Cracked my 555! Crap! Questions about 555 versus 520

[jonnymopar]

I discovered at 10pm last night that I had a crack in the bellhousing up near where the front engine mount bolts to it. One of the bolts for the front mount had loosened up and I'm guessing the added stress on the other bolt did it in. The location of the crack supports this hypothesis. I have a spare 555 to heave in, so I won't be out of commission because of it, but I've got some questions for the trans guys on here.

1. Is the 555 case just a heat-treated 520 case? Or is it a different part? I don't have a 520 to put side by side to compare.

2. Is the case on a 520 a weak spot? I'm wondering if I find a junk 520 whether I can just throw my 555 internals in and be ok.

3. Has anybody attempted to weld a cracked case on these particular transmissions? Again, it's not cracked all the way through. I can post pictures later. Poking around online, it seems like many people have had good luck welding and reusing cracked bellhousings on all sorts of different units. When I had my extra boss welded in for the 2.4L block ear, the guy that did it commented afterwards on how good the metal was.

Thanks.

[tryingbe]

I'd just weld it and move on.

[supercrackerbox]

I believe the 520 and 555 used the same casting. I have heard mention of the 555 case being treated for strength, but I'm not sure how. FWIW, the bellhousing on the 555 in my Charger was cracked, and I had it welded with no issues.

[5DIGITS]

I discovered at 10pm last night that I had a crack in the bellhousing up near where the front engine mount bolts to it. One of the bolts for the front mount had loosened up and I'm guessing the added stress on the other bolt did it in. The location of the crack supports this hypothesis. I have a spare 555 to heave in, so I won't be out of commission because of it, but I've got some questions for the trans guys on here.

1. Is the 555 case just a heat-treated 520 case? Or is it a different part? I don't have a 520 to put side by side to compare.

2. Is the case on a 520 a weak spot? I'm wondering if I find a junk 520 whether I can just throw my 555 internals in and be ok.

3. Has anybody attempted to weld a cracked case on these particular transmissions? Again, it's not cracked all the way through. I can post pictures later. Poking around online, it seems like many people have had good luck welding and reusing cracked bellhousings on all sorts of different units. When I had my extra boss welded in for the 2.4L block ear, the guy that did it commented afterwards on how good the metal was.

Thanks.

There's no difference in the metallurgical make up of the cases.
What's critical with any welding/repair in this that the interfaces remain true to each other, therefore avoiding stresses after the unit is repaired.
Weld as needed while chamfering the edges to insure the weld has adequate penetration and subsequent grind cleanup can be done to minimize the scars.

[jonnymopar]

Thanks guys. The trans is out. I took my moly end plate and transferred it to my spare 555 (I wish I had time to also transfer over my OBX). Tomorrow, once the RTV is dry, I'll put it back in and off to Carlisle I go! Common sense be damned!

As for the crack, this is the only pic I got so far:



I was afraid that welding in the extra boss for the 2.4L block ear caused the problem, but the crack is actually nowhere near it. It goes right through the lower bolt hole. This is why I think that it cracked because the bolt above it worked itself loose. Basically what you see in the photo is the entire thing. It stops randomly just past what can be seen here, so it's all in one piece still.

Once I get it stripped to the bare case, I'll have my aluminum welding specialist take a look at it. With the thickness in that area, I'm wondering if it's even worth welding it from both sides or just the outside.

[5DIGITS]

Remember, when aluminum is being welded the material is pulled towards the weld and does add metallurgical tension/stress.
Any attempt to elevate the case temp (put it in an oven) prior to welding greatly reduces the localized shock and stresses while increasing the repairs success.

[acannell]

Thanks guys. The trans is out. I took my moly end plate and transferred it to my spare 555 (I wish I had time to also transfer over my OBX). Tomorrow, once the RTV is dry, I'll put it back in and off to Carlisle I go! Common sense be damned!

As for the crack, this is the only pic I got so far:
I was afraid that welding in the extra boss for the 2.4L block ear caused the problem, but the crack is actually nowhere near it. It goes right through the lower bolt hole. This is why I think that it cracked because the bolt above it worked itself loose. Basically what you see in the photo is the entire thing. It stops randomly just past what can be seen here, so it's all in one piece still.

Once I get it stripped to the bare case, I'll have my aluminum welding specialist take a look at it. With the thickness in that area, I'm wondering if it's even worth welding it from both sides or just the outside.

I have an A523 housing thats crack free and pretty much fully stripped, would that work as a replacement housing?

If its a permanent fix your welding specialist might want to go to extra lengths to get the gas mix, preheat, and the zillion other parameters you can adjust with TIG to make the weld go as deep as possible. If its temporary until you get another tranny then I'd just have at it on the outside as a bandaid and hopefully it lasts awhile.

[5DIGITS]

If its a permanent fix your welding specialist might want to go to extra lengths to get the gas mix, preheat, and the zillion other parameters you can adjust with TIG to make the weld go as deep as possible. If its temporary until you get another tranny then I'd just have at it on the outside as a bandaid and hopefully it lasts awhile.

The welding isn't a big issue, if the welder is experienced.
Many of the prototype drive-lines I've dealt with including the early 568's bolted to 2.4L's all had the entire bell housing ring welded in place.

[going4speed]

Little Helium in the gas mix and a good clean prep with chamfered edges works great on Aluminum. That crack looks pretty major in that picture. Does it go into the boss hole? That could be a crack initiation point from an over torque or a lose fastener.

[jonnymopar]

I have an A523 housing thats crack free and pretty much fully stripped, would that work as a replacement housing?

I don't think it will work. Too bad because I believe only the 89 555 gear set will drop in there, essentially making it a 568. The cracked unit I have is an 87.

That crack looks pretty major in that picture. Does it go into the boss hole? That could be a crack initiation point from an over torque or a lose fastener.

It is pretty major. I'm honestly surprised with the length of it that it's still attached. And yes, it starts at the lower boss. Either I gorilla'd the bottom bolt, or it's because the bolt above it loosened up... or both. Who knows at this point. All I know is after a very long couple of nights, the spare trans is in, with chrome moly plate installed, and I'm in Carlisle right now! More pics when I get home.

[acannell]

okay looks like my tranny is 4446238, with case p/n 4431868

an 87 555 looks like it is 4446015? (service p/n, different than the one on the tag I think)

with case p/n 4348104 (sad trombone sound)

I wonder what the differences actually are

[jonnymopar]

I'm not sure, but I know the 87-88 gearset is slightly different than the 89. I'm almost sure that the 89 555 has almost exactly the same internals as a 90 568. Just different case and different shift selector housing.

If I'm wrong and my guts will fit that 523 case, that would be SWEET. Hello home-brewed small-spline 568!

[135sohc]

The 1988 and earlier units use a single larger brass cone synchronizer assembly on the 1-2. The splined area of the pinion shaft where the synchronizer hub is a fine splined configuration. The 1989 and later with the 3 piece synchronizer ring 1-2 uses a very different spline configuration on the pinion shaft. There much larger and fewer of them to allow the inner most of the 3 piece synchronizer ring setup to 'key' onto the pinion shaft while still allowing it to have some rotation capability to (I think, this is my theory, not an official quote) aide in the smoother shifting that the 3 piece synchronizer allows for.

Cliff notes version: The speed gears need to match the synchronizer hub and sliding ring/collar, the sliding ring/collar and hub need to match each other and the hub splines need to match the splines on the pinion shaft.

Not taking into account the shifting forks and their respective pads need to match the width of the respective sliding ring/collar. The 3-4 fork and pad width is the same width for nearly everything AFAIK, regardless of the unit. The 1-2 and 5th are different.

[acannell]

The 1988 and earlier units use a single larger brass cone synchronizer assembly on the 1-2. The splined area of the pinion shaft where the synchronizer hub is a fine splined configuration. The 1989 and later with the 3 piece synchronizer ring 1-2 uses a very different spline configuration on the pinion shaft. There much larger and fewer of them to allow the inner most of the 3 piece synchronizer ring setup to 'key' onto the pinion shaft while still allowing it to have some rotation capability to (I think, this is my theory, not an official quote) aide in the smoother shifting that the 3 piece synchronizer allows for.

Cliff notes version: The speed gears need to match the synchronizer hub and sliding ring/collar, the sliding ring/collar and hub need to match each other and the hub splines need to match the splines on the pinion shaft.

Not taking into account the shifting forks and their respective pads need to match the width of the respective sliding ring/collar. The 3-4 fork and pad width is the same width for nearly everything AFAIK, regardless of the unit. The 1-2 and 5th are different.

How on earth do you know all this??

So it sounds like you are talking about the guts matching the guts, but what about the guts matching the case? Can he swap his 87 555 guts into a 90 523 case and make a small spline 568 lol

How does one go about figuring this out....I suppose it would be easy to prove you couldnt but proving you can might be trickier. I.e. if its obvious that the 555 guts need a bearing cone or something of a certain size and the 523 case doesnt have it then thats pretty clear its a fail.

Jonnymopar, swapping your guts into a 523 case wouldnt really increase the performance/strength of anything would it? The guts would still be the same as they were in the cracked 555 right? Or is the case itself a major upgrade?

[acannell]

okay heres the 87 fiche vs the 90 fiche...

theres a second page as well but im lazy so if this page looks like the guts might be swappable then Ill do the second one too

[135sohc]

To drop a complete 555 gear set/pinion shaft into a 523 case:

The front of the pinion shaft would need the external pressed on race

The 1-2 shift fork and pad on the 523 is wider than the 555 shift fork/pad. It may be possible to lathe out the channel on the 555 sliding collar to accommodate the wider fork and pad, IDK for sure.

The 3-4 is not an issue.

The 5th synchronizer on the 555 uses the same narrow pad as the 3-4. The 523 5th uses the same wider pads as the 523 1-2. That is an easy work around though as the splines on the pinion shaft for 5th are the same size for everything and 5th uses the same brass ring for everything. Just pop the lock ring off and swap parts.

[acannell]

To drop a complete 555 gear set/pinion shaft into a 523 case:

The front of the pinion shaft would need the external pressed on race

The 1-2 shift fork and pad on the 523 is wider than the 555 shift fork/pad. It may be possible to lathe out the channel on the 555 sliding collar to accommodate the wider fork and pad, IDK for sure.

The 3-4 is not an issue.

The 5th synchronizer on the 555 uses the same narrow pad as the 3-4. The 523 5th uses the same wider pads as the 523 1-2. That is an easy work around though as the splines on the pinion shaft for 5th are the same size for everything and 5th uses the same brass ring for everything. Just pop the lock ring off and swap parts.

this might be a dumb question, but wouldnt he be swapping in the shift forks, pads, i.e. everything from his 555 as well? so then the only thing to do would be the external pressed on race onto the 555 pinion shaft?

[135sohc]

The 523 and 555 shifting mechanism/rails/forks ect are entirely different from each other.

The selector shaft seal and the adjusting rig pin are probably the only two things that are shared in common.

[acannell]

The 523 and 555 shifting mechanism/rails/forks ect are entirely different from each other.

The selector shaft seal and the adjusting rig pin are probably the only two things that are shared in common.

ahh okay...so in that case, hed need all the 523 shifting guts as well. jonnymopar just an FYI I sold all the guts to ondonti, all I have left are the housings and diff

[5DIGITS]

The 523 and 555 shifting mechanism/rails/forks ect are entirely different from each other.
The selector shaft seal and the adjusting rig pin are probably the only two things that are shared in common.

For this and many other reasons listed, it's wise and far less complicated when parts are exchanged within the same transmission family (555/520, 568/523, ....).
What is also different between the two hardware architectures are the speed rings.
I am not sure if the travel requirement of each while considering the change in shift systems will realize any complications.