What would cause chattering starting 1st gear? My manual says to check these in order:
clutch free travel
engine mount
equalizer bar
transmission mount
cab mount
then start looking at the clutch itself - pressure plate, flywheel, etc

Before I drive myself crazy looking at all these things, any words of wisdom to save me time?

1978 F100 6-Cyl 300 3-speed 2x4

 

If it only occurs at moderate to hard acceleraction, check the engine and tranny mounts.

 

Actually, it does only occur at moderate and hard, and especially uphill or pulling my 16-ft boat.
Also, the past owner said he put in a new clutch.

I'll check the mounts - I assume I don't have to actually take them off to check them...?

 

When I had my C4 rebuilt on my '79 300-6, I quickly noticed the chattering. The tranny shop checked it out and diagnosed it to be my mounts. From my understanding the engine and tranny combo are pulling/pushing the pinion out of alignment with the ring gear. I have been driving for the last year like this without major problems unless I gun it (yeah - whopee real fast in that 300 - HA HA)Anyways, I need to do my mounts very soon because the problem has progressed to the point where I can feel the engine lurch slightly forward on hard stops. The tranny shop did tighten the mounts' bolts to take care of the moderate accel problems but it didn't cure the problem. I wonder how my nine's doing in the rear. Probably due for a rebuild too.

 

[font size="1" color="#FF0000"]LAST EDITED ON 01-Aug-01 AT 02:40 PM (EST)[/font][p]If you have a really high geared rear end, it will chatter a bit in low with the 3 speed because the 3 speed has a high first gear, but, if it's chattering alot, tighten down your engine and tranny mounts, and try adjusting the clutch so that it engages earlier. One word of caution, if the mounts are loose, or are in really bad shape, don't let it go, I had a tranny mount break(studs broke off) wheeling before I converted to 4x4, I didn't think anything of it until I was out for a test run after breaking in my new cam, I had pulled the engine to replace the rear main seal at the same time, and hadn't torqued the engine mounts down, I went to pull a U-turn, and the clutch linkage came apart as I was shifting into second, and the pedal stuck to the floor, and I got to see what happens when you floor a 230 hp 300 in a sharp turn.... The tranny had only moved ~½", but it was enough to pull the engine mounted ball out of the Z-bar and render me clutchless, thank god the NP435 has clutch-type syncros, and can be upshifted without the clutch the same as if you were using it.
Evan MacDonald
82 F100 FlareSide 2wd
HD 300-6 9.5:1 CR
Clifford 270H cam
Hedman Hedder
SBC valved 66 240 head
Headlight Relays - Delanty Style
NP435(6.69 low)
3.55 Geared ARB'd 9"
31x10.50/15 Cooper Discoverer LT's

 

I crawled under and had my neighbor rev and put in gear, and no noticeable movement in the mounts. They don't look too bad either. He said he got some chattering with a new clutch (clutch plate wasn't exactly aligned) and it mostly went away with wear. Does this sound plausible?

 

To go a little further with this : the "chattering" problem I have with my rear end is more like a clunking sound. It's very dependant on the drive line and torque. It's not a ticking or accompanying sound, it's very real and I can feel it when I hit the gas hard. I though it was my tranny at first after the rebuild, but it made sense when the tranny shop traced the symptom to the rear end and mounts. You're concerned with the clutch. You mentioned you have three speed? Is this an AT or standard? If this was a clutch problem, wouldn't it show up in all gears at the same torque? I noticed small cracks in my mounts, I'm sure there's more to the story when the engine is under load. Believe it or not, if I hit the gas hard up a hill on the freeway into 2nd I notice a harsh vibration as if my drive axle is out of balance or out of alignment when I cruise into 3rd. The vibration seems to self correct, yet I can only attribute this sporadic problem to the mounts. Any one else following this?...or noticed the same problem?

 

Thanks guys for your help.

I took your advise tightening up a little on the mounts, one took only a little twist and the other frozen solid (sigh, replace that later if the WD40 doesn't do the trick). Then just for the hell of it, I checked the mounting brackets... Passenger side bracket was held by one bolt, the other three just rattling around! I almost cracked up. After all that poking around the mounts, the brackets on both sides were loose as a goose. I'm surprised the whole truck didn't roll over on its side when I gave it gas.

Much less chatter now - probably some new front body mounts would fix it fully - they're pretty lame.

faype02(No Email Addresses In Posts!)
1978 F100 6-Cyl 300 3-speed 2x4

 

Gotta do mine to. Good to read you've checked it out.