The Stovebolt Site Forums The Shop Area Driveline 3.55 R&P adjustment - opinions, please

GRNHydra is near the end of a R&P conversion in a 1954 3100.

He would like opinions regarding his backlash setting/adjustment.
It looks good to me, but I have only done this twice.

Photo 1
Photo 2
Photo 3
Photo 4
Photo 5

Thanks, in advance, for posting opinions/suggestion.

Was the contact pattern run with a little resistance held onto the pinion flange? I usually grab the pinion flange tightly with a welding glove, and turn the ring gear back and forth vigorously with a box end wrench on one of the attaching bolts. It gives a much more distinct contact patch to evaluate.

That pattern looks pretty good, but it's easier to read with a little more load on the gears.
Jerry

Yes, wearing a heavy leather glove on my left hand I put as much load as possible on the ring while my wife turned the yoke end. I for sure can put more pressure on the ring with a buddy turning the yoke. As soon as I can get him over to the house I'll try again. Appreciate the input.
Jim

Tim,

This shows how to interpret various contact patterns and make adjustments to correct them, if necessary:

http://www.differentials.com/technical-help-2/installation-instructions/

If you run out of the coloring agent I've used artists oil paint successfully. My favorite color for doing that job is titanium white.

Backlash is per the gear manufacturer's specifications.

Thanks, Jerry
Thanks, Ray

Thank you Ray.

The classic contact pattern indicator is white lead (lead carbonate) and linseed oil. I've got a lifetime supply of it in a 5-lb. can of Dutch Boy white lead pigment I bought on Ebay a couple of years ago. It's dried up, but grinding a little of it at a time back into a powder with a mortar and pestle and adding a few drops of linseed makes it usable again.

If you're a tree hugger and you go into heart palpitations and froth at the mouth at the mention of "lead" anything, try Prussian Blue as an indicator.
Jerry

My classic contact indicator is prussian blue (I used this before I became a tree hugger in the late 60s) - readily available in little tubes in most auto parts stores.

Permatex 80038 Prussian Blue

It looks a little to deep to me. Try moving the ring gear away from the pinion & try again. What is the backlash?

The backlash is at .008. The original 3.90 R&P had a .015 pinion shim. I used a .018 pinion shim on the new 3.55 R&P.

Update: When I removed the carrier to try the .015 pinion shim I noticed I had not seated the differential carrier bearings down to the carrier shoulder stops. After seating them properly I tried the .015 pinion shim and the gear pattern was way too high on the ring gear. I removed the .015 shim and replaced the .018 shim, set the backlash at .008 and the pattern was perfect. Per Patrick's 3.55 swap instructions I let the truck idle in high gear on jack stands for 15 minutes and then drove tthree 5-10 mile runs with cool downs in between. The truck drove great.
I do have a constant ATF leak between the lower transmission extension housing, seat, shims, 6 bolt collar area. I removed and checked the O-ring on the seat and it was properly seated, along with the thin paper shim on the collar. Re-torqued to specs and it still leaks. I'm probably going to remove again and apply Permatex "The Right Stuff" and reseal. I've always had a small leak in that area and noticed when I first disassembled that area it was loaded with silicone. Thanks everyone for your input and suggestions.

GRNHydra,


Just a FYI, I've seen some photos where the Hydra-Matic transmission's tail housing oil return hole was plugged with chunks of silicone. Not good.
Inside the tail housing, excess silicone at the ball housing seat connection must of broke off and found its way to the return hole.
If you use Permatex it should be used sparingly at the ball housing seat connection.
I have a drip in the same place.
Might be something to ask why to John at http://nwtparts.com/
He might have a little insight as to why the 4 3/8" Inside diameter rubber seal O-ring isn't sealing.

Read the last sentence in this POST under the photo that has the bolt with a nail in it.
Early Power Glide transmissions lubricated the u-joint and torque tube bushings the same way as the 54 Chevrolet 1/2 ton Hydra-Matic transmission does.
Power Glide Transmission -Rear Pump Section
It could be leaking on the shim side of the ball seat but don't think so.

Jorb,

Thanks for that info. I was thinking about Permatex getting into the trans also. The reason I was going to use Permatex is because a local transmission mechanic who works on Hydra-matics/Powerglides and torque tubes advised me the area has always been an issue as far as leaks. He uses "The Right Stuff" and has had good results, both on the seat to extension housing side and the shim side. I have made a thin paper gasket I was thinking of using between the seat and the extension housing to eliminate the Permatex issue and hopefully end the ATF drip.
I'll let you know what route I take.

On my backup Hydra-Matic transmission, someone used a spare shim between the ball seat and the extension/tail housing.
They first put the rubber O-ring in the groove, then put in a spare shim, then the ball seat.
Didn't see any adhesive and can't tell you if it worked because the transmission was out of the truck when I picked it up.

The outline of the ball seat matches the outline of the powerglide rear tail.
The outline of the extension/tail housing of the Hydra-Matic is slightly different than the outline of the ball seat.
They use the same ball seat on both the powerglide and the Hydra-Matic.
Between two of the six holes on the ball seat there is extra steel.
You can place the extra steel facing up or down on the Hydra-Matic extension/tail housing.
The ball seat will only lineup oneway on the powerglide.

Logic dictates when placing the ball seat onto the Hydra-Matic extension/tail housing. .
Place the extra steel towards the bottom side of the extension/tail housing, which may impede oil from leaking.

Another thing a person could do is slightly bend the ball seat bolt hole tabs away from the extension/tail housing.
When you tighten the bolts, the tabs will flatten out, and the inner portion of the ball seat will apply more pressure onto the rubber O-ring.
Which may create a leak free seal.

I tried the ball seat with the extra steel part up, as shown in the Truck Factory Assembly Manual, and it leaked. Tried it with the extra steel part down and it leaked just the same. I have an extra ball seat and actually made a gasket to fit the ball seat with extra steel section to put between the seat and extension housing. Will try it this weekend. At this point I could probably live with a drip once in awhile. Everything you keep sending me is great info.