Technical 51 Plymouth lowering question

It's my pleasure to help, and I always learn something because of all the questions I have to ask in these threads. So here's some more...

It's possible this car had a bad front u-joint, which trashed the tail shaft bearings in the trans. The joint got fixed but the bearing got ignored.

But if that were the case it'd be leaking a lot of oil. The trans and drive shaft would be all oily and so would your driveway.

You did check the trans oil level right?
It does this regardless of what gear you're in?
Are the rear motor mounts both intact and solid?
Does this vibration go away over 45 mph? How fast have you driven the car above that?

I'm thinking you might have a harmonic balancer that's "slipped", or maybe the wrong flywheel for your crank.


Some of these questions might sound stupid, but I once asked a guy whose car was overheating all the time if he noticed the water level dropping in the radiator. He said he didn't know because the cap was too rusty to remove.
D'OH!

 

Put it in a lift today everything is square the pinion is just a little low I mean little where the guy said it should bother anything

Vibration starts in high 2nd gear and bad in 3 gear so anything over 30 pmh and it stays that way if intake my foot off the gas it queits down some...had a trans shop look at of today they couldn't get it on there lift said "Too low" he said the motor has bad vibration in it he thinks motor mounts and trans mounts are bad but that's a guess he said

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It just funny because if I Jake the rear up a couple of inches the noise goes away ... He told me to make the trans with the drive shaft on take the drive shaft off and see if the front moves in or out if it doesn't he thinks motor mounts and trans mounts but why would the vibration stop when i jake the back up some

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get 4 jack stands like mentioned and get under there.
make sure the stands are under the suspension so the car is sitting at ride height (I shouldn't have to say this, but make sure the car is stable while on the stands).
put it in gear and start rolling around underneath it.

may be a good time to update the the driveshaft and rearend.

my '51 is only 1.75" in the back, I couldn't drive it around here if it was much lower.




jeff

 

Here is the car by the way lol

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New trans mounts new rear end oil also put the car up on stands drive staff straight no wobble it does rock back and forth I did put the spring back in....I'm have some grinding nose come from driver rear wheel but there is some vibration in the front not as bad only in high 3rd gear around 40 to 50 mph

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How fast did you run it on the stands?
Also, check that driver's side wheel bearing for slop. Make sure the brake's not dragging because the bearing's shot.

 

I went Thur all the gears it was really loud in 3 gear when I replaced the axle oil its a little better but grinding for rear driver tire also I took off ebrake and cleaned it good so no rubbing there them new trans mounts helped out some

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Jack up that wheel 2" off the ground and back off the brake adjustment a bit. Then put a crowbar under the tire and see if you can lift the axle inside the bearing. If the wheel moves up and the axle housing doesn't, you should feel a clunk which is the worn wheel bearing. Touch the backing plate and drum with one finger while lifting & you'll feel motion if it's bad.

If it's worn enough to make the brake drag, it'll possibly chatter making a terrible noise. If the bearing has been bad long, the bottoms of your rear brake shoes might be worn down to the metal.

 

OK I'll check the wheel bearing out asap

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Because every piece of metal in the drive train is connected together hard, under real pressure, when the engine's pulling the car at speed, the noise/vibrations at one point get reproduced and broadcast from other points in the system.

It's like those old prison movies. One guy taps on a pipe, and the other guy can hear him through the plumbing at the other end of the building. Because metal is dense, sounds travel through it really well. Things like big metal fenders on a car amplify and "bend" sounds as well.

Anyhow, all this makes it difficult to pinpoint the source of many noises and vibrations.

 

It will be Sunday but I will post up

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Some told me if it was my pinion I could use some shims to adjust pinion

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Read up on how to set up a differential. It's sort of a specialist business.

There's shims and crush washers and cushion washers, which all work together to get a good alignment of the gears and the correct contact pressure, all at the same time.

You can do it yourself, and I have done a few, but study what's involved first. It's not just a trivial matter of removing a nut & stuffing in some shims.

You won't get it right the first time, but the crush washer needs to be replaced each time you change the shim. That is how the pinion bearings are preloaded so they stay tight under pressure. You'll need some extras, along with the correct shim, and you don't know what size to buy, so you might end up buying extra sizes so you'll have the one you really need.

 

Since you didn't mention it, I'm guessing you used 3" blocks to lower the rear. If so, your pinion angle now changed & probably need wedge shaped shims to correct it. A few years ago, I installed 3" blocks to my sagging worn leaf springs in the rear of my '38 Plymouth & it started making the same sounds you're describing, usually in 2nd & 3rd gear til I get up around 50+ mph. It's not a daily driver, so I lived with it for a while. Eventually, I installed Posies 3" lowering springs & it solved the problem, only because it wasn't as low as the 3" blocks & worn springs.....and definitely not low enough for me. I removed 2 leafs from each side....better, still not low enough, so I cut my 3" blocks down to 1".....that's more like it.....but now the vibration is back. I have some weges, just need to install them to see if it solves the problem. Some of it may also be little or no movement in the drive shaft slip joint, worn parts, etc. We'll see.

Here they are....

 

Yep I used the square blocks that wasn't tapered then someone told be about the shims that goes with the blocks I think the ones he got have 2.5 degree angle i just don't known if that's enough and which way should the shim go I think my rear end is pointing up a little if any what I can tell

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Ooooooh!

Those aren't shims. Those are wedges. I thought you had a loose pinion now, but you're talking about correcting the pinion angle.

Wedge it until the pinion shaft is parallel with the transmission shaft, when the car is sitting at the stance you intend to run.

You need a magnetic protractor that will tell you the angles, then subtract one from the other and the difference is the wedge you'll need.

 

can i get one from a local auto parts store...thanks

 

Mine came from WalMart for like $7.

It's a Master Mechanic brand, which is a cheapo brand, but for this it'll be OK.

 

OK I'll checkbthere

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OK today I changed the trans oil and took square blocks off and grinded them to a taper only like 2/8 of a inch put them back one I still have vibration at 40 to 59 mph mainly when I'm pushing on the gas pedal so now I don't know if I put enough taper or the driveshaft is out of balance

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ground them to 2/8" ??????????
never heard it done that way, Did you keep the surfaces flat? You really don't want those blocks wobbling around on crooked surfaces.
and is 2/8 the same as 1/4"
;-)

theres a little more to setting pinion angle then grinding a random angle and hoping you got it right. did a quick google search for you:
http://www.carcraft.com/howto/91758/


jeff

 

Yell I saw that.. today I Lossen all the ubolts and jacked the rear up some to change the angle its slot better I can get to 50mph before vibration and nosie still sounds like its coming from the motor area

 

ok i changed my trans oil i drove it about 5 miles after i parked it for 20mins i see some oil dripping is this normal it wasnt doing this before the change also im still have the vibration after i set the pinion

 

Dripping oil isn't normal, although it can easily happen if you overfill the trans or the air vent is blocked.

Did you check the tailshaft bearing & seal?

 

No I did check pinion and I'm taking the driveshaft to get balanced tomorrow

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They told me today they could not balance my drive shaft told me there was no need to do it unless I bent it or cut it

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Getting my custom driveshaft back Wednesday I'll post how it works out

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It's been a few Wednesdays now...

Any luck with the new shaft?

 

59 posts and no one has commented that lowering the car 2 inches in the front will not alter the driveline operating angles one millionth of a degree. Lowering in the rear is a different story and the angles will change