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Old 05-05-2008, 12:01 AM   #1
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Default Rebuilding a 4T65E-HD - Part 2 reference material

More inspections.

Transmission Range Switch: This is the one that sits on top of the trans case, right where the shifter cable attaches. Took it through all the gear positions and it checked out according to the signal matrix in the FSM; OK.

Transmission Manifold Fluid Pressure Switch:

This funky thing has 6 separate pressure switches. It bolts to the top of the valve body and monitors whether the fluid is actually in the channels the PCM thinks it'* in The FSM has a signal matrix based on what combo of these pressure switches are pressed.

Three of these switches are "normally open." These functioned flawlessly.

The other three are "normally closed." I found these to respond (i.e., open/close) to press/release very slowly. So I pried off their sealing rings and membranes:

I found there was trans fluid behind the membranes. I'm guessing some gunk (clutch mud?) got in between the contacts. Some contact cleaner:

And replace the membranes and these switches are now as fast as the normally open switches. I read somewhere that the Overhaul kit comes with new sealing rings for these pressure switches...I hope so.

So, after cleaning, the manifold switch checks out versus the FSM matrix; OK.


Getting back to the mechanics of the transmission...

Drive Link Stretch Check:

The book says to replace the chains if the clearance between the chains and any the case (along the bottom) is less than 1/8" when the chains are pushed down taut with a fingertip. I measured a hair over 1/4" (and close visual inspection of chains saw no problems) , so I plan to reuse them.

Fourth Clutch Components Removal:

Drive Link Lube Scoop:

This scoop is color-coded and gear specific based on the driven gear'* diameter (33, 35 or 37 teeth). I'll be going from a 33 to a larger-diameter 35 tooth driven gear, so I'll just grind about 1/8" off the lip of this scoop to fit.

4th Clutches:

While the frictions actually look pretty good, these steels show significant "leopard spotting" due to overheating. This is apparently pretty common on factory 4th clutches. I'm told Borg Warner newer-style "OEM quality" 4th clutches put many more of the radial fluid channels in the 4th clutches and help prevent this overheating. All these clutches and steels will come with the Master Kit.

Fourth Clutch Shaft:

The shaft on the right is the 102k mile shaft out of this trans; on the left a hardened 2003+ replacement shaft I got for $30.
Once those teeth on the non-hardened pre-2003 shaft wear down completely, no more 4th gear. This is a must-replace on any pre-2003 4T65E.

Drive Sprocket, Driven Sprocket and Drive Link Removal:

The turbine shaft looks good, and with my anticipated power level I do not see the need for a high-dollar aftermarket upgrade. Sprockets look good, too; but I'm going to replace the 37 drive / 33 driven with 35/35 stockers (like from a GPGT or n/a H-Body) to wind up with 3.29'*. I expect to spend $75 to $100 for these sprockets; and I don't see the need to spend big $$$ on a single-chain "race" setup here.

Speed Sensor Reluctor wheel:

The pins are good and tight. Important thing to check, because if this comes loose off the drive sprocket, it will ruin the chains (and maybe the sprockets and some other things).

Here'* the driven sprocket support assembly:


Driven Sprocket Support / Fourth Clutch Piston Assembly, Second Clutch Assembly, Input and Third Clutch Assembly, and Input / Third Sprag were pretty tightly attached to each other and all came out together. I'll get more pics of these parts as I inspect them, but here'* what it looks like after these are out:

Reverse Band looks good and can be reused:

Reverse Reaction Drum also OK.


After Input and Reaction Carrier, Reaction Sun Gear, Manual 2-1 Band, 1-2 Support Drum and Forward Band removal:

I inspected the Parking Link:

And differential Ring Gear:

Inside the case. They are fine, and I'm not going to bother removing them.

The case 95% cleaned:

Pressure Test Plug and Vent check out OK, as do Forward and Reverse Servos and the Drive Sprocket Bearing:

TC Stator Mount looks good.

TC Oil Seal:

Got the TC oil seal out with a Harbor Freight tool:

Another look at the Differential components now that they are all cleaned up:

This metal clad axle seal needs replacing, and that comes in the Overhaul kit:

Here'* the roll pin that holds in the spider gear pinion:

If that roll pin falls out, then this pinion:

Is free to sling out of the diff carrier and bust your extension housing.

Alternatively, sometimes the spider gears sieze to or wear down the pinion and the gears or pinion itself breaks.

None of these things is good, all are caused or accelerated by rough treatment, and this is why we are all warned not to do one-wheel burnouts

There are aftermarket limited slip differentials (LSD); but from what I've read the clutch-based ones do not have a good track record for longevity, and the true posi-lock GM Torsen diffy costs more than my car is worth.

There are also aftermarket beefed-up output shafts, half axles, etc., but I'm not expecting to need any of that.


Input Sun Gear, Input and Reaction Carrier:

Input Sun Gear checks out OK. Input planetaries are well within play spec as per FSM.

One of the planetaries on the Reaction Carrier has slightly more play than the others, but is still within FSM spec. I'm calling it OK:

If you've ever considered an -HD diffy upgrade, you may have been warned to be careful about a lube dam that the output shaft goes through. It sits between the Input and Reaction Carrier:

This old plastic part was so brittle it literally started to crumble in my hand:

Luckily, I can get a replacement for about $2


Reaction Sun Gear and 1-2 Support Drum:

The Support Drum has a one-way roller bearing inside:

Both parts checked out OK, and the one-way bearing does its job.

Manual 2-1 Band:

The 2-1 manual band is marginal for reuse. For $10 I'll just get a new one.

Forward Band:

The forward band is burnt and must be replaced (About $50)


More parts inspection.

Reverse Drum:

Part is OK.

I picked up this tool to take apart the clutch assemblies:

2nd and Input / 3rd Clutch Assemblies:

2nd Clutches:

These steels have some severe burned spots, and the frictions are pretty worn down. More evidence that the original owner of this tranny liked to punch it. The Master kit will have Borg Warner clutches and new steels.

2nd Clutch Spring and Piston:

The piston has a rubber seal bonded to the bottom and must be replaced; that will come with the Master kit.

Unfortunately, the 2nd clutch springs are very strong, and I bent the heck out of the spring assembly with the tool:

And I wasn't careful with removing the retaining ring, and it curled back in somehow and scratched the crap out of the brass bushing:

I have no means of replacing the bushing, and the spring assembly is fubared. Luckily, the same EBAY guy I bought the harness from had a replacement 2nd clutch assembly for me for $30 shipped:

On the replacement assembly I discovered I can pop the retaining ring off the spring without first compressing the it with the tool, which not only saved the spring but prevented the ring curling and scratching anything. I also discovered I can invert the the old 2nd clutch piston and use it to distribute the force of the tool to depress the new spring assembly without bending it, and have room to push the retaining ring back into place. Nice save

Input / 3rd Clutch Assembly:

3rd Clutches:

The 3rd clutches are different, in that they are steels on one side and frictions on the other (rather than separate steels / frictions).

These 3rd clutches are badly coned:

And even have some "chips" missing from the frictions:

Although some coning from heat is to be expected in the 3rd'*, this kinda proves the original owner was a leadfoot. The missing chips from the 3rd'* are what I believe the "paint chip" looking things in the filter were.

The Master kit will have new Borg Warner 3rd clutches, which I understand are made from a woven graphite material supposed to be much more resilient and fluid-absorbent than the OEM'*.

Input Clutches:

The steels have a few burnt spots, but overall these actually look pretty good. The Master kit will have new BW clutches (more radial fluid channels than OEM) and new steels.

3rd Clutch Spring and Piston:

This spring assembly was considerably less strong than the 2nd spring, and was a piece of cake. Like the 2nd piston, this one has a bonded seal and must be replaced (comes with the Master kit).

Input Clutch Housing, Spring and Piston:

This spring was weak and easy, too.

The input piston is rather worn inside, where the input piston inner lip seal rides:

And this (along with a crappily-designed OEM inner lip seal) is what leads to the infamous "bang start" in these transmissions:

The TransTec brand Overhaul kits include a re-designed "long-lip" inner seal (along with some other fixes) designed to fix this:

I also got a new input piston off EBAY for $10, and it is nice and smooth inside:

Input / 3rd Sprag:

This part checks out functionally in that the gears counter-rotate one direction and lock in the other. According to the book, the retaining ring on the top is not reusable:

And I don't know if the Master kit comes with this retainer. I ordered one from a local dealership for $6 just in case; when that comes in I'll be able to pop this open to inspect its innards.


Driven Sprocket Support, 4th Clutch Spring and Piston:

This spring was really tame. The 4th piston has some scoring inside:

There are no particular warnings about this in the book, nor have I read about this as a problem; but I don't like the looks of it and must find a p/n for a replacement.

The thrust washer behind the driven sprocket assembly:

Looks as if it had a teflon coating of some kind that has mostly worn away. I will be getting a thrust washer kit (about $15) that should replace this and many other thrust washers.


Another look at the Drive and Driven Sprockets:

The 37 / 33 originals at top, the 35 / 35 set I picked up at bottom.

Even though I said I was planning to reuse the Drive Link:

I'm having second thoughts about putting extra power to a 102k mile chain, and will likely order new ones for about $70.

Turbine Shaft looks fine and will be reused:

A look at the 1-2, 2-3 and Manual 2-1 Accumulator parts:

Everything in order there. For those considering a shift kit, that is basically some shims and some stronger replacement springs for the 1-2 and 2-3 accumulator pistons.


All the brass bushings (except the one I messed up and subsequently replaced) look great. All the roller bearings, roller thrust bearings, and selective washers are fine.

I've now inspected everything I can (at least until the sprag retaining ring arrives). I've gone ahead and given this rebuild the green light, and ordered the Master kit (about $175); when that comes I can start reassembling stuff.

For now, everything bagged, tagged, and boxed:

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