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Author
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Topic: Lowering them arms
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JClark
Journeyman Posts: 14
From: Atlanta, GA USA
Registered: Jun 2002
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posted 06-19-2002 09:49 AM
   
I am new to this forum, but it appears to be a very informative one. None of the flaming I'd become accustomed to at the old Delphi site. Congratulations to you guys (and gals) on that!
I am looking for opinions on the Ol' Shelby trick of dropping the A-arms.
First, is it worth it on a street car? I have a '65 convertible 289 that is currently only used for pleasure driving. But my definition of pleasure driving is quick and hard. I don't necessarily drive really fast, but I like corners and acceleration. The problem is, the old girl doesn't like them as much as I do. Presently she is fairly stock on the suspension. Her only aids are a 1" front sway bar, poly bushing all around, and disc brakes. I intend to replace the springs with 1" drop 620s up front and 4 leaf mid eyes on the rear.
Second, looking at the location where the new holes would have to be punched, it appears that the rear one would either go through the seam on the tower reinforcement plate (stock) or place the nut directly on the seam. Has anyone had any issue with this?
Third, the template that is available appears to somewhat off. I know the 1/8" displacement they show actually measures to less than 1/8", and can only assume that other dimensions are a bit skewed. I noticed this when I tried to recreate using AutoCAD and when I compared the results, they did not match.
Fourth, am I going to burn through tires after doing this?
Fifth, how does this mod affect bump steer.
Any opinions on these or any other points I may have missed would be greatly appreciated. Thanks.------------------
Justin Clark
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MDF99
Gearhead Posts: 231
From: Hamilton, Ohio, USA
Registered: May 2001
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posted 06-19-2002 01:58 PM
I did the drop on my 66 coupe. For the templates, I had a pair made at a local machine shop for cheap. They charged me about 20 bucks I think. I took in an A arm and had them use the bolt center lines for the width dimension. They drilled the 17/32" holes, went down the 1" and back the 1/8" and drilled a couple small pilot holes. The stock they used was heavy, about 1/8" thick steel, so I removed an 1/8" of shim when I bolted it back together. I've been away working on a job since I got it back together and haven't really driven it much yet, I don't know about tire wear, etc.------------------
Matt Fraley
1966 Mustang Coupe; 289, T-5, 9" 3.50
http://mdf99.tripod.ca/289_Side.jpg
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460-67Stang
Gearhead Posts: 288
From: Southern Ohio, USA
Registered: Feb 2001
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posted 06-19-2002 04:33 PM
JClark - I did this mod and recommend it highly. My steering is much more responsive, especially in curves which is where it helps the most. I'm only 600 miles into it, but tires are wearing super. Also, I had the car aligned by an old-timer who has been doing alignments since these cars were new. I've found it's importnt to find someone who knows how to align properly. FWIW. Cheers,
Brian
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Jeff
Gearhead Posts: 306
From: Moore, OK USA
Registered: Mar 2001
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posted 06-19-2002 05:22 PM
First, is it worth it on a street car?Well, yes...based on what you said. You want to pull a half "G" on the corners (or more) so the Shelby drop is one way of accomplishing this objective. Note there are others such as Global West "A" arms. Second, looking at the location where the new holes would have to be punched, it appears that the rear one would either go through the seam on the tower reinforcement plate (stock) or place the nut directly on the seam. Has anyone had any issue with this? Yes, you have to do one of two things: use washers with an edge cut off to space the toplock nuts high enough to clear the ridge OR cut the ridge away. Third, the template that is available appears to somewhat off. I know the 1/8" displacement they show actually measures to less than 1/8", and can only assume that other dimensions are a bit skewed. I noticed this when I tried to recreate using AutoCAD and when I compared the results, they did not match. There is more than one template around, so I suppose it may depend on which you have. Buying plates from ProMotorsport or Branda is one way to be sure. Fourth, am I going to burn through tires after doing this? No, just the opposite. You're burning through tires now because of the positive camber you're likely to have. They should be wearing on the outside edges now, right? After the change the tread should contact the road more squarely in turns resulting in less tire wear. Fifth, how does this mod affect bump steer. Doing the Shelby drop is right at the limit of movement where bump steer becomes noticeable. If you also cut the ride height by using lowering springs you're sure to have it. With standard springs you'll most likely not have a problem (just depends on your springs, which ones they are and what the rate is, and lastly how old and saggy they've become).
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Paul Leonard
Gearhead Posts: 108
From: NLR, AR, USA
Registered: May 2000
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posted 06-19-2002 10:26 PM
Silly question, but what is bump steer exactly? I've heard it mentioned, but can someone explain it to a backyard mechanic like myself?Paul
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senzstang
Gearhead Posts: 237
From: perry, oh, usa
Registered: May 2002
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posted 06-20-2002 07:48 AM
I have a Template in .PDF file. I have no idea how to attach it to this post  If you send me your email I will forward to you.
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senzstang
Gearhead Posts: 237
From: perry, oh, usa
Registered: May 2002
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posted 06-20-2002 07:51 AM
OK - not only am I new to the site, I am an idiot  I just found your email and will forward you the .PDF It will be from PSENZ. (not junk mail!) Sorry for the stupid post 
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JClark
Journeyman Posts: 14
From: Atlanta, GA USA
Registered: Jun 2002
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posted 06-20-2002 08:47 AM
Paul,
Bump steer is induced when the swing arc of the tie rod and the swing arm of the suspension are not equal. When the suspension hits a bump in the road, the spindle will move up through an arc defined by the suspension's pivot points. If the geometries are incorrect, the differing arcs will cause the steering likage to pull the spindle in a direction other than the one dictated by the steering wheel. Lesser degrees can cause a car to feel unstable at speed over uneven terrain, worse cases can be dangerous. Since I'm concerned both about my safety and about the "feel" of the car, I want to be sure that I won't make an existing problem worse. Here is a sight with good info: http://www.heidts.com/heisinfo.htm
Take care.------------------
Justin Clark
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jkilroy
Gearhead Posts: 1808
From: Vicksburg, MS
Registered: Dec 99
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posted 06-20-2002 08:51 AM
If you are interested in lowering I would suggest getting a negative wedge kit and doing to the full 1 1/2 inch drop. Talk about make a difference! My 68 handles better than my 98, no lie. The lowered arms are hard on ball joints and the wedge kit reloates the ball joints to rectify this. The kit also comes with new hardware and steel plates as templates. You bolt the plates in the original holes and then drill through the holes in the template, which is 1/8 inch steel plate. ------------------
Jay Kilroy
68' Fastback GT 390
"No such thing as a cam thats too big"
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JClark
Journeyman Posts: 14
From: Atlanta, GA USA
Registered: Jun 2002
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posted 06-20-2002 08:52 AM
Thanks Senzstag. That is actually the same template I had that doesn't measure out correctly when printed. The 1/8" dimension they list is actually more like 3/32". With any one of the dimensions being off, all come into question. What I need to do is accurately measure the the centerline distance on my car and create an exact template from that measurement.------------------
Justin Clark
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JClark
Journeyman Posts: 14
From: Atlanta, GA USA
Registered: Jun 2002
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posted 06-20-2002 08:57 AM
Jay,
The biggest reason for considering the Shelby mod versus the negative wedge kit is money. I've already got a ton of other things to do (money to spend) to take this car from good driver to near perfect. I mean, free vs what, $600 or so? It's hard to justify. That said, I would love to do that.------------------
Justin Clark [This message has been edited by JClark (edited 06-20-2002).]
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Paul Leonard
Gearhead Posts: 108
From: NLR, AR, USA
Registered: May 2000
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posted 06-20-2002 05:12 PM
Justin,Thanks for the info. That is a very good site explaining bumpsteer. Thanks,
Paul
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jkilroy
Gearhead Posts: 1808
From: Vicksburg, MS
Registered: Dec 99
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posted 06-21-2002 04:44 PM
I paid less than $200 for my negative wedge kit and it included lots of hardware, new upper ball joints, and heavy duty templates. It also came with a nice set of alignment instructions.------------------
Jay Kilroy
68' Fastback GT 390
"No such thing as a cam thats too big"
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hgufrin
Journeyman Posts: 37
From: North Carolina
Registered: Feb 2004
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posted 03-15-2004 01:01 PM
JClark,Are you still out there?
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Hell_Fish
Gearhead Posts: 860
From: Austin, TX.
Registered: May 2002
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posted 03-17-2004 10:29 AM
Is there a happy median between the shelby drop and needing the wedges? Like at 1"? Can you buy just the wedges by themselves? I want to do this drop on my 69 and have the template plates already.------------------
Dustin C
"The Mopar Guy!"
CRC Motorsports
56 F-100
Mech. for wifes 69 Mustang coupe
65 Plymouth Barracuda
70 Dodge Swinger
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