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Engine Vibration after Manual Swap

T

TheLoganZilla

Member
Joined
Oct 5, 2020
Location
Morris County, NJ
Hi everyone,

I just finally completed my CD009 Transmission swap -- or at least completed to a driveable level. Everything feels pretty good except for the fact that the car has developed a very noticeable vibration at certain RPMs. It can be strong enough to make the seats shake. I notice it especially in middle gears, but I have a feeling that may be due to increased load due to acceleration. Below 2300 rpm it feels normal, then from 2400 up it seems to get progressively worse. I do not think it is the driveshaft because at any speed if I clutch in or put it in neutral and let off the gas, the vibrations go back to normal levels. I am worried that it may be the flywheel or harmonic balancer, but any other ideas are welcome.

Thank you,
Logan
 
Motor mounts still appear to be good. Nominal amount of engine movement under acceleration. I used a polyurethane bushing between the transmission and the crossmember. That may be contributing to the vibration as I have never used a poly bushing before and may just be experiencing normal vibration. I did discover a loose plug wire that did appear to correct some of the feeling, and I believe that the transmission I bought may actually have a worn input shaft bearing, as it is noisy even in neutral with the clutch out. Hopefully what I?m feeling is just normal for a stiffer bushing setup; any other ideas?
 
TheLoganZilla said:
Hopefully what I?m feeling is just normal for a stiffer bushing setup;
Click to expand...

Ah yes, the dream scenario. Good luck with that. :nod:

I can't think of any reason for vibration that doesn't involve either balance (offset weights rotating) or alignment (U-joint angles.) You've eliminated the latter, by coasting in neutral and watching vibration disappear. Since it vibrates when you rev it up, car not moving, that points to engine... but presumably you didn't change anything there, and presumably the engine wasn't vibrating prior.

So... clutch pressure plate out of balance? Missing a bolt?
 
Stiff transmission mounts transfer a lot of vibration into the car, for sure. If you had an automatic transmission before, they dampen engine vibration more than a manual transmission as well.
 
Seems par for the course. B230s are naturally buzzy. Volvo’s solution on later cars was a combination of soft mounts, a heavy tuned mass damper for a crank pulley, and an even heavier flywheel.

You take those elements away and the result is quite the connected feeling.

On the other hand, we can’t get a feel for how severe the vibration is without firsthand experience. It could be either mild for redblock standards or bad enough to make interior pieces fall off.
 
What is your driveshaft situation? Is it straight, balanced, no funky angles at u-joints?

Transmission centered in the chassis with a good x-member?

Maybe it is just the poly and some bad motor mounts? Can you get a "stock" rubber transmission mount to swap in and test?
 
I had a mystery engine vibration recently. Turned out #2 spark pug wire was about 1/4 inch off of the plug.
Dave
 
Hi everyone, sorry for the delayed response, I’ve been driving across the country to move into university. I like the idea of the rubber mount, a couple other mechanically minded friends of mine have suggested the same, so I’ll be looking for one in the same style as the poly mount I’ve used. Unfortunately, as a result of not exactly knowing what was causing the noises and vibration, and also a bad experience with the shifter I bought from Autosports engineering, I decided that driving the car 2000 miles wasn’t a good idea. So I won’t be able to test any of these good suggestions until winter time. I am proud of myself for finishing the swap in a drivable way in under 2 months, but it was inevitable that there would be a couple small issues I’d need to solve but wouldn’t have time. I’ll update this post or make another one as soon as I’m able to work on the car again, and as I said before, any other ideas are always appreciated. Also, would people here appreciate a review of the shifter I purchased? I haven’t seen anyone else mention it. Thank you.
 
I would love to know more about the shifter, for one thing.

Also, for what it's worth, with stiff motor mounts my experience has been that a rubber mount can actually make the vibrations worse. You want them all to have roughly the same natural frequency.
 
I read an article on another forum about a manual conversion that was done on a toyota pickup that had similar sounding issues with vibration after the swap. turned out in his case he had a pilot bearing that was too large ID and caused a mean shake under load but not any other time. I'm not familiar with the CD009 swap, but you may want to make sure the parts used were all correct dimensionally if you had to measure and find things to work. Just a thought.
 
stevE85 said:
turned out in his case he had a pilot bearing that was too large ID and caused a mean shake under load but not any other time.
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Oh that'd be bad. I do know that there were some variances in the input shafts of those transmissions too, so it could definitely be a factor.
 
I’ll write up a review soon, I’d post that to the performance section as well I assume. As for the pilot bearing, it came with the deeworks kit. I do remember checking to make sure that it fit the input shaft before I installed it into the crank, but I have my suspicions about it as well. I’m a little concerned I may have crushed it while I was installing the transmission, though I figure it’d make a terrible noise if that we’re the case. Has anyone else experienced the motor mount frequency issue? I can’t say I’ve ever heard of it, but I’m open ears to the possibility.
 
Post Resurrection and new info

Hi everyone, I?m resurrecting the post with some new info. I yanked the trans back out a couple days ago to do some double checking and swapping of parts. While the trans is out I?ve been doing a little bit more testing on what exactly is the root cause for my vibrations. Firstly, with the transmission out, the vibration issue is an order of magnitude less severe, but still barely noticeable. At roughly 2400 rpm the whole cabin buzzes just a little bit, and by 3000 it?s gone again. So that writes out the pilot bearing as the root cause or any other transmission imbalances. I?ve checked the engine mounts and they really don?t look like the issue either; neither are collapsed and the engine, while stiffly mounted, can still shimmy a little when I push on it. It always springs back into position. That leaves me with three options as I see it: The pressure plate/clutch/flywheel are out of balance, the harmonic balancer is busted, or the vibration is normal and the poly bushing is just amplifying it a lot. Is there some way for me to write out the balancer as a factor? And does anyone else notice a small vibration in their car right at 2500 ish rpm? I?ll be posting a little more about my experiences to do with this swap in the coming weeks as I remember to, is there anything in specific that people want to know?
 
That’s just 2nd order resonant vibration. This is why Volvo used a 30 lb flywheel and 10 lb harmonic balancer coupled with mushy soft mounts. 96mm bore FTL.
 
Harlard said:
That?s just 2nd order resonant vibration. This is why Volvo used a 30 lb flywheel and 10 lb harmonic balancer coupled with mushy soft mounts. 96mm bore FTL.
Click to expand...

Gotcha, just happens that the engine happens to resonate at about that rpm is what you're saying I take it. And with a lighter flywheel and much stiffer transmission bushing, I feel the effects greatly. So other people with stiffer bushings/different flywheels also notice a similar vibration?
 
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