(SBF 302) very BAD vibe around 3500RPM's..

Jacob

Jacob

Forum Member
Long story short and im on 3hrs of sleep so please bare with me...This was a MM members car and he fully rebuilt the whole engine..Sold it to another guy and told him about the vibe and the guy never bothered to have it taken care of..Didn't drive it much and pretty much sat in storage...Now that I have it,im trying to fix it with no luck what so ever :( ..Not sure how the engine was put together and im thinking somthing is going on with the crank..Im thinking bent crank or spun bearing but again,thats what im thinking..Never bent a crank or spun a bearing so don't know if either will do this..
When I talked to the MM member that did the build,I think he said the vibe started a little after the rebuild..Not really sure so i'll message him with a link to this thread and hope he will add a little input on this that could help track down the issue..
Anyways,
Anything after 3500RPM will give a BAD vibe through the drive train..When I take off from stop lights or pushing the gas at low RPM to go around someone while driving,I can hear a click,click,click coming from the bell housing area..I thought it was the trans and so did the guy that built it so I replaced EVERYTHING..Flywheel,whole clutch set,throw out bearing,pilot bearing and put another trans in it that is 100% perfect as it was out of my old car..
Got everything done and was happy as hell thinking it was fixed but how wrong was I..When for a test ride and its doing the exact same thing :( ..
Also,
Before changing everything,the rear seal started leaking bad..As soon as I started the engine,it was dripping at idle and the drive was conisitent as in every half sec..Changed the rear seal and it didn't even last a day..Drove around (keeping it under 3000RPM due to the vibe) and after 3 or so hrs,the rear seal is leaking again..Not bad at all and after 3 weeks,oil is still full but I also don't drive it much..Heres a video I took today and just watch how bad my hand vibes on the shifter.... Thanks for any input I can get on this..

 
Mine had a similar vibration then the crank broke at the second main cap. Trashed everything. If I had it to do over I would pull it down and inspect everything.
 
if you can feel it with it just sitting there running Id check to see that the balancer is correct and not spun make sure you have the correct flywheel. Possibly something internal in the engine causing the problem wich would require a tear down and everything balanced.

bad u joints click and vibrate also
 
fastredgmc said:
if you can feel it with it just sitting there running Id check to see that the balancer is correct and not spun make sure you have the correct flywheel. Possibly something internal in the engine causing the problem wich would require a tear down and everything balanced.

bad u joints click and vibrate also
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i would pull the drive shaft to rule this out and see if it does it still just dont over rev it since it wont have a load on the engine.
 
X2.

Sounds like the driveshaft. Mine did the exact same thing after i removed it and didn't mark it.

Sent from my XT907 using Tapatalk 2
 
Super duper dildo lmao.

Guys if hes getting the vibration with the car revving in neutral while not moving its definately nothing to do with the driveshaft.

I'd say toss a stock 50oz balancer on it thats known to be good, just to eliminate that possibility. Other then that, if it still vibrates I'd be pulling the motor and tearing it down. Do you have any sort of build sheet on the motor? Do you know what parts were used?

I had a buddy that bought a car with a "built" motor and it had a hell of a vibration. He thought maybe it was a bad balncer or flex plate. Turns out the hillbilly that built it had 2 different kinds of pistons in the motor.

Also, are you sure that it was built as a 50oz imbalance and not a 28? It seems retarded that someone would build a motor and keep it at the shitty 50oz OEM Imbalance.
 
Flex plate / flywheel correct for application? Dyno tech can also balance a motor while it's in the car if needed (Just have your wallet ready lol)
 
The drive shaft isn't going to do this and flywheel/balancer is 50oz..i'll post more info in a sec,trying to unload the wifes car...
 
Ok,heres the car I bought and the whole build/info is posted in the ad ..I didn't buy it from him,I bought it from the guy he sold it to but when he sold it,the car had the vibe issue so it had the vibe when he built it or had a shop build it..I sent him a message with link to this thread and hope he replys with info that can help a little..
I did go by his house and got some info but not enough..From what he told me,he did a AOD to T5 swap with a Tremec..Thinking the input shaft that gos into the pilot bearing was bad so I swapped it with a worldclass T5 from my old LX 5.0 ..I also replaced the flywheel with a brand new 50oz flywheel along with brand new pressure plate,clutch disk,throw out bearing and pilot bearing and that didn't change anything..Im 10000000% sure the trans I put in it is perfect because it was in my other Mustang that I sold...I do have another 50oz balancer a buddy give me to try but haven't put it on yet,hoping I can get that done tomorrow but I have a bad feeling i'll be taking the engine out..The car hasn't been tuned but everyone I talked to said a tune won't do this..
 
Falcon64 said:
Are you sure the timing is correct? I have mine a tooth off and had a similar issue.
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Im not sure how the cam was installed and thats why I hope KC90GT can add a little info as hes the one that built it..My 5 year old is home from school with a bad cold so not sure if i'll beable to swap the balance today but if I do,i'll post on how it gos..Thanks again for the replys :) ..
 
So this was my car, and you got a hell of a deal on it.. if you want to sell it back to me in a few months for what you paid that would be cool. :) Anyways here's the history on it all before I sold it. I bought the shortblock from another MM member who worked at state motor on Gratiot. It was all redone and supposedly balanced and done right. I bought the heads and cam from another MM member (both used). The distributor, waterpump, intake, exhaust, and rockers I re-used from previous motor. The rest I bought all new, like the oil pump, pushrods, SFI balancer, gaskets, etc. The motor ran like a champ the first couple years, during which I went from auto to T5 and it still ran like a champ. The flywheel, driveshaft, all that stuff is correct, since I just said it ran great with all that up until one day. I was at the dream cruise one year and did a first and second gear burnout and followed it by full dragging it up to 4th gear. After that night is when the vibration first became noticeable. It was very very minor but I could feel a little something. Drove it like that for a while until it slowly got worse. I remembered when I did the T5 swap that I did not put the alignment pins in the flywheel so I thought ok the clutch must have shifted a little on the flywheel and thats what was causing the vibes. So I dropped the trans, put a new flywheel / TO bearing / pilot bearing / new bolts and new alignment pins, also fixed the speedo gear in the trans. I didn't check the input shaft at the time and put everything back together. I was already trying to sell the car but wanted to see if I could fix the vibration. After I put that all back together the vibration was still there but it was a little better then it was before (less shaking). I thought maybe the trans was junk and the input shaft was bent but was done messing with it and just wanted it gone. Right after that I sold the car to the guy that you bought it from.

So anyway, if you swapped the trans and its still doing it, then I would start looking at the motor. I already tried pulling the belt off and running with no accessories but it still had the vibe. I would try swapping the balancer just to be sure and if that doesnt do it then take the oil pan off and check up in there, then go to the rockers, pushrods, valve springs and check there. Worse case is its a spun bearing or something else in the block.

Hope that helps and good luck.
 
look for the weight on the flywheel, look for any signs of moment on the balancer. if both look ok, pull the engine and the pan.

note- If you have a tubular k member, you can mostlikly pull the pan with the engine still inside the car by unbolting the pan and the engine mounts and picking up on it with a cherry picker.
 
KC90GT,
Thanks sooooo much man,that helped a TON and pretty much pin pointed the problem..When I stopped by,we only talked about it for a little bit and we both thought it was the trans..Wish I asked more questions but really didn't wanna bother ya too much about it..I should of ask when the vibe started because for some dumb reason,I thought it started from day one....Im going to look for another crank when I save up some $$ so I can have it ready to drop in when im able to pull the engine..
Yup..Even with it needing a crank,he give it away to me haha..Not going to sale it but if I ever do,i'll message ya first... Thanks again for the info,was super helpfull...
 
nitrouspete said:
look for the weight on the flywheel, look for any signs of moment on the balancer. if both look ok, pull the engine and the pan.

note- If you have a tubular k member, you can mostlikly pull the pan with the engine still inside the car by unbolting the pan and the engine mounts and picking up on it with a cherry picker.
Click to expand...

I looked at the balancer a few times and its perfect and after the info KC90GT posted,its for sure a main bearing at the rear..The vibe is more at the rear and its killed both rear seals,new one I put in lasted almost a day..The clicking at low RPM when I push the gas is the main bearing spinning and hitting the notch the bearing sits in...No tubular K-member so has to come out for sure...Would be nice if I could lift the engine enough to do it...Thanks so much man :) ...
 
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