Wilwood Drop Spindle

[69gmachine 15]

I know this would be much better with pictures, but I've been unable to upload any because my internet connection is too slow (satellite sucks!). They just time out.

 

Anyway, I've been working on redesigning my front suspension using the new Wilwood ProSpindle. I don't think I would have tried this had I realized just how invloved it would become, but I'm close to getting the car on the road, so I wanted to give a write up on how it has gone so far.

 

The design goal was that this had to be bolt in, no cutting and welding. Using the stock pick up point for the LCA, a Moog 772 (OEM Mopar) upper ball joint and a ride height that is lowered approx 1.75 from stock, the drop spindle results in a roll center of 7.75 inch. This is OK for normal cruising on the streets, but not ideal for a corner carver. The wheel rate using a 400 lb/in spring came out to be 205 lb/in.

 

In order to get the RC in the sweet spot (2 to 3") I will have to lower the pick up point for the LCA 2.5" and use adjustable upper ball joints to raise the upper ball joint pivot point about a 1/2". Lowering the LCA pickup 2.5" will require a new centerlink and possibly a new centerlink adapter to keep the bumpsteer in check. The good news is that this would virtually eliminate the moment arm acting on the rack and pinion so I shouldn't need any kind of anti-torque guide.

 

I'm using a prototype -10 degree steering arm right now, which required a 1/2 inch wheel spacer to clear the ('94-'04) 17x8" wheel. I'm going to try a new design with a -12 degree ackerman and just a little less length in order to clear the wheel better. The use of a wheel spacer resulted in a 3.25" scrub radius and a track width of 58.125".

 

An 18 inch (even an 18x9") wheel would clear no problem, but I don't like the look of an 18" wheel on the early cars. I accept the look of a 17" wheel as I feel form follows function, and a 17" wheel provides the perfect balance of weight and tire aspect ratio IMO. I might use 18" wheels at the track once I correct the roll center as I could get rid of the spacer to shorten up the scrub radius. With a P275 tire on a 9" rim I would need to use some sort of wheel stop to prevent the tire from contacting the frame in a full lock turn (not something that's required on a road course anyway) so I would only use them at the track.

 

The main design goal for using the drop spindle in the first place was to utilize a shorter steering arm to improve the turn radius, and a secondary goal was to fit inside a 9" wide wheel. I haven't driven the car yet with the new suspension, but judging from the angle of the wheel at full lock the turn radius will be excellent, on par with any modern car.

 

Wilwood also has a non-drop spindle that uses a bolt on steering arm that would be much easier to adapt to the early Mustang chassis. I will just have to give up on the 9" wide wheel.

 

I will post pics as soon as I can.

Edited December 29, 2009 by 69gmachine
spelling

[buening 63]

Sweet! Looking forward to the pics. Is this the one you are using? http://www.wilwood.com/PDF/fl193.pdf

 

The flier says that both have the bolt on steering arm.

[69gmachine 15]

Yes, I'm using the drop spindle version.

 

Both of them use the same arms that are designed for front steer.

 

If I have to I'll load the pics on a thumb drive and take them to a friend to upload on my Cardomain site. Then I can link to them on these threads.

[69gmachine 15]

Since most of you also check in at StangNet, I'll put up some different pictures here. The full picture layout is on page 5 of my Cardomain site.

 

This is the spindle and hub assembly installed on the car. I retained the C5 PBR calipers as I really like them, and of course I already had them.

 

This is the back side of the spindle in a full lock RH turn. With the tire installed, it is only about a 1/4" from contacting the frame. I had to move my cut off switch out of the way. I'm using spacers to set the ackerman. After taking this picture I replaced these spacers with thicker ones to give me a little more clearance.

 

Although nothing fouls in a full lock RH turn, a full lock LH turn will cause the inside of the driver's side tire to rub the end of the rack. I moved it inboard 3/8" to give me as much travel as possible, but I couldn't move it in any further without modifying the headers. When I moved the rack in I had to move the holes on the centerlink in to match. Fortunately I had a spare that was drilled wrong in the opposite direction, so I was able to re-drill it for use with the relocated rack.

 

I also had a unique custom hat, rotor and caliper mounting bracket made for use with the Ford Cobra/Bullitt caliper. I plan to put together a display using these parts since the calipers have the nice running pony logo on them.

[Grabber70Mach 107]

Please clear your PM box it says it is full. Thanks. :)

[69_Mustang 26]

Awesome! I found your old thread. :D I'm thinking of picking up those wilwood 2" drop spindles soon!

[69gmachine 15]

I changed to the Wilwood non drop spindle as I found the drop down design created geometry and packaging problems for the steering arm. I sent you a PM.

 

Awesome! I found your old thread. :D I'm thinking of picking up those wilwood 2" drop spindles soon!

[RPM 1,190]

Really top shelf work. Sure wish you'd have done your research and work before I started my front end :)

[buening 63]

Now that you have some miles on the suspension, have you checked that strut arm clevis for any stress fractures?

[69gmachine 15]

Well the approximately 10,000 street miles don't even come close to the loads I generate when negotiating an autocross course in a nearly 3,300 lb car, but no there are no stress cracks. I even took off my dress shirt threw on a work shirt, grabbed a flashlight and crawled under the car tonight to verify.

 

Next year I will put my p275 Toyo RA1s up front when the race season starts (last year they were on the back and I had to use p275 street tires up front). As soon as I can afford it I'll put Hoosier A6 slicks up front. If you drove that hard on the street you'd get arrested, and street tires can't come close to holding the loads that my Toyo's do much less Hoosiers.

[69_Mustang 26]

Well the approximately 10,000 street miles don't even come close to the loads I generate when negotiating an autocross course in a nearly 3,300 lb car, but no there are no stress cracks. I even took off my dress shirt threw on a work shirt, grabbed a flashlight and crawled under the car tonight to verify.

 

Next year I will put my p275 Toyo RA1s up front when the race season starts (last year they were on the back and I had to use p275 street tires up front). As soon as I can afford it I'll put Hoosier A6 slicks up front. If you drove that hard on the street you'd get arrested, and street tires can't come close to holding the loads that my Toyo's do much less Hoosiers.

 

:gunsmilie:

 

Awesome!

[buening 63]

Good to know. A guy on the VMF took some heat for using a clevis on his strut rod (DIY coilover conversion) and Shaun posted a picture of a broken clevis on a similar LCA that you are using. Glad to see you haven't had any issues.

[69_Mustang 26]

Good to know. A guy on the VMF took some heat for using a clevis on his strut rod (DIY coilover conversion) and Shaun posted a picture of a broken clevis on a similar LCA that you are using. Glad to see you haven't had any issues.

 

Do you remember the title or have the thread link by chance?

 

 

69gmachine, say we are interested in your kind of setup and would like to run it on our cars and you offer it to us; in the super rare case that something does fail, do to tracking, autox, etc, would there be some sort of warranty to replace that component?

[buening 63]

Looks like it was a thread hijack, but regardless here: http://forums.vintage-mustang.com/mod-custom-forum/608626-tubular-control-arm-custom-suspension-3.html

 

 

 

Original thread for the coilover sertup is over on mustangforums here: http://mustangforums.com/forum/classic-mustangs-tech/628980-homebuilt-coilover-system-17.html

[69_Mustang 26]

Thanks That definitely looks way different than 69gmachine's, which I'm sure is a good thing. But that sucks for that guy.

[RPM 1,190]

That clevis on the lower control arm design has been used by several different mfgs on thousands of cars w/o issue. Seeings how there are at least 2 broken clevises in this pic, I'd like to see more than this picture before finding fault. A mistake as simple as the tab on the lca not properly fitting the clevis throat can cause part failure. Carroll Smith has a very good book titled "Engineer to Win", it's a good read. Bad design, stress risers and people cause most part failures.

 

Bob

[69gmachine 15]

There is simply not enough information to draw any conclusion on what caused the clevis to snap. We don't know if the car was in a wreck, if the front of the strut rod was in a bind (most likely), or if there was excessive play in the clevis causing torsional movement (also very plausible).

 

As Shaun points out on VMF, the loads on the track (especially with race tires) are many times the loads seen in normal street driving, but beyond that there is no way anyone can draw a conclusion from a photograph without knowing more about the installation and circumstances.

 

As RPM stated, there are tens of thousands of racers all across the country who use a clevis style strut rod on countless dirt tracks and asphalt tracks every weekend of race season. They bang against each other routinely, especially in the dirt. If the design was inherently bad, it would have fallen by the wayside years ago. There's more to this story than the picture is telling us.

 

I will honestly report if something fails on my car, along with the context. Next year I will put a lot more stress on my chassis and suspension when I put the 275 Toyos up front, and hopefully by mid season 295 Hoosiers (and a Monte Carlo bar). You will never be able to generate those kinds of loads with street tires.

 

Consider all the things that typically break when you have over 500 HP and you go drag racing on slicks. When you have that much power and that much tire, you will find out what isn't designed to take punishment. The same is true of steering and stopping a nearly 3300 lb missile. Something could very well break, and I will have to re-evaluate the design, but I'm betting that my parts won't have a problem.

 

I will warranty my parts against material defects and workmanship and unlimited street miles, but once you go racing, you're on your own. I don't know any manufacturer in the world that will warranty a part against breakage when racing.

 

I will also sponsor the first person who completes at least 8 races in a single season in an SCCA sanctioned Autocross C prepared class with a complete front suspension steering and brake package at 50% off when you prepay for the next entire season. I will provide parts that will be competitive with almost anything you will be up against (unless you happen to be in Mike Maier's chapter in LA). I will also pay you $200 for the first win and $100 for the first 2nd place trophy. I doubt you will get that offer from anyone else.

[69_Mustang 26]

I'm in LA county. :/ The east side, near Pasadena, though. I thought Maier was near the San Fran area?

 

I'm going to look up the C prep class right now. I'm not sure what exactly is allowed and whatnot.

Edited December 11, 2012 by 69_Mustang

[69gmachine 15]

I stand corrected, he does indeed race in the San Fran area.

[69_Mustang 26]

I stand corrected, he does indeed race in the San Fran area.

 

Thank god! Ha.

 

So, pretty much anything goes as long as the chassis isn't heavily modified into what it's not? I noticed that C prep says the car can be as light as 2500 lbs with a 351... that's super light. I think, when I have the funds, I could easily get sub 2800 lbs, without any "hardcore" mods. Mostly just fiberglass parts, lexan and stronger, lighter suspension. Not counting fiberglass doors, which would probably drop another 100+ lbs.

[69gmachine 15]

I'm not sure where you got the 2500 lb weight from, but the 2012 rule book Appendix A section 9, page 207 has a table for minimum weights.

 

V8s greater than 5100 cc have a min weight of 3000 lbs. If your wheels are more than 16" in diameter or in excess of 10" wide there is an additional 50 lb penalty each per section 17.4 With a 351W and 18" wheels you're looking at a minimum weight of 3050.

[69_Mustang 26]

Maybe I read the wrong class.

 

Even then, 3050 lbs isn't bad if I ran 10" wheels in the back with 305 or 315s. It should hook up just fine.

 

Car is at about 3200 lbs as it sits now... So much to do, so little money.

Edited December 13, 2012 by 69_Mustang