i cant figure out why, but two times already the bellhousing on my tuck has cracked. its a 700r4. the only thing i can thiink of is that the motor mounts arent very soft, and the tranny mount is rubbermounted, would that let it tweak to much? anyone have any ideas?
i had a 65 chevelle and broke 3 th350 at the track and the problem was bodymounts where warn out and missing so every time i lanched the frame would flex enough to brake my trans swapped out the body mounts and ran 11's all day long
What motor mount setup are you running? I assume that it is in a 64 GM pickup from your screen name and the reference to your "tuck" but is that the vehicle it is in? <input id="gwProxy" type="hidden"><!--Session data--><input onclick="jsCall();" id="jsProxy" type="hidden">
There has to be something twisting the trans or the engine till it puts too much pressure on the bell housing till it gives way . It has to be the engine mounts or the trans mounts . Also check your cross member and make sure its tight . Also check the trans bolts to the engine block to make sure they are also tight . Imagine the engine and trans as a straight board . If it twists too much or gives way either up or down at the bell housing it will break . So you need to check all those points .
its a 64 chevy truck, the truck is bagged its got a porterbuilt dropmember. the motormounts came with the crossmember setup. the truck lays frame, but that shouldnt be the problem i dont think the frame is twisting or has enough strain on it to crack the bellhousing, but then again im not sure thats why i posted this haha
How far forward are your motor mounts? 57 Chevys used to have a mount at the bell housing to prevent just that. It was too far from the front engine mounts that were off the front of the block to the trany mount and developed too much weight pressure on the bell housing area. Just a thought but more info or pictures would help.
the crossmember i got for the truck brought everything forward like an inch or so, but it came with a new tranny crossmember so everythings in the right spot, the motormounts are pretty hard i dont know if that has somethin to do with it
without seeing it we can't answer the question. We are a transmission shop in business for 18 years, we have seen this happen but its NOT always for the same reason. If you are still running the front engine mount and a transmission mount, thats why its breaking, the engine will have to be changed over to side mounts.
yes that is the crossmember i have, side motormounts. and no, the tranny doesnt touch the bottom of the cab at all, i had to cut out the floor and raise it otherwise it would have
three things to look at ,if all three mounts are hard plastic or just rigid then remove the trans mount and go rubber .the other option is a soft right engine mount ,its never good to have three solid mounts unless you add a mid mount . also check pinion angle along with drive shaft being to long and bottoming out against the tail shaft .or maybe ya just messed every thing up and need to look every thing over for human error .good luck .c
Without pictures or a solid description of the cracking we are all just guessing. Cracks are caused by stress, so something is going on. Maybe the bolts are a bit too long and bottoming out in the block before tightening the trans. Bellhousing on the trans is irregular, back of the block maybe.
Here's another crazy dumb question , are the 2 mounting studs still on the engine block that the trans goes on to . If these are missing the trans will shift and put all the torque on the trans bolts . Just tring to cover the dumb things . BTW the pictures didn't work !
Like was said before, check your driveline angles. If you've been getting a vibration while driving, I bet it is due to some misalignment and the vibrations are causing the cracks.
thats it i had a body dropped v8 s10 did the same thing fixed pionon angle never happened again im 99% its ur drive sharf angle or bind thats the problem
Yes! i do get a vibration while driving, i bet it is a misaligned driveshaft angle. i drove the truck up to santa maria for the cruzn nationals and i it was doing that. that would be my best bet
im gonna get the truck up a rack and take a look, i bet thats what the problem is, thanks for the help guys its been very expensive and a massive headache dealing with it! Thanks Again!!
My brothers truck did the same thing when he bought it, Turns out the whole thing was put together by someone on a bent up frame. When he would gas it hard and all that torque would kick in and things would start to move and tweak and the bellhousing would crack. That was a kind of expensive one to figure out.
Highschool Auto Shop... if you look at a ujoint between 2 straight shafts there is no difference in the radius measured from the shaft center followed by each cap opposed to each other on the same joint. The ujoint center is aligned with the shaft center. If you put the turning driveshaft into an angle something changes. The orbits of the caps around the center of the driveshaft swing from a larger outer radius to a tighter inner radius. The primary shaft with a steady rpm turns the secondary shaft from different radii and the resulting physics is that although the primary shaft has a steady rpm, the secondary shaft speeds up then slows down it's rotation in a 180 degree interval because of the change in geometry. U-joints are clocked on the shaft so that the changes in geometry counter each other. If the drive-line angle of the first ujoint is equal and opposite of the second ujoint then the mid shaft will speed up and slow down in an invisible ocillation that does no harm. If the angles are not equal and opposite they will fight each other and the oscillation of the midshaft will be forced upon either the transmission or the rearend. The greater the angle, the greater the amount of oscillation in the center shaft but as long as you have your angles equal and opposite then there are no damaging forces reaching the tranny or rearend. The driveshaft centerline can drop down or go up t the rear. it can even go off vehicle center like if your rear's pinion is not centered and the engine is (or vice versa, like in a van). Whatever angle from plumb your front yoke is set at (by how your engine and tranny is installed in the chassis) needs to be the same angle for your rear yoke and everything in between if you run a carrier bearing should be in a straight line
ya the rack ive got is the kind you drive onto, the trucks too damn low to get under and check it on the ground haha.
Some GM trannys use a strut rods between the block and the bell housing. It's bolted at an angle either to a bracket on the engine, or to the motor mounts, and goes downward to where it attaches. Perhaps fabricating something similar might take some ot the stress off of the bell housing? Also you mentioned dowl pins. If you don't have them in the block things won't center properly, and that may also cause cracking at the weakest point. Is the crack always in the same place?
Had a customer a few years back who had craked the bellhousings on 3 t-350s behind a stock 400ci sbc before he brought it to us. It had a small viberation so we trought it was a drive shaft issue but the drive shaft check out. Looking harder for the cause of the viberation we had the balance of the flywheel checked and it was also ok. We then had the converter check out and it was out of balance. Changed the converter and it has not craked any more trannys.
I say check the dowel pins in the block(already mentioned) and see if the are engaged in the trans.case. the often times get pushed back in the block especially during machine operations.Had the same problem using mid plates until we started using longer pins.
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