Vibration at higher rpm's

Joined
Nov 30, 2008
Messages
99
I am new to the foruma and to FJ40's. I recieved a stock 72 FJ40 from my uncle a few months back. I have done a few things to make me feel more in control of the machine. I put front and rear disks on it and am so happy with the outcome. I have changed all of the fluids becuase it sat for a long while. I also changed the seals in the tranfercase as a precaution. Since driving it more I have noticed a vibraion that feels like it is coming from the tranny, engine area. I first thought it could be drivelines but checked it out sitting still in the garage. While reving the engine up a vibration become very apparent at aound 3/4 of full rpm range. It is an F enige, never been torn into before with high miles but not known how many for sure. I have not done a compression check yet but it runs very well and smokes little to none. I have no knowledge on these engines but am alarmed by the vibration and do not want to do any damage by driving it this way. Are these engines known to have any corks like this or do you have any ideas as to where i should start looking first. I appretiate all your ideas and time. Also I have spent countless hours reading so many wonderfull theads and think this site is great. Although my wife is already wishing I had not found it. Thanks again and I look forward to your thoughts
 
Last edited:
Joined
Oct 31, 2003
Messages
5,025
Location
Meridian,TEXAS
Check the harmonic balancer, make sure its secure and running true........ if that's OK, look at the clutch, a hunk of the disc may have let go........
 

JohnnyC

Long ago TLCA# 2231
SILVER Star
 
Joined
Jun 17, 2005
Messages
15,826
Location
Nys
did it have this issue before removing the transfercase to replace seals?

did you take out the x-case? or do it in truck?

x2 what grant5127 said

also

Welcome to mud
 
Joined
Nov 30, 2008
Messages
99
Well to be honest with you I did not drive it much before I worked on the t-case. I was told a cruiser sitting that long would need a new seal between the trans and t-case or it would pump oil from one to the other so I did that first. Correct me if I am wrong but if i am sitting still just reving the engine would the t-case have any affect in the situation? Also it does it weather the clutch if engaged or not. Thank you so much for your replies.
 
Joined
Sep 18, 2005
Messages
2,417
Location
Willamette Valley-Oregon
Well to be honest with you I did not drive it much before I worked on the t-case. I was told a cruiser sitting that long would need a new seal between the trans and t-case or it would pump oil from one to the other so I did that first. Correct me if I am wrong but if i am sitting still just reving the engine would the t-case have any affect in the situation? Also it does it weather the clutch if engaged or not. Thank you so much for your replies.

If you have the transmission in neutral when you are revving the motor the output shaft of the transmission and the transfer case will not be turning. Only the tranny input shaft will be turning. So the cause of the vibs will be from that point and forward.

X2 on checking the clutch and harmonic balancer. There are some other things to check also. One or more misfiring plugs, one or more bad plug wires, a cracked distributor cap, tracking/cross firing between the metal "lobes" inside the cap, a cylinder with very low/no compression. These items connected with ignition are the most common causes of a rough running motor in my experience. However they are often noticable at idle also.

Just a few ideas. Hope your roughness is an easy fix.
 
Joined
Nov 30, 2008
Messages
99
Well I have looked at the harmonic balancer and the flywheel. Both seem to be tight and free of any problems. As well as it runs at low rpms or past the spot that vibrated I doubt it is missing, but I have seen stranger things. One thing that I am not sure of is where the shift fork is. I took of the inspection cover and while it is running I can see the fork move a fair amount. It looks like there is a bit of a wobble to it and a little bit of wear to the peice it presses against. Is there a bushing there that could be worn? Is there supposed to be movement there? It just seems the area I feel the most vibration is by the transmision, but I do understand that may be deceiving. I do need to do a compretion check anyway to see where I sit in the whole scheme of things but will check the rest of the described items. Thank you all for your time, it is all appreciated.
 

Pighead

Stop calling it an FJ
 
Joined
Aug 31, 2004
Messages
7,592
Location
Denverish
One thing that I am not sure of is where the shift fork is. I took of the inspection cover and while it is running I can see the fork move a fair amount. It looks like there is a bit of a wobble to it and a little bit of wear to the peice it presses against. Is there a bushing there that could be worn? Is there supposed to be movement there?
Are we talking shift fork or clutch fork here? It sorta sounds like the clutch fork is what you're looking at...
And, no. It shouldn't be moving or even wobbling. And yes, those ears on the throw-out bearing holder do get worn. And there are two weak-ass little clips that are supposed to hold those ears to the clutch fork ends.
How does it shift? Any symptom that the throw-out bearing or it's holder is bad?
Not sure that that would give you your vibration, but would not rule it out either.
 
Joined
Sep 12, 2008
Messages
390
Location
tuscaloosa,alabama
I just put a slave cylinder on my fathers 78. He has a wobble on his shift fork also when he revs it up. I was concerened about this ,but he has no vibration at any speed, So Im not sure that is where your problem is.
 
Joined
Nov 30, 2008
Messages
99
Yes I am sorry it is the clutch fork. That is the wierd thing though is that it shifts well. Also when I am driving it changes the tone and way that it vibrates when there is more or less of a load. I mean if I am climbing or on a flat.
 
Top Bottom