Vibration - foot on brake, truck in gear

[hillcountryflt]

One of the "nuisance" issues I am having since moving my 71 (240 CID) from its original 3-on-the-tree to a C4 automatic is that there is a lot of vibration when I put it in gear and hold the truck with the brake. Does it in all gears including reverse. This truck is not legal at present so its trips have been limited to around the block type of things since putting my rebuilt 240 and the C4 in it.
Also needing to find a replacement fill tube (goes into the pan) and figure a way to secure it - but those are not that pressing at the moment.
As to the vacuum line coming from the back of the transmission, I have it plugging into manifold, not carb controlled vacuum source.

[BobbyFord]

Engine/trans/exhaust is hitting the body or frame. Mount could be bad or loose, crossmember could be loose.

[hillcountryflt]

thanks. Removed the cross member during the initial install, so that would be the most likely culprit. Also, one of the trans mounting bolts for the rear support does not tighten down as tight as the other (stripped), so that is another contributor, I guess. Engine mounts are solid. Old but solid. I don't be believe my exhaust can easily touch anything.

[hillcountryflt]

One of the bolts holding the crossmember supporting the rear of the trans was loose. also both bolts holding the trans down were loose. No improvement once tightened. Nearly positive engine and exhaust are not tough the frame, except through their mounting points.

[BobbyFord]

Hmm...
If you are positive that nothing is loose and nothing is touching the frame or body then I would be looking at what you changed. Possibly flywheel imbalance...

[hillcountryflt]

Well that won't be fun (: Flywheel is a new part. Zero counterweight. Transmission, on the other hand, is said to be rebuilt, never used by previous owner.

[radioactivelarry]

One of the "nuisance" issues I am having since moving my 71 (240 CID) from its original 3-on-the-tree to a C4 automatic is that there is a lot of vibration when I put it in gear and hold the truck with the brake. Does it in all gears including reverse. This truck is not legal at present so its trips have been limited to around the block type of things since putting my rebuilt 240 and the C4 in it.
Also needing to find a replacement fill tube (goes into the pan) and figure a way to secure it - but those are not that pressing at the moment.
As to the vacuum line coming from the back of the transmission, I have it plugging into manifold, not carb controlled vacuum source.

Did you use a used tranny and torque converter? Does the torque converter make any noise like squealing or a rattle? did you use the proper flex-plate? Is the other end of your modulator vacuum hose in good condition without leaks? Does the vibration go away when you drive it or is it constant and does it shift OK? Sounds like something is out of balance.
Let us know.

[hillcountryflt]

Transmission is used (but supposedly rebuilt and never used afterwards - was going to be a tranny for a guy's rock hopper project - did have all of the nice aluminum covers wrapped around all openings). The torque converter came with it and appeared to be in good condition (but I would not know). Flex plate is new Ford part and was part number for one with zero weight (not sure of the correct term). No unusual noises whatsoever. New vacuum line from tranny to engine manifold source. Seems to shift OK - tight, but OK. However, I have not had it out on the highway and it has very, very few miles on the install (perhaps 10 times around the block).

[Ranchero50]

I'd recommend a tune up and make sure the engine is as smooth as possible, especially idle quality. 6's shake at idle under a load more than a V8. Converter might be too tight for the 6 at idle. Didn't really read a good description of the vibration so it's difficult to give better advice.

[hillcountryflt]

Engine is a fresh rebuild and is running very smoothly. Idle is a little fast. By too tight, what do you mean in terms of the converter? I torgued the nuts securing the torque converter to the flex plate/flywheel (forgot which goes with an auto trans) "normally."
The shake is noticeable and only experienced with foot on the brake and in gear (any gear). And it is quite noticeable.

[Jacksdad]

Tight refers to the stall speed. If it's too low, it can load the engine and pull the RPMs down. That could potentially cause the motor to idle poorly enough that it could feel like a vibration. Conversely, a "loose" converter will allow the motor to rev higher in gear with the brakes applied.

[BobbyFord]

In gear puts a counter-clockwise (from the front) load on the motor. I still think something is loose or something is hitting frame or body.
The motor is idling higher in neutral than it is in gear. If it were a balance issue, I think it would be more noticeable at a higher RPM.

[hillcountryflt]

Will be working on the truck this long weekend some. Removing or moving the bed, installing tie rods and power steering gear. So I will verify that nothing is touching the frame.

[67 StylesLide]

Maybe the Brakes are robbing vacuum and making the engine idle rough.
Or are you sure you have a torque converter for a 6cyl? A V8 torque converter would start to hook up at a lower rpm.

[hillcountryflt]

It has been so long, I don't recall the specifics of my torque converter, but I am going to look into a possibly vacuum/carb related issue. Don't think the two are related, but will see. I noticed the other day, that when I press down on my air breather, I have a (heck can't describe the sound) where it seems like the engine is venting or the like. Sometimes it will do it on its own after running for a while and then being turned off and just sitting.