cortex watts link

[SoundGuyDave]

You really don't need lubrication with the teflon-lined sphericals, I just use WD40 to act as a rinse to flush any contaminants out that might gall the lining. Wiped down to reduce the "grit magnet" affect, and carry on...

I do this as part of my post-race maintenance schedule, and so far I have the original joints on the rear LCAs that are still tight, showing no play or tendency towards being "sticky." YMMV, of course.

 

[Norm Peterson]

Every so often, the rod-ended endlinks on my car get the same WD-40 and wipe treatment.


Norm

 

[B2B]

Finished installing the Cortex watts link this weekend. Except for the hand pump exploding while trying to pump 75W-140 gear oil in 40 degree temperature, the installation was a no-brainer. Doing the installation while laying on my back made it an all day job. But it won't take more than 3 hours if you have access to a 4 points lift and pole jacks.

I have the "street" version, which substituted rod end with a poly bushing on the chassis mount side of the horizontal links. My guess for retaining the rod end on the differential end of the links is to compensate for different pinion angles… Time will tell how well these rod ends will hold up.

I figure it was either pure dumb luck, or Cortex and Ford both did their homework… The two horizontal links came “pre-adjusted” out of the box. After bolting everything up and made zero adjustment to the horizontal links, I took a measurement from the rotors to the frame rail on both sides and found them to be identical. I was convinced that Ford couldn’t possibly form a frame rail that perfectly (backed by years of experience setting up a Fox and then SN-95 Mustang…), so I was fully expecting to make final adjustments once the car is taken off the jack stands.

After lowering the car to the floor, the rear axle was sitting ~1/8” toward the passenger side. After I took a lap around the block to settle the bushings (I did control arms and relocation brackets at the same time…), the axle was perfectly lined up when I pulled back into the garage. After hours of “fitting and adjustments” using files and BFH while installing the full GR-40 on my ’93 GT, I was left speechless on how perfectly the Cortex watts link fit together with the car. Ford definitely have came a LONG way since the Fox Mustang…

As it was too cold and wet to get some SOP feedback, the lowered rear roll center was immediately noticeable and the weight of the car felt much more forward than before. This is a very different feel than simply cranking up rear roll stiffness. First impression is that I may have to increase front roll stiffness to balance out the car. But I’ll have to get more seat time before making any adjustments.

I’ve seen others describing their watts link made their car feels “plush”. Well, I don’t think that’s really the right word to describe it, but I would describe it as movements in the rear being much more controlled and equal (left and right). But it was a very short drive after laying on the icy cold garage floor for a lot of hours. So let’s call it “plush” for now.

Can’t wait for TWS later next month to put the car through some real corners...

Full Weight on axle:

 

[NoTicket]

You may want to extend both of those arms in equal measure if possible to get that propeller to be as vertical as possible at rest.

 

[B2B]

You may want to extend both of those arms in equal measure if possible to get that propeller to be as vertical as possible at rest.

As long as I have full range of travel, I'm not going to worry about making the propeller vertical.

The propeller will keep moving as the rear axle goes through its vertical range of motion, and if I change to a different RC height on the differential cover.

 

[BMR Tech]

Looks good!

Not sure if you are using "full weight on axle" for any adjustments you are making to the suspension - but remember, jack stands on the axle does not load the suspension fully. The axle assembly will "raise up" into the car about 1" further, once the car is sitting on the tires.

 

[UNDRTKR]

I like this design. Are they still available?

 

[B2B]

Looks good!

Not sure if you are using "full weight on axle" for any adjustments you are making to the suspension - but remember, jack stands on the axle does not load the suspension fully. The axle assembly will "raise up" into the car about 1" further, once the car is sitting on the tires.

Kelly,

I only used the "weight on axle" position to take initial measurements just to make sure everything is within the ball park. I made sure that the car is on the ground before even trying to check the final alignment.

FWIW, you can come pretty close to having full weight on rear axle by putting the front tires on a set of ramps. The weight from the front of the car will fully loads the rear suspension, but not if the front half is sitting on jack stands on the frame rail... Learned this from too many nights in the garage with the car up on jack stands...

Looking forward to your new rear sway bar as my Whiteline rear bar doesn't clear the passenger side chassis mount. Going to use my OEM 24mm rear bar for now and see if I can make it works. But it's always welcomed to have the option to fine tune these adjustments.

 

[B2B]

I like this design. Are they still available?

This is Cortex's current design.

 

[UNDRTKR]

This is Cortex's current design.

Oh yea. I got Cortex and Techo mixed up.

 

[NoTicket]

As long as I have full range of travel, I'm not going to worry about making the propeller vertical.

The propeller will keep moving as the rear axle goes through its vertical range of motion, and if I change to a different RC height on the differential cover.

It is a simple adjustment to make, but obviously you can do what you like. Having the propeller vertical minimizes the possibility of lateral motion due to suspension travel. The arms look like they are fully adjusted inward, so you clearly have plenty of room to play with.

 

[Pentalab]

It is a simple adjustment to make, but obviously you can do what you like. Having the propeller vertical minimizes the possibility of lateral motion due to suspension travel. The arms look like they are fully adjusted inward, so you clearly have plenty of room to play with.

Will the propeller even rotate at all... with suspension travel ? Doesn't matter who makes the various watts links, I have yet to see one that has the propeller dead vertical. I will check the WL manual, but I believe they don't even mention having the propeller vertical. It would be fairly simple to tweak the arms so the propeller is vertical.... no big issue really. What am I missing here ?

 

[Norm Peterson]

Will the propeller even rotate at all...

It has to.

Consider a Watts link position with both links horizontal, which does not have to be at static ride height.

As the rear suspension goes into 'bump', the passenger side link end at the propeller moves in an arc upward and to the right relative to its chassis attachment point. The driver side link end at the propeller moves up and to the left. The propeller has no choice but to rotate (clockwise in this example), else the links would have to pull the chassis attachment points enough closer together to be able to watch (if, say, you put a GoPro back there).

This rotation isn't going to be huge, and a little simple triangle trig will give a close enough answer.

Strictly speaking, a Watts link does not provide mathematically perfectly vertical motion (the true motion is kind of a very lazy "S" shape), so there may well be some optimal non-vertical propeller orientation that depends on the WL's geometry and amount of suspension bump and rebound travel. But it's close enough over the relatively small amounts of suspension travel we're involved with, compared to the link lengths and propeller length, that propeller orientation probably doesn't matter on a practical level as long as it is close.


Norm

 

[Whiskey11]

It has to.

Consider a Watts link position with both links horizontal, which does not have to be at static ride height.

As the rear suspension goes into 'bump', the passenger side link end at the propeller moves in an arc upward and to the right relative to its chassis attachment point. The driver side link end at the propeller moves up and to the left. The propeller has no choice but to rotate (clockwise in this example), else the links would have to pull the chassis attachment points enough closer together to be able to watch (if, say, you put a GoPro back there).

This rotation isn't going to be huge, and a little simple triangle trig will give a close enough answer.

Strictly speaking, a Watts link does not provide mathematically perfectly vertical motion (the true motion is kind of a very lazy "S" shape), so there may well be some optimal non-vertical propeller orientation that depends on the WL's geometry and amount of suspension bump and rebound travel. But it's close enough over the relatively small amounts of suspension travel we're involved with, compared to the link lengths and propeller length, that propeller orientation probably doesn't matter on a practical level as long as it is close.


Norm

Or for those who are visual types:

Image Courtesy of Wikipedia

 

[jayh007]

Workmanship looks top notch. I guess we can put the issue of welding to rest.

 

[B2B]

I finally drove the Mustang around after installing the Cortex watts link last week. Since TWS is still a month away, I do not have any feedback from the track yet. However, there are some very noticeable change in how the car drives on the street that I have not seen mentioned before. Since most of our cars are dual purpose DD/HPDE cars, I thought it is appropriate to share my observations.

My car started as a 2011 GT with Brembo package. Then updated with Koni Yellow, Steeda Sport springs (200F/175R), Strano front sway bar, Steeda panhard bar (poly bushing), WL relocation brackets, WL lower control arms, and WL rear sway bar. Last week, the Steeda panhard bar, and WL parts was replaced by a Cortex street watts link, FRPP 302R lower control arms (poly bushing), and FRPP relocation brackets.

I’ve outgrown the novelty of driving a track toy on the street after owning a ’93 Fox Mustang with full Griggs GR-40. The goal for the current car is to address the handling issues without going off the deep end again. After a couple of days, I’m glad to report that net increase in NVH is minimal. When accelerating from a stop, I can hear and feel occasional driveline clunks, and some faint gear vibration through the seat belt buckle and transmission tunnel. Consider that the differential cover is now pressed against the main bearing caps and connected to the frame via rod ends and small poly bushings, the increase in vibration was well below what I was expecting. Note that once the car is moving, I cannot feel any increase in NVH from my previous setup. Almost forgot, the car also have a WL MT82 tranny bushing and MGW shifter. Bottom line, if you have an axle back on your car, you probably won’t even notice there are any NVH change from the watts link.

There is a stretch of freeway that I commute on that’s uneven and have some pretty good size dips. Driving over them @ 70+, I have to keep a firm grip on the wheel to keep the car from darting out of my lane. Skittery and nervous are probably the right words to describe how the car feels. The first day with the watts link, I kept a firm grip as usual, but the car went over that section of the road and never weaved. Thinking I must have been going too slow, I went back over it again that afternoon and then again this morning @ 90+. Again, the car was straight as an arrow and I was barely touching the steering wheel. The rear of the car does rotate from side to side (it’s a watts link, not an IRS…) from the bumps, but the car was not darting left and right anymore.

The whole time prior to this, I was thinking my car had a bad case of bump steer even with a mildly lowered ride height. Thinking about it a bit more, I suspect that the panhard bar was probably transferring vertical axle movement as diagonal force into the passenger side subframe. Without the huge OEM rubber bushings to soak up this movement, this force was obviously enough to make the car wanted to change direction. With the watts link, all axle movement is taken up by the propeller and not transmitted diagonally/horizontally into the chassis. I was very pleasantly surprised by this discovery and I now completely understand why others describe the watts link as increasing driver confidence over rough section of the track. If it works @ 70 MPH, it’s going to be even better @ 110…

Again, I’m not trying to compare my daily commute with driving on the track because it would be down right irresponsible to push the car that hard on the street. But there is no question that the watts link made some very noticeable change to the car’s dynamic that clearly are applicable to track condition as well. Anyway, that’s all for now and I’ll wait for TWS next month to get the “rest of the story”.

 

[Sky Render]

What rear sway bar are you running with the Watts link? Does the Whiteline bar fit on there?

 

[B2B]

What rear sway bar are you running with the Watts link? Does the Whiteline bar fit on there?

I went back to the OEM rear sway bar for now. Bought some Energy Suspension bushings but have not got around to putting them in. Unless I drop the Whiteline bar *way* down (from the axle mounts and the end links), it won't clear the passenger side mounting tower. :-(

Still need more seat time to get a better feel on how the watts link handles so I don't know if I needs an adjustable rear bar yet. Previously, I used the softest rear bar setting to help the car cope with bumpy corners on tracks. Not sure if that's still necessary with the watts link. The change in RC and dynamic makes everything I used to know about my car goes out the window. Which is a pretty significant change from a single suspension part.

Francis

 

[Norm Peterson]

Without the huge OEM rubber bushings to soak up this movement

Did you ever notice if hitting left side one-wheel bumps/heaves was particularly worse than hitting right side bumps?


Norm

 

[B2B]

Absolutely. Hitting bumps on the left side rear wheel in a right turn was enough to make the rear skip to the left. Similar bumps on the right rear wheel in a left turn is noticeable, but doesn't upset the car much at all.

I should clarify here. The whole rear end actually never physically skip/slide to the left. But the car was jolted so that it felt like it was skipping to the left. Just doesn't have a better way to describe it...

FWIW, it may not be an accurate observation because I really can't say I'm hitting both left and right turns at the same speed...

Francis

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