Seeing inside many transmissions of various condition, mileage, and, age you begin to see all the common problems. Worn synchronizers, bad bearings, leaking seals, even cracked or broken transmission cases are regular occurrences.

Normally we are rebuilding transmissions that either grind, make noise, leak, or just don’t feel good anymore. Every once in a while we get something slightly different.

This customer said his car was popping out of 6th gear. Its unusual for a Getrag to pop out of gear unless it has fork damage or shift selector damage.

Very often the roll pin will work out of a fork or even the shifter assembly tower on the top of the transmission.

Sometimes people will believe a bad synchronizer will cause a transmission to fall out of gear and when they are speaking of the synchronizer friction ring, this is just not the case. Once a shift is completed the synchro ring is just along for the ride.

After ruling out the common causes a very close inspection of this transmissions 6th gear revealed the cause of the transmission popping out of 6th.

Engagement Teeth Damage

Engagement teeth wear was causing this unit to pop out of 6th under any kind of load. There is a back taper to these engagement teeth that is designed to actually make the slider push towards the gear, further into gear undo load. If this is worn away it will pop out of gear and you will not be able to hold it into gear.

It’s very common to see the points worn off the top of the engagement teeth, which causes hard shifting, but this is an un-common place to wear, especially for 6th. The unit in question did have high miles. Paying attention to details like this is what makes for a successful rebuild.  

If you decide to do a synchro swap on your 6 speed AWD transmission there is a very important item to be aware of.

Above 4th gear is a ball bearing that holds the thrust washer from rotating. If you try to press all the gears off in one shot you will crack the bearing sleeve and damage the input shaft.

The key is to place a sharp bearing splitter under the 4th gear engagement teeth and press 4th gear off once you have 5/6 out of the way. 

The most critical factor for a good performing and long lasting transmission in any car is a clutch that releases completely. A dragging clutch will cause the transmission to feel notchy, block you out of gear, and wear your transmission extremely rapidly.

When the clutch drags the synchronizers are attempting to slow or speed up the entire engine to match the shaft speeds. Rather than just the inertial of the input shaft and clutch disc the synchros are fighting the entire engine and they cannot cope with this.

If the car is driven with a dragging clutch and forced into gear the synchros can be rapidly worn to nothing and the transmission will begin grinding.

If you are having issues with shifting one of the first things to do is check for a dragging clutch. The easiest way to do this is to find a safe place with nothing in front of you, place the car in 1st gear with the clutch fully depressed, and bring the engine up to redline. If the car tries to move forward at all before the rev limit then your clutch is dragging and it should be addressed. If you know of a shop with a lift that will safely test this for you that is another option. The wheels should not rotate with the clutch pedal depressed fully even if all 4 are off the ground.

Clutch drag can be caused by hydraulic issues, physical problems with anything in the clutch assembly, or simply a poorly adjusted pedal.

It is important to have some clutch pedal free play to prevent clutch slip, but it should not be excessive. A common target is .5″ to .75″ of clutch pedal free play. Please view the attached video for a general idea of the process and what to look for.

Please do not drive a fresh transmission without adjusting the pedal first. When changing any part of the clutch system or the transmission the pedal may need adjusting.

In order to repair 3000gt synchronizers it is good to be informed about the different types that may be found. There are four commonly found synchronizer material types and all four have been available for the Dodge Stealth and 3000GT AWD Turbo and VR4 models.

Brass Synchronizers

3000GT brass synchro

A Poor Copy of a Synchronizer

This is a commonly found overseas copy of the original synchros and it made completely out of brass. It is easy to spot because it is very bright. They do not have nearly the friction co-efficent as the oem synchros and our OEM gear codes are not designed to grip very well with them. They are usable on Reverse and possible gears 5/6, but should generally be avoided. They grind almost immediately if used for 3/4. There only advantage is they are very cheap to make and insensitive to fluid types. Do not use if you want a good performing transmission.

They may work in other makes and models with different rotating weights and/or gear designs. They were very typical of early model 4 speed muscle cars, which had closer gear ratios and lighter input shafts than we see in today’s 5 and 6 speed Getrag transmissions.

Fibrous / ATX Style 3000GT Synchronizers

This is an OEM Getrag 3000GT synchronizer from the early model transmissions. It was used on 3,4,5,r on the 91-92 5 speeds and can sometimes be found on 93 models. It has a good coefficent of friction, but was not really designed for the type of oils used in these Getrag transaxles.

Fibrous 3000GT Synchronizer Performance

This synchro would actually perform best with ATX fluids such as Redline D4, which we have run succesfully in Getrags when the best possible cold shifting is desired, but it is slightly thinner fluid than recommend for heavily loaded gears.

3000GT synchros should be replaced during any overhaul. Using a standard 90 weight type gear oil can ruin these synchros and the way they absorb fluid and metal particles make them unsuitable for re-use.

Sintered Bronze VR4 or Stealth Synchro

Great Performing 3000GT Synchronizers

These are another OEM synchro, used on all later model 5 and 6 speed transmissions. They can be identified by their steel/dark yellow colored body and seperately applied hard bronze friction surface. They have nearly the frictional performance of the fibrous synchros, but are much longer wearing, and much less sensitive to fluids.

They perform best with Redline MTL, Pennzoil synchronize fluids, or OEM Mitsubishi fluids. They do not like thicker fluids as they have small oil channels.

3000GT sintered synchro’s cold performance may be worse than the fibrous synchros because the fibrous ones have very large oil channels.

Carbon Fiber Lined Synchros – Pro Carbon by Synchrotech

Carbon 3000GT synchros are a relatively new addition to available synchronizers for our Getrag transmissions. Combing many of the best attributes, better frictional coefficent than sintered bronze and much surface area than the other synchro types.

These synchros also prefer thinner fluids, such as Torco MTF or Pennzoil Synchromesh.

Cold performance has been noted to be slightly worse than sintered bronze, but once warmed up these perform very well. Carbon VR4 Synchros have only been around a short period of time, so their lifespan remains to be seen, but Synchrotech has been around for many years and has a great reputation.

One of the most overlooked bearings in these 5 and 6 speed Getrag 440 and Getrag 446 transmissions is the input shaft bearing in the end case. This bearing is opposite of the bellhousing bearing that contains the throwout bearing collar.

This bearing is responsible for supporting the input shaft on the end case side and a failure in this bearing can lead to exacerbating the famous “Getrag Rattle” these transmissions are known to do at idle in neutral and also lead to poor shifting and eventually major damage.

This bearing is somewhat hard to obtain as it is not a typical bearing part number that has many crossovers. We have this bearing available as a kit, including new bolts, on our website.

Bearings in a transmission are not something that should be installed blindly. There are pre-load or endplay settings that must be correct to assure long life, good shifting, and a quiet transmission.

In the following video we will explain what bearing endplay or pre-load is and why its important to set this up correctly. We will walk step by step throughout the process of setting up the bearing endplay and installing your end case input shaft bearing.

We also offer shims for all of the bearing races for these transmissions.

In order to cost effectively offer both a front wheel and all wheel drive option Mitsubishi used a transverse layout for all 3/S cars. With the engine “sideways” in the engine bay this meant that somehow the power from the transmission needed to go back towards the rear end and make a 90 degree turn.

Mitsubishi’s solutions on the 3/S, DSM, and EVO cars are all slightly different, but they all consist of a centrally located transfer case that bolts onto the transmission and receives its power from an “output shaft” coming out of the transmission. 

In the case of the 3000GT VR4 and Dodge Stealth R/T Turbo the output shaft is a dry coupling to the transfer case input spool. As a result unless the shaft and coupler are greased often rust often sets in and slowly both the input coupler on the transfer case and the output shaft from the transfer case will wear away from corrosion and the sawing action that occurs due to the ever loosening fit. Its highly recommend to use anti-size on the splines with re-installing a transfer case or transmission.

We wanted to show some examples of wear. The following is an 18 spline unit that is over 50% worn. The 18 spline shafts are not known for their strength when in new condition and with this wear level it is only a matter of time before the splines completely strip and the vcu can be damaged and the car immobilized. It does no good to rebuild a 3/S transmission and not consider the wear level of the output shaft and the corresponding t-case input spools, so both are carefully inspected as a part of any of our rebuilds. If a customer sends in a trans with a worn output shaft we will request pictures of the t-case spool splines and recommend replacement as necessary. Failure to replace on or the other will rapidly wear both parts from the loose fit.

You can see where the splines are worn nearly away.

The splines are a new unit. Note this is a 25 spline example, but the 18 spline is the same design.

 A 300m new output shaft and center differential.

Transmission Sealant

Getrag used an anaerobic sealant in their 3000GT and Dodge Stealth Transmission builds. An equivalent that can be used today is Permatex 51813.

Many of the transmissions we rebuild here have been rebuilt in the past at least once and its very common to see black, grey, or orange RTV sealant used instead of the anaerobic sealant.

The RTV sealant will seal up the transmission case, but there are some disadvantages. The #1 problem is excess RTV sealant will circulate through the transmission, clogging up synchros, hub/slider splines, and needle bearing oiling holes like the one below.

The oiling groove hole is completely blocked in this transmission. This will lead to the failure of the gear’s needle bearing.

This is the hole unclogged. You can also observe orange RTV on the needle bearing that has migrated from the sealant used on the case.

Anaerobic Sealant Advantage

The biggest advantage to the anaerobic sealant is that it will not cure in the presence of oxygen, so it only hardens in between the metal surfaces. Any excess sealant will be harmlessly carried away on your first trans fluid change, rather than hardening and clogging up the transmission.

VCU Failure

The viscous coupling unit in the 3000GT and Dodge Stealth AWD cars is designed to limit the amount of slip between each axle set. It is a limited slip unit for the center differential. When they get old, or are abused by running with a broken output shaft, or towing with the car not on a flat bed they will leak out all of their viscous fluid. This fluid will often color the entire inside of the transmission black and contaminate everything in the trans. This is why its so important to clean every component and while you should not just replace parts that appear bad when taking the time to disassemble one of these transmissions.

In this picture you can see VCU good was clogging up the sleeve/slider splines.

 This VCU goo came out of the center of a counter shaft and illustrates how a VCU failure necessitates a full rebuild.

Yikes!

They say a picture is worth a thousand words, so we just started with a picture of what can happen when you shift a 6 Speed 3000GT VR4 or AWD Dodge Stealth like you really mean it…

That aluminum piece that is fractured on the edge is the 1st and 2nd gear shift fork. Hard shifting will break the fragile stock cast forks. If you are lucky you will “only” lose 1st and 2nd gear, and if not you may jam the trans in 2 gears at once or have large pieces of aluminum bind up your gears and cause a lot of damage.

Fortunately there is a solution…

When the 3000GT or Dodge Stealth AWD VCU fails it leaks its silicon fluid throughout the transmission and causes a lot of synchronizers, bearings, hubs, sliders, etc to all gum up and cause poor shifting and pre-mature wear.

When this happens to you its important the transmission is completely disassembled, each shaft and gear, and giving a very good cleaning to avoid future problems.

When we have completed our cleaning process each transmission will be as spotless as this one, it is the only way to ensure a quality rebuild and a long lasting transmission. 

That would cause some grinds…

This is an unusual thing to see, but this used OEM Getrag synchronizer has delaminated from its backing. It just highlights how important it is to carefully inspect the ENTIRE transmission and all components and not take things at face value.

It also highlights to be careful using solvents on synchronizers, we never soak any synchros in any type of parts cleaner or brake cleaner.