Unusual vibration (3 Viewers)

Joined
Aug 9, 2020
Messages
16
Location
Meridian, MS
My 1988 FJ62 makes a very rough vibrating feeling and loud vibrating sound. It does not happen often but when it does it feels and sounds like you are running over rumble strips on the side of the road. And it sounds like it is mechanical that is either behind the dash or under the floorboard. I've tried to recreate it many of times. If I'm driving about 51-52 MPH and about 2100 RPM while accelerating, I am able to recreate it most of the time. When it happens, I usually just accelerate or decelerate through the narrow window with which it is affected. I've been told that the driveshaft may need to be aligned. Not sure if that is the case because about 6 months ago, I was getting a vibration that reminded me of the feeling of tires needing to be balanced. When I took the car to the shop, I was told that the tires were properly balanced and aligned. They aligned the keys on the driveshaft and the vibration went away. This unusual vibration that I'm trying to diagnose is more of a mechanical sound and feel rather than a tire being improperly balanced feel. Any ideas? Thank you.
 
Joined
Feb 27, 2019
Messages
34
Location
Orange County, CA
I have this exact same issue, it usually starts around 50 - 60 mph and I can accelerate through it with enough force that it stops. Cut the throttle and it stops, partial throttle and it starts back up immediately. I have not been able to find any other threads talking about this issue, so glad I saw this.

I have already pulled the driveshaft and it is completely balanced and rebuilt with new Matsuba U joints. Vibration still persists.
I believe it to be a torque converter issue after eliminating the driveshaft from the equation. The fact that it happens around lockup speed is also a characteristic that points to TC related.

I checked the fluid in the trans recently, and it was well over the HOT mark on the dipstick when cold.
I am planning a trans/rodney flush soon, so I will address the fluid level and in addition to that, I have read that "Lubeguard" (Transmission additive that I purchased on amazon) has been shown to help on several rigs here on MUD.
 

EscapeWagon62

SILVER Star
Joined
Jun 29, 2017
Messages
841
Location
Longmeadow MA
You are probably on point with the torque converter
I also had a weird speed dependent low bass sound. Balanced tires, shafts. Turned out I had an off center rim.
 
Joined
Jan 17, 2005
Messages
5,619
Location
Southern Colorado
This unusual vibration that I'm trying to diagnose is more of a mechanical sound and feel rather than a tire being improperly balanced feel. Any ideas? Thank you.

Wheel bearings? When the truck is actively vibrating, try steering slightly to the right or left - if the vibration goes away, that points more strongly to wheel bearings. Beyond that, drop you rear driveshaft and manually swivel all the u-joints (and grease them) to be sure they are tight and smooth.
 
Joined
Feb 27, 2019
Messages
34
Location
Orange County, CA
This unusual vibration that I'm trying to diagnose is more of a mechanical sound and feel rather than a tire being improperly balanced feel. Any ideas? Thank you.

Wheel bearings? When the truck is actively vibrating, try steering slightly to the right or left - if the vibration goes away, that points more strongly to wheel bearings. Beyond that, drop you rear driveshaft and manually swivel all the u-joints (and grease them) to be sure they are tight and smooth.
I should try that as well. I also have a lot of random vibrations which are, no doubt, a cumulation of probably a lot of things that went overlooked. But the original post topic is definitely the most concerning as it is a vibration that shakes anything and everything inside the car and is very un-nerving.
 
Joined
Jan 17, 2005
Messages
5,619
Location
Southern Colorado
How about a cracked flexplate that vibrates at certain RPM. Rare, but not impossible. You might pull the inspection cover off the bellhousing and check the nuts for tightness and the flexplate for any obvious cracks.
 
Joined
Aug 9, 2020
Messages
16
Location
Meridian, MS
Care to share what happened?
I decided to drive 4 hours to my parents house in Memphis. 20 minutes south of Memphis I pulled over to get gas. Pulling into the gas station I starting getting smoke coming up through the floorboard and hood that continued for about 25 minutes even with the car turned off and that smelt like rotten eggs. The "AT Oil Temp Light" on the shifter also came on and did not extinguish for about 45 minutes. What looked like oil at first but I believe now was AT fluid was leaking from the bottom of the car. After the oil temp light went off and the car quit smoking, I attempted to drive the truck around the block to see if it just needed to cool down. Less then 300 yard down the road I was at 3500 rpm and 10 mph as I pulled into another parking lot. I tried to put the car into park but it would not catch. I pulled the emergency brake and called a tow truck.
 
Joined
Jul 10, 2017
Messages
1,441
Location
DC
Unfortunately my transmission just went out. It will be interesting to see if when I replace my transmission the vibration goes away. I can only hope.

bummer. If you’re looking for a good used auto transmission I have one. It was functioning perfectly and has had an aux cooler on it since I’ve owned the truck (3 years). it’s coming out for an H55f swap.

Only catch is it’s in northern Virginia.
 
Joined
Aug 9, 2020
Messages
16
Location
Meridian, MS
bummer. If you’re looking for a good used auto transmission I have one. It was functioning perfectly and has had an aux cooler on it since I’ve owned the truck (3 years). it’s coming out for an H55f swap.

Only catch is it’s in northern Virginia.
Thank you for the offer. I have a guy that is has a parts truck with a transmission he said he could rebuild for me. But I'm leaning towards a H55 as well. I'm still in research mode...
 
Joined
Aug 9, 2020
Messages
16
Location
Meridian, MS
bummer. If you’re looking for a good used auto transmission I have one. It was functioning perfectly and has had an aux cooler on it since I’ve owned the truck (3 years). it’s coming out for an H55f swap.

Only catch is it’s in northern Virginia.
With the cost of an H55 swap, I'm getting some recommendations to do a V8 swap. Why did you choose a H55 instead of a V8 swap?
 
Joined
Jul 10, 2017
Messages
1,441
Location
DC
With the cost of an H55 swap, I'm getting some recommendations to do a V8 swap. Why did you choose a H55 instead of a V8 swap?

That math only works if you make an apples to oranges comparison.

If you’ve got the time/skills/space and you use a takeout engine plus do the work yourself doing it right costs $12k-$15k.

The high figure is double what I’m paying an LC pro to do the H55f swap for me with all new parts. I don’t have the space/time/tools to take on the H55f swap let alone a v8 swap either.

Apples to apples in my situation to accomplish a full engine swap with new parts and having someone do it is 25k-30k.

Also, with the H55f I’m more inclined to keep the 3fe a lot longer and maybe forever if the tranny swap is as good as people say.

When/if I eventually do an engine I’ll put the H55f I already have behind it.
 
Joined
Nov 1, 2003
Messages
1,571
Location
Klamath Basin
With the cost of an H55 swap, I'm getting some recommendations to do a V8 swap. Why did you choose a H55 instead of a V8 swap?
Do you have an engine problem? Why replace the motor when the transmission is the problem? You will still need a trans even if you swap motors. Either replace/rebuild your A440f or put a 4 or 5 speed behind your 3FE.
 

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