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Here's a couple of pictures of the 1973 Corvette IRS build up. A brand new 73 Corvette of this era would pull about .7 G's . 

 

What does the NHRA think of the IRS? What does this rule say to you?

 This is right out of the rule book page 19 under rear end. The NHRA requirements for an IRS are "Must have 360-degree, minimum 1-Inch-wide by 1/4 thick axle retention loop on each axle." and "Car running 10.99 (*6.99)or quicker that weigh more than 2,000 pounds with independent rear suspension without upper and lower (both) control arms must replace swing axle differential with conventional differential housing assembly (Example 1963-1982 Corvette). Cars with independent rear suspension with upper and lower (both) control arms may retain swing axle assembly regardless of weight or e. t.

The Dragvette 6-Link Suspension System makes your IRS legal for any e.t. or any weight at NHRA tracks!

     In Dec 29. 2004 Thoughts and plans to build a six link suspension for my 73 had formed  This was only the beginning of a long slow struggle to focus on a project while living life day to day.

  March 26, 2005 Not much happening on the project.  I have gotten the seats back from the upholster they look real nice and were 300.00 for the pair I provided the seat covers they came with the car.

May 9, 2005 Has it been that long! I have been a little distracted with the addition to the shop. Six hundred square feet and 10,000 lb car lift is way over due. Well it's not a big surprise the left front brake caliper went bad from sitting around and not being used on a regular basis. I always bleed my brakes at the beginning of every race season on the 76 and this 73 will not be any exception. A little tip for you guys that haven't done this little exercise much. It helps to jack the end of the Corvette up depending on which end your bleeding. That is jack the front up if your bleeding the front brakes and jack the rear up if your bleeding the rear brakes. Air bubbles float up stream it seems to help. Also bleed the brake closest to the master cylinder. Front driver, front passenger, rear driver, rear passenger, in that order. I need to bolt the seats in. 

Jan 6, 2006 The addition to the shop is complete. I thing I will make a DVD of the IRS build up so that will slow me down a bit. I have many people wanting to purchase the 6 link  system as soon as it available. I have talked a lot about it and I am finally in  position to start making things happen on it. So hold tight its launch time.           

 

 

 

 

 

 

                 

  April 21,06. The 6 link for our favorite IRS is taking shape. As usual I have a number of issues with the first proto type and am already making changes with this unit as you are reading. The number one change I will be making is to make the bottom link the same length as the half shaft. The one shown is 16 inches long that's 1 1/2 shorter than the stock unit. It still needs to be about 2 inches shorter before it will be acceptable for our needs. That being done it will need a proper mounting bracket. That is practically completed. The second issue I have it the top mounting link for the upper strut rod is to tall and may interfere with the body under heavy roll conditions. I already have a different mount design in mind it should allow another 1 1/4" of clearance which should be plenty of clearance. That will put my mind at ease. The plate that I normally use to relocate the strut bracket has been reduced by a 1/2". That will help reduce the interference problems with the stock exhaust system and align the bottom strut rod to the perfect mounting position.

 

Thoughts of a level II suspension kit have been scraped as the physical world and the theory world did not coincide. There were safety issues that simply could not be resolved with out extensive testing and the fact is there are no safety issues with the level III design and the cost is not so much greater then the level II unit I had proposed to manufacture at one time  

   

 

I have thought about marketing the new 6-link. Those that have bought the original Basic  Dragvette Suspension Package will be offered a trade in allowance of $149.00 for there original kit and safety loops. This would position them to upgrade to the Level 3 System. 

    Greenwood offered a 6 link system for a short period of time only a few kits were sold. The reason was simple why it did not become a traditional upgrade for Corvette owners every where. It was simply to costly for the average person to purchase. Billet castings and stainless steel are great but add a great deal of expensive to the price tag for the consumer. There may have been other issues such as poor marketing and any other number of unknowns.    

       

 
   April 28,2006    As you can see from the picture above the mount on the top of the 6-link system has been changed the former mount while easy to build was to tall. It was able to contact the body on extreme body compression. We all know that the drivers that use our products will push there machines to the limit so the mount had to be modify to minimize mounting height so the suspension would no longer present the possibility of body interference.   
      Here is a view of the new mounting location of the strut bar. After measuring the amount of movement with a 16" long strut bar we determined the only way we were going to get the 6-link to work properly would be to use a strut bar exactly the same length as the half shaft and create a mount that would allow the strut bar to be parallel to the half shaft  as you can see the strut bar is the same exact length as the half shaft and it will forms a perfect parallelogram.    

    Without a top link bar wear in the posi-tract clutch plates allow movement in the side yokes. The top link will stabilize the movement of the side yoke and provide support for the Corvette should the half shaft decide to take an alternate path down the track or street.  

  May 7,2006 WOW I have been able to finish the 6-LINK!! I know that many of you have heard about this happening and being in the works for years. I was finally able to focus all of my attention on this project. I am glad to be able to say I have resolved all of the issues I had with the design and I am very pleased with the out come. In order to determine how perpendicular the tire was to the ground I set a digital protractor on the brake rotor and moved the suspension through it entire range of motion about 8 inches. The protractor varied .2 of one degree that is a total of .0096 variation on a 28 inch tall tire. here are a few quick shots of the proto type I took with my digital camera.     
 
  The picture above are the parts of the proto type 6-link. the pictures below are pictures of the proto type 6-link installed on the 73 project car. 

  Notice the additional safety loop on the half shaft nest to the differential. Another feature is the horizontal bar the runs across the back of the rear cover this will give the rear pig more rigidity the same as a rear cover girdle. There are additional gussets welded on the center section support you are viewing here. This is just one of the development stages. 
  Here is another shot of the 6-LINK in development. Please note this is not the finished product this is a picture of the unit in development. Product pictures will be posted in the next week or so. I will currently be tied up editing an instructional DVD that actually shows installation of the 6-LINK.This is currently free for the asking. I will continue to offer this as long as it does not become a huge expense and we sell a reasonable number of Dragvette 6-Link Suspension Systems in comparison to free DVD's. 
   I am pleased to announce Dragvette Products has finished the development of the 6-link and we will now offer it to our customers at the prices stated above. 
   

  

     This is a disassembled view of the same upper link. The securing shoulder bolt has a 1/2" body with a 3/8 thread, it also features a nylock insert on the thread so the securing  nut will not back off.( This has been updated to a 1/2" fine threaded bold and 1/2" Nyloc Nut. These pictures are left on the site to demonstrate the developmental steps of our product this design has been superseded since july 30,06)
  This is a front and rear view of the center section plate. As you can see gussets were added to insure the maximum strength in the weldment to minimize deflection in the center section. The zinc plated hiem joint (above) is reflected in the finish of the safety loop and it doesn't appear to have a finish that is any better then the safety loop.     

     There has been some discussion as to weather the clips on the side yokes are required for this system as I see it you may keep the clips on if you wish. However the half shaft has been relieved of supporting the Corvette. As long as the Level III, 6-Link Suspension System is adjusted properly there will never been any problem resulting from the clips being removed. It has been asked if Tom's parts are compatible with the Dragvette Level III, 6-Link System.

     March 22,07 Dragvette Products now offers a 6-Link that is compatible with the Tom's trailing arms and the over sized half shafts and 1480 joints. We also fit all other stock and aftermarket trailing arms including offset trailing arms. We are continually accommodating more after market systems. Case in point is the recent development of a 6-Link that is compatible with the VB & P dual mount mono spring.

    I took the 73 Vette out for a seat of the pants test spin. I was impressed by how flat the Corvette cornered as this Corvette does not have a rear stabilizer bar, fancy tires or an alignment tuned for cornering. I don't know what the minimum turning circle of the Corvette is but after 5 or 6 tight circles I found myself quite dizzy after straitening the wheel out. This was on asphalt and I was surprised the wheels were not squealing they just seemed to grip incredibly well. Sure I would be biased but if there was anything at all not to my liking or unusual in a handling sense I would have to have to include that in my seat of the pants test. Dragvette is committed to quality products and we have always had a 100% refund policy no explanation needed but appreciated as it may be some valuable feed back.                      

  June 3,06 This is a complete kit with the exception of the 8" long screws that are needed to adjust the half shaft level with the street or track. The Dragvette Level III System is shipped semi assembled to make your installation process easier. We also send a DVD installation video with each Level III System it shows every step off installation and adjustment it is approximately 1 hour in length. 

      The girdle bar in the center of this kit will be included in all kits regardless of color choice with   " Dragvette   6-LINK    products   inscribed on the girdle. It is one of the finishing touches that is still ongoing. We also have a couple of small refinements will be added. Please note any updates that are made and have any significant benefit for a Dragvette Level III System will be sent free of charge to any customer that has already made a purchase. Dragvette service and a great product is what will make Dragvette Products a great company that customers will want to utilize.  

 

 
  July 9/06. Here's a look at the latest Dragvette 6- Link level III Suspension System. This unit is headed to Patrick Armstrong of Michigan, We have delivered a previous unit to Leon Sabelka of Iowa. We are currently working on unit for Hennik Anderson of Sweden, Brad Ecker of Maryland, Vasco Arosemena of Panama, Andrew Hodgson of Australia, Jason Mackey of Indiana, and Micheal Dobesh of Alaska.    

 

 
  Oct 9,2006 We have currently delivered 15 Dragvette Level III Six Link Suspension System and we are just now receiving some customer feed back. The first kit immediately ran into a heavy duty aftermarket rear cover. So we made some adjustments. We then determined that  the 1/2" shim plate was only perfect on perfect Corvettes so we added some shims and a stud kit to accommodate some not so perfect cars. It was really a variation between cars that should have been expected. We also decided the drain plug needed to be a little more accessible so once again we made another adjustment. So there were basically two small issues and one bigger issue that were all addressed. We also issued the upgrades to any customers that had not received those items to begin with at no additional charge not even shipping.
 

Please note the heavy duty covers are not included in the Dragvette 6-Link Suspension System. They are in the pictures to give you a reference as to its location to the rear differential. Heavy duty covers are available through us for $109.00.  

  The following feed back resulted in a 

6-Link for the VB&P Dual Mount Spring

and Tom's Differential system for Vette's  

Customer Feed Back 

    Andrew of Australia has informed me the Dragvette 6-Link Suspension is not compatible with the after market VB&P dual mount fiberglass spring. We had compared some preliminary measurements and it appeared they should intermesh. The 6-Link was designed around the standard single mount spring. We are working closely with Andrew to make sure he ends up with a working 6-Link, we have sent down a number of parts at no additional cost to Andrew to make his Corvette suspension work. It appears it would be simpler to start from scratch with the dual mount spring.

    After a number of inquiries from Corvette enthusiasts that own a dual mount VBP mono spring we have decided to fire up the Auto Cad and see what we could develop. Armed with some critical dimensions and a nice selection of pictures sent to us from our Corvette friends we have been able to develop a mounting bracket for the top link of our 6-Link. There was no way to incorporate the inner safety loops or the stud girdle bar with the Dragvette Products logo. The problem being the dual mounts for the mono spring are massive and directly in the area where the safety loop would be effective. The new bracket goes up and over the top of differential in front of  the cross member that the differential is mounted to.

    The development of the dual mount spring by VBP is important to the auto cross enthusiasts as the dual mount spring acts as a rear stabilizer bar and is a desirable suspension component for auto crossing. A stabilizer bar lifts up the tire that does not have any weight transferred on it while cornering hard. This would be the tire on the inside of the turn. This is good for preventing car roll, however this same suspension trait on a drag car will contribute to wheel hop by lifting the tire with the least weight transfer. The lifting of the tire with the least weight transfer on the launch while drag racing is the opposite of what is desirable when drag racing. The stabilizer bar actually reduces the ability of the tire to adhere to the track. The best of both worlds would be to use a standard stabilizer bar for autocross and then loosen or disconnect the stabilizer bar when running at the drag strip. If wheel hop becomes a problem while drag racing. The HP of your Corvette and track conditions will determine if a stabilizer will cause traction lose. This is not to say the 6-Link suspension is not compatible with a stabilizer bar. This is to say a stabilizer bar is not a preferred suspension part for drag racing.

  The big advantage of a dual mount VBP mono spring is the adjustability. I have found that a  good drag race/ street  spring is 360lbs while I suspect this is to soft for auto crossing. The range of 415 lbs is good for auto crossing and drag racing but it's way to stout for street driving. So the adjustability of the dual mount mono spring is huge. It's like getting 4 springs in one if your wrong about the stiffness or lack of stiffness for your application you don't have to live with it. You just adjust.

 

  March 20,2007 Dragvette 6-Link Suspension System for Dual Mount Spring 

Responding to our customers needs Dragvette Products has designed and currently has a 6-Link Suspension System that will accommodate Corvettes with the Vette Brakes and Products "dual mount rear mono spring" There are unfortunately a few disadvantages with the new system because of the room restrictions the dual mount rear mono spring creates.

>The mounts for the dual mount spring preside exactly where an inner safety loop would be effectively positioned, so the inner safety loop is omitted.

>The rear differential must be removed to install the upper link support bracket.

>There isn't any space for the rear girdle/logo bar so that to has been omitted.

On the plus side.

>The price is the same $895.00 for the Dragvette 6-Link Suspension System for the VB&P dual mount mono spring.

>This design leads the way for the development of a Dragvette 6-Link System for Tom's Differential design.

March 29,07

   Thanks to Mudge Gordon for providing these great pictures of a Dragvette 6-Link Suspension System he is installing on his Corvette. The Dual Mount Spring is available through Dragvette Products as we have been an authorized vender for the full line of Vette Brakes & Products great Corvette parts for some time. We offer our customers the convenience of one call ordering and the same low price VB&P lists in their catalogue. 

Click here for Mudge's Corvette Forum post detailing his 6-link installation

 

 

FEB13,07  Herb Adam requested an overview of the basic alignment of the Dragvette 6-Link Suspension System be posted on our site. Well here it is!

Basic Alignment Procedure This procedure applies after the trailing arm safety loops and center support plates have been installed.

1. Install the half shaft and set it level with a measuring device. Use a jack and move the trailing arm until you are satisfied with the result.

2. Measure the length of the half shaft, center to center of the universals. Now adjust the bottom strut rod to the same length. Next install the strut rod. Note your half shafts may be different lengths. 13-3/4quarters vs 13-15/16ths.

3.Install the shims provided in the 6-link system to adjust the strut rod bracket so the bottom strut bar is parallel to the half shaft. Start with the 1/4 thick only and adjust the height as needed. Note the half shims to adjust one side differently than the other side.

4. Use the stock cam bolt on the strut bracket to adjust the camber. Zero degrees for drag and street driving or 2 to 5 degrees for street and serious auto-crossing. This can be changed at anytime depending upon your driving preference.

5. After the camber is set to your liking. Install the top link. Simply adjust it until it fits loosely into position. Now adjust the rod out until it gets tight, next adjust the rod shorter until it tightens up. Now adjust the rod length to the center of the 2 previous adjustments.

6. With the spring disconnected move the swing arm through out it's complete travel making sure no binding does not occurs. Attach the spring to the trailing arm with the 8 inch long screws leave about 1/4 of thread sticking through the nut.

7. Set the Corvette on the ground. Adjust the 8 inch screws until the half shafts are level with the ground. If you are a serious auto-crosser adjust the half shaft so they are 1/2 inch above center. You will have to play with the camber for your best results.

8. Go for a drive and feel out the performance of your suspension. Gradually work your way up to full out. Be sure to monitor the condition of everything under your Corvette with visual inspections. Caution should be exercised to insure your safety. You may have overlooked something during the installation! Now ENJOY the the way your Corvette handles! 

 

   Thanks for looking at Dragvette Products IRS Build Up!! 
   
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