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Discussion Starter #1
OK guys, I've got some issues. First off, I never installed the Z06 endlinks and I raised the V back to stock height for the track. Which was a great decision when running at Grattan Raceway.

Grattan does a number on your suspension with a couple of hard grip enhancing compressions on Turns 10 and 12. Add a lot of off and on camber and a hill that you can indeed jump and it is brutal. If I had the V lowered as when I'm on the street, I would've bottomed out repeatedly. But then it also caused an issue...

Late in the day I started getting a clunk in the rear suspension. I got underneath and checked endlinks, the Ground Control coilovers and the wheels itself. Everything seemed tight. So I went back out. The V tracks fine and is solid at speed. But I get a knocking around. Now, once I loaded the V back up the clunk wasn't so pronounced. But it's there. It seemed louder in the RR over the LR. Since the coilovers were installed, I've had a small clunk that Feffman's fix almost got rid of in the clunk in the RR and almost totally got rid of it in the LR. So this new noise seemed like either the washers had deformed or the gap was widened.

Today was the first day since I got back Tuesday night that I got to drive the V. And now it's empty again. Also, I ran another track day at Putnam on Monday. The suspension clunks around at all 4 corners. It sounds similar to my old race prepped SHO that wore out its strut mounts. The V just rattles at all corners.

Now, the kicker. I'm getting enough knocking in the rear that the Nivomats are adjusting for it. When lowered, the V's rear tires almost tuck into the rear fenders. But after driving around with the knocking, the rear raises to about an inch above the top of the tires. So something is definitely going on with the struts or mounts. Anybody with an intricate knowledge of the Nivomats and the GC/WW mod??


Let me add another thing. My heel and toeing is almost nonexistent at the track. On the street I'm OK, I just don't have the ability at speed. So I was banging through the downshifts at Grattan. Putnam is easy on the transmission with 2 shifts per lap. But everytime I was hitting the end of the straight at Grattan, I was getting a touch of wheelhop on the downshift. And I think that accelerated the clunking from the rear suspension. But here's something else. My differential clunk has become violent. Very loud and almost impossible to avoid.

So...what are your thoughts???
 

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Re: Grattan is a Bitch!

Grattan is so much fun. That bump on the back scares the shit out of you the first time you hit it. :D

I got nothing about the clunk though.
 

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Re: Grattan is a Bitch!

  • make sure you're rev matchin' while downshiftin' - this can be done with a quality blip/shift/brake back on the throttle for entering the corner and mid throttle excelerating to a push in mid corner
  • dump your nivomats and get some real shocks - Penske/D&D/T2/ something
  • diff support and new fluid - I bet your loose in the diff - bushings
  • keep your v lowered and look into rolling your fenders (If I'm correct you'll be rubbing in a 6 inch upper well patch)
Au Grattan is a Bitch for some....-

Preparation time: 55 minutes
Total time: 30 minutes
Serving size: 4 to 6 servings.

Ingredients

1/2 bag (40 nuggets of creamer potatoes diced into nuggets )

1/4 stick butter, melted (plugra)

Sea Salt and pepper to taste

1 tsp chipotle puree

1/2 meyer lemon juiced

1/2 cup devonshire cream

1 Tbsp. diced onion or shallots

1tsp minced elephant garlic

1/2 cup fresh Parmesan cheese or Gruyere

1 cup shredded Sharp Cheddar cheese (Wisc.)

1/2 cup french bread croutons


Steps

Place diced potatoes in medium casserole dish.

Add onion; drizzle with melted butter and sprinkle with sea salt and pepper to taste and add all other ingredients.

Top with Parmesan/gruyere , Cheddar and croutons.

Lightly cover casserole with aluminum foil. Bake at 325°F for 20 minutes. Uncover and bake for additional 10 minutes or until hot and cheese is melted.
 

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Discussion Starter #6
Re: Grattan is a Bitch!

  • make sure you're rev matchin' while downshiftin' - this can be done with a quality blip/shift/brake back on the throttle for entering the corner and mid throttle excelerating to a push in mid corner
  • dump your nivomats and get some real shocks - Penske/D&D/T2/ something
  • diff support and new fluid - I bet your loose in the diff - bushings
  • keep your v lowered and look into rolling your fenders (If I'm correct you'll be rubbing in a 6 inch upper well patch)
I know how to heel and toe and rev match, but doing it in the V at speed with the way I'm positioned in the car is difficult. I rev match all the time when downshifting on the street. Right now, no $$$ for "real" shocks Mr. Moneybags...:bouncy:
 

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When my front Nivomats were going bad they started clunking a lot. Do you have any leaking on the shocks? I also get a clunk in the rear when the pinion bolt at the top of the rear diff get's loose. I end up checking/tightening that one every time I get under the car.

I'll be at Grattan in September for the West Michigan Porsche club event. It's a great time! http://wmi.pca.org/driving/grandprix/Grand_Prix_of_Grattan.htm If any one wants to join me, the Porsche guys over there are great and get a real kick out of having a Cadillac out there with their cars.

I have the same issue with heal toeing at Grattan. Do fine on the street but lots of stuff going on coming into the hairpin and I never seem to get it right. With my Maggie I seem to do pretty well in 3rd for most of the track and only downshift to 2nd at the hairpin and have to go into 4th by the end of the front straight.

I did my GC install right after going to Grattan last year so I haven't run there with it on. I'm glad you mentioned raising the car back up for the track. I hadn't thought of that but you're right, the hill in the back and the camber on the turns will probably bottom things if I don't.
 

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Discussion Starter #8
When my front Nivomats were going bad they started clunking a lot. Do you have any leaking on the shocks? I also get a clunk in the rear when the pinion bolt at the top of the rear diff get's loose. I end up checking/tightening that one every time I get under the car.
Since I had to raise and lower the V twice with the 2 track events, I've had some really good looks at the suspension and I don't see any leaks. It just seems odd that all 4 corners would get a loose feel and clunk like crazy at the same time...
 

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I always say this, but I consider it good advice: Start with the obvious. Retorque your top shock mount nuts to see if they've come loose after the workout from Grattan.

I'm not knowledgeable about the GC kit, so that's all I've got.
 

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ACNA at Mid-Ohio they were talking about how bad the end of the front straight is getting at Grattan. Have not been there since '05 but it was noticeable then. Unless you hit the down shift perfect on the uneven surface while braking it will probably slide a tire. Your not sliding a tire under braking but just clutch engagement?

Norm
 

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BJ -

I'm stumped here. The differenttial clunking is likely the top pinion bushing and/or bolt, as previously posted.

The 4 corner clunks, though, can only be shock related. The WW/Nivomat mod if done correctly should leave no play in the shock when mounted. The easy way to test is remove the shock and drive around the block (OK, not so easy). Actually, jack the car up, remove the lower shock mount and grab hold of the shock wiggle, wiggle - make sure the top mount is not loose at all. Should feel VERY tight.

Also, take a good solid look at the endlinks of the sways. Are they coming into contact with anything? Did the fronts tear apart?

If all else fails, buy a case of dark beer and offer the V for trade on cars.com for a SHO. You know that's what you really want anyway - whiner. :thepan:

WW
 

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I know how to heel and toe and rev match, but doing it in the V at speed with the way I'm positioned in the car is difficult. I rev match all the time when downshifting on the street. Right now, no $$$ for "real" shocks Mr. Moneybags...:bouncy:
I'eem jus a seeempul cooook ese...No deneiro jus very creative. I did think about onebadcads cz removal with the wife rings:eek:

I hear you about the heel/toe - It's pretty weird with the V set up so I sort of do a little of both - rev match blip touch braky onto the throttle.


I'd check the arms/toes (do you have additional toe and arm support?), Hotchkis hitting, re-torque everywhere (you've been hitting the track quite a bit) and I'm sure there's some wear down under. Diff bushings may be shot as well.

Cheeeef
 

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I've got nothing to add, but just wanted to comment that, bigjim, you may be treading on new ground here. Lot's of good suggestions, so far. Since I'm hoping to do Grattan this September with Ron's Porch buddies (geez, Ron, I hope they've got a sense of humor :rolleyes:), this is a very timely thread. I, for one, will be tuned into this one very closely. :thumbsup:
 

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Discussion Starter #14
I've got nothing to add, but just wanted to comment that, bigjim, you may be treading on new ground here. Lot's of good suggestions, so far. Since I'm hoping to do Grattan this September with Ron's Porch buddies (geez, Ron, I hope they've got a sense of humor :rolleyes:), this is a very timely thread. I, for one, will be tuned into this one very closely. :thumbsup:
If you want, i can put up some video on Grattan and show you where I found success and where I need to improve next time I hit that place. The Bowl is the hardest to get right. Not my favorite track but definitely the most technical I've been on for the total distance. When I start, I use Competitive Driving Mode to keep myself in check and go without towards the end of the day. At Putnam, I'd never see the screen flash. At Grattan, it's on at every curve.

As for getting under the V, I didn't have a chance since I got back. I may be able to get working on it on Monday night. I need to figure it out before I do another track day. Enough excuses for sefa01. I need to do a Northeast event with him...
 

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I'eem jus a seeempul cooook ese...No deneiro jus very creative. I did think about onebadcads cz removal with the wife rings:eek:

I hear you about the heel/toe - It's pretty weird with the V set up so I sort of do a little of both - rev match blip touch braky onto the throttle.


I'd check the arms/toes (do you have additional toe and arm support?), Hotchkis hitting, re-torque everywhere (you've been hitting the track quite a bit) and I'm sure there's some wear down under. Diff bushings may be shot as well.

Cheeeef
I don't have any of the toe/arms from BMR. The diff bushing has always been clunking but now it's almost impossible to avoid the clunk. But I'll tighten down that bolt and see...
 

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Discussion Starter #16
BJ -

I'm stumped here. The differenttial clunking is likely the top pinion bushing and/or bolt, as previously posted.

The 4 corner clunks, though, can only be shock related. The WW/Nivomat mod if done correctly should leave no play in the shock when mounted. The easy way to test is remove the shock and drive around the block (OK, not so easy). Actually, jack the car up, remove the lower shock mount and grab hold of the shock wiggle, wiggle - make sure the top mount is not loose at all. Should feel VERY tight.

Also, take a good solid look at the endlinks of the sways. Are they coming into contact with anything? Did the fronts tear apart?

If all else fails, buy a case of dark beer and offer the V for trade on cars.com for a SHO. You know that's what you really want anyway - whiner. :thepan:

WW
I'll have to give that a try. When I first started getting the clunk at Grattan, it sounded like an amplification of the clunk that Feffman came up with the fix for. But I only used 1 washer per side and the left rear was almost always perfect, the right rear did still clunk a little. I'm wondering if there is still play that the washers can deform...

Trading the V? No. I love the SHO but I'm all V now. Next year may be truck and trailer purchase with a used Z06 in a couple years and then the V is total garage queen. As in no snow, rain or anything that would hurt it. 1-2000 miles per year.

At least that's my dream...
 

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Discussion Starter #17
ACNA at Mid-Ohio they were talking about how bad the end of the front straight is getting at Grattan. Have not been there since '05 but it was noticeable then. Unless you hit the down shift perfect on the uneven surface while braking it will probably slide a tire. Your not sliding a tire under braking but just clutch engagement?

Norm
It didn't seem horrible. The Hoosiers did a good job, it was just getting into 3rd that I'd chirp a little. By the end of the day, I was hitting the brakes well past the #5 on the straight. And that was on mild Hawk Blues...
 

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Discussion Starter #18
I always say this, but I consider it good advice: Start with the obvious. Retorque your top shock mount nuts to see if they've come loose after the workout from Grattan.

I'm not knowledgeable about the GC kit, so that's all I've got.
That's what I'm hoping. I will start with that. I'm also going to check the cradle bolts as well...
 

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If you want, i can put up some video on Grattan and show you where I found success and where I need to improve next time I hit that place. The Bowl is the hardest to get right. Not my favorite track but definitely the most technical I've been on for the total distance. When I start, I use Competitive Driving Mode to keep myself in check and go without towards the end of the day. At Putnam, I'd never see the screen flash. At Grattan, it's on at every curve.

As for getting under the V, I didn't have a chance since I got back. I may be able to get working on it on Monday night. I need to figure it out before I do another track day. Enough excuses for sefa01. I need to do a Northeast event with him...
I'd love to see some video :)
 
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