Shudder from a stop after a bang :-(

[budwich]

Was at a stop light waiting for the advance left turn signal. Came on and went to move forward with moderate gas. Bang on the front passenger side, "lifted vehicle in the air" like I jumped a curb or hit a bit pot hole (none visible). After that, I can feel a shudder taking off from first to 2nd, then seems ok after that although I haven't done significant "testing". On the road at high gear, and kicking down to 3rd or 2nd doesn't seem to have any issue. Of course, the vehicle is moving at that point.

Any guess as to what or where to look. Shudder to me always points to the tranny or torque converter. The thing that I don't understand is the "large jump / bang" at the front end on the passenger side.

As far as history, I bought the vehicle (2008 trailblazer 4.2) used in 2013. Don't have any history before that but with readings of here, I changed fluids (tranny, transfer case, cooling system) and have done transfer case at least twice since along with the tranny again as part of adding a transmission cooler. The vehicle has about 260kkm currently... and I need more cause they don't make this size and capability any more....

 

[Mooseman]

Maybe clutches failing would be my guess. What's the fluid like?

 

[budwich]

Tranny fluid looks ok (on the stick)... doesn't smell "bad".

I have tried stepping on the brake (ie. holding the vehicle at rest) and lightly increasing engine rpm to 1500 or so. Don't feel anything "slipping" / jerking. Doing the same in reverse, also OK. I also tried 4w activation (ie. 4w lo) in the same "brake hold". Didn't notice anything different there.

Checked for mis firing... all counts are zero (in history and current) so it doesn't appear to be engine related.

Manual shifting, starting at 1st, doesn't seem to have an issue although I only went thru sequence once.

 

[Mooseman]

I dunno if a Tech 2 could be useful here. I don't think it can give actual gear clutch slippage.

 

[JayArr]

To get from 1rst to 2nd the band engages and then because of that the forward low roller clutch disengages.

If it's shuddering from 1 to 2 then either the band is not fully engaging which could be a servo problem or the forward low roller clutch has had some sort of failure and is not quickly disengaging.

 

[budwich]

thanks for the info as this type of "failure" is way beyond my knowledge outside of "shudder ain't good"... :-(

Its probably not related to the shudder but maybe related to the bang. I crawled around under the vehicle to look to see what areas around the transfer case, transmission, motor and front end. Didn't find anything there directly obvious.
Also did some "brake pedal on, tranny in drive, light to medium gas (1500rpm or so). The driver's side motor mount lifts significant compare to nothing on the passenger side. I guess the engine torque is a lift on the driver's and a "crunch" on the other so somewhat expected but may the mount has past its life?

Since I was under / around checking things... dropped the passenger tire to look close at the hub. It seem good with no detectable "bear noise" that I have heard in the past (twice replaced... one original and then a failed replacement).

Anyway, the tires haven't been rotated in a while (my bad) so I thought to rotate that side. Pulled the rear passenger tire off and saw that a component of the suspension was "cracked". Not sure when that happened but maybe that was the bang that I heard. My question is. what is that part called? Somewhat related... but is it possible that the part is putting strain on the drivetrain causing issues for the "line" of power from front to back?

 

[JayArr]

Cracked? That's broken in two!

That part holds the rear axle at a 90 degree angle to the centerline of the vehicle. It's very important and may be the cause of the shudder, maybe the rear axle is moving around or 'shuddering' at low speeds.

It's called a rear trailing arm and it's only about $20-$30 and changes with two bolts. Time to call Rock Auto.

 

[Mooseman]

It's also known as a control arm.

Autoshack also sells them. Free shipping from their Stittsville store (or pick up)

Rear Upper Control Arm Driver or Passenger Side | CAK636 | AutoShack | AutoShack.ca

Discover a wide range of Rear Upper Control Arm Driver or Passenger Side at AutoShack. Order your CAK636 today and enjoy great prices, fast shipping, and excellent customer support.

www.autoshack.ca

Buy the pair if you want to replace both sides at an even more advantageous price:

Rear Upper Control Arms Set of 2 Driver and Passenger Side | CAK636PR | AutoShack | AutoShack.ca

AutoShack: Your trusted source for Rear Upper Control Arms Set of 2 Driver and Passenger Side . Order your CAK636PR now and experience the best in quality, affordability, and customer satisfaction.

www.autoshack.ca

 

[budwich]

thanks.... I just rotated the other side tire and yep, that side is gone also.
thanks for the link.... I assume at this point in the metal, iron is iron is iron so any parts will do. I can walk to their store.... I am assuming in store pickup works.

Is this a "one day / diy" or do you need a "cutting torch" to get the remenants off ...

 

[JayArr]

Depends on the bolts. Lots of liquid wrench may be enough.

 

[budwich]

Cracked? That's broken in two!

That part holds the rear axle at a 90 degree angle to the centerline of the vehicle. It's very important and may be the cause of the shudder, maybe the rear axle is moving around or 'shuddering' at low speeds.

It's called a rear trailing arm and it's only about $20-$30 and changes with two bolts. Time to call Rock Auto.

Here's hoping. Of course, my u joints are original so they probably don't appreciate "deviating" from their last 15 years of "positional orbit".

 

[Mooseman]

I've never had an issue with those bolts so it should be an easy fix.

Yeah, a lot of their stuff I wouldn't buy since it's CCC, like their hubs, brakes or ball joints. But for solid pieces like this, they should be alright. I'm waiting on a pair of upper A-arms from them shipped through UPS free (why would I drive and burn my fuel to get them).

 

[budwich]

I've never had an issue with those bolts so it should be an easy fix.

Yeah, a lot of their stuff I wouldn't buy since it's CCC, like their hubs, brakes or ball joints. But for solid pieces like this, they should be alright. I'm waiting on a pair of upper A-arms from them shipped through UPS free (why would I drive and burn my fuel to get them).

the links that you posted seem to be dead this morning. maybe they are no longer in stock. :-(
It seems that there site is down... always happens when you need something...

 

[Redbeard]

I checked also and it shows website down, but info was still on the page. I found a phone number on the page that did pull up, maybe give them a call.

Call Center Phone & Hours​

• Toll Free Assistance
• 1 (866) 990-3871
• Mon to Fri: 8 am to 7 pm EST
• Sat: 9 am to 6 pm EST
• Sun: 9 am to 5 pm EST

website used: https://www.autoshack.ca/CAK636

 

[Mooseman]

Main site is ok but says there are no parts available for it. Gives an internal server error. Call them. I'm sure they have them.

 

[budwich]

site finally came up.... they only had 2 pairs here in ottawa. Grabbed one, now the fun part, rust here I come

 

[JayArr]

When you go to the store see if you can buy new bolts in case the ones on your vehicle are rusted to the inner metal sleeve of the bushing.

Do you have acetylene? It's not necessary but it sometimes makes a hour job only 5 minutes long. Hack sawing a rusted bolt is no fun.

If you don't have acetylene you can look at the MAP gas kits at Canadian Tire,

General PDP Template

www.canadiantire.ca

If it shortens your job by a couple of hours it'll be $120 well spent. I used a kit like this for years before I bought my acetylene torches. The gas is more expensive because you're buying it a small bottle at a time and retail but it does a great job of freeing up rusted nuts and bolts under the car.

 

[budwich]

OK... bolts came out readily... appear to have been treated with "factory anti-seize / "silverish zinc". Anyway, the main fun part was getting the left over front end "knuckle" out from the receiver. That took lots of swearing. Anyway, it does not look good for a long lasting fix as the picture shows what was waiting on the other / inside thereafter. :-( .... a significant rust out at the base of the inside nut area. Hopefully, there is enough left to give some service life. Comments? Is this a "death nail"?

 

[Mooseman]

It can be. It's a bitch of a repair with a welder. If there is still some good metal, maybe weld some plating to reinforce it. Treat and protect that whole area.

That's why I get it oil sprayed every year and even that may not prevent the inevitable.

 

[JayArr]

I've seen worse.

The outer metal looks intact and still quite thick so the inside rust may not be death nail.

As long as you can get the bolt to tighten up to specified torque then I'd keep driving it.

If the outer 'cup' eventually shears off then the repair will actually get easier, at that point you can weld a flat gusset across the frame and over the entire hole and then weld a new 'cup' onto the gusset. The new 'cup' doesn't need to be that molded or curved, it could be cut from a 3" piece of U-Channel. That's probably a pretty easy weld job.

For now I would treat the rust with Naval Jelly and then some rust paint to stop the rust so it doesn't continue to deteriorate.

What's the other side look like?

That picture sure makes me glad they don't use salt on the road in British Columbia.

 

[budwich]

The other side looks better with no visible hole but rusted.....BUT I have another problem. :-( So the removal was easier since I "learned" a technique to open the "cup" up more / easier (ie. thin chisel)... but trying to get the new part in, it doesn't align front to back. Its almost like the angle is wrong on the part.... visual it looks similar to the removed part. I didn't compare the two new units because they were in seperate boxes... mistake maybe. So the question is, do I actually have to lift both sides of the back end (both sides off the ground) to get things positioned.

When I did the first side, the arm basically dropped easily into position in both cups.
I can easily put the arm into the front cup. So I guess, I then need to leave the thing in free space at the back. Mount the tire back, drop the vehicle on to the back tires and then lift both tires off the ground thereafter to get the rear "aligned"?

 

[budwich]

It can be. It's a bitch of a repair with a welder. If there is still some good metal, maybe weld some plating to reinforce it. Treat and protect that whole area.

That's why I get it oil sprayed every year and even that may not prevent the inevitable.

:-( "treat and protect"... :-( I have never had / seen much success try to stop significant rust with anything beyond "cutting and replacing" which I am not capable off. I guess I am going with the "gamblt" of some rustoleum type paint and hope.

 

[budwich]

I've seen worse.

The outer metal looks intact and still quite thick so the inside rust may not be death nail.

As long as you can get the bolt to tighten up to specified torque then I'd keep driving it.

If the outer 'cup' eventually shears off then the repair will actually get easier, at that point you can weld a flat gusset across the frame and over the entire hole and then weld a new 'cup' onto the gusset. The new 'cup' doesn't need to be that molded or curved, it could be cut from a 3" piece of U-Channel. That's probably a pretty easy weld job.

For now I would treat the rust with Naval Jelly and then some rust paint to stop the rust so it doesn't continue to deteriorate.

What's the other side look like?

That picture sure makes me glad they don't use salt on the road in British Columbia.

hmmm... I haven't used naval jelly. I guess I might have to at least redo that worse side... although I am not sure how much more "playing around" the cup and the beam can take.

 

[Mooseman]

May have to move the diff up or down so the Panhard bar brings it into line.

 

[budwich]

May have to move the diff up or down so the Panhard bar brings it into line.

?? I have to look at what the panhard bar is not how this can ever be aligned. Here a picture of the back cup. The control arm knuckle is basically askew with the cup. The front cup / knuckle has not be bolted in because I can't align the hole straight thru at that point as the control arm then bangs into the body frame member.
I think maybe I have the thing reverse... :-( maybe.

ADDED: I just went and reverse the ends... of course it fits. I was going by the labelling stamp on the arm which i thought should be up.... but I guess the arm is NOT symetrical...

 

[budwich]

ok... switch around should have been obvious. Anyway, they are installed (I had to jack at the shock mount to cause a rotation forward a bit to get the back knuckle to align) and I will go from there with the "cancer", praying for a miracle. The shudder is gone so that's a great outcome. Thanks for the guidance and hints.

 

[Mooseman]

The Panhard bar is the one that goes from side to side from the frame to the diff. It keeps the diff from moving side to side.

Good you got it figured out.

 

[JayArr]

Naval jelly is neat shit, it just turns the rust this black colour and the chemical reaction is stopped dead in it's tracks. Then you can just paint over it. It doesn't restore anything or reverse any damage but it stops the rust.

If you've ever been on a ship and noticed that the paint is all uneven on the railings and outside decking it's probably because it rusted, they used naval jelly to neutralize it, then they slap a coat of paint on it. It will rust again but not until the paint chips and the moisture gets back in. If you paint over rust without naval jelly the rust continues underneath the new paint.

 

[budwich]

I think in the past I have used things like "rust check" which is "similar". Maybe my application hasn't been very good. At this point, I am somewhat "resigned" to things as they are. Probably a bad attitude to have. :-(

 

[TJBaker57]

I think in the past I have used things like "rust check" which is "similar". Maybe my application hasn't been very good. At this point, I am somewhat "resigned" to things as they are. Probably a bad attitude to have. :-(

FWIW, I have seen both kits with the pieces blanked out ready for welding, and preassembled mounts to weld in if that becomes a possibility in the future.

 

[JayArr]

That would sure help

Being older now (approaching retirement) a great piece of advice for anyone in their 20s or 30s would be to get yourself a welder. Torches to start then some kind of low end Mig with gas is all you really need. Don't worry about tig or spool guns or anything like that right now. I bought a Hobart 135.

The ability to weld on a simple bracket like this can mean the difference between fixing your car on a Saturday or blowing out your budget and making payments for a year buying a replacement. The number of things you can repair and fabricate are almost limitless.

My Mig cost me about $1400, years ago, and I went hungry for about 6 months, no restaurants, no pizza, no movies, I watched a lot of TV and made all my own meals at home and paid off the credit card balance. I've now owned it for 25 years and don't regret the temporary poverty it cost to get it.

Budwich is in that decision point right now, he can get some welding equipment or buy another car.