Authors: TurboGLH
Last modified: 12-21-05
Stage: 95%
Type: How To

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12/21/05
This has been up in it's original form, typo's and all, since july on boostedmopar. So I made a few changes, added some pics and generaly cleaned up. If I missed something, or made a mistake, please let me know so it can be corrected. Thanks.
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THIS IS NOT A STEP BY STEP FOR REBUILDING/BUILDING YOUR TRANS. THIS SIMPLY GOES OVER THE DIFFERENT PARTS REQUIRED AND HELPS IDENTIFY WHAT CORE TRANS YOU WILL NEED AND THE PARTS FROM EACH TRANS!

You will need a FSM and all the tools listed in it.

Lets imagine something......

You're running a moderate to high power L or P body, or a high powered G body or Mini-Van. Now imagine that your running a 555/586 in one of these cars. Do you want better gearing to help keep you from spinning when you launch and give you a better top end? I hope so, cause your in the wrong place otherwise.

Get your core trans together

Ok let's start with the good trans that you'll need, a 555 or 568. There are a few different models over the years.

Type 1 - 87-88 555 Brass Synchro
Type 2 - 89 555 - Two piece steel/plastic Synchro
Type 3 - 90 568 - Same as 89 555 with revised three plane shifter setup
Type 4 - 91 568 - Large input shaft introduced
Type 5 - 92+ 568 - Replaced 3.00 first gear with 3.31

Now you need a 520/523 to go with your good trans, I'll list the type(s) of good trans below and the corresponding donor trans next to them

Type 1 - 87-88 520
Type 2 - 89 520
Type 3 - 90 523
Type 4/5 - 91 523

IMPORTANT 91+ 568's need to use a 91 ONLY 523. After 91 the 523 got a slightly revised gearset that included a more coarse tooth pitch and a 3.77 F/D. The F/D ratio makes this trans useless for this purpose.

IMPORTANT The 89 stick minivans used a 87-88 style 555, so if using one as a core you require a 87-88 520.

Get the parts you need from the donor trans

From your donor 520/523 you require the diff and the mainshaft. Strip the donor mainshaft down and throw the gears in the garbage. However you should keep the synchro assemblies so you can pick and choose the best parts from either trans.



You must use the donor mainshaft with the donor diff, the 555/568 mainshaft has the wrong tooth count/pitch and will not work. So no cutting corners.

If the donor trans was not well maintained for if it was abused the mainshaft can have damage where it rides in the case bearing. Check for chip's for pot marks where the bearing rides, they can be repaired but for the cost it's most likely cheaper to get a new donor.

Parts you will need from your good trans

Strip down you core trans and after putting the case and misc hardware off to the side you'll end up with this...



Strip down the 555/568 gearset and place everything off to the side to be cleaned. Take the bare mainshaft annd diff and put them on the shelf, you never know when you might need them.

Misc. parts and pieces

Case - Either one will work, just pick the better of the two, unless the core is from a TIII, then you have to use the case from the core trans.

Synchro's - When your picking through to find the best parts remember that the 1-2 synchro is different than the 3-4 so you don't try to use two 1-2's or 3-4's.

Nuts, bolts, bearings - You should replace all the bearings, it's just good insurance. The mainshaft case bearing requires a special tool to pull it, so if it looks good and you don't have the means to get it out don't worry too much. Keep the hardware for each trans separate, it can keep you from using the wrong parts in the wrong places.

Now it's as simple as following the rebuild instructions in the FSM.

Wait, I want a LSD

Well you've got a few choices here, you can go with a phantom grip style. Either from T-Nation, alabama man (edit: Not any more) or from phantom grip themselves.

The second choice is to use a quaife from a stick neon. The quaife designed for the T350 is a bolt in deal due to the diff design being the same. Since I originaly wrote this another option has come on the market, OBX posi. It's a cheaper ($400 vs 1200) option to the quaife. I've never used one, installed one or known anyone personly who used one and only a few people have even made a single pass on them, so time will tell.