Input Bearing Failure Signs? Ford F700 Dump Truck

Lanse · Nov 2, 2016

Hey guys!

So, I'm trying to fix up my old Ford F700 (1984) with a 4 speed manual. I dont know what make the transmission is, but its painted green!

Anyway, it makes a noise that sounds like a bearing thats gone bad at any speed in first gear and reverse. I've removed the driveshaft and confirmed its coming from the transmission! A buddy of mine says it sounds like a failure of the input shaft bearing, but I dont know - I wanted to see if anyone here has dealt with issues like this before. Any thoughts? Anyone know a transmission mechanic in the Fort Worth area thats any good?

What else might this be? I think its unlikely that both first and reverse gears have identical damage. Theres zero noise in 2nd, 3rd, or 4th.

LP GAS ONLY · Nov 2, 2016

An input bearing would make noise in every gear. Even neutral I would think. Sound more like a counter shaft bearing to me.
G.

flembo · Nov 2, 2016

I agree with lpgasonly I had an 8n with a bad input bearing and it sounded bad in all gears including neutral.

Bob · Nov 2, 2016

"I think its unlikely that both first and reverse gears have identical damage."

WRONGO!

In a typical 4-speed truck "crashbox" first and reverse DO share gears.

The rearmost gear on the mainshaft and the rearmost gear on the countershaft are used for both first and reverse.

In "first" they mesh directly, in "reverse" the reverse compound gear gets shoved between them.

So, likely, one of those two gears is damaged, and makes the noise you are hearing in both "gears".

Dune Country · Nov 2, 2016

Those 4 speed manual trannys are really simple to work on ,get a manual manual

and go for it.

Determined · Nov 2, 2016

Had one that was making a nasty noise like a bad bearing as you would get up to speed.
Turned out the driveline park brake on the back of the tranny was dragging slightly.

Rex in Australia · Nov 2, 2016

Front bearing will be noisy in all gears including neutral. Countershaft bearing similar but the noise goes away in 4th.
But which one it is doesn't make much difference. Replace them before it does further damage.
Rx

Steve@Advance · Nov 2, 2016

Dune, I agree! Taking that somewhere to be repaired would be asking for trouble, probably cost more than the truck is worth. I live just south of Ft Worth, work in Ft Worth, don't know of any shop that I would trust to do the job.

Job is somewhat physically demanding, getting it in and out, but once on the bench not that bad. No special tools other than access to a press and some bearing pullers that I remember.

Reminds me of one of those Chinese wooden ball puzzles, got to do some studying to figure out how it comes apart!

notjustair · Nov 2, 2016

The 700 series four speed was a New Process. That's what all my four speed school buses had.

MARK ROBKE · Nov 2, 2016

Lanse-Bob has it exactly right: it is not the input bearing.Input failures make the most noise in ALL lower gears.I would not take it any where- I would do it myself.I have rebuilt a lot of truck trannys,and they are not rocket science.There are a few tricks,about disassembly and reassembly,but most tools used are common: snap ring pliers,bearing splitter(maybe),hammer and long punch,white lube,and possibly a sawed off broom handle.It is harder to pull and reinstall back in the truck than it is to rebuild;for that you need a good transmission jack.Look at things before disassembly,lay it out in order,take pics;most problem causes are real obvious.You may not need to disassemble the main shaft: in some trannys 1st and reverse come off the rear.Post back - we can help.Mark

Input Bearing Failure Signs? Ford F700 Dump Truck

Lanse

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LP GAS ONLY

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flembo

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Bob

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Dune Country

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Determined

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Rex in Australia

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Steve@Advance

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notjustair

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MARK ROBKE

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