My bell housing has about an 1 inch diameter piece chipped from the trans input opening. It's right at the bottom edge where the tranny hung up and was then forced in by snugging up with the bolts.. There is no other cracking that I can see. Is it okay to use or should I replace it? I'm trying to upload some pictures but am having issues...Thanks,Jack
-
Jack Ottofaro -
Re: Chipped Bell Housing - is it Okay to Use?
pictures...Jack Ottofaro -
Re: Chipped Bell Housing - is it Okay to Use?
Most bell housings are cheap versus the potential problems My 2 cents worthFounder - Carolinas Chapter NCRSComment
-
Re: Chipped Bell Housing - is it Okay to Use?
Not usable. Replace it.
That large hole locates the transmission and ensures that it is co-axial with the crankshaft. With that piece out of the bottom, the transmission will not be correctly centered. Bad things will happen.
JimComment
-
Re: Chipped Bell Housing - is it Okay to Use?
That small missing piece won't throw it off center at all but I would take it to an aluminum welder and have it repaired.Comment
-
Re: Chipped Bell Housing - is it Okay to Use?
Bell Housings are cheap buy a new one.Comment
-
Re: Chipped Bell Housing - is it Okay to Use?
I think it depends on how rare/expensive a proper bell housing turns out to be. A good aluminum welder should be able to rebuild the horizontal inside reinforcing rib. The whole opening doesn't have to be filled up, but the edges should be smoothed down with a file.
How did it get damaged?
DukeComment
-
Re: Chipped Bell Housing - is it Okay to Use?
Well, it's one of those "against my better judgement..." stories. I've done many clutch jobs and have even replaced the one in this car once before but I've had several issues with this job. On my first try at reassmbly the trans would not go all the way in so I tore it back down and found that the pilot bushing ID was too small so I went to a GM bushing. Second time through assmbly the trans got to within about 1/4" so "against my better judegement" I used the trans bolts to snug it up. Did not take a lot effort so I was not worried about busting the trans ears however there was a pop which I thought was simply the bottom of the trans clearing the bell housing opening. I then had an interferrence noise when I went to turn over the engine. Tore it down again and found that the pop was actually the chunk of bell housing busting off which got hung up and was hitting the presure plate. As it turns out, on closer inspection of the front of the trans the bearing retainer plate used to lock the bolts did not fit correctly and was situated outside of the edge of the bearing retainer and therefore preventing it from being inserted. Long winded answer for "I did a dumb thing".
So Duke, are you saying that some welding to shore up the internal webbing is all that is needed? I did smooth all of it out completely with a dremel tool.
The reason for this entire job was to simply put the original trans back in the car which I have rebuilt. The previous owner replaced it with a later model trans, not sure why, but what I was hoping would be a simple trans swap grew dramatically since the late model trans has a different spline count.Jack OttofaroComment
-
Re: Chipped Bell Housing - is it Okay to Use?
We all make mistakes, but I think this one is recoverable. Based on my engineering intuition of how the bell housing is loaded and stressed, I believe that a good aluminum welder could build up the inside area to restore the section thickness where the damaged part of the internal horizontal reinforcing rib is located, and it doesn't even have to look pretty. He may also be able to weld the broken piece back on.
The key if to find an experienced welder and get his opinion. Bring what's left of the broken piece along. Also, ask him about stress relieving and warpage. I'm not sure about aluminum, but welding steel causes residual stresses due to the high temperature gradients that exist during welding. Welded steel parts can be stress relieved by high temperature baking. So ask the welder about this. If aluminum can be similarly stress relieved after welding, the bake temperature would be much lower than with steel.
Also, before you have any welding done, check the rear face for flatness. Check again after welding/stress relieving, and if there is any warp, have a minimum cut taken across the face - probably no more than .010" - to restore surface flatness.
Since 621 bell housings don't grow on trees, you should make a maximum effort to save yours.
DukeLast edited by Duke W.; December 29, 2013, 11:24 AM.Comment
-
Re: Chipped Bell Housing - is it Okay to Use?
Tom------
Yes there is. I have 2 NOS GM #3899621 bellhousings [none for sale].
By the way, not all GM #3899621 bellhousings have that number cast on them (although mine do). Some have casting number GM #464697. This bellhousing, which has a "dual boss" for the clutch fork ball stud, was machined into either a finished GM #3899621 or a GM #464697. The latter was used in some light trucks. The difference is that for the 3899621 the ball stud boss is machined into the top of the boss and for the 464697 it's machined into the bottom of the boss.
The 464697 casting number is probably correct for later C3's. However, a bell housing with that casting number and the proper ball stud position is 100% functional for any Corvette originally equipped with a bellhousing with a 3899621 casting number.In Appreciation of John HinckleyComment
-
Re: Chipped Bell Housing - is it Okay to Use?
I've got the bell housing being repaired. I've had two welding shops refer to the bell housing as "pot metal" basically saying it's a very poor quality metal mix as opposed to quality aluminum and for that reason welding it is difficult. The one I chose said he could repair it but would not guarentee it down the road so far as cracking again.
JackJack OttofaroComment
-
Re: Chipped Bell Housing - is it Okay to Use?
Jack------
I think those welding shops don't know what they're talking about. The bellhousing is die cast aluminum, not "potmetal". By the way, "potmetal" is zinc diecast.
They should have been able to tell just by the weight. Zinc diecast is heavier than aluminum.In Appreciation of John HinckleyComment
-
Re: Chipped Bell Housing - is it Okay to Use?
I ABSOLUTELY agree with Joe!!!!
Not only should you run away from those welders, but DO NOT ever go near them again!!!
As Joe said, 621 housings are die cast alum, AND, on top of that, they are a pretty good grade of alum alloy.
I cannot count how many alum bell housings I have had weld repairs done to, and ZERO problems. I have a dear friend that is a genius at welding anything, and he has never hesitated to weld, or at least attempt to weld, anything I have taken to him, including bell housings, manifolds, FI parts, etc. He even welded a W30 exhaust manifold for me one time.
By the way, I keep forgetting to ask you if you have the broken chunk? I can't speak for the welders in your area, but my friend could weld the chunk right back in place.Comment
-
Re: Chipped Bell Housing - is it Okay to Use?
To amplify of what Joe and Tom said, "pot metal" is a colloquial term for many zinc-based alloys that usually include among other nonferrous metals, copper, lead, tin, and aluminum. These alloys have a low melting point and flow well so they can be used to make intricate castings, but they have relatively low strength and ductility, so they are not used for parts that have significant loading. Emblems and ornamental hardware are common automotive uses - or at least they were back in the day.
As stated the bell housing is aluminum, and it is a die casting. I don't know what the alloy is, but 356 is a common alloy for sand castings, and I expect it is equally useful for die castings.
I agree that you should consult other welders, and if they say "pot metal" explain to them that the part is die cast aluminum.
I also asked about whether you have the missing chunk and if it can be used in the repair.
If the repair is already done, please post a photo of the repair from inside the housing.
DukeComment
Comment