My 1970 FJ40 arrived yesterday and I've noticed the 1st problem not mentioned in the inspection report. I'm hoping someone can help me diagnose it. It's got the original F engine with the 3 speed transmission. It drives fine and changes gears smoothly, but whenever it is in gear and moving, every time I take my foot off of the accellerator it makes a grinding noise. Then as soon as I put my foot back on the gas it stops. Any idea what's going on???
Grinding Noise
- Thread starter CruiserFL
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splitshot
Head cook, Bottle washer, and Peace keeper.
Almost sounds like gear or bearing pitting. If it has sat along time, try changing fluids and adding a quality additive like Lucas and see if it helps.
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There are a LOT of potential sources. A couple of simple tests and observations will get you better imput.
Does the noise just get louder and louder the faster you go, or does it reset each time you upshift from gear to gear, or only happen in one gear?
Will the noise go away if you shift into neutral?
Best
Mark A.
Does the noise just get louder and louder the faster you go, or does it reset each time you upshift from gear to gear, or only happen in one gear?
Will the noise go away if you shift into neutral?
Best
Mark A.
inkpot
SILVER Star
Howdy! When I first go my FJ 55 it made more driveline noise while decelerating that accelerating. At first I figured it was just hiding the noise with the sound of the engine during acceleration. Later I found out that the idler shaft in the transfer case was badly worn, and the idler gear was worn more for the forward direction, since it usually runs that way, and it really did not like running in reverse at all. I think it was caused by running low on gear oil. John
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No, it doesnt get louder. In fact, you cant hear it at all while the car is moving. But basically what happened was I took my foot off of the accellerator as i was approaching a stop sign and then there came a loud grinding noise that i could feel beneath my feet. The car drives and shiftes fine and you would never even hear the noise if you didnt take your foot completely off of the gas. The car is also fine in neutral.
Also though....you cant shift into 1st gear unless the car is at an absolute standstill or else it grinds. Is that normal too. Sorry if this sounds stupid. Not used to old transmissions.
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- #7
That would make sense. I have a feeling this truck might have some oil issues (leakage?) which could have resulted in this. If im looking at the same issue you had, around how much might that set me back?
Last edited:
inkpot
SILVER Star
Howdy! I had mine fixed many years ago. Don't remember the cost, as it was done with a lot of other work. Sometimes it is easier and cheaper to just buy a used transfer case in better shape. The 3 speed transmission does not have syncrhos on fist gear, so it is supposed to grind unless you are dead stopped. You can avoid this problem by learning to double clutch. You may be a good candidate for a minor upgrade to a 4 speed tranny and transfer case. It has a synchro on first, and the first gear is a bit lower ratio. The transfer might be younger and fresher. Welcome to the world of 30+ year old parts. John
Also if you're in neutral, shifting to second before first makes it slide in easier....
Make friends with someone with a 3 speed 40 and compare sounds as well....
Make friends with someone with a 3 speed 40 and compare sounds as well....
- Thread starter
- #10
So if i can find a rebuilt transfer case, that would also include a rebuilt and functional idler gear?
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Look at everything you want to. Education is cheap, and it's good to know what your options are.
Diagnosis is still premature.
You could just as easily have a backlash issue in the differential as the t-case, ASSUMING we're talking about a backlash issue at all. Still not convinced of that from your story.
How about taking the truck to a local mechanic just to get a 'professional' opinion? Or a local cruiser club, for a cruiserhead opinion?
Best
Mark A.
Diagnosis is still premature.
You could just as easily have a backlash issue in the differential as the t-case, ASSUMING we're talking about a backlash issue at all. Still not convinced of that from your story.
How about taking the truck to a local mechanic just to get a 'professional' opinion? Or a local cruiser club, for a cruiserhead opinion?
Best
Mark A.
Did have one ,a 4 speed though,where the pinion pre load in the rear diff was so bad it took the bearing out.It sounded the same ,no noise going forward, upon deceleration a real howel through the whole driveline.
Also though....you cant shift into 1st gear unless the car is at an absolute standstill or else it grinds. Is that normal too. Sorry if this sounds stupid. Not used to old transmissions.
Sounds pretty normal....the grinding going back to 1st that is...Every 3 speed I have heard grinds like that. But thats just what we have experienced. Good luck with it
I have had some issues similur to the vibration/grinding on my 40.
Turns out the rear pinion retaining nut was loose. At first I thought it was my u joint inthe back. When I dropped the DL the problem was obvious. I have a solid crush washer in both my pots so I just wrenched it down and no more vibration/grinding. Give that a looky loo too.
Turns out the rear pinion retaining nut was loose. At first I thought it was my u joint inthe back. When I dropped the DL the problem was obvious. I have a solid crush washer in both my pots so I just wrenched it down and no more vibration/grinding. Give that a looky loo too.
X2
The idler shaft and bearings are the weak link in the drive train and the usual culprit in noises that change when you let off the gas pedal. They usually show up as metal flakes on the magnetic drain plug of the transfer case.
Glad you found it .There should be lots of donar parts out there to get you going,especially a spare diff,if you get a spare make sure its the right ratio 4.11,probably cheeper that way than buying bearings and gears.Good luck
