WDYD Popping sound under passenger side footwell on 75 series Troopy (1 Viewer)

What did you do....
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Hobart, Tasmania
Hello everyone,
Over the past 6 months I have been doing my best to bring an old 1992 75 Series Troopcarrier back to its former glory. Since buying it, I have noticed some clunks coming for the front end of the vehicle under certain conditions. I have noticed that the the front leaves tend to pop and move around when they are wet causing some unpleasant sensations when driving.

There is however this 'pop' coming from what feels like under the passenger footwell at random times. Its very abrupt and my girlfriend who sits in the passenger side says she can feel it in her feet in the footwell. It appears when the vehicle undergoes heavy load, heavy accelerations, changes of directions (forward and backward) and large bumps. It appears completely randomly (only some bumps cause it) making it difficult to reproduce for diagnosis.

So far I have tried:
Replacing leaf spring bushes
Replacing tie rod ends
Replacing sway bar links
Removing the sway bar completely to see if the noise goes away (it didnt)
checked the shock for play and or movement
Tried tightening to body mount under the passenger footwell

So far all of these attempts have failed and the 'pop' is still present.

Anyone got any ideas of what else could cause this? its driving me nuts
 

ceylonfj40nut

Waiting for Barn Time
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Some undercarriage pics would help.
 

jblueridge

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I have polyurethane spring bushes that clunk. I imagine deteriorated rubber bushes could clunk too.
 

Honger

Joel, TLCA #21509
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I'm here with the same problem. Exactly the same. Mine is a 1991 FJ75 Troopy.

I've done spring bushings (mine were done two years ago and this noise developed about a year ago).
I've done sway bar bushings (also done two years ago).
I've done tie-rod ends.

I've been speculating that it's a transmission or motor mount issue... so I'm curious to see if you fix it with motor mounts.
I've also been thinking it could be an issue in the shock body.
 
Joined
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Location
Hobart, Tasmania
I'm here with the same problem. Exactly the same. Mine is a 1991 FJ75 Troopy.

I've done spring bushings (mine were done two years ago and this noise developed about a year ago).
I've done sway bar bushings (also done two years ago).
I've done tie-rod ends.

I've been speculating that it's a transmission or motor mount issue... so I'm curious to see if you fix it with motor mounts.
I've also been thinking it could be an issue in the shock body.
I'll let you know once I get them in. Been putting it off as its quite the job!
 

Honger

Joel, TLCA #21509
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I've been toying with mounting my GoPro underneath and going for a drive... see if I can see the problem as well as better pinpoint the issue.

Curiously... yours is on the passenger side as is mine, but I think our passenger sides are opposite each other.
 
Joined
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Hobart, Tasmania
I've been toying with mounting my GoPro underneath and going for a drive... see if I can see the problem as well as better pinpoint the issue.

Curiously... yours is on the passenger side as is mine, but I think our passenger sides are opposite each other.
GoPro under the body seems like a good starting point. I have successfully filmed the leaves fanning out causing a distinctive ‘pop’ and ‘clunk’ during turning AND the leaves are wet (suppose it increases/decreases friction between them).

This is however a seperate issue as far as I am aware. The ‘pop’ i’m describing in this post occurs on what feels like directly under the floorboards in the passenger side (mine is a RHD so passenger on left facing forward).

From what I can eliminate it is NOT the following:

Sway Bar - I temporarily removed the sway bar completely and it still occurs

Leaf spring polyurethane bushes - I personally replaced these a month or two ago

Gearbox Mount and/or gearbox crossmember - I have replaced the mount and the crossmember is in good working condition

Tried tightening the body mount in the footwell - this I still cannot confirm is NOT the cause as the rubber is a bit tacky

As mentioned earlier, I have bought new Engine Mounts. The ‘Pop’ can occur during starting the engine (particularly on cold, rough starts with a lot of vibration).

To me this leaves me with only a few more possible causes:

- LHS shock could be buggered (Will need to remove to confirm)

- Some sort of play/slackness in the LHS ball pivot to the wheel

- I’m incredibly unlucky and it is in fact a body mount

- Engine mounts (They look fine but I do have a lot of vibration in the cab which I have just assumed is normal for a big diesel engine)

Tbh I personally have faith it is the engine mounts as it seems to occur in high torque applications (such as accelerating) which would create a torsion force against the motor mounts thus knocking against the chassis.

I guess it is equally likely a shock as during high torque applications AND/OR changes in directions OR large bumps the shock will compress/depress. If the shock is buggered it could potentially transmit a shock through the chassis to be felt in the passenger footwell.


Thats my analysis so far. I hope that helps you out a little in diagnosing yours - keep an eye out on this thread as ill get back to you on how to engine mounts change things!

Good luck!
 
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The loudest pop/clunk I have had on my 88 hj75 troopy is springs. Even after new bushes urethane or rubber. The only way was to replace the springs for me. They were the original 32 yr old springs at the time. I inquired upon resetting the springs, but was close to the price of getting new ones, so got new. Major difference.

I frequent long bad roads.

Later on I developed another subtle clunk/pop. Went over the whole front 2x, knuckle rebuild, etc, there are a few components there.

My relay rod end connecting to the steer box arm was worn, so replaced. There is a video on here about it, I thought it was the steer damper but it was the relay rod end.

The stabilizer bushes need to be kept in check too.

But the most subtle was the engine mounts gremlin. They looked fine in the engine bay, but upon replacing them little diagnol tears can be observed in the rubber which cannot be seen with the engine weight on the mounts in situ.

But, do you get a pop/clunk when the car is stationary? If so, my bet is mounts.
 
Joined
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Location
Hobart, Tasmania
The loudest pop/clunk I have had on my 88 hj75 troopy is springs. Even after new bushes urethane or rubber. The only way was to replace the springs for me. They were the original 32 yr old springs at the time. I inquired upon resetting the springs, but was close to the price of getting new ones, so got new. Major difference.

I frequent long bad roads.

Later on I developed another subtle clunk/pop. Went over the whole front 2x, knuckle rebuild, etc, there are a few components there.

My relay rod end connecting to the steer box arm was worn, so replaced. There is a video on here about it, I thought it was the steer damper but it was the relay rod end.

The stabilizer bushes need to be kept in check too.

But the most subtle was the engine mounts gremlin. They looked fine in the engine bay, but upon replacing them little diagnol tears can be observed in the rubber which cannot be seen with the engine weight on the mounts in situ.

But, do you get a pop/clunk when the car is stationary? If so, my bet is mounts.
Yep sometimes get a pop/clunk when the car is when the car goes from stationary to forward/reverse and there is a large load on the motor.

Also can occasionally occur during starting the engine which the vehicle is completely stationary.

I got some new mounts and I’ll put them in next week. not looking forward to that job but hopefully fixes it.

I did just replace the trans mount and it had signs of wear so hopefully the engine mounts are bad too.

Thanks for your input!
 
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pretty easy, make sure you unbolt the lowest nuts from below the cast iron brackets to the chassis..you won't reach the lower rubber mount nuts in situ. Big fat blocks of wood below the sump with a jack, remove rad shroud, air filter house, I also took out the alternator for better access.
Best to do all at the same time as you shall have to loosen the trans again.
It was a subtle lift of the engine when turning slow and or starting from stop without steering.
 
Joined
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pretty easy, make sure you unbolt the lowest nuts from below the cast iron brackets to the chassis..you won't reach the lower rubber mount nuts in situ. Big fat blocks of wood below the sump with a jack, remove rad shroud, air filter house, I also took out the alternator for better access.
Best to do all at the same time as you shall have to loosen the trans again.
It was a subtle lift of the engine when turning slow and or starting from stop without steering.
Thats great info, thanks so much for that. didnt think of removing the airbox and alternator so that will save me some hassle!

From what I can tell the clunk you describe sounds identical to mine, so im really really hoping its the motor mouts.

To be honest I’m not entirely sure where I will start if it doesnt solve the issue..!

cheers
 

jblueridge

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When I replaced my mounts I jacked from below but also had a strap to lean the motor from one side to the other to get some clearance.
Installing the mounts was easy then but later I found I had crushed a metal vacuum line against the firewall.

Try not to do that.
 
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mounts are well worth replacing if over 30 yrs old rubber. Next; springs and shackles, I like the dobinsons greaseable anti inversion ones, good design. When you say under passenger side, suspect rear front spring pin.

just have to spend money and replace most drive train gear at that age. troopies are becoming rare and going up in value. There is a guy in the diesel section nearing 700k kms on his hz. The record is over a million kms on a hz.

92 is hz?
The adventures you shall have in it, are priceless.

may also be your unis in the front driveshaft. being part time 4wd ,if driveshaft is not used much, the shaft can flop about if neglected. This happened on a 40series I use to have. If I am correct the hz had the same front diff as the rear, so chances a pretty fresh spare diff if your rear is worn. The earlier LCs are the same diff rear and front.
 
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When I replaced my mounts I jacked from below but also had a strap to lean the motor from one side to the other to get some clearance.
Installing the mounts was easy then but later I found I had crushed a metal vacuum line against the firewall.

Try not to do that.
was that the vacuum line from the alternator pump to your booster?
You have the 3b I guess.

must have got pretty high, I could do both of the fronts same time on the 2h.
proceed with caution indeed, just enough.
I have extractors/headers and custom exhaust, so a bit more simple on that side.
 

jblueridge

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RHD 13bt. I think it was the line that runs around to the engine kill vacuum switch.
 

Honger

Joel, TLCA #21509
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Had my dad(@KSDaddio) come over yesterday to try and help me ID the knocking issue. He walked beside me as I drove the truck... weird thing is he couldn't hear the knock from outside, only when the window was open and he could hear it from inside. Weird.

He crawled around, we jacked it up on stands and wiggled things, etc. We jacked the engine block up to see if the motor mounts had slop, nothing. The engine and chassis raised at largely the same rate.

So I did the GoPro video idea...


Dad observed the bushing material hanging out from between the leaves... could be the springs knocking together somehow. Could also be the shock... maybe something internal?
 

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