.

The only difference between the R/T, ACR harness is the MTV circuit, and ABS where applicable. Everything else is pretty much the same as far as wiring goes. The '02 R/T pcm is supposed to be more aggressive than the '01 to make up for the smaller cam. The '02 is also more aggressive with the misfire monitor. It does not like a UDP.

Oh yeah, the water will travel along the sides of the trunk and fill up the rear seat area, and the rear floor boards. Both my taillights leaked when I bought mine. The rear seat and the floor were soaked, the spare tire well was bone dry.

Posted: Sun Nov 27, 2011 5:47 am
by chew*
Interesting, I just dropped my nov 2001 RT pcm in, fired it up ran 2 seconds at which point it shut down.

Replugged my 01 pcm fired up, tried my 02 mtx pcm that also worked.

Curiosity, what cluster are you using in that car and is the VAT bulb pulled?

Gonna read up on some remote start info, preety sure there are other ways to by pass it.

Posted: Sun Nov 27, 2011 7:36 pm
by occasional demons
The R/T PCM is prolly SKIM. It was pretty a part of the R/T package. IDK if they could be ordered with SKIM deleted or not. ACR pcm's are a better chance of no SKIM. But good luck finding one for sale.

Danteneon wrote: The non A/C ACRs do not have SKIM IIRC. All A/C ACRs do have SKIM.
The cluster I have is an R/T cluster. I don't recall the year tho.

Not sure what you mean by the VAT bulb. I know the brake bulb is pulled, but not sure on the red dot/SKIM bulb. I'm pretty sure pulling the bulb will not prevent SKIM from locking down the PCM tho.
These are the two related codes I have:

P1289 Manifold Tune Valve Solenoid Circuit An open or shorted condition detected in the manifold tuning valve solenoid control circuit.

P1686 No SKIM BUS Messages Received No J1850 messages received from the Smart Key Immobilizer Module (SKIM)

There is no (reasonable) way to bypass it. It shuts off the internal PCM ground to the coils, the injectors, and the ASD relay. So even if you bypass the ASD and starter relays, it still won't fire the ign. or injector coils. Unless you can hack the program, and know what to disable, SKIM is there to stay.

A new PCM will do it, but it can never "see" a SKIM module, or it becomes SKIM. This applies to all PCM's

Basically to use that R/T pcm, you will need a complete SKIM from a donor car, the keys, and the SKIM code. If your car had been SKIM already, I think that SKIM code could be flashed with your VIN, but I may be wrong there.

That was the risk I took by bidding on my R/T pcm. But I got it very reasonable, as no one bid against me. I knew I could eventually sell it for what I had in it, if it didn't work.

If I actually knew what was keeping it from locking down, I'm sure I could make some decent money from that info. But I could also be possibly looking at jail time too. Prolly not, but you never know what happens when something like that leaves your hands.

I think car thieves just use MS and possibly something like tuner studio packed into a box with oem connectors to steal cars anyways. A quick and easy way to get around security. All they have to know is the basic tune for the vehicle they have targeted. From the Program I watched the other day, going undercover with a car thief, it seemed exactly what they did. It ran crappy for a bit, they did a little tune on the fly, and it ran great. The truck was very gone in a matter of seconds.

Posted: Mon Nov 28, 2011 7:08 pm
by chew*
Hmm I might grab a skimmed sacrificial PCM at boneyard then for some investigating as to what grounds they are knocking out.

Really it's even more simple than that. In many cases they just use a resistor in a key. Once you know the "general value" they use say between 0-10K ohms you can just insert a variable resistor inline and trim it.

I used to bypass GM's like this all the time since customers didn't want to pay the labor involved with the correct fix for the wires that always break in column.

Posted: Tue Nov 29, 2011 7:10 pm
by chew*
Got it figured out.

Cars running now with the 02 R/T pcm with my non skim ignition key :rockon:

Tossed front brakes on last night as the warning tabs were starting to squeak, pumped it up, solid pedal, fired it up backed it out and no brakes......master cylinder let go. :banghead:

Posted: Tue Nov 29, 2011 7:34 pm
by a23dranger
so what did you do to bypass it.

Posted: Tue Nov 29, 2011 10:38 pm
by chew*
Apparently all Neon's come prewired for the immobilzer box.

That said I didn't need the wiring harness from R/T. ( in car harness, still need engine harness for MTV )

Pull battery.

Disconnect PCM, do not plug a non skim pcm in once the following is done, it will probably skim your non skim pcm if you do.

I just took the immobilizer box off the R/T column, plugged it into my 01 ES wire harness, ziptied the key I had found to the immobilizer and ziptied that under dash for now.

After that I plugged the skimmed R/T pcm in, connected battery and fired it up with my original key and ignition. Works like it should from factory without me having to make more keys or change my column or Ignition.

The red skim light also functions like it would normally and goes out now instead of staying on.

Now that i have it all set up I can also test the input/outputs of the 4 wires that plug in, I should be able to determine a way around it now that I can mimick a start/shutdown in 2 secs versus a start and stay running condition.

Posted: Tue Nov 29, 2011 10:49 pm
by a23dranger
Yeah basically what a 556u from dei does for remstarts. I figured that's what you did. I'm not sure the chrysler key skim is like the old gm vats and such where you can find the value. Those old gms where easy to bypass. Even the new gm immoblizer setups with one key and ur obd2 port they have modules that learn the code and bypass it. Dodge and most fords need 2 keys to do that but same deal.

For the average person if you get the ecu, skim ring and 1 key your set to do what you did and I've done before.