dalet

Still trying to get the bugs out of my 87 ta,
I put a new set of toyo's on the rear to eliminate shaking over 63 miles an hour. Car still shakes after having wheels balanced by four different garages. They say the wheels and tires are next to perfect, but it still shakes... The car sat for probably a number of years before I bought it about 3 weeks ago. There is absolutely no rust under the car. It looks like it was made yesterday. The rear end howls like it has been worn out, but there are no signs of an oil leak or anything. I've driven other chevy's with the same noise in the rear end, but they never shook. The odometer says 96 thousand miles. Could the bearings on the axle, wheel bearings, or rear end gear bearings cause a shake at about 65 and over? The wheels themselves are 16X8 which looks mighty wide to me. I'm wondering if the wide wheels have caused excessive wear to the axle bearings or something... Can anybody clue me in on what to look for?? Thanks, Dale

toomany

16x8 sounds like a factory wheel.

If you can hear the rear end making noise, I'd look there for the vibration. Check the u-joints and while you're down there grab the pinion and try to move it around. If you can move it (up/down/left/right/in/out), the bearings are bad. If that checks out to be good, it could be the wheel bearings. I've never experianced it, but have heard that bad wheel bearings can/will cause a vibration.

stealtht/a

iTrader: (1)

mine has a similar vibe. im pretty sure its because the rear track bar/panhard bar bushings are toast. if you push the rear of the card sideways, is there squeaky movement?

Stephen

iTrader: (12)

Bent driveshaft/worn u-joints/bent axle(s)......Could be any of those things, a combination of, or even something else entirely.

dalet

Alright,
I've finally got a couple of responses to some of the suggestions of everyone. The car is still in the garage, (the 87 305 ta.) I ended up taking it to a place which I won't mention the name for now, looks to be kind of a speed shop a guy owns where he works on the older muscle cars. He's had the car for about a week and a half. I told him the problem I was having with the shaking in the rear and so he took the wheels and had them once again for the fifth time now, balanced and "checked". Everyone says they're good! So he commensed to doing other things to rule them out as the problem. So far he has changed front and back u-joints of drive shaft. He has today had the drive shaft balanced which didn't need much. He has pulled the rear end apart, replacing the spider gears which he said were pitted and not to be put back in that way. He informed me that it cost him several trips to the supply shops because it was some kind of 'rare spider gears' in a 2.73 highway rear end??? He says that after all this, the car still shakes and he's afraid to drive it fast around the small town because of possibly getting a ticket... When he runs it on stands in the garage, he says he can see no movement or shaking in axle. He wants to check front wheels when there is no shaking in steering wheel whatsoever. Personally, I think it is either a wheel or the Toyo wide tires. If the car wasn't in such good condition (rust wise) I probably wouldn't put so much into it, but my wife and I need a good ride to cross the country with before we get too old to appreciate it that aint gonna fall apart all the time like a honda. The newer cars don't look good to me. I guess I'm old fashioned. I'm not the most knowledgable as you can tell and I'm beginning to start forgetting some of my old car knowledge. We've been shopin lately for bullets for our deer guns and I got the numbers mixed up with rear end gears. Just spent 45 mins trying to find road gears for the 87 ta. Wife used to shoot a 243 and now she shoots a 223, like my old m16 in the war. Maybe we should've put the 223 in the rear end just to see how it would do?? If they got in the way, it might mow down a water buffalow or two... So far, I've kept it together. I hope I'm good for another few years or so...

UMI Sales

Hello
Like mentioned above I would look to see what type of shape the bushings are in. The number 1 thing that kills a rubber bushing is storing it over a long period of time. And its possible if they are ruined they could cause the rear to be shifted just enough to get a whining noise. That is just something else for you to consider. If you have any other questions feel free to ask and I will be more than glad to help.
Thanks
Brad

dalet

Brad,

I asked the mechanic to check the sway bars out and he said they all looked ok. I don't know if he pushed on the side of the car out though. I'm planning on picking the car up on Monday and will ask him once again to check the bushings out. Another thing he found when removing the drive shaft to get it balanced was the transmission end had spindle gears twisted. It was causing the drive shaft to fasten on and stick to the spindle. He replaced the yoke on it and is planning on driving it to see if it took any of the shaking out. Thanks for your advice. I'm taking all advice very seriously...
Dale

dalet

Follow up on the shaking 87 ta,
I picked up the car from the shop and brought it home today. It still shakes. The mechanic was at his wits end and said he couldn't do any more to it without sending the trans. to a trans mission shop to have taken apart and examined mainly to see if the tourque converter was causing the problem. In short, the whole process of overhauling the trans would cost me around $1000. I don't have that kind of money, especially after having all the things done to it already.

Maybe someone out there who is experienced with gm, or trans ams would have an idea of what to do next. The trans is a 700R4 that's hooked up to a 305. One of the things not mentioned on the bill was that he took all the wheels off and put on another set all the way around, took it for a test drive and said it did the same thing. I don't know the shape of the wheels he tried and am still inclined to think that the problem is in either the brake drum, wheels, or the new toyo tires I put on the back. The trans shifts so smooth that I would be amazed if it was the problem. The car has a little over 96000 on it. Another thing to mention is that the front yoke of drive shaft was stuck on to the spline of the trans mission. He found that the teeth in the inside were twisted. Personally I think that when ever the damage was done to this part, the same damage was done somewhere else down the line. The car hasn't been abused and is like new. I think it was probably a one time happening and nobody wanted to spend the money to fix it which was probably the reason it sat so long without being driven. There is absolutely no rust on bottom of car and it is a Kentucky car. It feels to like it's on the tire or wheel, but I'm not a mechanic... When I took the wheels off the back, one of them practically fell into my lap. I've never seen that before. He said he checked the drum and axles, to what extent, I don't know. Any other suggestions would be appreciated

Dale

Stephen

iTrader: (12)

On jackstands, in gear & revved like driving (not "raced"), do you get the vibrations? That should narrow it down to the driline or, at least, the wheels & tires. Without feeling it myself, I can't say whether the vibes you are feeling are coming through the fronts or the rears.

Got a buddy who you can borrow his known good wheels & tires from, for a spin around the block?

AM91Camaro_RS

If the teeth (splines) inside the yoke are twisted, I would say your problem is there or the driveshaft. try finding another drive shaft to put in it. Surely you can pick up a used steel drive shaft cheap to put in it. The next question is, are the splines messed up on the output shaft of the trans?

Blind Driver

Late model aluminum shafts will also fit.

ziggy89

drum brakes? ive seen drums through the weights and cause the same problem. and if its a howl in the rear it sounds like bearings to me. probably a wheel bearing if it sat wich can cause a vibration. a whine is usually associated with gear noise.

dalet

shaking ta,

The drive shaft was balanced. The twisted yoke was replaced. They said they put another set of wheels on it and drove it. They said it did the same thing. They said the brake drum looked ok, but it fell into my hands when I was taking one of the wheels off.
I'm gonna continue to look at the wheels and the tires for the problem. Does anyone know what the chances of this smooth shifting 700r4 are for it to have something wrong with the tourque converter?

Thanks for the many responses to my concern,
Dale

dalet

shaking ta,

I'm wondering what other damage could have been done when the inside of the yoke got twisted. Maybe it also twisted something on the spline shaft going into the trans? Today while on a divided highway at 80 mph I dropped it into neutral to see if it shook when out of gear and it continued to shake. I'm still thinking it is probably a wheel or tires. Is anyone familiar with something like this happening? I just put 700 dollars into this to eliminate the shake and no one can seem to find the problem...

ziggy89

does it get worse the faster you go???

i no its been said before but check the u joints. if one of the is tight it can cause a vibration problem. when installed check for slop. pull it out and make sure they they swivil easy. ( the trans yoke should fall under its own weight)

dalet

Now that the yoke has been replaced, because of it being twisted on the inside to where it was sticking to the spline, it works smoothly. One thing I've noticed when driving the car is that there is a lot of slack between reverse and drive and it takes a second or two before it engages when taking it from reverse to drive. I have to be careful not to give it too much gas, or it will be like popping the clutch on a stick shift car. I don't know much about working on these things and so I have to pay some one to check these things out and I'm about out of money. The trans otherwise shifts very smooth and seems to work real good. The universal joints on both ends of the drive shaft were replaced and the drive shaft was balanced and they said it was only out of balance a little bit. It starts shaking around 65 mph and keeps shaking strong about the same, no matter how fast you go. Thanks for getting back with me about it, Dale

Blind Driver

What rpm does the shaking start?
Does it shake in all gears at the same rpm?
Does it shake only in od?

jb3829

iTrader: (1)

before I replaced my open 2.73 rear with a used 3.23 posi.....I had no vibration at highway speeds (65 mph and up). After I swapped rearends, I noticed a vibration at 65mph and up to the point where the dash bounces up and down rapidly. The vibration is felt in the seat not the steering wheel. I replaced the wheel bearings and seals before installing the rear, upgraded the old discs to the pbr setup, kept the same driveshaft, ujoints & tire/wheel combo. I checked to see if the axel shafts were spinning true with the rotors off. (I know....I only eyeballed it, but didn't see anything out of the ordinary). So I'm guessing the problem is somewhere in the differential itself. Maybe someone rebuilt my differential at some point....who knows. Hope this helps

dalet

It looks like I've got to check some things that the mechanic said he already checked. I think the first thing I'll do is get it up on jack stands and see if I can feel the vibration with the wheels off the ground. Then I'll get someone to replace the sway bars bushings if it's not too expensive. After that, I don't know what I'll do. Thanks for the info from everyone!

jb3829

iTrader: (1)

I'll bet my bottom dollar it's not the sway bar bushings......I had poly bushings on before and after the swap AND I use them on the rears of my pathfinder and quest. If I hadn't reinstalled the driveshaft in the SAME position it came off, I'd say maybe that was the culprit. It's gotta be something in the gears.....these cars are 20+ yrs old.....who knows what's been done to them since then

Guest

I gaurantee its tranny related. You have had a reputable hotrod shop (sounds like that does custom stuff- since you listed he works on alot of muscle cars) that is used to alterations in drivetrains and the normal basic culprits of virbrations.

Lets look at the facts.-
You have ruled out wheels and tires, driveshaft, u-joints, rearend, and I can tell you from my own expertize in suspensions it is not suspension bushings casuing this.
You have told us and yourself a major clue- Twisted spines on the tranny yoke. What about damage to the output shaft on the trans splines and other internal damge tot he trans DUE TO WHAT EVER CAUSD THAT SPLINE DAMAGE. Those splines have to mate as the suspension articulated AND as the critical speed of the drivetrain increases. You can not replace a trans output shaft without removing the trans.

the other two things that cuase vibrations are cracked flexplate and a bad harmonic balancer, BUT both of those as well as any torque convertor problem (aka flexplate area) would be rpm sensitive and not just speed sensitive.

Remeber, part of the trans is speed sensitive, part of it is rpm sensitive depending what gear you are in (could have a bad gear internally you shift to, etc). The output shaft is speed sensitive, the imput shaft is rpm sensitive.

Good luck. I know things like this are frustrating especially in the pocket book.

Dean

dalet

It's been a while since responding to anyone about my shakin' 87 trans am and would like to give a situation report on it. I found some one who was able to take my rear wheels and tires and get them road force tested for 30$ per side. They took the majority of the shake away, but it still shook from 70 on up. I figured then that it must surely be the tires. Took them back and the tire folks gave me a new pair of Ventus HR 2 which are a cheaper version of the toyos I had. At 65 or 70 and above it still shook. The tire man noticed that the rear wheel on drivers side, could be moved at top and bottom, not on the sides, enough to look a little sloppy. I plan to look at rear wheel bearings and see if that might be the problem. I've replaced front bearings before, but not rear wheel bearings. Can anyone tell me how to go about it? I'm also thinking there might be something wrong with the hub...

dalet

jb3829

iTrader: (1)

Check this out
https://www.thirdgen.org/forums/tran...ing-axles.html

I installed new bearings in mine and still have the "shakes"

dalet

Dale T, and my shakin trans am.

I finally ruled out about everything I can think of to the best of my ability and the ability of several other people. When I bought the car, I figured it would be factory ok, especially because it was GM, like most of my other cars in my life have been. But, not so exactly. For some reason, they chose to put 16" wheels and tires on them which I thought they knew what they were doing, so ok. It's the first time I had to think about tires and wheels that size, so I never really thought about it that much. The deal is this, the wheels are too close to the ground and there's not enough clearance between the tire and the wheel to take up major impact such as with pot holes, curbs and other obstacles that get in the way. Also, if the tire gets just a little low on air, there is nothing to protect the wheel from getting banged real good. I believe that most of the damage will be to the front wheels because of carrying all the weight of the v8 motors. I had two wheels shipped to me from Boston from a private owner who said they ran smooth on his car, but both of them, which were front wheels had just enough dent in the rim that it made my car shake at just under 70 miles an hour. And so I am still unable to take my wife for a trip across the country on the expressway with it. A new wheel, from what I can see on the internet, costs over two hundred and fifty dollars. We don't really want to have to buy one or two of them, brand new. For now, she is going to help me switch the wheels to the back of the car so I can spin them to find the dent and try to pound them out. The dents are so small that you can just barely see them. They showed them to me at the tire store. If anybody has what they know is a perfect front wheel for sale that is much less than 250 some dollars, please let me know. They're 16"x8 20 slot wheels on an 87 trans am. Take care for now.

dalet

A question for 87 trans am specialists,

First, I got rid of the shakkin problem. The front wheels were dented slightly, but got a couple of them that weren't too bad and they seem to be ok. The problem with the shakkin was due to a bad rear end. Someone had hammered it somewhere along the line. After taking a ride on the highway and then putting it up on a hoist, we could feel a mighty hot rear end cover. The drive shaft hook up on the differential was slightly out of round and when you spun the axle, you could feel that the bearings inside were shot. Anyway, it goes pretty smooth now, but after changing the rear end, the speedo appears to be off about ten miles an hour or better. They tell me that all trans am 87's have the same gear ratio, and that I shouldn't have to worry about the gear ratio being different. I'm trying to educate myself a little before getting back with them on this. They said they can recalebrate the speedometer for me, but why should they have to if the rears are all the same gear ratio. Could it be that the one that was originally in it were incorrect? What's the scoop on the factory rear ends. I'm trying to get good mileage and have low rpms at top speeds.

Thanks!

Stephen

iTrader: (12)

They are far from "all the same".

There was the 9-bolt & the 10-bolt. Neither have the same gears. Close, but not quite. Maybe close enough to use the same speedo gears, but I dunno & doubt it.

Do you have a 9 or 10? What was in there before? (count the # of center section cover bolts...9 bolt heads=9-bolt, 10 bolt heads=10-bolt) Or even faster...9-bolt rears have a rubber plug that can pop out,. 10- bolt rears don't.

dalet

A question for 87 trans am specialists,

First, I got rid of the shakkin problem. The front wheels were dented slightly, but got a couple of them that weren't too bad and they seem to be ok. The problem with the shakkin was due to a bad rear end. Someone had hammered it somewhere along the line. After taking a ride on the highway and then putting it up on a hoist, we could feel a mighty hot rear end cover. The drive shaft hook up on the differential was slightly out of round and when you spun the axle, you could feel that the bearings inside were shot. Anyway, it goes pretty smooth now, but after changing the rear end, the speedo appears to be off about ten miles an hour or better. They tell me that all trans am 87's have the same gear ratio, and that I shouldn't have to worry about the gear ratio being different. I'm trying to educate myself a little before getting back with them on this. They said they can recalebrate the speedometer for me, but why should they have to if the rears are all the same gear ratio. Could it be that the one that was originally in it were incorrect? What's the scoop on the factory rear ends. I'm trying to get good mileage and have low rpms at top speeds.

Thanks!

dalet

Stephen,

They both have 10-bolts.
I just looked at them.

Stephen

iTrader: (12)

OK....

The gears inside could have ranged from a 2.73 up to a 3.73.

You can check both by rotating the brake drum/disc & counting how many times the pinion rotates, for 1 revolution of the brake.

2 3/4 turns = 2.73
3 turns = 3.08
3 1/4 turn = 3.23
3 1/2 turns = 3.42 (but i'm thinking that is a 9-bolt gear ratio, can't recall)
3 3/4 turns = 3.73

Do that to both rear ends & see what the gear ratio of each is. I'll look for the corresponding gears that work for each ratio.

Stephen

iTrader: (12)

Found a chart for the gears.....
http://www.austinthirdgen.org/index.php?pid=39

And info on changing them if you have a 700R4 tranny......
http://www.austinthirdgen.org/index.php?pid=6

micktroup2

Check the torque arm bushing up by the trans...

dalet

Stephen,
The pinion goes 2 3/4 turns to one rotation of the end of the axle. The man at the shop told me to go out on the highway and do a check, by going 60 miles and hour between 1 mile markers along the road and time it. It was 70 seconds per mile which I think makes the speedometer about 10 miles an hour too fast. I've been hoping to have a high gear rear end that will keep my rpms down for gas milage on some long trips this summer. What do you think about it? I've also got some bad valve seals that make it smoke when you first start it up. It doesn't appear to be burning any though. I'm wondering whether to just replace them, or do more to the heads for better mileage and performance?
Thanks!

Stephen

iTrader: (12)

Sounds like you went from a 3.08 to a 2.73.

I assume the new rear gives you the 2 3/4 turns? Does the old rear give you 3 turns? If so, there is your 3.08 to 2.73 swap, which should help in highway mileage, but could hurt mileage if you do a lot of stop-n-go, like downtown or heavy highway traffic that stops a lot.

dalet

Stephen,
The 2.73 is the old one and I haven't checked what the new rear is yet. The 60mph test was done with the new rear and it reads 10 miles an hour faster than what it should be. Would maybe a 3.08 rear account for the speedo being off by that much?

Stephen

iTrader: (12)

You could try this..... http://www.wallaceracing.com/gear-speed.php

Using 4th gear, will give you a 1:1 tranny ratio. Try different gear ratios & it will tell you what RPM you should see at what MPH.

kit-ss

iTrader: (1)

Never trust a balance of an old drive shaft, just get a new Aluminum one. Solved my vibe instantly after throwing all sorts of parts at it.

The first thing I did was balance the shaft and 6 months later AH HA!!