During the last 3 weeks or so, my SC430 started making some new creaking noises. It always sounded like it was coming from the top and kind of towards the rear passenger area. I lubed the top with no change. The noise typically manifested itself when I was pressing or releasing the brake, though occasionally not related to the brake. Speed didn't matter nor did bumps seem to make a difference.

I took it to one garage and their first thought was that it was some suspension related item. But when they checked it out, they decided that the noise was in the top, which they don't deal with (and fortunately admitted to such). So I took it to an indy Lexus shop. What they found was that there is a brace in the front of the car that had a couple of bolts loose and when the frame flexed it would creak or pop. It looks like this is a brace specifically for the convertible. It is located just above and in front of a brace that goes across the car (left to right) and is just above the engine under cover. The brace in question is an A-frame type brace with the apex located near the center of the left to right brace. The other two ends of the A-frame attach near the front of the car. It was these two bolts that had barely come loose. Apparently it took a lot of force to move the brace so the bolts were still fairly tight, just not tight enough.

Hopefully that helps someone else out there. Unfortunately, I don't have pictures nor diagrams nor know the name of the brace.

However, I can say this, my car seems a lot quieter now than before and it seems to be smoother riding also. Though it is possible that the smoother portion is just related to reduced noise. Apparently, there was more noise going on than just the major (and annoying) creaking that was going on.

 

An A Frame type brace plus a brace that goes across the front above the engine cover sounds like some kind of aftermarket bracing and not OEM. It would be interesting to see some pics. The cross brace sounds like a Cusco type brace meant to reduce body flex by adding additional structural support from the strut mounts on each side. Give us some pics when you have time Please. Thanks.

Paul

 

Harold57;
I am experiencing the same issue. You are located in Texas like me.
Can you share the indie you used to find the problem?
Thanks

 

If you ever get a chance, please take a picture of the bolt location that needs tightening up. Thanks.

 

Pictures will require removing the engine undercover, so maybe I can get the mechanic to do that next time I have it in there. (I didn't get to see it either, only drawings.)

The A-frame and cross brace are standard OEM pieces from what I can tell. The shop showed me drawings of them from their manual on their computer. If someone has a repair/shop manual, hopefully they can look it up and find them

The Indy shop is called Davenport Motors. They have 2 or three locations in the DFW area but this one is in Plano.

 

This cross brace in the front of the car? Or perhaps the rear? I have to go underneath to see the braces.

 

Oh I'm sorry. I misunderstood and thought you were saying that the braces went across the top of the engine. Now it sounds like they were retorquing the sub-frame.

Paul

 

Thanks Harold57;
I have used their Colleyville shop for service.

 

The only cross brace I can think of is the sway bar. Maybe they re-torqued lower arms number 2. Also, the steering rack will creak and pop if not torqued properly. Honestly the OP's description is rather confusing.

 

Where is @VVTiBob when we need a diagram?

 

 

In the photo above, The third cat and mufflers are different than our production cars.
the car above has two mufflers, we only have one.

 

Yep, the photo above is sourced from the Tom’s aftermarket website. I’m looking for the frame bracing diagram(s) in my archive.

 

The braces mentioned are between the engine under cover and the engine. In Bob's picture and Mandyfig's drawing, the brace is covered up by the engine under cover. It looked like the A-frame brace's bottom two points would have bolted down near the front bumper and the apex would bolt near where the oil pan is but the drawings that he showed me were not connected, just showing loose pieces and approximately where they connect. (I will ask Daniel there if he would send me a screen shot.)

 

Here's the diagram. The A-frame brace is highlighted in green.