Engine Pans- vibration source?

Barry in St.Paul

Barry in St.Paul

Senior Member
after recently pulling my engine and having the crank rebuilt (counterweights) and everything re-balanced, etc... I am extremely sensitive to vibration in my car these days. (just got the engine back in and running last weekend; definite improvement, thank goodness!). One thing I noticed this week is that the re-installation of the engine-pans seems to make a negative impact on vibration. Never thought about it before, but doesn't this make sense? We worry about how loose or tight that little bolt is on the front engine mount, but yet we then clamp the engine to the frame with three bolts on each side of these stiff engine pans!!?? I drove the car the first few times (last week, after re-installation of engine) without the pans installed while I was confirming everything was "good" and not leaking, etc.. I was very pleased with the improved vibration. Then I put the engine pans back on, and it seems to me that vibration is worse. Again, I'm so anal about vibration right now that I almost feel vibration when the engine is off :o but wonder if any of you have noticed a difference in vibration (or noise) with engine pans on vs off?
 
You shouldn't notice any difference as those pans are pretty thin and flexible compared to the mass of the engine block. Drive it awhile, it should smooth out after break in. The four cylinder will always have a little vibration. I wish mine was as smooth as my P.T. Cruiser but the P.T. has a balance shaft in it so it will never be.
 
thanks for the replies. They sure seemed "stiff" and capable of transmitting vibratinon when I was laying on back trying to push the pan over to line up with the frame holes :-)
 
The pans aren't touching the cross-member are they ?? Mine were and it appeared that they made an irritating vibration..
 
Patrick, no, they are not touching the cross-member. I have a finger-thickness clearance in the front (i remember, 'cause I could just get my fingers thru to hold the wrench on top-side! :-) Clem, my pans are very tight, and that is what concerns me, but if the bolts are NOT tight, they'll come loose/fall off! I had to pull hard on the side of the pan to get the holes to line up on the frame, so the entire pan is basically a "spring" exerting 'outward' pressure against frame and block. Significant enough to transmit noticable vibrations? Maybe I'm being overly-sensitive, but considering how quick people are to jump on the front motor mount being a couple of turns too tight, I'm surprised this isn't also considered a culprit for vibration. Hopefully it does 'loosen up' and/or take a set; I very much like the idea of having engine pans installed !! :-)
 
I installed rubber grommets sized to the pan holes that fasten to the frame. Hole modification was not necessary. The bolts were installed with self locking nuts to allow only slight tightening to avoid squeezing the grommets much and not loosen up. I believe this helped reduce the vibration/noise transmission to the frame a little. It could be the placebo effect - if you think it helps , it does.
 
good idea Bob. I'll consider that. How thick were the grommets? I'm picturing little O-rings with the ID equal to the bolt-hole diameter.....??
 
I can't tell that there is any vib in my pans. There was something in the service bulletins about the front of the right hand pan touching the cross member. Bill
 
I'm just curious, Does anybody have a model A without any vibrations? I have nobody around here that I can jump in their car and compare it to my two. I've been asked many questions at car meets about rear view mirrors shaking and tail pipes rattling, windshields vibrating etc. I just tell them it's equal to my old Harley Davidson's.:)
 
I have an H&H insert engine with counter balanced crank and have some vibration. It is worse at about 40mph and I can't see out of my rear view mirror. At slower and faster speeds there is less vibration. I was wondering if I didn't get my flywheel aligned close enough would there be just one rpm that makes it worse?
 
Bob, that was my question exactly, when I first 'finished' the body work and was calling my restoration 'complete' in January. Seemed too much vibration, but it had been 10 years since my garage blew down on it and I couldn't REALLY remember if it had been better then, or even if it HAD, was it because my body and sheet metal was so loose back then? (all body panels and seams are much tighter in all regards during this re-restoration!) The key for me was having two guys from the local Model-A club, and my Dad (who has a '29 roadster) drive it. All three immediately said "there is too much vibration! Something is wrong!!" Now, with a lot of fine-tuning of flywheel and crankshaft (straightened crank a bit, added counterweights, re-balanced flywheel and pressure plate WITH the crank.. and a little more attention to squaring up the flywheel housing) there is a noticeable improvement. But, obviously STILL a four-banger Model-A and still vibrates. :-) But my headlights are no longer vibrating to the point it looks like they'll fall off, like they did a month ago! Per my original post at the beginning of this thread, as I am so keenly sensitive to the vibration aspect now, post-rebalancing, it sure seemed that adding those engine-pans increased the 'noise' level while driving. I really want to drive a few other Model-As now and compare!! :) My dad's '29 roadster is just 'too different', being open-bodied like that. And, his has always been an un-usually smooth engine, by all accounts, so a high-standard even there.
 
I have a quick question concerning engine pans. Can they be installed on a '28 Roadster without pulling any other components? I tried fitting mine the other night and it seemed as if I'd have to beat them into place to get them to fit into the space they needed to be.....over the steering and brakes, in front of the bell housing, under the steering column etc.....thanks!
Dave
 
From just re-installing mine last week, all I had to do was slip them up from the bottom, laying on the floor under the car. I recall moving it carefully in and up, to avoid scratching the oil pan or steering unit, but didn't have to maneuever TOO much to get them in the right spot. First thing I did was to place all six of the little frame bolts in from the top, so they stuck down through the frame before I got under the car. Then from under the car, I loosened the four oil-pan bolts almost all the way, to make it easy to slip the engine-pan tabs inbetween. Then, I simply slipped the engine-side of the pan into place (under the oil pan bolts), and with some effort, pulled the frame-side of the pans in to get the frame bolts to fall into the holes. (the amount of force it took to 'compress' the pan to do this was my first thought about 'how can these buggers NOT transmit engine vibration to the rest of the car??") With the force of the pans against the little bolts, I could then thread the square nuts on and tighten things up. You can barely get an arm up and over the pan (from back side) to hold a wrench for the back two bolts, and just get your fingers up between pan and front-crossmember to hold a wrench for the front bolt. So, a little bit of a pain, but no 'clearance' issues with actually putting them in, at least on my 30 coupe, and don't see why a 28 would be any different....
 
Barry - I cannot recall the size of the grommets which look like smaller versions of the grommet for the speedometer cable hole in the firewall. I purchased them at a local hardware store.
 
I had some vibration with mine so I mounted them with fibre tap (You would say faucet) washers between the frame and pans No vibration now .Karl
 
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