How-To: Build up a atx for a turbo

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How-To: Build up a atx for a turbo

Post by chrono_killa » Tue Mar 27, 2007 9:36 pm

Hey guys, thought I might share some of what I've learned about the
31th. Please if you have a different opinion or trick please let me know!

Clutch packs: The forward clutch pack is just fine stock. The Neon box
comes with the 4 disc pack and holds up to as much as 1100 hp!

The high gear clutch pack is were the problem is. I'm using the Alto 6 disc
pack in mine and it does a great job. You will have a problem if you
stay with the stock 4 disc pack. I really don't know how much power it will
hold but I'd guess in the 250-300 hp range depending on what's been
done to the valvebody.

Band: I like to reline mine with either a Kevlar or carbon lining. I also
consider it a must to weld the tabs on the band before it's sent for relineing. Even the best lining will burn up w/o valvebody mod's.

Planetarys: All the Neon trans's I've seen have come with the HD 5
pinion front planet and the 4 pinion rear. It's smart to weld the shaft
that the gear spins on, these can break with either high miles or lots
of power.

Gearing: We have 2 final drives, 3.05 or 2.85. The 3.05 is in the DOHC
cars and the minivans, the 2.85 is in everything else.

Transfer Gears: Stock Neon is 1.04, the early Omni gears are 1.22.
(to find your gear ratio multiply xfer gear and final drive)

Diff: Good luck here, just as wilh all Chysler's we have a weak dif. At
least put the dif tabs on to keep the dif pin in place! We can go Phantom
Grip Extreeme or some kind of knock off, the Quaife or new OBX will
fit with a spacer and some mods to the cover. Or of course if you are
a hard core drag racer welding the dif is an option. Be SURE to stress
releive it when you are done welding or you may break the carrier,
and you better be using good axles.

Torque Converter: My opinion on this may differ from many but I really
like to keep the lockup clutch. When the lockup turns on in 3rd gear you
will have no slip from the converter. The stock lockup is a POS, it won't
work in even mild applications.

You can go with a stock size converter and get stall speeds as high as
5000 rpm, efficancy will suffer though. For the hard core guy a smaller
converter (7-8 inch) might be better.

The way to check stall speed is to just floor the gas and hold the car with
the brake pedal. Your stall speed will be were the car either starts to
move or the rpm stop climbing. SO many things can effect stall speed,
engine size, compression, turbo size, brake size, final drive will all have
an effect.

As a rule of thumb, small turbo-nitrous cars will need a lower stall.
You would need a higher stall for big laggy turbos, NA cars, or cars
running on street or drag radials.

Valvebody: There is a couple ways to go, Reverse manual, Manual and
modifyed stock, just don't stay with the stock one! I've never messed
with anything but the stocker so I can't comment, I DO know you will
lose the lockup funtion with one of these though.

The stock VB does a great job of giving nice smooth slow shifts, just the
reason you don't want it in you perfomance trans!

Line Pressure: Stock pressure is limited to about 85 psi, it's safe to go
to 100ish with the stock band before the tabs rip off. With welded tabs
140-145 is plenty.

Higher line pressure will really mess with the stock shift points. You can
mess with the governer to bring the shift points back or you can just
disconnect the tv cable to the throttle body and adjust the lever to get
what ever shift point you want. You will get no kickdown though, you will
have to manually down shift the trans.

Weak Links: There's a couple places that need some extra attention.
For 400 hp or more you really need to work on one of the thrust washers.
These even go bad on high mileage transmissions. This is one of the tricks
I devoloped so I can't go into detail.

Input shaft, no worry's here up to about 500 then you need to do some
heat treat work. Do not use the old solid input, these twist off around
500 ft pounds or torque.

Output shaft, this one wears out on stock tran's and should be checked
for spline damage.

The case is fine till you really start beating on it, it will hold 1.65 60 foots
all day long. Once you want better times or spray off the line with big
slicks you WILL break it. It needs to be reinforced.

The rear band strut can break with high line pressures and should be
replaced with a HD unit.

Pinnon shaft, if you are breaking these you are making about 1000 hp,
we should be so lucky!

Axles, an auto is just much kinder on the axles then a stick but you
should still do at least the shadow-PT upgrade.

Other area's: One of the tricky parts with a Torque Flite trans is timing
the shifts. Bind on the 1-2 shift, flare on the 2-3 shift are what's common.
I have my own solutions to these.

Some other little tricks: you should tap the case for access to the pressure
adjustment screw, makes setting pressures a breeze, adding a drain plug
and a hole for the temp sensor in the pan is a good idea. Shortening
up the dipstick can save alot of room too. The accumulater and 2nd
gear apply piston need some work as well. A modifyed stock shifter can
give you no miss shifts and still looks stock...

OK, my head is starting to hurt now.....

BIGRAM wrote:i ain't gay you sucked my dick
My Cars-98 plymouth highline neon, atx, msd coil, 3.0 intake, ebay udp
Future mods- magnum head, magnum header, rims, msd wires, 60mm tb, dohc pistons, 2.5" dual exhaust, modded valvebody, filled mounts, switch to a tach cluster with green leds and some more shit

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Post by Lackof » Thu Mar 29, 2007 3:22 pm

Might as well add this also then ...
Skill wrote:Here is some info. regarding what you would need for a ATX in a turbo application.
The ATX is quite hardy and can take quite a bit of boost actually. In fact its gearing 2.86 ring gear with the SOHCs 1.04 transfer gears that come stock int eh Neon ATX (A670) which gives you a final drive of 2.97 which is just about perfect for turbo. If you want to stretch the gears out even longer you can order a set of .91 transfer gears from Chrysler (they are a direct drop in) and mate them to the 2.86 ring gear giving you a final drive of 2.60. Although in order to do that you will need to beef up the ATX.

Overall though, the stock ATX is ideal for a turbo application. Its got some flaws, things as bearing age, struts and the major weakness beaing the differential. You can easily run around 275 to the wheels through the stock transmission without a secondary cooler.

The only reason why you'd really need to add a secondary cooler is if the TC no longer locks up or the solenoid is malfunctioning. Of course that isn't to say that a secondary cooler is a bad idea because its not.

In all honesty though, you'll have a higher risk of blowing something up in your engine before you destroy something in the ATX with a turbo.

Things to consider with teh ATX when going turbo. These things are listed in order of importance, the top being the most important.

-Differential by far the weakest part in the ATX. UPGRADE a Phantom or Alabama Man are the two cheapest LSDs. OBX is second best option. Quaife can't beat it with a stick and by far the best choice in LSDs.
-Rear band strut its the second weakest part in the tranny, replace it with the HD strut.
-Bands (they need to be semi-rigid) (since you have a 99 this is a non issue) Reweld the front kickdown band where it is tack welded. Also think about HD bands Carbon is good but Kevlar is much better.
-Governor; valve stick in the governor is common. There are several fixes as well as different valves you can put in it.
-Transfer gears. 1.04s (stock are ideal) .91s are a little more extreme.
-Planetary sets, stock ones are ok. But you should think about rewelding them too.
-Valve body street/strip, Manual Valve Body or Reverse Manual Body
-Clutches probably the last thing you should look into.

Things you should do.

-Upgrade your differential.
-Replace the rear strut.
Street/Strip Shift Kit -
Performance Valve bodies
Street/Strip valve bodies that fits Chryslers Neon with A670 Transmissions. The Street/Strip is fully automatic and produces tire chirping shifts. Filter, gasket and instructions are included and installs in less than two hours with simple hand tools. Get the performance you need! Unit only works with the three speed transmissions from 95-2001.

Please note: This unit does not change anything inside the cabin and works to change how the transmission shifts.
The Street/Strip valve body is fully automatic (just like the stock one), but will give nice precise shifts, and you won't have that "searching for a gear" feeling, when the transmission doesn't know what gear it wants to be in. Also the shifts will be spread out alittle longer letting the engine rev up in the RPM's abit. the shifts aren't as hard as a MTX but feel similar. Harder shifts means that power gets transfered to the ground quicker, and allows for less slipping of the transmission. This intern means that less heat is generated, making for a longer living tranny.

The Performance Automatic valve bodies are specifically designed internally to give the best shift without having to worry about adjusting line pressure, and playing around with the little metal rod that replaces the shuttle spring.
This will give you full control of your transmission. As you CAN manually shift it without it affecting your tranny or eating it alive. You will be shifting backwards with it though and can get confusing if you do not have no experience with it. Hence not for a DD, only a track car.
Custom Neon wrote:Ok, here's how you make your VB into a RMVB.


Pretty straight forward. This one is mine. Its non-lockup hence why there is no lock-up solenoid on it. If you want to make yoursnon-lockup all you have to do is take the solenoid off and make a plate to block off where it goes. (Note: if you are going to remove your TCC solenoid be prepared to replace your TC because you will destroy it. I've got a hybrid and don't have a lock-up TC.)

When installing the RMVB do not put the governor tubes back in. You don't need them. In effect you can remove the governor as well. You can even go so far as to get set screws and screw them into where the tubes go. But its not necessary to do either.

I've also got my line pressure turned rediculously high, something like 7-8 turns. I don't recommend this on a stock transmission.

Go here for trans for the neon if want turbo applications.
http://importperformancetransmissions.c ... ofwd.shtml

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Post by chrono_killa » Thu Mar 29, 2007 7:47 pm

with that link in your post. that a fully built atx ready for a turbo? will it be all that i need?
BIGRAM wrote:i ain't gay you sucked my dick
My Cars-98 plymouth highline neon, atx, msd coil, 3.0 intake, ebay udp
Future mods- magnum head, magnum header, rims, msd wires, 60mm tb, dohc pistons, 2.5" dual exhaust, modded valvebody, filled mounts, switch to a tach cluster with green leds and some more shit

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Posts: 2599
Joined: Mon Feb 05, 2007 10:24 pm
Location: Jacksonville, FL

Post by Lackof » Thu Mar 29, 2007 8:06 pm

yes they are perbuilt .. the specs are there with the bullets next to them. but they are def. not cheap ;)

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