PDA

View Full Version : Vibration on acceleration, only when warmed up



mitchell27
15-06-2015, 05:18 PM
Hey guys,

I have a 95' 4 cyl TS manual Magna, which is having a slight (potentially large, depending on feedback!) issue. When the car is well and truly warmed up, it will vibrate on acceleration, this is acceleration only. I can sit there and pin-point when the engine is putting force to the wheels, as the vibration will effectively turn on and off like a switch as I slightly depress and let up the accelerator. Hopefully relevant information:

-I believe this began occurring after a new clutch was put on the car at the beginning of the year. But it been slowly getting worse, so this may be a coincidence as I would have been paying more attention to it after the installation of the clutch.
-The new clutch slipped on the first 1-2 drives I did, only when the car was getting hot (after the fan had kicked in for a while) and when I was switching gears often. There was no free-play on the clutch pedal, so I adjusted it and that seems to have fixed it (I researched that it was something to do with pressure build up when there is no free-play, I think).
-I have a very slight 'knocking' in a CV joint, only when turning right. Only just noticing it lately, goes away when car is warm.
-Have got new spark plugs and leads, new distributor (but old rotor, just sanded it back). cleaned the injectors 4 months ago. Only other stuff I've done to it is routine (belts and oil).

I'm a uni student, on a uni student budget, that's why i've come to this forum! But I love doing work like this. Having said that, I have no mechanical background to speak of, apart from avid fascination and previous tinkering.
My only current thoughts are that the clutch plate wasn't machined when it was replaced and it's warping slightly when it gets hot (but I don't know if that would result in the vibration I'm getting). Or some component that transfers force from engine to wheels (Is it a driveshaft in a front wheel drive?) has degraded.

Any help would be great, I'm flat out on placement (mon-fri 9-5) and working most nights at the moment, but I'll get back on here as soon as I can!

Thanks in advance! (also it's my first post, but I have searched on here and couldn't find anything exactly describing my cars woes, but point in the right direction if I've missed it!)

magna buff
15-06-2015, 08:22 PM
vibration could be these

engine mounts
front hub bearings
out of round trye or one off balance
cv joint diagnosis
http://www.aa1car.com/library/cvjoint2.htm

mitchell27
16-06-2015, 06:00 AM
Only got new tyres at the start of the year, can't recall hitting any major potholes since. So shouldn't be that.
Engine mounts I i'm unsure of, I can test this by getting someone to put it into reverse then drive when stationary and looking for movement in the engine block yeah?
CV joints seems the most likely, given it only happens when warm (drove it this morning and due to colder temp and shorter distance, there was virtually no vibration at all for the whole trip). So i'll replace those asap!

Cheers for the help!

ps. I cannot even recall what the problem was, nor that I posted. But i'll retract that 'first post' statement regardless!

MadMax
16-06-2015, 08:31 AM
-I have a very slight 'knocking' in a CV joint, only when turning right.

Knocking = worn CV joint, and this causes the vibration on acceleration.