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1970 Chevelle ss turbocharged 427 4 speed sled from hell
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Discussion Starter #1
Hey fellas new to the forum, thanks for the knowledge you all offer here. Now for my question, I’ve been looking around and haven’t had any luck. I have been told that the chevelles hook up best with a level angle on the lower trailing arms. I’ve seen many brackets to create more angle but nothing to create the angle without lowering the car. I don’t mind lowering the car a bit but I’m not sure how far to go with all the options in lowering springs. So from a performance stand point not visual how far are y’all lowering these cars to allow proper transfer. Maybe I’m way off base so please kindly direct me. ;D
 

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You can get bolt on or weld on relocation brackets. These actually lower the rear mounting position. I just mounted the weld on ones. Using the bottom hole, about 3" lower than factory. Took it to the track last Sat. and got my best 60' yet. Factory ride height. Now for DA shocks.
 

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Weld-on brackets are the way to go. Also, a taller/shorter tire will change the angle too.
 

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1970 Chevelle ss turbocharged 427 4 speed sled from hell
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Discussion Starter #6
Specifically drag racing, in curious tho dident the relocation brackets end up creating more angle on the trailing arms? I thought the weld in or bolt on ones attatch at the axle tubes right?
 

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I liked setting the lower bar parallel to the ground and raising the rear of the upper bar. I tried the SSM bars 25 years ago but with stock type shocks and springs it seemed to squash the sidewall and then rebound and spin. It had a very hard initial hit.
 
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On a factory set up and for street, you want the lowers to be as parallel to the ground as possible. On my 70 with factory setup (one hole in the lower bracket to choose from) with rear lowered 3-4", it put them exactly parallel. The QP 9" rear in it now came with adjustable lowers (6 hole bracket) welded. Now the lower arms are in the 3rd hole from the bottom for a slight angle down going back. One more hole up would be parallel for me. If I was to go to the track I would probably leave it where it is at first. Mainly due to what
bracketchev1221
stated above. on the QP 9" the upper ears are 5/8 higher than a stock 10/12 bolt rear. Also something
bracketcheve1212
eluded to, if taking to the track, bar adjustment also depends on your shocks and springs as the entire system works together. To include the front. I have Viking double adj. coilovers all around.

Mike.
 

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I used UMI bolt-on lower control arm relocation brackets on my 69 Malibu, made a HUGE improvement in traction. 11.50's in the 1/4 mile, best 60' times in the 1.5's. See photo.



 
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Georgia69, It looks like you have adj. lower brackets and your bars are on the lowest setting. What springs and shock settings are you running?

Mike
 

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I also use the UMI relocation brackets, arm is in the lowest hole. Car is lowered too. Brackets are the bolt on but welded....D/A front shocks and stock rear shocks...been 10.70's with 1.52 60' so far.
 

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Specifically drag racing, in curious tho dident the relocation brackets end up creating more angle on the trailing arms? I thought the weld in or bolt on ones attatch at the axle tubes right?
Here's a link to help get you started -- http://www.wallaceracing.com/coilspring.htm. You do not want the upper and lower arms parallel to each other. SC&C also has great info on chassis setup -- SC&C Street/Strip Package 1964-72 GM A body (Chevelle, GTO, 442, etc.)
 

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Georgia69, It looks like you have adj. lower brackets and your bars are on the lowest setting. What springs and shock settings are you running?

Mike
Stock rear springs for a 69 with BB, and stock replacement shocks. In the lower photo, I have a stock rear anti-sway bar. You can see that the car twists a little bit on launch and lifts the left front tire much more than the right front. It would pull a good bit to the right. I had air bags in the rear springs at that point, with substantially more air in the RH bag, to correct this. In the upper photo, I have replaced the stock rear sway bar with a BMR bolt-on anti-roll bar. This didn't improve the 60' time appreciably, but made the car lift much more evenly and leave perfectly straight. I was then able to do away with the air bags.

Time slip below for best ET, speed, & 60' with the BMR bar added to the UMI relocation brackets and UMI adjustable upper control arms - 11.37 @ 117

 

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1970 Chevelle ss turbocharged 427 4 speed sled from hell
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Discussion Starter #14
Here's a link to help get you started -- http://www.wallaceracing.com/coilspring.htm. You do not want the upper and lower arms parallel to each other. SC&C also has great info on chassis setup -- SC&C Street/Strip Package 1964-72 GM A body (Chevelle, GTO, 442, etc.)
So please correct me if I’m wrong but it seams the only way to get the trailing arms parallel to the ground is to lower the car. I suppose a guy could fab brackets to lower the front mounting point for the arms but I’m curious if this could throw off the geometry of how the suspension transfers the forward motion to the frame. Maybe I’m over thinking it, I do have the adjustable uppers and Boxed lowers, gm12 bolt, haven’t bought shocks yet but sounds like a few guys have done well with 80/20s. I’m sorry guys I’m just a little slow I guess lol but it looks like the relocation brackets lower the rear pivot point of the lca, this would also create more of an angle to the ground right? Or am I missing something cuz that seams counter productive.
 

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So please correct me if I’m wrong but it seams the only way to get the trailing arms parallel to the ground is to lower the car. I suppose a guy could fab brackets to lower the front mounting point for the arms but I’m curious if this could throw off the geometry of how the suspension transfers the forward motion to the frame. Maybe I’m over thinking it, I do have the adjustable uppers and Boxed lowers, gm12 bolt, haven’t bought shocks yet but sounds like a few guys have done well with 80/20s. I’m sorry guys I’m just a little slow I guess lol but it looks like the relocation brackets lower the rear pivot point of the lca, this would also create more of an angle to the ground right? Or am I missing something cuz that seams counter productive.
Mine dead hooks everytime, leaves level and car goes straight down the track...really don't even have to steer. Depends how fast you are going on the shocks. My rear shocks are just stock cheapies.

I never worried about whether the lower arms were parallel or not. My brackets have 3 spots, tried the upper and it spun...lower it didn't so that's where they have stayed. Used the adjustable uppers to set the pinion angle...Car is lowered about 2" or so in the rear (65 Olds F85 rear 6 cylinder springs).
 

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So please correct me if I’m wrong but it seams the only way to get the trailing arms parallel to the ground is to lower the car. I suppose a guy could fab brackets to lower the front mounting point for the arms but I’m curious if this could throw off the geometry of how the suspension transfers the forward motion to the frame. Maybe I’m over thinking it, I do have the adjustable uppers and Boxed lowers, gm12 bolt, haven’t bought shocks yet but sounds like a few guys have done well with 80/20s. I’m sorry guys I’m just a little slow I guess lol but it looks like the relocation brackets lower the rear pivot point of the lca, this would also create more of an angle to the ground right? Or am I missing something cuz that seams counter productive.
I'm not sure why you are so fixated on the idea that the lower control arms need to be parallel to the ground. You can clearly see in the second photo I posted my arms at a pretty aggressive downward angle, and that car flat hooked and lifted the tires - no wheel spin. Is it counter-productive? Again - look at the photos and the time slip.
 

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1970 Chevelle ss turbocharged 427 4 speed sled from hell
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Discussion Starter #18
I'm not sure why you are so fixated on the idea that the lower control arms need to be parallel to the ground. You can clearly see in the second photo I posted my arms at a pretty aggressive downward angle, and that car flat hooked and lifted the tires - no wheel spin. Is it counter-productive? Again - look at the photos and the time slip.
Sorry I dident mean to say yours wasn’t good enough, I was just trying to understand why there’s a lot of people saying level arms work the best. That was my only purpose of the post.
 

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1970 Chevelle ss turbocharged 427 4 speed sled from hell
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Discussion Starter #19
I only ask because I’m in the rough stages of the car so any fab or fitment I need to do id like to do now
 

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I'm not sure why you are so fixated on the idea that the lower control arms need to be parallel to the ground. You can clearly see in the second photo I posted my arms at a pretty aggressive downward angle, and that car flat hooked and lifted the tires - no wheel spin. Is it counter-productive? Again - look at the photos and the time slip.
I am also more in favor of lowering the rear of the lower control arms and raising the rear of the upper ones. This is what I've always read about which gives the best results to hook the car at the track.
Also, I've read the article which "pannetron" posted and I think that what matters the most is (correct me if I'm wrong) to have the "instant center" point as much to the rear as possible.

Claude.
 
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