I have a 79 GMC 3/4 ton and the bell housing is cracked. It is on a granny 4 speed attached to a 350. Does anyone know of what bell housings are compatable off of other cars I could use?
This is an aluminum bellhousing, some steel ones may work, but best to get another aluminum one. Try truck junkyards or eBay, 100% chance of finding one there.
Car-part.com calls for the bellhousing from 1999 down to be on the interchange for that 1979 truck. I found 9 pages of bellhousings for sale at 125 or less depending on the seller..
Car-part.com is a great resource if looking for stock replacement parts I have found..
Fail because '86 was hydraulic clutch release, with an external slave cylinder, '85-back was mechanical instead. No SM465s after '91, the NV4500 bellhousings are different and in high demand, and those changed in the mid-'90s to an internal slave cylinder. So from '79-'99 there ar 4 different bellhousings just in the fullsize pickup trucks. Plus the early-'80s had the NP A833, that bell won't work, then the Getrag, that bell was integral, then the NV3500, also integral.
Any bell housing from any sm465/420 equipped truck will work with a stock clutch. The sm465 has the larger hole. But I have had numerous sm420 bell housings "opened up" to allow for a sm465 to fit.
I have a collection of aluminum bells. I keep a open ear and tend to get them along with used good running sm465's picked up for under $100.
Here is one of my "car" sm420 cast bell housings. It is becoming "rare" so I keep it on a shelf.
Here is a hydraulic clutch bell. You can adapt any older bell to this setup with a google search on how to do it.
Short version is that I don't like to run the aluminum bells as they do crack easily. 450ft/lbs or so and dumping the clutch will do just as you have described. Longer version is that a cast bell gives you a bit of protection against a flywheel exploding. Your best bet is to get a steel bell housing. Buy it once and don't worry about it again.
You can get a used (sfi expired) 1/8 thick Lakewood bell for under $400 that will not only be a direct bolt in. It will never crack and protect you from the event of a flywheel coming through your leg. One thing that I found out is that some starter cones hit the inside of the bell housing. A mini starter is the fix.
When opening the bell up you need to be careful that the machinist takes note of the lip of the ball pivot mount. Never had them hurt there machines but it seems like it is possible.
Here is my 2006 lake wood bell set up for 4 speeds that I had "opened up". The sm465 fits snug inside.
I can not seem to find better pictures of the face. But the pivot ball should be left in place to avoid the mill from nicking on the edge of the ball mount when removing the material. My local shop takes a few days and $50-70 depending on who is working to open up any bells I feel like dropping off.
Here is almost the same as what I bought. Found in under 3 minutes searching "Lakewood" and clicking "used".
Lakewood Steel Scatter Shield Bellhousing Chevy 11" Clutch Explosions Proof SFI | eBay
I got mine with the block protector for $300 to my door and would hold out for one with a block protector. The one above(and many that you will find) will need to be opened up. Keep a eye out in your local race parts swap meet, craigslist, forums, or ebay and you will find better deals then in the link above. It is just a example how easy finding a used Lakewood can be.
Alignment is important. Use a dial indicatior and get within 5. If more use adjustable pins to get to within 5 of true.
They break because you have a 700 piece of steel in front of them and a 250 piece of steel behind them both pushing down on the bell. When that 700 piece rotates the 400 to 700 ft lbs the two front rubber mounts flex while the one mount on the transmission does not flex as much. The weak link to all this twisting is the aluminum bell and the hole at the clutch fork. If you have a married transfer case that adds to the stress. Maintain good mounts and torque under 400 lbs and a aluminum bell will last a long time.
You can start to crack them with less then 400 with stuff that will break u joints like clutch drops, rockfords, heavy downshifting/engine breaking, or driving in situations that will flex the frame.
This is a '55-57 Chevy bell. I thought it was a truck bell until I ran the numbers. I had it in a few cars and am using it again, this time with a Muncie M20.
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