Worrying tranny problems

[josh817]

Long story short, I put a long box 5 speed (the one from a 280z I believe where 4th and 5th are very close together ratio wise). I made a simple L shaped mount for it and bolted it in. I'm pretty sure the tranny has rubber on its side of the mount but the mount I made is just bolted in solid connecting the chasis to the rubber mount already on the tranny. I could be wrong though.

 

Anyway, I put a new rear seal in, put the proper plug into my rear flange, shortened the drive shaft but DID NOT replace U-joints yet.

 

Ever since I have had the truck driving it has had a drive line vibration, right in the tunnel area, at 25MPH. As soon as you get to 27MPH its gone. The vibration will not occur if you are coasting or going down a hill. If you put it in 4th and chug up to 30MPH or chug up a hill, the vibration is pretty intense.

 

I need to fix this because despite the new rear seal, I have been leaking. When parked, I only get like a drop of oil every few days at most however when I look under the truck the bottom is coated with oil. Since September-ish, it drained itself out to about half a quart! I will get to this later. I suspect the vibration is messing up the seal and it spews every time it vibrates and flings oil on the underside. A drop here or there sitting still does not explain all the mess.

 

Also I noted today if I hovered in the vibration zone going slowly, not only to you hear the deep rumble but you can hear a "ting" noise like a thin piece of metal is slapping something real quickly while spinning. I would like to think that this confirms my thoughts of the vibrations causing the leak because the flange has that dust cover/cup thing that covers the rear of the tranny. If its wobbling it's probably slapping around.

 

So, do you guys think this could be old u-joints? I'm changing them next week. Do you think its the hard mount? Maybe the carrier bearing is bad? It spins freely.

 

 

 

 

Onto my next situation. I drove 30 miles at 65-ish just fine on Friday. Something must have happened, enough oil leaked out finally or something, but I was cruising 75-80MPH to the track, when I left that night to come home there was chattering in the gear box. It only started after 50MPH. It was late, everything was closed, I didn't have any choice but to drive the hour and a half back home with it chattering. Topped it off with oil, which is when I saw it was very very low. Now it doesn't chatter unless you are going 60MPH. As soon as you go under or above 60MPH, it stops. Chattering stops if you take it out of gear and coast.

 

It doesn't sound like gears meshing so I suspect a bearing got chewed. I just don't understand why it only occurs at 60MPH. Every gear shifts butter smooth, doesn't pop out of gear, doesn't get stuck in gear, doesn't grind, doesn't whine. Don't know if I should worry.

 

I would like your thoughts on this.

 

 

If I need to swap trannies, I will snatch the one from my Z. I am just curious if I have to pull the motor because when I was under there... it didn't look like there was any room to slide back. That will suck.

 

I have a feeling though that keeping oil in the tranny will keep the problem from spreading, which is why I asked the first question about u-joints.

 

Thanks guys.

[I'm BLUE]

Who shortened the driveshaft?

Why no NEW u-joints on driveshaft?

why are you in 4th before 30mph :blink: ... of course ... it will vibrate :unsure:

 

2.1 quart trans capacity and only. 5 quarts came out?

 

 

Before swapping to other trans ...

get driveline balanced (if a home shirtening job)

and install new u-joints at the very least ...

or you will probably ruin it to ...

Put in new seals carefully ... in next known good trans ...

 

If it ran a while ... that low on fluid ...

your probably screwed and need to switch trans ...

But idk for sure ...

Redline 75w-90 if you want to treat your tranny right ;)

 

Before taking out

A trans shop can diagnose why driving truck

or at least narrow your issues and give an idea on prices

Be honest ... it gets issues solved faster

 

Good luck

[wayno]

If you solid mount a tranny, or an engine for that matter, your going to hear all sorts of noises, and feel all sorts of vibrations, thats just life with solid mounts.

BTW, if you solid mount a tranny, and you don't solid mount the engine, you might start breaking stuff, like the tailshaft of the tranny.

What truck is this transmission in?

When you made the tranny mount, did you check the clearances, or was the tranny just sitting on the cross member?

When we know more, it will be easier to figure out.

[josh817]

I must have had a typo. I put in about a quart of oil when I topped it off. Didn't realize it had oozed so much out the back since no symptoms showed! It was just like all of a sudden after a highway trip it was done even though the day before I did a highway trip just fine.

 

 

Drive shaft was shortened by a trusted shop. I told them no u-joints because I was broke at the time as in like in the $500 hole with my mom until I could get the truck on the road and sell my other car. They balanced it and everything was done well.

 

 

Rear seal was tapped in with a large socket and a small plastic mallet. I knew it was installed well because the first freeze plug I had put into the center hole on the flange was the wrong size and when I quickly slid the flange in the plug popped out! Everything was nice for a few weeks and then I started noticing oil on the underside again. It wasn't enough to draw attention and again, everything is butter smooth in the tranny, no noises until last night.

 

 

I forgot the weight I was using but I know it was the proper AL AT whatever 4 oil.

 

 

 

 

 

 

Any new thoughts based on this revised info? Motor has to be pull? I was thinking if I can pull the radiator and take off the fan, I can get the engine puller and instead of pulling the entire thing out, just slide it forward so the back of the tranny can drop out from the cross member. Unbolt her, put the new one on, go back into place. Doing that should angle the back of the block towards the ground and maybe help me align it easier.

 

Then again, at that stage I might as well just take it out and set it on the floor for super easy tranny installation. I don't like the idea of pulling the motor but I won't lie, it's only draining the water, taking the intake and exhaust off (was going to do that anyway) and undoing like... 2 wires. hah! But still, I liked how it played out when I did my Z tranny in 6 hours no hassle.

 

I already decided I won't get one rebuilt. I don't need a brand new tranny, I just need a working one and I cannot afford down time. My Z has the same tranny, same ratios and everything, and I have been wanting to do a KA tranny swap in the Z which makes me feel better for pirating from it. I just need to plan accordingly if I am pulling the motor in the 521 to do the swap. Account for any snaffoos I may run into so I don't get screwed and have to return to school car-less.

[wayno]

I see now that this is in the 521 section, so it is a 521.

One trick I found to get a modern 5 speed tranny(shortshaft) in and out of my 521 is to move the trans. as far back as you can get it, then remove the clutch cover/disc, then the transmission will drop out for me, but I use the 85 shortshaft tranny in my 521 work truck, I have no idea how hard it will be getting a longshaft out, there may be no differance as long as you remove the tunnel cover, and maybe the bench seat, that depends on how far the tailshaft sticks up when dropping the front of the tranny.

[josh817]

I will snap a picture of it really fast right now. Hopefully I don't get mugged outside lol.

[josh817]

Alrighty here we go.

 

There is indeed a rubber isolator. You will not in the second picture that there is a gap, I do need to fix that. It's overlapping on the mount from the way I welded it. However I do not see that as the root of my problem.

 

I want to say, if I remember correctly, the tranny was indeed lying on the cross member however the picture seems to show otherwise... There was not enough tunnel space to raise it up much and I didn't want it rattling on the tunnel if it was to load over. I can fix this while addressing my mount by drilling a new set of holes if need be.

 

 

Do note that all those bolts are tight, nothing is able to wiggle around.

 

[wayno]

You need to check the clearance on the second cross member, the one that the torsion bar ajustment is on, although with the longshaft, the driveshaft connection to the tranny might be in back of it, my short shafts driveline u-joint is right over it.

You do not want any metal to metal connections, it causes a lot of noise.

I am not a big fan of putting soft plugs in the tranny yokes, but it has been done before without issues.

The height of the tranny looks good to me, you need to find out where the leak is, check around the rear seal, check the yoke soft plug, there is not a lot of things that leak on these transmissions, unless it is cracked(the tranny), there isn't any other place except inside the bellhousing, and where the two cases come together, and neither of them throw oil around under the truck.

[wayno]

Make sure that the metal part of the tranny side of the mount isn't touching your tranny mount in this photo.

You can see when I made this mount, I had to cut the metal away from the sides of the mount where the tranny mount sides drop down.

[josh817]

Second cross member... I will take a peak tomorrow.

 

 

It is leaking from the rear seal, I know this for a fact. As you can see, it has been flung around under there.

 

 

I'm open to all possibilities and not doubting you but do you think this is really the issue behind a vibration that seems completely resonant?

 

It does not sound like it is coming from anywhere up front. It sounds completely from the rear of the tranny back, in the drive shaft somewhere. That's why I was saying I suspect that every time it vibrates at 25MPH it is breaking the contact surface with the seal and allowing fluid to come out. One drop of oil every few days while parked does not constitute the mess.

 

To answer the why 4th gear question.... I'm sure you already know how low these things are geared. I don't have a tach but I can cruise lovely in 5th gear at 30MPH and accelerate well. Lots of bottom end grunt, which is what I wanted, I stayed all stock when rebuilding except for a Weber DGV carb. 1st gear shift at 5MPH, 2nd goes to like 10-15MPH, 3rd to 25-30MPH, usually skip 4th and go to 5th for anything more. Quite handy in traffic! can idle down the road in 3rd gear without huffing!

 

I digress, it's nothing to do with being in the wrong gear to say the least. It happens in any gear, with a load, pulling through 25MPH. I won't load the truck up or tow anything until I get this resolved so I don't crack a case, break a UJoint, or anything else!

 

 

EDIT:

Say your second post, copy that. You can see the rubber mount is gapped there, again because in the picture, the two pieces I welded together overlap and it's sitting on the overlap bit. I can fix this, allow it to sit flat. I will do this on Friday when I'm out of school and doing the Ujoints. If the vibration persists I guess I could have a bad carrier bearing or an unbalanced shaft.

 

 

When I had the drive shaft shortened I only brought the front shaft that goes to the tranny. Should they have balanced both together? If they shortened and balanced the front shaft, and the rear shaft has been untouched would this screw things up?

[wayno]

I have no idea about longshaft 5 speeds in a 521 frame, all my 521s except for the work truck are sitting on 720 frames, and everything about that 521 work truck of mine is modified, it's a frank'n truck, the only stock things left are the cab and glass.

When one starts changing things, angles can change causing vibrations, like when one lowers the 521 enough, guys have been shimming the carrier up a bit, to keep the same driveline angle.

I don't know if you should have taken the whole 2 piece driveline in, as it has a slide yoke in the second piece, I can't see that as being the issue, but when you took the front half in, what did they say about the carrier, as it is part of the front piece?

[skyblue]

If the shaft was balanced and you're hearing a "ting" noise then i'd say it's your u-joints. and they will cause weird vibrations. Although usually i've heard you should get the drive shafts balanced together or they'll vibrate. Mine did that a few months ago and as soon as i replaced the u-joint it stopped vibrating and "tinging". The leak is a problem i've been having too and i can't seem to figure out where it's leaking from so sorry i can't help there but i'd love to know what you find out. I just lowered mine and now one of my u-joints is making a "ting" sound and truck vibrates at high speeds now. i feel your pain.

[josh817]

They didn't say anything about the carrier. I trust in them that if it was bad they would mention it. They mentioned UJoints are a bit old which is when I opt-out of that. When I take the drive shafts out on Friday I will check for extra movement in the carrier bearing.

[banzai510(hainz)]

Is trucked Lowered more than 3 inches??????

If so a spacer is neede under the carrier bearing

[datzenmike]

Pull drive shaft!!!

 

 

 

While it is out replace the rear seal, it's pooooched.

 

 

 

Get new U joints installed and that should fix your problems. These should always be replaced as a matter of course when doing anything to a driveshaft. How the hell was it possible to ballance it with old worn U joints in it??????

 

 

I swapped a 5 speed recently and the new transmission is actually holding the drive shaft slightly higher than where the 4 speed was so if this is the case here, you may have to lower or raise it to preserve drive line ankles to prevent vibrations.

[josh817]

Truck isn't lowered.

 

Balancing... I was under the impression they balanced without the flanges, otherwise every time you replace ujoints you have to balance it and I haven't seen anyone go through that extra step before.

 

 

Regardless, thanks for the help guys. Rockauto has cheap ujoints but just to get it done on Friday I'll stop by the local Napa. They're showing around $15 a piece and 6 for the rear seal. Not if it fixes it!

 

I'm going to have to look in the manual or eyeball the drive line real close to view the angle. I never owned the truck with a 4 speed so I don't know how it's suppose to look. I imagine just as straight as possible.