Banging from underneath when shifting

[Budweasel]

Thanks in advance to everyone who can shed some light on this issue.

I recently purchased a 1968 camaro and I am learning about its idiosyncrasies.

When shifting from 2-3 or 3-4 with 3/4 or more throttle I get a loud clunk from what seems like right side of car. Possibly near subframe connector or right leaf spring. Tonight I went into fourth with some more exuberance than before and the clunk came followed by the rear of the car mildly swinging to the left, (I'd guess no more than a foot). Shift happened near 60 mph as I was exiting an onramp to the interstate.

What could be causing this? What should I look for? Broken leaf spring? Loose subframe connector? Axle out of alignment? After losing traction at highway speeds right after the "klunk", I'm having safety concerns.

Background on the car: 489 cubic inch crate motor advertised as 575/575. Transmission is TKO 5 speed. Global West upper and lower control arms, Heidts lowered ball joint, Wilwood brakes, Hotchkis subframe connectors, leaf springs, and front and rear anti sway bars. Caltracs traction bars. Tires are 255 BFG g-Force KDW. I have not identified rear yet, (was told 3.55:1 ratio).

[Sieg]

Get it on a lift or jack stands asap and thoroughly check the health of all suspension components, mount locations, and frame rails.

On throttle application the top of the rear end housing is rotating back toward the fuel tank, during a hard shift it's snapping back.

Is the pinion bump stop on the car?

With 575/575 you roughly have twice the power the chassis was engineered to handle.

Let us know what you find. :thumbsup:

[Vince@Meanstreets]

I'd like to hear about the pre load or lack of in them cal tracks


Your gonna be looking for pounded rust dust somewhere on the suspension.

[Budweasel]

I have the car on stands now. I will report with my findings hopefully by end of weekend.

Cheers!

[Sieg]

Good for you! :thumbsup:

[GregWeld]

My guess is it's the pinion hitting.... Look for a "witness" mark of fresh metal or "damage" to the undercoating or paint above the pinion.

My guess is also that the dance / side step - is caused by the rear end not being in correct alignment with the front -- or "square" to the front of the car... you might take it in for a FOUR wheel alignment.

[Budweasel]

So far here is what I have found:

1. Front drivers side spring mount has one of the three bolts missing. Threads are bad, need to chase with tap in order to get the bolt back in.

2. When measuring between center of wheels on drivers side versus same dimension on passenger side there is a 7/8" variance. Passenger side of axle is farther back. Center pin on leafs is bent, looks consistent with out of square axle like Greg said.

3. U bolts on axle are not torqued properly. A couple on passenger side were less than 40 ftlbs, should be 120 ftlbs according to specs I found on Eaton's site. Could these being loose contribute to the bang?

4. All other fasteners, subframe connectors, body mounts, anti-sway bars, were tight.

5. I found no evidence of rotation between the shackles and the axle tube, (looked for fresh scratches, no grease, etc.). There is a pinion bump stop present and as far as I can see there has been no contact between pinion and stop or body.

6. I will check the caltracs preload when I get the car back on the ground. Maybe the right one has no preload and is "slapping" into the front spring mount?

For what it's worth. This has happened before but never so violently and it's only been me in the car. Last night when this happened there were three of us in the car; two in front and one in back. The person in back did not feel anything with his posterior NVH receptor. In case it matters: driver 215lbs, front passenger about 170lbs, rear passenger (sat behind driver) 280lbs.

Thank you all so much for your help. It's the people that make this site so wonderful!

Here is a picture of the right rear from in front of the axle.

http://i632.photobucket.com/albums/uu42/Budweasel/20150328_194323.jpg

[GregWeld]

It's hard to see from this one picture and the angle -- but it appears you may possibly be bottoming out the shocks. You said you had 3 pretty good sized boys in the car which would also be a contributor to that.


Tie a piece of string around the shock "rod" - and push it down against the top of the body.... then go out and hammer it just a bit so you're loading the rear end... come back and see where that string ends up as it's pushed towards the top of the rod.... Do this on both sides because that will be measurable to see the loading as well -- left vs right side.

The shock should have sufficient length so that you have an equal amount of compression and extension... and when sitting with weight on the axle (as though it were on the ground on its tires) the exposed rod should be about half of the total (so 2" of compression and 2" of extension = for 4" of total travel)...

Put the jack stands under the axle --- and then measure the exposed rod length. It looks short to me.

[Vince@Meanstreets]

Good eye, if that's full droop I'd say you are right.

Nevermind stand is under the rear.


You can see the dirt and clean section from the shaft seal.

[GregWeld]

Good eye, if that's full droop I'd say you are right.

Nevermind stand is under the rear.


You can see the dirt and clean section from the shaft seal.



Yeah -- but that's the driver side --- I learned a while ago (50 years?) that the passenger side loads pretty hard during throttle use.... LOL

[GregWeld]

Yeah -- but that's the driver side --- I learned a while ago (50 years?) that the passenger side loads pretty hard during throttle use.... LOL




Never mind -- it appears to have been taken from the front of the car looking rearward.... which would make that pic of the passenger side.

[Budweasel]

The picture is the passenger side. I was laying on floor in front of right rear tire. Sorry I couldn't get my camera and iPhoto to play together. I have an update available so maybe that will resolve my issues.

Today I took off the Caltrac at the axle spring perch on the passenger side so I could move the axle forward. I loosened the already "not tight" u bolt nuts and kicked the right tire forward so i could center the rear end. I lightly tightened u bolts and set car on ground, then bounced the rear a few times by pushing on bumper. I then proceeded to torque the u bolt nuts to 110 ft/lbs. I double checked measurements and now have the same distance from center of front wheel to center of rear wheel on both sides. I guess the car was crabbing before so now I'll be needing that alignment Greg mentioned.

I mounted the Caltrac bar onto the spring perch and went to adjust preload. The "bushing" on top is already against the top of the spring and I'm unable to adjust the bar, (I don't own a 1-1/8 wrench yet). I don't know anything about these things so I'll read up on adjusting them in a thread a found at yellow bullet forum. If I can't figure them out they will go away. I'm not sure they are helping anyway with the wheelspin I'm getting.

Something I didn't notice before is one nut is missing from the bottom shock mount on passenger side. The drivers side has a nut on both sides - passenger side just has one nut on the front side.

I will button up the rest of the loose / missing hardware tomorrow. Then I will borrow, or buy, an action camera so I can get video of the rear in motion. I will share with you what I am able to capture. Might be a few days though. Hopefully I can find a place to mount it that captures some evidence.

If this is in the wrong section I apologize. I thought it was a driveline issue... now I'm not sure. :EmoteClueless:

[GregWeld]

The CalTracks are there to help you with WHEEL HOP --- not really "traction" bars .... They'll keep the leaf spring from wrapping up and creating the wheel hop - which if you experience violently -- will break parts like no tomorrow! Leave 'em on -- just get 'em set right.


NOW TO MY CONCERN.... maybe you explained it wrong - or I read it wrong -- but here's what I'm concerned about.


On the TOP of the spring - there should be a small "post" which fits into a hole in the spring perch mount on your axle. This is there to INDEX the rear end to the center of the springs (fore and aft). The U bolts simply hold the perch tight to the spring. The perches are welded on the axle tube with the correct (stock location from the factory) pinion angle (again - this is as from the factory when built).

My issue is I don't think you should have been able to move the AXLE fore or aft -- if it was properly indexed on the posts! Maybe the posts are missing?????

In order to see them -- you'd have to loosen the U bolts enough to allow the axle to go up away from the spring enough for you to see them (probably 1/2" or more). They need to be in place of your axle will move on the spring and just be out of alignment again.

[Budweasel]

Greg,

That is bad news. When looking up from under the spring I could see what looked to be a post or bolt that was bent nearly flat toward the rear of the car. That was my second indication the axle was not centered, which caused me to get out the plumb bob and measure everything I could. That is when I found the 7/8" variance.

Sounds like this spring issue has moved to priority one. Is the post part of the spring or is it a boss on the axle?

Is it possible the kick I described when going into fourth was the axle moving back on the spring? Maybe I just broke that part and the banging and axle misalignment are not directly correlated.

Thanks again for all your help and interest in this. I owe you guys a beverage. Maybe I can make good on that if any of you are doing St Louis leg of power tour.

[GregWeld]

Sorry Jason -- Your description isn't very good.... so I'm not sure what you're looking at from where.

You should have to SEPARATE the perch from where it sits on the spring.... and a post should be between there to index the axle.


http://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0CAcQjRw&url=http%3A%2F%2Fwww.efsstore.com.au%2Fleaf-springs.html&ei=06sYVeEyz6iiBOb3gEg&bvm=bv.89381419,d.cGU&psig=AFQjCNE5dWgT0H7l0PBX8WIw2fcv5IyyZg&ust=1427766519967673


The link should take you to a picture of a leaf spring -- you'll see the post in the middle -- on TOP of the spring. That post should fit in a hole that is in the perch welded to the axle.









Greg,

That is bad news. When looking up from under the spring I could see what looked to be a post or bolt that was bent nearly flat toward the rear of the car. That was my second indication the axle was not centered, which caused me to get out the plumb bob and measure everything I could. That is when I found the 7/8" variance.

Sounds like this spring issue has moved to priority one. Is the post part of the spring or is it a boss on the axle?

Is it possible the kick I described when going into fourth was the axle moving back on the spring? Maybe I just broke that part and the banging and axle misalignment are not directly correlated.

Thanks again for all your help and interest in this. I owe you guys a beverage. Maybe I can make good on that if any of you are doing St Louis leg of power tour.

[Vince@Meanstreets]

very true.

[Budweasel]

I took a few pictures today to help with my inadequate vocabulary.

I ordered a new shock mounting bolt from QA1 this afternoon from Amazon. Should be here Thursday. Below are a few pictures. I'll report back after I get the shock mounted on Thursday.

Shock mount with no nut on rear facing side
http://i632.photobucket.com/albums/uu42/Budweasel/2015-03-30160004.jpg

Shock mount threads stripped
http://i632.photobucket.com/albums/uu42/Budweasel/1968%20Camaro/20150330_172339.jpg

Shot of "stud" coming through Caltrac perch. This is what I was trying to describe. I don't know the proper terminology, bear with me. Also note the 1/4" of clean threads after torquing the u-bolts to 110.
http://i632.photobucket.com/albums/uu42/Budweasel/2015-03-30160134.jpg

[GregWeld]

The Caltrac is on the bottom of the spring -- and it's formed a sandwich with the perch on the axle -- with the spring being in the middle.

There is another bolt/stud like that on the top of the spring - that should fit up int the perch that is welded to the axle (hopefully)

[Budweasel]

I took spring down by backing off u-bolt nuts to end of u-bolt. Then I was able to see the boss on top of the spring that is supposed to go into the spring perch to locate it. Problem: no corresponding hole in spring perch. I guess this is not the correct rear end for this car.

It looks like this spring pad is an adapter of sorts. I looked it up and it's an Energy Suspension universal type application.

I don't know what else to do but button it all back up and make sure the u-bolts don't get loose again.

Here are some shots.
looking up above spring
http://i632.photobucket.com/albums/uu42/Budweasel/Mobile%20Uploads/CameraZOOM-20150331171836789.jpg

closer shot of perch with no hole
http://i632.photobucket.com/albums/uu42/Budweasel/Mobile%20Uploads/CameraZOOM-20150331171858221.jpg

http://i632.photobucket.com/albums/uu42/Budweasel/Mobile%20Uploads/CameraZOOM-20150331171953415.jpg

mystery rear end
http://i632.photobucket.com/albums/uu42/Budweasel/Mobile%20Uploads/CameraZOOM-20150331172943183.jpg

http://i632.photobucket.com/albums/uu42/Budweasel/Mobile%20Uploads/CameraZOOM-20150331172958093.jpg

[GregWeld]

So the CalTrac has a locating hole and post off the bottom of the spring - and with that bolted to the axle housing via the U-bolts -- the rear end won't move - so it's "okay" - as long as those bolts stay torqued.

My guess is -- when they were loose - it was allowing some (minor) movement which is probably why that lower "post/bolt" was a bit damaged.

There appears to be a spacer in between the spring and the axle perch... and you can see that it has a hole in it. That would have sat over the post if there was one on the top of the spring. Sometimes those spacers are tapered and are used to get the pinion angle correct. Yours appear to just be spacers to lower the car half an inch or so.

Put some RED Loctite on those U-bolts so those nuts won't come loose again.

[GregWeld]

I took a few pictures today to help with my inadequate vocabulary.



Your vocabulary is fine --- describing some of this stuff is difficult when trying to do discussions like this via "the web".

[Budweasel]

Thank you all for the help. I have the problem solved.

Both bolts that go through the springs were broken. This allowed the leafs to shift fore and aft; affecting suspension movement in unpredictable ways.

Bolts replaces, axles centered, all good!

[Sieg]

You might consider stouter leafs in the car. The Global West L2's are dimensionally larger, enough that you can use the isolator pads in the perches.
They aren't exactly plush riding though. :)