Bad sounds coming from the tunnel to the rear of car

[Whiplash]

Heya Michael,

Oddly enough I *just* had a shop deal with something exactly like this on my Avalanche. Very nice guy and it cost me $160 bucks.

Call Ariel at G&M auto body in Colma. Number is 650-301-8800.

245 Collins Ave-right where all the auto dealers are near Serramonte. About 10 mins North of you. It's not a total performance shop-but they took care of me, quickly, and charged me fairly.

Good luck-see ya in a few weeks when BDR 479 shows up. I'm gonna hit ya up to go over the "process" and invaluable advice you gave me a few months ago regarding where and who as far as registration (I have it all in a word document).

Cheers

-Sean

[aldersonjames20]

Congrats on finding the issue yourself...and its a fairly simple problem to boot. Good luck getting it fixed and back on the road.

James

[Doug I]

Dino - glad it was a relatively simple fix.

I don't know how long you've wrestled with that bolt already but now that it's Friday and the weekend is upon us I'd give it another shot. This time round it may catch and you're done.

Everyone - add to the list of things to check on a new car ?

Doug I

[Backdraft]

Hi there,

To get the bolt back in you would need to loosen the lower bolt on the shock absorber. This will remove the tension from the spring and allow you to move the arm around a bit. If the bolt is damaged you need to mark the swing arm bracket(To keep the alignment specs) and then loosen the lower 3 nuts on the underside of the bracket. The bracket will then swing out and you will be able to replace the bolt.

The car under goes 2 seperate PDI's, and this should have been checked at both of them. If you need a better explanation please give the shop a call and we will be able to give a better verbal explanation.

Regards Reg
www.Backdraftracing.com
561-752 3693

[CobraEd]

The irony of all this is that the old bolt came right out on its own with no human intervention at all

Now it will take an act of God to get a new one in.


.

[Dinobyte]

Well...I ended up unbolting the shock..jacking up the half shaft, unbolting the trailing arm alignment plate, which gave me enought play to bolt the trailing arm back to the plate. PS>>>I used lock tight on the bolt to prevent this from happening in the future.

I tried to keep it all aligned, but I am sure it is off. I will have to go have an alignment done to make sure.

What a job!

Thanks for everyone's help.

Michael

[madmaxx]

make sure you check you drive shaft bolts where they bolt to the rearend flange for precaution.

[Dinobyte]

Well...the test drive did not go so well. The sound/vibration is back...just as when the bolt was loose. When I accelerate and the car squats, the sound gets worse. No sound/vibration in normal grandma type driving. Even in light acceleration, there is vibration.

I am diving back under the car to see if anything is rubbing or still loose. Arrggh!

[round_midnight]

Check the condition of the bushing and make sure the rubber isn't torn. Also make sure that the bushing is not loose in the trailing arm. Another possibility is that in your picture, it looks like the bracket that the bolt goes into may be bent, allowing free play.

Also, just a short FYI. e36 BMWs and hence BDRs like to have some toe-in at the rear wheels. .25 degree is good. Mine handled like a pig until I found out that someone had put .25 degrees toe-out instead of toe-in. Terrible oversteer, even with no throttle. Handles like a completely different car now.

P.S. Have the alignment shop use alignment specs for a '97 BMW 328is when they align it.

[Dinobyte]

Guess what I found....a sheared bolt!



Trying to identify the correct name for the bolt and nut so I can go pick one up. Does anyone know the correct name for this and what happens if it is not bolted?

It is located right under the diff.

[Trueoo7]

Dino
Been there done that, Snapped a bolt in the rearend
What worries me about this is, thats the bolt that has been replaced due to the previous smaller ones breaking. If the upgrade is starting to break now, thats not good. I'm not sure of the size but I can tell you that you can buy it from McMastercarr.com. I know Cashburn has the size, maybe he'll chime in. If I don't see an answer by tommorrow I'll check my spare one and let you know its proper size.

Also there is no nut. It is screwed directly into the rearend housing which tells me that the other end is still in the housing. Your best bet (and this is important) is to remove the Diff from the car and then try to drill out the bolt using a counterclockwise drill bit. If that doesn't work then you can use an easy-out. Don't do like I did and try to do it in the car and snap the bit off in the bolt...what a headache !

[DC COBRA]

DINO

It amazes me that some of the cars break these bolts with very limited hard use and some cars that run over 600 hp with somewhat hard use is still on the original (little) bolts. I think now would be the time to upgrade to the solid bushing as getting rid of the rubber means less movement and possibly less breakage and besides its cool to have solid bushings.

Good Luck
DON

[aldersonjames20]

My front and rear control arm bushings have been replaced with PTFE lined spherical bearings, and despite that some think it will kill your comfort quotient in the ride, it really isn't that bad at all. It was done by previous owner and I wasnt' aware that less breakage was one of the advantages.

James

[Trueoo7]

Dino
Just measured my spare and it is 2.0cm x 14 x 80mm. Hope this helps. Not sure of grade, but you might want to do a search here on CC for metric grades. There was a thread that discussed this with some good info.

[Dinobyte]

Guys,

I have been on the phone with Tony Martin, and he has promised to make this right for me. I have also talked to Jay and Brian at Vintage, and they are also stepping in to correct this.

I will keep you posted.

Thanks for all the help and advice. Hopefully we learn something from this.

Michael

[Rwillia4]

The McMaster.com part number is 91310A792 (with a black finish). They come in a pack of 5 for $8.32, these are metrix Grade 10.9 comparable to standard Grade 8...as hard as they get.

No sense in fooling around I'm going to change it before it breaks off in the hole.

[#136]

what are the torque settings for these bolts? and are these being over tightend causing breakage? Just a thought.

[Trueoo7]

My guess is that when the left rear trailing arm came apart that put a lot of stress on the front diff bolt which caused it to break. Main reason why I think that is because in the picture he shows the broken bolt which should have fallen out somewhere on the road. So it couldn't have been broken for very long at all. It probably happened simultaneously.

When I replaced mine I made sure I put a lock washer under the head and check it every once in awhile.

Dino, what is Tony's feeling on this as to why it broke because in the picture that looks like the upgraded 10.9 bolt?

[DC COBRA]

Guys, there may have been more stress on the diff when the trailing arm problem started, I personally don't think so as this is IRS and most of the stress would be coming from the driveshaft movement due to the application of the power and torque thru the tranny. Might want to chalk this up as possibly a bad bolt, or maybe installation error (left somewhat lose), there could be some possibilities of this nature due to the trailing arm bolt being lose. Now I not bad mouthing any production or pre delivery sequences but things do happen especially in hand built cars with more than two hands. I would definately consider the solid mount as to help control any movement due to stress and so forth, it will not change any ride qualties or pose any more vibrations. something to think about.

DON

[Dinobyte]

Question to the group...

For those of you using all aluminum bushing on this part, have you noticed any extra sounds coming up? Brian at Vintage indicated I might hear the gearing due to the metal on metal.

Any thoughts on this?