BMR Watts Link - Teaser

[todcp]

Actually there have been several cases of axle clamps slipping..and by as much as .4" . I will try an dig up the info if at all possible. Some of the earlier clamp designs left a bit to be desired. Some issues may have been due to improper install. JDM engineering won't even sell the fays2 or steeda watts link anymore.

Are you sure? They still sell camber bolts and feel good about that but won't sell the Fays2? Odd. Did this concern originate with the early Saleen Watts Link or Lakewood that had issues?

I will mark my axle clamps to the axle and keep an eye on it. Just finished a track day at NHMP with a couple of fairly severe bumps and had no movement.

 

[sheizasosay]

Saleen is diff mounted.

 

[Sky Render]

Saleen is diff mounted.

Anyone have a pic? I've never actually seen a Saleen Watts link.

Sent from my toilet using Tapatalk

 

[fdjizm]

Found this for Saleen, is a non adjustable watts link even a good idea?

 

[sheizasosay]

Without adjustable arms you will not be able to center the axle perfectly. The only benefit you would see is not having the arc that the phb generates and more similar left/right turn vs phb.

It is about the same as lowering your car without an adj phb. Not ideal, but also not the end of the world.

 

[GrnBullitt08]

Found this for Saleen, is a non adjustable watts link even a good idea?

That's scary how cluttered that is on the drivers side going over the axle. I barely have any room as it is now with my OTA pipes on the drivers side now.

 

[NoTicket]

If I am remembering correctly a JDM rep came in to one of our many watts link threads and said they will never sell the fays2 again, then later revealed they never had sold it before. He also said that a customer brought his car in to their shop with slipped axle clamps, but then said they did not do the original install, and had no idea if the clamps had slipped or were placed incorrectly in the first place.

Regardless, the BMR watts will obviously not suffer this possibility since it does not use axle clamps.

 

[sheizasosay]

If I am remembering correctly a JDM rep came in to one of our many watts link threads and said they will never sell the fays2 again, then later revealed they never had sold it before. He also said that a customer brought his car in to their shop with slipped axle clamps, but then said they did not do the original install, and had no idea if the clamps had slipped or were placed incorrectly in the first place.

Regardless, the BMR watts will obviously not suffer this possibility since it does not use axle clamps.

That's fucking retarded.

 

[popeye]

That's scary how cluttered that is on the drivers side going over the axle. I barely have any room as it is now with my OTA pipes on the drivers side now.

Actually there was a ton of room on that setup. With the Fays if it isnt perfectly setup I would ping into the over the axle pipes and wasnt the easiest to get it just right. With the Saleen they were never even close and as to some elses point the Saleen was centered when installed and doesn't allow the side to side movement. The Saleen unit worked very well but had that fatal flaw of the center bolt. I rode mine hard for year and a half before my bolt popped. As for the Fays unit, it worked well but the car felt twitchy. I like the geometry of the Saleen unit much better. At the price the BMR setup is planned to sell for and how its anchored,,,,well they will sell a lot of them.

Sent from my SAMSUNG-SGH-I337 using Tapatalk

 

[sheizasosay]

As for the Fays unit, it worked well but the car felt twitchy. I like the geometry of the Saleen unit much better.

When you changed from the saleen to the fays what other work did you have done? Because twitchy is something that can be adjusted by spring rates and roll centers. The Saleen unit RC is dead center of the diff. High by some accounts. If you look at the Cortex unit, none of the adjustments are above the center of the diff. Griggs, same way. Whiteline, can't see enough to tell. Anyway, the real point here is if you didn't put the roll center in the same spot as you had on the Saleen, the you have entered a variable that absolutely affects if the car will feel twitchy. I'm also not saying that using the RC above diff center is bad. It's pretty close to adjusting rear swaybar (kinda).

 

[popeye]

It was with the same setup. The Fays was fairly close in location, but it was lower. Its been quite a while as I have been building a car, quite slowly I might add, for the past year and a half.

Sent from my SAMSUNG-SGH-I337 using Tapatalk

 

[Whiskey11]

Without adjustable arms you will not be able to center the axle perfectly. The only benefit you would see is not having the arc that the phb generates and more similar left/right turn vs phb.

It is about the same as lowering your car without an adj phb. Not ideal, but also not the end of the world.

Your watts link arms have to be the same length, using them to adjust the position of the rear axle forces the rear axle into a non-vertical (possibly non linear too) path and is a horrible idea because the arms move through different arcs of travel. The only way to adjust the diff mounted units is by sliding the mounting points on the chassis until the axle is centered.

 

[BMR Tech]

^ The above statements are part of the reason we had a meeting a few hours ago, about possibly having both a "diff" and a chassis mounted system.

Also - some people prefer a rear RC stationary to the pavement/axle....some prefer the RC stationary to the CoG.

That said, most diff mounted systems do not have much adjustment within their chassis mounting points. To get the rear axle aligned "exact" - more times than not, the lengths of the arms will differ, just ever-so slightly. Of course, if you prefer to have the arm lengths exactly the same - and the system is engineered well, then you should not have an axle that is "too far" out of alignment within the rear chassis.

An axle that is 1/4" off square from the chassis...with a Watts, will still outperform (debatable, I know) a typical PHR System.

 

[B2B]

I had an email exchange with Filip about how to center the axle with a watts link. Which required one horizontal link to be longer than the other. Here's Filip's response:

"Having slightly different length links causes some minor side to side shift of the differential, but no bind. The links on this system are long enough that the error is extremely small and you will not see a significant shift at the travel limits (maybe only a couple thousandths) which will not show up in the handling of the car."

 

[BMR Tech]

^ He is correct.

 

[Whiskey11]

I had an email exchange with Filip about how to center the axle with a watts link. Which required one horizontal link to be longer than the other. Here's Filip's response:

"Having slightly different length links causes some minor side to side shift of the differential, but no bind. The links on this system are long enough that the error is extremely small and you will not see a significant shift at the travel limits (maybe only a couple thousandths) which will not show up in the handling of the car."

He certainly has a point but if I wanted lateral displacement of the rear axle, I would have kept the PHB and ran rod ends to keep that lateral displacement to less than a few thousandths. Not only is it cheaper but it is a lot less of a PITA to set up. Keeping the links the same length eliminates this hassle entirely and ensures your rear axle isn't a pendulum under the car that changes the loading as the suspension articulates.

 

[B2B]

I think it is missing the point to focus on lateral movement of the axle with a panhard bar and ignores the effect of the panhard bar on the chassis end.

If one assumes the chassis end of the panhard bar does not moves at all, then it is correct that the axle swings in an arc during suspension travel. But when the axle is pushed into the ground by the weight of the car, one have to consider what happens to the chassis side of the panhard bar because it is certainly not fixed.

So while it is correct that unequal length horizontal rods on a watts link will result in some lateral movement of the axle, it is complete unnoticeable from inside the car due to where this movement is transmitted to the car.

Sent from my DROID RAZR HD using Tapatalk

 

[Norm Peterson]

So while it is correct that unequal length horizontal rods on a watts link will result in some lateral movement of the axle, it is complete unnoticeable from inside the car due to where this movement is transmitted to the car.

So is a few thousandths or even a few hundredths with a PHB, which essentially disappear in overall combination with PHB bushing compliance and lateral tire deformation. Just that with the PHB you also get into unsymmetrical roll center height migration and roll steer behaviors, left vs right, which the Watts link solves.

You'd really have to run the geometry numbers for a variety of Watts link configurations, each at a number of different heights to see what's going on. A small length difference means the link inclinations no longer remain equal and opposite, but differences between right and left (1-cos)*[link length] terms that go along with the changes in ride height are still going to be very small. Not anything I'd want to do with pencil & paper and longhand math more than once, though.


Norm

 

[Pentalab]

On my WL watts link, they supply the eq of a pan hard bar upper BRACE. The oem ford pan hard bar brace is fubar imo... just 3 sided. Originally I tossed the oem ford PHB and brace and replaced it with the BMR on car adjustable PHB and heavy duty upper PHB brace. That BMR brace is made from rectangular tubing..and makes the oem Ford brace look like junk.

The eq of that brace that comes from WL is chromoly tubing. I can see the brace in the pix that kelly posted. At $500.00 they will be flying off the shelves.

 

[BMR Tech]

Kelly, how high above the axle centerline do those RC adjustments go and how low? That thing looks like it could take some major abuse.

Man, I have no idea how I missed this post.

IIRC, the current RC adjustments are roughly about 3/4" above the axle centerline....down, close to 3" or so below.

I think those RC locations should work for the majority, ya think?

On my WL watts link, they supply the eq of a pan hard bar upper BRACE. The oem ford pan hard bar brace is fubar imo... just 3 sided. Originally I tossed the oem ford PHB and brace and replaced it with the BMR on car adjustable PHB and heavy duty upper PHB brace. That BMR brace is made from rectangular tubing..and makes the oem Ford brace look like junk.

The eq of that brace that comes from WL is chromoly tubing. I can see the brace in the pix that kelly posted. At $500.00 they will be flying off the shelves.

Correct - I have an OEM brace laying around somewhere at the shop, that I bent by hand (with the assistance of a table)

You'd have to run ours over with a semi, to bend it.

Since the PHR support has been brought up - I still don't understand why/how we are STILL the only company that designed our PHR support with a bend in it, for clearance of the Panhard Bar when relocating it, or for really low cars. It boggles my mind, actually. Can;t say how many of my customers call and have PHR to Support Clearance issues on various set-ups.

Anyhow, as for the Watts - we are making some changes. I promise, you will love the next round of pics. I just hope they come really soon. Our car will be "on the road" for a few months straight soon.....so I am begging my design guy to get rolling on finalizing the diff mounted design.

It will probably be later into the year, or early next....before we finalize the design of the Chassis Mounted kit.