Thread pitch and bolt size..

R Dubya · May 11, 2005, 03:53:24 PM

I need to know the size and thread pitch of the two bolts that hold the exhaust downpipe bracket to the rear head. I think that I damaged the threads on the pass side of the car, and forgot to fix it before I finished the job last year. Now that thing rattles and creates an unpleasant vibration audible from the inside, which I can't stand any longer.

If anyone has an engine out and has means to measure the thread pitch, or even has two of those bolts they are willing to part with I would be willing to buy them. If not, if anyone could help me it would be great, GM sold them with the bracket, but they are no longer available.

TIA to anyone that can help!!

GangstGP · May 13, 2005, 02:31:42 PM

I could get you those bolts soon,or check the thread pitch,I guess.
Don't you mean the x-over bolts? The downpipe does not bolt to the head, it bolts to the turbo. Please make it perfectly clear what bolts you need. Because it is your luck I will be pulling those bolts off my donor in the next week or so.

R Dubya · May 13, 2005, 03:36:09 PM

I apologize if I am confusing you, but I mean the flexible steel line that runs from the turbo to the downpipe. That flex line bolts to the rear head. The bolts are larger than most of the others on the car, and I need a pair from a TGP preferably so I know the exact pitch and size, so I don't go damaging the head.

GangstGP · May 15, 2005, 01:07:40 AM

Sorry, lost you again. You must mean the oil return line that goes below the front head ?
No you said the rear head. You mean the EGR hose?

I apologize, I have never seen a flexline that bolts to the rear head and runs to the turbo.

turby · May 15, 2005, 06:15:39 AM

There is a bracket on the down pipe. I think he means the bolts that hold the bracet to the rear head.

R Dubya · May 15, 2005, 08:23:47 AM

That's it turby. Those two bolts that go on either side of the rear head.

no1kicker · May 15, 2005, 11:04:02 AM

I looked in my manual, and the size isn't listed. It does say the bracket to head bolts are torqued to 35 lb ft (48 N m), and the bracket to downpipe are 18 in lb (25 N m).

It also says at the front of the manual the most common bolt sizes on the car:

M6 x 1
M8 x 1.25
M10 x 1.5
M12 x 1.75

R Dubya · May 15, 2005, 12:27:13 PM

Thanks man. I know it's a larger bolt.. comparable to the size of the ones that hold the harness to the engine and tranny in several places. I will go to a store tomorrow and look for those bolts and see if they are right.

turby · May 16, 2005, 08:11:25 AM

If you don't find them let me know. I should have the TGP in the garage Tues. to start pulling parts.

GangstGP · July 16, 2005, 04:49:16 PM

WTF? looks like some posts on the Forum got deleted. Anyway I have the bolt in my hand. Do you need me to send it to you now?

R Dubya · July 16, 2005, 06:57:16 PM

yes! I need the two of them though. We are talking about the two bolts on the rear head that hold the "v" shaped bracket down correct? I am in dire need. Let me know what you need for them.

GangstGP · July 17, 2005, 12:47:45 PM

Yes, the y- shaped bracket. There was only one of them on there of the two, but I got it. I can get the thread pitch as soon as I find my tap/dye set with my thread gauge if ya like. The bolt head has a little CH on the top and below that says 9.8 Forget what that means but the threads below the head measure 26 mm.

GangstGP · July 18, 2005, 12:21:41 PM

The thread pitch is 1.5 but I know how it is hard to get the perfect replacement bolt unless you take it into the hardware store with the right bolt in your hand. PM me with your address.I am going to the hardware store later to get my buddy Turbo Mike his dog bone washers, so I will be able to get you the exact threaded bolt.