3500rpm vibration

[BMGTZ]

I have recently done a VR4 4G63 transplant into a gsr. the full history of the engine is unknown however the engine shows all the signs of a rebuild in recent past. It has great compression and is very crisp at idle with some big cams.

the problem is a vibration at 3500 in any gear.......the type of vibration that makes shit come loose and fall off.

I thought it might be balance shafts out of sync and .....sure enough when I checked they were out of sync. So after fixing that and putting another near new harmonic balancer on the vibration was less but still pretty bad. :angry:

I have also had a good look at the engine mounts and put a new fidanza alloy flywheel with a exedy clutch onto the engine.

there arent any oil leaks at the seals to indicate a bent crank or the like.

would a fucked gear box exhibit this behavior? the one in it has fair bit of roll over noise..


it is pissing me off because last night the coil pack fell off!!:blink::blink:

any thoughts are appreciated

 

[Gianni]

That's alot of shaking. If it was the gearbox I'd be thinking the dif not gripping the drive shafts properly. I had a problem a few months back where it finally gave in and it would shake major bad an that's what the problem was. The diff just jammed up on one side. Couldn't even push it.

Then again I have never experienced anything else but thats all I can think of hope u find it bro

 

[Rockabilly]

Is the oil pump cog lined up at tds ? It aligns every 3 revolutions.
Cheers !

 

[turbovr4]

sounds like the balance shaft on the oilpump is 180deg out.turn the motor over to top dead center and with all the marks lined up,then remove a bolt on the block near the starter motor and you should be able to put a screwdriver through.if the balance shaft is out of sync then the screw driver wont go through the hole.

 

[BMGTZ]

balance shafts were out but are now right. is it possible that they could be the wrong ones? The reason that i say that is that the car the engine came with had a whole bunch of 4g61 parts in the boot.

 

[brisvr4]

Do the shafts turn easily by hand Brian?
I'd hate to think that it might be a balance shaft bearing on the way out and that 3500 is the sweet spot for it's vibrations?

 

[VR-4Squid]

balance shafts were out but are now right. is it possible that they could be the wrong ones? The reason that i say that is that the car the engine came with had a whole bunch of 4g61 parts in the boot.

4G61's don't have balance shafts (it's the 4G61 stub shaft for the oil pump that is included in bs elimination 'kits').

 

[BMGTZ]

Do the shafts turn easily by hand Brian?
I'd hate to think that it might be a balance shaft bearing on the way out and that 3500 is the sweet spot for it's vibrations?

yep they turned really well........and I thought that after I had found they weren't in sync that would end the problem. but no not to be!!

 

[BMGTZ]

4G61's don't have balance shafts (it's the 4G61 stub shaft for the oil pump that is included in bs elimination 'kits').

thanks for the heads up on that......I don't have any real experience on a 4g61.

the engine had a botched up flywheel attached that I think from the number cast into it was a 61 flywheel so I thought they may had done some other swapping as well

 

[SIVART]

I felt a similar type of vibration in my vr4 and it was the Uni on the tailshaft to the yoke, which was getting loose

maybe not it but worth alook

 

[bazeng]

So at idle it is fine?
If stationary and you rev it, no issues?

 

[Jonson]

^^ What baz said. You need to do process of elimination. With the car no moving, rev it, does the vibration happen? Or does it only happen while driving? If it only happens while driving, like Trav said I think it will be a siezed uni on the tail shaft.

 

[JSTYLE]

does the car make boost?.

Jon

 

[coop1er]

If it's been rebuilt and the oil pump has been apart, it is possible that the gears in the oil pump were not aligned correctly. This would mean that the lower balance shaft would be out of phase.

 

[BMGTZ]

If it's been rebuilt and the oil pump has been apart, it is possible that the gears in the oil pump were not aligned correctly. This would mean that the lower balance shaft would be out of phase.

mmm....food for thought. there I will check it out.

 

[BMGTZ]

thanks for the replies

front uni is new in tail shaft......but unis and gearbox other than input shaft would make the issue speed related wouldnt it? this is at the same revs in every gera regardless of vehicle speed


the vibration is there when staionary but not as bad

 

[JSTYLE]

100% balance shafts!!!!!!!!
or something in your front casing definately!

Jon

 

[BMGTZ]

it is a pain ....but here we go again with the balance shafts. I think they are coming out

 

[EVO-00X]

Still, dont rule out a loose or dodgey flywheel or clutch assembly if its also vibrating in neutral.

 

[JSTYLE]

Still, dont rule out a loose or dodgey flywheel or clutch assembly if its also vibrating in neutral.

That is a thought too i had this happen before when i didnt use loctite!

Jon