Do we need subframe connectors
10-13-2014, 11:06 AM
#44
Pretty sure he means the gen IV diff. The clunk has everything to do with gear backlash. It was initially thought that diff bushings and trans mounts would cure it, but you can't cure an internal problem like that.
11-21-2015, 06:39 PM
#49
A year later, I've come to the conclusion that the v1 can benefit from some sort of frame reinforcement. The biggest problem is wheel hop but after seeing several wrecked cars getting totaled because the roof and rear quarters buckled when hit in the rear, I went looking for a weak spot. Laygo's car folded like a wet noodle when it got rear ended and other than the buckling, that car looked like an easy fix. Other than that, this car can be a pain in the *** to jack up and there aren't many places to put jack stands either so I made not only some "traction bars" but some "rocker supports" as well.
After looking at the floor pan, it seems to me that the weakest point is going to be where the fuel tank well meets the floor pan. To help support this area, I made a full length rocker support that is plated to pick up the 3 threaded holes just ahead of the rear wheel well. These rear plates are long enough to span over the seam at the fuel tank well/floor pan. I could have stopped there but no, the rocker supports run the length of the car and pick up the large flat surface that spans between the frame rail and rocker at the front of the car. As these shouldn't need to be removed for any reason, I plan on taking them to the local muffler shop where the guys have agreed to weld them to the car if I can get them hung. There is a support in the middle of the span that can be welded into the hollow rocker without having to worry too much about setting the carpet on fire and then again at the before mentioned flat at the front of the car. I will suspend these temporarily with some self tappers so I can get it to the muffler shop. The 1x1 tucks in nicely and you can barely see them sticking below the folded rocker lip.
The traction bars are bolted to a piece of 3x3x3/16 angle that bolts to the forward trailing arm mount on the cradle. Because this surface isn't level with the bottom of the car, I back cut the angle a little and bent it down so I could butt up against it at a 90 and then welded it. I plan on having this 3x3 tack welded onto the cradle just because but the traction bars bolt to it there as well as the frame rail up front so they can be removed for servicing. I left a 1/4 gap between the cradle mount and the bar by "washering up" so I could squeeze a piece of urethane in there to help combat any noise transmission. I have about 3/4" clearance between the cradle mount and the gas tank after I trimmed the mount and maybe 1/2" to the floorpan in general, maybe less.
From there, I carried the bar 52 inches forward so that it spans the trans crossmember mounting point because it seemed logical. I used 3 bolts up front because its better than 2. The bars are flush to the bottom of the frame rail so that I could drill through holes without having to worry about hitting the hardlines mounted on the inside of the passenger side frame rail. The holes are a little off center of the trans crossmember bolt so I could drill through the frame rail without hitting the bolt.
The pictures show a roughed in assembly so there will be some trimming, paint and sized bolts before the final install but the holes are all drilled and I feel pretty good about it.
I used a .120 1x1 because that what seems to be speced by BMR etc and all the plating is in 3/16 because again, that seems to be what everyone else specs for this application.
Yes, this is a bit hackish because I'm working on jack stands so the quality of these would be considered prototyping at best. But, they'll work so I probably won't bother trying to improve them any unless I have some sort of problems. I won't be driving the car for a week or so so no final results are in but I'm not expecting any drastic improvements other than diminished wheel hop, protection for the "crumple zone" and an easy place to jack and support the car while I work on it.
This was inspired by various others who came before me so thanks to all who contributed....
Failed project alert...if you notice one of the pics shows a v2 strut tower brace I got cheap and was hoping to hack it up and put it on the car but that ain't happening. In other words, I have a cheap v2 strut tower brace if anybody is interested.
EDIT: The traction bars don't seem to hang any lower than the resonator/stock exhaust crossover but I've got an 8.8 so the pipes hang a little lower than stock. The way they're made, they should slide off any sharp edges I may eventually catch. I'll take more pictures at the muffler shop if any one is interested. I'm guessing all this weighs about 60lbs...OK maybe 70.
After looking at the floor pan, it seems to me that the weakest point is going to be where the fuel tank well meets the floor pan. To help support this area, I made a full length rocker support that is plated to pick up the 3 threaded holes just ahead of the rear wheel well. These rear plates are long enough to span over the seam at the fuel tank well/floor pan. I could have stopped there but no, the rocker supports run the length of the car and pick up the large flat surface that spans between the frame rail and rocker at the front of the car. As these shouldn't need to be removed for any reason, I plan on taking them to the local muffler shop where the guys have agreed to weld them to the car if I can get them hung. There is a support in the middle of the span that can be welded into the hollow rocker without having to worry too much about setting the carpet on fire and then again at the before mentioned flat at the front of the car. I will suspend these temporarily with some self tappers so I can get it to the muffler shop. The 1x1 tucks in nicely and you can barely see them sticking below the folded rocker lip.
The traction bars are bolted to a piece of 3x3x3/16 angle that bolts to the forward trailing arm mount on the cradle. Because this surface isn't level with the bottom of the car, I back cut the angle a little and bent it down so I could butt up against it at a 90 and then welded it. I plan on having this 3x3 tack welded onto the cradle just because but the traction bars bolt to it there as well as the frame rail up front so they can be removed for servicing. I left a 1/4 gap between the cradle mount and the bar by "washering up" so I could squeeze a piece of urethane in there to help combat any noise transmission. I have about 3/4" clearance between the cradle mount and the gas tank after I trimmed the mount and maybe 1/2" to the floorpan in general, maybe less.
From there, I carried the bar 52 inches forward so that it spans the trans crossmember mounting point because it seemed logical. I used 3 bolts up front because its better than 2. The bars are flush to the bottom of the frame rail so that I could drill through holes without having to worry about hitting the hardlines mounted on the inside of the passenger side frame rail. The holes are a little off center of the trans crossmember bolt so I could drill through the frame rail without hitting the bolt.
The pictures show a roughed in assembly so there will be some trimming, paint and sized bolts before the final install but the holes are all drilled and I feel pretty good about it.
I used a .120 1x1 because that what seems to be speced by BMR etc and all the plating is in 3/16 because again, that seems to be what everyone else specs for this application.
Yes, this is a bit hackish because I'm working on jack stands so the quality of these would be considered prototyping at best. But, they'll work so I probably won't bother trying to improve them any unless I have some sort of problems. I won't be driving the car for a week or so so no final results are in but I'm not expecting any drastic improvements other than diminished wheel hop, protection for the "crumple zone" and an easy place to jack and support the car while I work on it.
This was inspired by various others who came before me so thanks to all who contributed....
Failed project alert...if you notice one of the pics shows a v2 strut tower brace I got cheap and was hoping to hack it up and put it on the car but that ain't happening. In other words, I have a cheap v2 strut tower brace if anybody is interested.
EDIT: The traction bars don't seem to hang any lower than the resonator/stock exhaust crossover but I've got an 8.8 so the pipes hang a little lower than stock. The way they're made, they should slide off any sharp edges I may eventually catch. I'll take more pictures at the muffler shop if any one is interested. I'm guessing all this weighs about 60lbs...OK maybe 70.
Last edited by ls1247; 11-21-2015 at 08:21 PM.
11-21-2015, 10:20 PM
#50
I think you might be thinking about this wrong.
ANY car can suffer from wheel-hop and you will not make it go away in any car.
I have tried in many cars to get the rear to hop and it is fairly easy.
My car is more rigid with the SFCs and when I jack it up one one corner the corresponding side goes up as well, so yes they help.
You are on the right track, but a little overkill.
ANY car can suffer from wheel-hop and you will not make it go away in any car.
I have tried in many cars to get the rear to hop and it is fairly easy.
My car is more rigid with the SFCs and when I jack it up one one corner the corresponding side goes up as well, so yes they help.
You are on the right track, but a little overkill.
11-22-2015, 07:44 AM
#51
I work for a German engineering firm so yes, I'm sure its overkill. The rocker bars are probably excess baggage to some degree but having the extra collision insurance and having a good place to put a jack stand meant that I felt it was an acceptable application of overkill.
The traction bars are a simplified version of what you had designed as it only attaches at one point on the cradle instead of 2. I never really saw the point in that although your design influenced mine...Thanks!!
I've never designed or built a set of chassis braces before but after owning and working on F-bodies and Fox bodied Mustangs, I haven't departed greatly from what I've seen in practice. If there's a better way of building something like this, I'm all ears!
EDIT - I was hoping, based on these threads, that firmly attaching the cradle to the car would keep it from moving around.
https://ls1tech.com/forums/cadillac-...2005-ctsv.html
How have yours been working? I guess your account data limit has been reached but I wish you could put some pictures back up of your original designs.
https://ls1tech.com/forums/cadillac-...me-mounts.html
Talk about simplicity! I plan on keeping the car so I felt it deserved a little more effort than that but this is, again, testimonial evidence that securing the cradle at the front trailing arm mount is a viable way of eliminating wheel hop on this platform.
Last edited by ls1247; 11-22-2015 at 07:57 AM.
11-22-2015, 10:03 AM
#52
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The chassis is definitely stronger than my other 2 cars, but there's still room for improvement with the rocker reinforcements.
11-30-2015, 02:04 PM
#55
HOLY FN Shiite!
When I jack my car up, it is even, not "eventually".
I cannot guarantee that the subframe does not move, but it is much better.
Still have hop in the rain with 275s.
There is one guy that welded his subframe TO the frame and claimed ALL wheel hop was gone.
When I jack my car up, it is even, not "eventually".
I cannot guarantee that the subframe does not move, but it is much better.
Still have hop in the rain with 275s.
There is one guy that welded his subframe TO the frame and claimed ALL wheel hop was gone.
12-01-2015, 11:09 AM
#58
The biggest challenge I'm running into is not being able to weld underneath the car. I have to dimension it, unbolt it and carry it somewhere else to have it welded. It'd be a lot easier, and way more effective I'm thinking, if I could just bolt my plates/fixtures in and weld the tubing to it all at the same time. It would be a much tighter fit than what I'm able to achieve right now and while I could just have it all welded in, I really don't want to do that if I can get a tight enough fit as a bolt in.
After looking at it again, I found a threaded hole in the bottom side of the frame rail just forward of the transmission crossmember. If you made a plate to catch that hole and the hole for the trans crossmember, another plate to catch the 3 holes just forward of the rear tire, made your fixture for the front trailing arm mount on the cradle, you could just tack weld the tubing to tie these 3 points together with all of it still bolted into the car but I don't have that luxury.
I don't see how the cradle could move if you triangulated all this but I'm open for suggestions if anyone has any. Got to do something cause the wheel hop just isn't going to work.