Popping noise?

**Tide** · 09-09-2006, 07:32 AM

Under hard acceleration (i.e. dropping the hammer from the start (enough to spin the tires), full throttle shifts), I'm hearing a pop from the rear end. I don't think its axle hop, and to be completely honest, I'm not sure that its the half shafts slipping in the boots.

Ideas?

**Sarge** · 09-09-2006, 09:59 AM

You just discovered the rear end "pop" clunk" snap"...I've heard it called a ton of things and many things have been found to cause sounds under acceleration....I recall some 2004 GTOs did not have both bushings in the rear subframe (missing the top I believe) from the factory which would cause a clunk or clank....the evap canister on the passenger side has been found loose on many....causing a clanking clunk whatever....simply tighten up the clamp fixed those....But the number one reason was so bad...Pontiac finally put a TSB out on it....here I'll find it for you....
Here ya go...
Knocking Noise from Rear of Vehicle on Aggressive Launch or Acceleration (Install Rear Suspension Crossmember Front Mount Insulators) #04-03-09-003A - (Apr 20, 2004)
Knocking Noise from Rear of Vehicle on Aggressive Launch or Acceleration (Install Rear Suspension Crossmember Front Mount Insulators)
2004 Pontiac GTO

Built Prior to VIN Breakpoint 4L246712

This bulletin is being revised to change a torque specification within the correction procedure. Please discard Corporate Bulletin Number 04-03-09-003 (Section 03 -- Suspension).

Condition
Some customers may comment on a knocking noise coming from the rear of the vehicle. This noise occurs during an aggressive launch or acceleration and will be more common on vehicles with a manual transmission.

Cause
The cause of this condition may be contact between the body and the rear suspension crossmember.

Correction
Install insulators, P/N 90447991, and new bolts, P/N 92038482, between the body and the rear suspension crossmember using the procedure listed below.

Important
Only remove the bolts from one side of the suspension crossmember at a time, and DO NOT loosen the opposite side, until the insulator is installed on the first side and all fasteners have been tightened to the specified torque setting.

Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle in the General Information sub-section of the Service Manual. Position rear hoist.
Support the rear suspension crossmember just under the brace using an adjustable jack stand.
Remove the 3 brace to underbody bolts.
Remove the front mount bolt attaching the rear suspension crossmember to the underbody.
Lower the jack stand slightly to allow clearance between the crossmember and the underbody.

Important
When installing the insulator onto the crossmember front mount bushing, face the corrugated side upwards, so it bears against the underbody.

Install the insulator between the underbody and the upper part of the crossmember, ensuring to seat the insulator firmly onto the center of the crossmember front mount bushing.
Raise the crossmember using the jack stand until it is pressing firmly against the underbody.
With the jack stand still in position to support the crossmember, install the new front mount bolt and the 3 brace to underbody bolts. Tighten
Tighten the crossmember front mount bolt to 125N·m(92 lb ft). Use J 45059 Torque Angle Meter in order to tighten the bolt an additional 40 degrees.

Tighten
Tighten the brace bolts to 65N·m(48 lb ft).

Remove the jack stand.
Repeat steps 2 to 9 for the opposite side.
Parts Information
Part Number
Description
Qty

90447991
Insulator, Rear Suspension Crossmember Front Mount (2 Per Package)
1

92038482
Bolt, Rear Suspension Crossmember Front Mount
2

Parts are currently available from GMSPO.

Warranty Information
For vehicles repaired under warranty, use:

Labor Operation
E9407*
Rear Suspension Crossmember Front Mount Insulators -- Install
0.5 hr

*This is a unique labor operation number for use only with this bulletin. This number will not be published in the Labor Time Guide.

**Tide** · 09-10-2006, 11:35 AM

Thanks for the info, Sarge. I was actually about to search the TSBs available at alldata before I read your response.

Now, to see how long it will take the local Pontiac dealership to fix it...

**Sarge** · 09-10-2006, 01:12 PM

Well Wade...around here they all have been pretty good...even on a couple of modified GTO's.....let us know...I'd print off the TSB and take it with me...tell the service writer...see this...it is happening to me....fairly open and shut case for warranty rear end IMHO.

**Tide** · 09-10-2006, 06:00 PM

I've used the TSBs from alldata on several cars, most notably my wifes old Maxima in dealing with the local (shitty) dealership.

Good info to have when dealing with a service manager that doesnt want to play ball.

**Sarge** · 09-10-2006, 06:11 PM

I'll get off my lazy ass and post all the TSB's out on the GTO 04/5/6. Make it a sticky.

**newguy WS6** · 09-19-2006, 03:33 AM

I discovered a knocking noise coming from the front of my 06 after only 2 weeks of ownership.

After extensive investigating I discovered that the rubber bushing on the end links of the sway bar had "washed out" I was like WTF?

I took it to the delaership and they were very good in helping me find a remedy.. only after i showed them what it was.. they told me they had like 6 or 7 come in with the same problem. So once I showed them what it was they were very happy to help find a solution.

the solution was the cupped shaped washer that the bushing rides on were upside down.. dont know if it was on purpose or just a build mistake anyway after hitting a few bumps in the road the bushing eventualy works its way over the washer... and then knock knock knock everytime you hit a bump.

We simply disassembled the end link assembly and turned the washers upside down and they installed a set of urathane (sp) bushings.. after that.. no more problems.. ride quality was like it was when the day it was new.

I did have the car dynoed this weekend and made 333hp/332Tq..A/F was at 10.5 so it was a little rich.. I will have it tuned soon hope to get about 25 hp out of it. Car is bone stock down to the paper air filter..

Steve

**Sarge** · 09-19-2006, 04:53 AM

Pig Rich

You got a lot of ponies waiting to get out with a proper tune for sure.
At idle we run 14.8-14.3
At WOT we run 12.1-11.8
Cruising down the highway at 75mph we are at 15.2-14.9