The Vintage Mod E-letter

                   Volume V, August 2003

THE IRS ISSUE

Q. - Will your kit fit the 1965-1966 Mustang chassis?

A. - YES and NO.

1965 Mustang Fastback with a 2000 Cobra R Independent rear suspension.  This sweet ride is owned by fellow Hoosier Dale Irwin 

     Back in January we promised an answer to the question of whether or not our kit to install the IRS from a late model Cobra would fit into the 65-66 chassis, and we thought we would have a quick answer.  The 1965 fastback above was going to be used as our guide for any changes that would need to be done to make our system fit the early cars.

    What we didn't know at the time is that this car came with a set of beautiful rear fender flares, which look great but didn't help in one key aspect of determining fit on the early chassis.

The flares on this car were great, but it prevented us from confirming the width of the IRS unit to the original wheel flares.

 We knew the IRS setup was an inch wider on each side in the 67-8 chassis, and we knew that the 65-66 standard axle is an inch shorter than the 67-70, we just didn't know if the wheels would fit under the standard lip of a 65 Mustang!

First things first.  Since we knew we would have tons of room to put massive amounts of tire under this car with the new flares, our first goal was to see if our kit will physically bolt into the 65-6 chassis. Answer - YES!  The frame rails and position in the rear of the chassis allow for the physical installation of the IRS unit.

  Trick slotted and plated rotors courtesy of SSBC!

    Only three real modifications were needed for the installation of the kit into the 65 chassis.  We had to notch the upper left hand corner of the front bracket to clear the indentation of the rail assembly.  The rail itself is thinner and will require a spacer on the outside to make the kit bolt together properly. Inside, this drip rail on the early car (middle photo) is right in our way, so we'll have to make a longer insert to clear the strengthening rib.  The final photo is the floorpan of a 70 Mustang.  Note no rib!

Looking to the inside of the wheel well, there is plenty of space with the early cars.  There is about an inch to go before you start having clearance problems with the rear bracket and the coil over shock - just as you do with the later 67-70 installations (we note this for a reason).

No clearance problems on the inside of the wheel well.  Our alignment guy says a 9 inch rim is max before you start hitting things.

So what's the problem?  Here's our problem - the unit is wider than the factory Mustang wheel lips.  The stock 65-66 wheel lips are approximately 66 5/16 inches wide from inside lip to inside lip.

Using a real high tech method of lug nuts and string, we measured a 65 Mustang that still has it's original quarter panels (repo panels may be different!).  Inside lip to inside lip is approximately 66 5/16 inches wide.

    Now, using the stock late model Mustang rims (17x8 with a 5.72 inch offset) and 245/45 series late model tires, we measure 69 1/2 inches from outside tire to outside tire.

Missed it by that much!

So, what is the solution?

    We need around 3 inches to make this work.  The solutions to make it fit are as follows:

1. Large, way cool wheel flares as shown above.  A bit radical, but it does work.

2. Roll the rear fender lips under.  This will provide about and inch total additional clearance.

3. Wheels with a larger offset.  We mentioned there is room on the inside to offset the rim some more, but the wheel is going to be very flat. We're looking into wheel manufacturers and hope to have a list of recommended wheels soon.

4. A mild roll of the wheel lip to gain additional clearance. A proper body shop can expand the wheel lips and make them look nice.

    Probably a combination of the above items are needed to make the wide unit fit the 65 chassis.  Sooooo, if you were thinking about big flares or some other means of widening the rear of your car, the IRS WILL fit the 65-6 Mustang - with some modifications!  Thanks to everyone who has been patient with us!

Lowered Expectations

John Devine's beautiful '69 convertible with the new lowered IRS kit!  Get Down!

    When we first introduced our IRS kits we intended them to be designed to install the system with a minimum of modifications to both the car and the IRS unit.  The unit works and looks great, but we knew there would be those who would like a little more lay down in the stance of the car.

70 Mustang with the standard ride height. Although it's level, the trend is to lower the stance from the original Ford settings.

    DVS Restorations, Inc. now has a program for those IRS users who want to have a lower stance for their vintage ride. The IRS in base form sits level, but the lowered kit allows for up to 2 inches lower stance while adding road clearance and adding to the travel of the suspension.

Photo on the right shows the "standard" ride height using the lowered subframe.  Improved suspension travel and an additional 1.75 inches of ground clearance.  The photo on the left shows the cradle down a full two inches - about 3/4 of an inch to spare!

    Road clearance is gained by changing the angle of the front mount to near horizontal.  The mounts are flat and not angling up towards the chassis.  Road clearance can be improved up to two inches! By raising the subframe in the chassis, the suspension travel is also improved. 

The lowered system consists of the following items:

1. Lowered subframe unit

2. Special lowered shocks

3. Optional spring rates if necessary

Ground Clearance - With the non-altered cradle the ride height is about 3.75 inches. With the lowered unit, the ground clearance is much better, with about 5 inches for the standard and 4 inches at the maximum lowered height.

If you would like to consider the lowered unit, you need to consider the following:

1. You'll have to cut out the entire axle snubber assemblies. They will interfere with the travel of the upper control arm.

2. For some applications you will have to dimple or modify the trunk area to make clearance for the swing of the upper control arm.

3. This will require a special shorter shock absorber. This is a no cost option when purchasing the lowered unit with the IRS install kit. Exchanges may be available - contact us for more information..

4. With some shock combinations you may be required to run a 7 inch spring. Call or e-mail for more information. Optional springs may add to the cost of the IRS install kit.

5. You have less than one finger's worth of travel between the lip of the wheel well and the tire. Radiusing the wheel lip opening is highly recommended.

6. Remember 245s will drop the car even farther. 245/45s are standard equipment on late model Cobras/ Mustangs.

Please contact us for any further questions on the lowered IRS units.

IRS Facts, Fiction and Useless (and useful) Trivia

Q. - So what's the difference in the 99, 2000 R, 2001-2 and 2003 Units?

A. - Here's what we know so far:

    1999 - small 28 spline axles, 3.27 gear, posi center, soft rubber in subframe mounts.  

    2000 Cobra R - a true beast.  3.55 gerodisc hydro-mechanical posi center, massive 31 spline axles, improved CV joints, upper camber slot moved in 5mm to improve camber adjustment, rubber bushings are the hardest installed, reduces body hop.

    2001-02 - mild improvement in axles - 31 spline on the inside while still 28 on the ends.  Still has 3.27 gears.

    2003 - a lot of parts from the 2000 R unit make it to the 2003 units.  31 spline axles (slightly shorter) 3.55 gears (standard posi and not the expensive Gerodisc), stiffer but not as stiff as the R units rubber subframe bushings, improve camber and new for 2003 - the inner tie rod mounts are lowered 6mm to improve bump steer.

Q. - Will standard GT brakes fit on the IRS unit?

A. - Yes.  GT and Cobra brakes will interchange.  The Cobra is a bigger brake unit so it has a larger throat on the calipers.  The rotors are E4ZZ parts - they haven't changed since 94.  The late model Bullit cars had Cobra size calipers and rotors.  So, if you find an IRS unit without brakes, GT brakes will work in a pinch!

Q. - I've heard the IRS units are weak.  Is this true?

A. - Yes and no.  They are weak if you take them to the drag strip, install a set of slicks on them and pull 5000 rpm hole shots through them.  There are five transfer joints in one of these things - you can hurt them if you abuse them.  These things aren't the best solution for drag racing anyway.  If you are road racing the car you shouldn't have a problem.  Also note that in the Ford Motorsport Catalog they state that gearing higher than 3.27 can reduce the lifespan of some of the parts in these things - higher gears mean more torque transfer. 

Q. - What about the tie rod connecting rods bending?

A. - There have been a couple of guys who have bent them, but it doesn't seem to be a major issue.  If you are worried about them, Kenny Brown sells a set of hardened connectors and that should more than take care of the problem.

Q. - Will a Super Coupe IRS unit work with your kit?

A. - Nope.  Although the SC and Lincoln pieces are more plentiful, they are bigger, heavier, weaker in some places and the mounts are completely different.  Here's a shot of each for comparison:

Cobra IRS on the left, T-bird IRS on the right.

IRS DEALZ

New and Used IRS Units

1999 unit shown

    We have a limited supply of new and used Cobra IRS rear axle assemblies available on a first come, first serve basis.  Please contact us for more information.  Shipping is not included in the advertised prices, and all units are sold "as is" with no warranties expressed or implied.

Used 2003 Cobra Rear Axle on 2000 Cobra R frame.  $2000

    This unit was a used 2003 Cobra unit that was remounted onto a brand new Cobra R subframe.  The differences between the subframes are that the Cobra R has much stiffer subframe bushings while the 2003 unit has the lowered inner tie rod positions.  Other than that they are identical.  This unit comes complete with brake calipers and rotors.

Used 1999 Unit Complete - $1500

    A complete used 1999 unit less emergency brake cables.

BRAND NEW 2000 Cobra R units - $2295

    We have a very limited quantity of the massive Cobra R rear axle assemblies. This is the unit that the 2003 gets most of its parts from.  The biggest difference in these units is that they have the Gero Disc posi centers.  These were designed to handle the massive 5.4 engines! Brand new! The units come without brake assemblies.  See below for brake options.

PRICE REDUCTION on 2003-04 Current Production IRS units - $2999

    These units are available as a pre-order only.  Brand new units directly from Ford. The come less brake assemblies.  Call for more information.

Brake Assemblies/options:

Rear Cobra R calipers and rotors and standard brake pads - Add  $350

Cobra R spec racing pads - Add $100

Wilwood or Bear Brake Options - CALL

Custom slotting and plating of rotors - CALL

Lowered IRS Subframe - $120 Exchange.  Contact DVS Restorations, Inc. for more information.

Nice Ride

Mike Ma sent us pics of his beautiful 1967 convertible.  We were immediately envious!

This sweet ride is complete with a late model IRS unit, Bullit rims,  reliable 5.0 fuel injected power under the hood and tons of custom features.  We gotta think of a reason to score get a ride in this bad boy!

Got a cool ride?  Send it to us and we may just put it in the newsletter!

 Copyright 2003 DVS Restorations, Inc.  No part of this publication may be used or reproduced without permission.

DVS Restorations, Inc.

11 Meahme Trail, Crawfordsville, Indiana 47933

(765) 361-1822 www.dvsrestorations.com