Mazda Rotary Club

General => General Technical => Topic started by: CSE on August 12, 2007, 01:19:47 PM

Title: Vibration on full throttle
Post by: CSE on August 12, 2007, 01:19:47 PM
hi guys
 
i\'ve just bought a relatively stock 94 Rex and i\'ve noticed that on full boost when the 2nd turbo kicks in the whole car kind of vibrates when its pulling, it\'s more noticable in first gear and a bit in the rest but i guess as its not climbing through the revs as quick it doesnt do it as much.
 
is this normal ? any idea what it could be ?
 
cheers
Title: Vibration on full throttle
Post by: banned advertiser on August 12, 2007, 11:48:51 PM
No not normal and could be a host of things, engine mounts, diff mounts, bushes, steering linkage
Title: Vibration on full throttle
Post by: CSE on August 13, 2007, 07:23:33 AM
hmm i thought it might be exhaust related, i\'ll have to get someone to check it out ...
 
anyone else had this ?
Title: Vibration on full throttle
Post by: Grizzly on August 13, 2007, 08:58:05 AM
I had something simalar when i first bought my Turbo2, i checked every thing (engine mounts,gear box mounts etc etc) after messing about for quite some time i remembered it had a new Clutch just before i got it and lone be hold the gear box-Engine bolts wern\'t tight and there was a Gap between the two.

I have also heard of Bolts being missing from the Prop shaft that also causes a Vibration under load and higherish speeds.
Title: Vibration on full throttle
Post by: Martiny on August 13, 2007, 08:58:39 AM
Well, I guess that if the exhaust is touching any part of the car, you will get vibration.

Could it be a broken engine mounting?  They are only rubber and are prone to fail if oil gets on them.
Title: Vibration on full throttle
Post by: Grizzly on August 13, 2007, 09:40:28 AM
Does your Gear selector move about if you excelrate and let off quite hard? (usaly a sign of a Dodgy mount)

I think if i was you i\'d jack it up and put it on stands, then have a good look at the easy stuff first Things like exhaust hangers, shake the exhaust Back box up and down and side to side (listen for knocking) then follow the exhaust to the front of the car and make sure its not jamed against something. Then put the jack under the gear box and Carfully raise the engine and box assembly and have a good look at the Mounts (they should\'nt move too much without it raising the body too) but look for Cracks or sections where the rubber has come away from the Mounting plate the engine ones are a Bit of a Pain to see but you can usaly tell if the engine moves away from the subframe more on one side than the other.

Whilst its up grab the Prop shaft and shake it quite hard (this is to see if there is any movement in the UJ joints) also check the Prop shaft bolts are Tight at the Diff end, Whilst you are there have a look at the Diff mounts they do tend to crack and fall apart but its a more dramatic vibration.

Out of intrest have you had your Wheels ballanced recently? if you have lost a weight it may make a Vibration but i don\'t think it would explain the Exhaust noise?
Title: Vibration on full throttle
Post by: CSE on August 13, 2007, 05:34:28 PM
thanks for all the good advice, i do plan to get it up on a ramp next week to have a good look at the underside and see whats what.
 
its definately not wheel related its something \'body\' wise and it only happens on 2nd turbo boost, maybe a gasket blowing could cause small quick vibrations if enough gas was going through?
 
anyway thanks for the help guys i will follow them up :)