904 rebuild questions...

[JKCuda]

Getting ready to order some parts to finish my 904 rebuild and accumulator/servo's are on the list. To block or not to block, that is the question?

Keep reading quicker shifts as being the main reason behind this, any negatives? Surprisingly I've had trouble finding a lot of info on this. Not doing anything nuts. Rebuilding with a race overhaul kit from Mancini, B&M shift kit, billet servos/accumulator from CRT, just unsure if I should get the blocker rod or not? Or just re-use the stock spring? Also...the front servo from CRT only comes with the large outer spring. Can I disregard the inner one or should I reuse it with the new servo?

Car will have a built 360 in it, I'm guessing mid-upper 300's for the time being.

 

[Chryco Psycho]

the spring dampens the piston movement for softer shifts , the faster it shifts the less damage / wear to the clutches , I would always make them shift harder .

 

[JKCuda]

the spring dampens the piston movement for softer shifts , the faster it shifts the less damage / wear to the clutches , I would always make them shift harder .

Sounds like I'm going with the rod then... Thanks.

Now just gotta figure out the inner spring situation.

 

[moparroy]

If its a 904 - originally a 318 car? Check your u-joints and get good HD ones and loctite the bolts in the ujoint retainers on the diff yoke.
I put a Transgo kit into a 904 behind a 318 years ago. Shifts were firm - and it was just a 2 bbl 500 cfm. I got real good at changing u-joints - it ate them - suspect they were small ones maybe not the strongest. Also the bolts came loose on me a few times on the yoke.
I actually removed the race shift kit from my 727 also on a 360 in my Cuda. I left a B&M HD set up in it - I don't want my teeth to jar on shifts anymore. Must be getting old - nothing new there.

 

[JKCuda]

If its a 904 - originally a 318 car? Check your u-joints and get good HD ones and loctite the bolts in the ujoint retainers on the diff yoke.
I put a Transgo kit into a 904 behind a 318 years ago. Shifts were firm - and it was just a 2 bbl 500 cfm. I got real good at changing u-joints - it ate them - suspect they were small ones maybe not the strongest. Also the bolts came loose on me a few times on the yoke.
I actually removed the race shift kit from my 727 also on a 360 in my Cuda. I left a B&M HD set up in it - I don't want my teeth to jar on shifts anymore. Must be getting old - nothing new there.

Yeah it's a 318 car. I'll be sure to check the joints, I'm sure they're shot like everything else has been. Honestly I'm so far into this now that it would've probably made more sense to 727 swap it but it is what it is now. I'm just doing the b&m shift kit so it shouldn't be too harsh. Just trying to build it as strong as I can to take the extra power.

 

[moparroy]

It will help the 904 deal with the extra power for sure

 

[JKCuda]

Some other questions if anyone is looking here... Input shaft has some weird patterning on it. Shaft isn't worn or anything, almost looks like the metal is stained or more polished in some kind of pattern. Any concern?

 

[moparroy]

Not 100% sure but if I am right that section rides on a bushing inside the pump - guessing that bushing is toast and if so then yea this shaft is not reusable. If I have the part in mind correctly

 

[JKCuda]

Not 100% sure but if I am right that section rides on a bushing inside the pump - guessing that bushing is toast and if so then yea this shaft is not reusable. If I have the part in mind correctly

Yeah that's the part that rides inside the pump... Replacing the bushings but wasn't sure if this would matter on the shaft. Not what I was hoping to hear haha.

 

[moparroy]

Yea that will chew up a new bushing pretty quickly

 

[JKCuda]

Yea that will chew up a new bushing pretty quickly

Yeah... Was kind of hoping it could slide because 904 input shafts aren't exactly easy to find. I still need to find a decent bushing kit.

 

[JKCuda]

Just out of curiosity since you seem pretty knowledgeable on these... The sun shell has what seems like an awful lot of play between it and the gear. No in and out play but there's side to side play where I can make it clack by turning it back and forth. Normal? Or wear? I haven't been able to find anything in the books...

 

[moparroy]

Well actually have never rebuilt a 904 and I have more experience with FWD 4 spds than even my 727. I did rebuild my 727 a year and a half ago but to be honest that one has not been tested yet . So maybe knowledgeable enough to be dangerous LOL. I did do several successful surgeries on 42LEs.
Play in the planet is a little tougher to answer without feel. I would say some is normal. Suggest you look closely for wear - on the planet, sun and annulus gear. If it helps here is what the front planet on my 727 looked like coming apart. When you say "sun shell" are you referring to the sun gear (middle) or the annulus gear ring (outside "shell")
The only failure I have personally seen on a planet set involved a complete failure of the annulus - it split and separated from its support in a 42LE but even then I did not recall wear on the gears (other than chips broken from the failure).
There is lots of good info on line and good references - videos and supplier docs - that might help more than books. I don't recall seeing anything specifically about planet play but I do believe I came across videos including how to assess wear on the gears.

 

[JKCuda]

Let me see if I can get the wife to take a video for me so I can show you what I mean....it will explain better than me.

 

[moparroy]

This is one of the references I used - its for a 727 but principles apply - his inspection of gears and guts starts around minute 6.

I see around minute 19 he is talking about "sun gear and shell" - though he does not talk about play - I do remember there was movement there - don't remember how much.
Maybe that's what you mean - the drive shell. He does not separate the sun gear from the shell. I wonder if you take the snap ring out if you could then see if there is wear on the shell or the gear

 

[JKCuda]

Sun gear play

youtube.com

There you go. I'll check out that video, I've watched a few but not that one.

 

[JKCuda]

Based on his video he's got about the same amount of play as what I'm seeing. He mentions the holes are for lubrication purposes so makes sense.

 

[moparroy]

Looking at yours that is about what I remember too

 

[JKCuda]

Nice. Appreciate all the help. I do all my own wrenching but this is my first time cracking open a trans so I don't want to miss any stupid details. Hopefully my motor is back from the shop by mid-June and I can get this thing on the road shortly thereafter.