http://www.clubcobra.com/classifieds/showproduct.php/product/3404/cat/4/perpage/12/date/1164777064

Yes it is. Sorry I thought I read in your post that you were interested in the watts for the inner brake also.

37ford wrote:

1.  What would be the better side to have a single shock?  Front or rear?
2.  Is a top mounted watts link really much different than a botton mount?  I realize the point is trying to take the stress off the hub, but is a failure really a possibility in most street applications?  Jaguar designed the unit without an UCA or any other stabilizer on the upper hub, right?
3.  It seems like there would be a lot less room to pull of an upper watts link for most applications.  Can this be a factor?

Watts link both upper and lower is something we have talked about in great detail on the forum.  If you do a search for "watts" you will pull up about 20 different posts.  There is nothing I hate more than posting a question on a forum and some jerk responds with "we have already talked about that do a search" So thats not what I am doing.  Just letting you know there is some good supplemental reading after we discuss it here  

1.  If you go to a Jag forum  and ask where to put the shock, front or rear, they will tell you the only way to do it it to run two. ask me how I know.   I asked this very question once on the Jag lovers forum and they told me I was crazy  and it was the worst idea they ever heard of, (they were almost rude about it)but then of course Jag owners are fiercely passionate about their cars and are working on a complete car that was put together by Jag in a specific way, so their attitude is "the way Jag did it is the only way to do it"  Starting with that bias their responses was that having only one coil over would put unequal forces on the wish bone and causing a twisting motion during compression.  I can see a little truth to that.  Do I think it is enough to matter probably not but it does put extra strain on the wish bone pivots.  My solution is two fold first by running a sway bar on the rear it will provide some downward force that will help balance the system out part way.  Second I am going to use the front location for my single coil over and then after it attaches to the wish bone solidly mount the shock to the trailing arm.  This will not only put the bottom shock mount is double shear but will allow me to have three pivot supports and effectively mounts the shock in the middle of a 3 pivot LCA.  This set up should eliminate any potential twist. here is a thread on the subject

2.  The top and bottom mounted watts are for two totally different purposes.  the bottom Watts is there to stabilize the wishbone like a trailing arm would do.  it eliminates for and aft forces on the arm that put strain on the inner wishbone pivots.  The upper watts link is there for the purpose of stabilizing the top of the hub and eliminating strain where the hub meets the wishbone.  The main reason to run a top watts is to help eliminate wheel hop.  The twisting of the hub caused by acceleration is often deflected by the moving parts of the IRS and is why IRS is prone to wheel hop.  By stabilizing the Hub you eliminate much of this.
older post on top mounted watts

3.  Both watts are hard to do.  The bottom watts is hard to get the correct fit to the frame especially since one of the arms has to be lower than the wish bone.  the upper watts is easier to attach but there are clearance issues, with tire fitment and frame rails.  I contacted the guy that Ralphy linked and mocked up a cardboard version of his set up to see if I could make it clear in my application, but I could not.  I may address it further at a later time, because I do think it is one of those mods that can make a big difference on a street car.

37ford wrote:

The main thing I was wondering was if the difference in the outboard hub would allow for an easier bolt-on utilizing some of the holes already there.  There are two at the top on the semi-flat area.  I don't know what they were originally intended for.  Plus you have the two dog ears for the brake calipers.

The hole you speak of was there for the ABS sensor and I agree that it would be a perfect place to use as one of the attachments for an upper watts.
upper watts link, what if a person used newer hubs

that is why we are here is to help you weed it all out.  It also is why I made the post about how much is to much.  The good news is it can be put in simply enough.  Just run normal trailing arms and worry about an upper watts later.  Jag rears have been put in countless cars and most do not use a watts link at all.  This can be done, in most cases knowledge is power but here on this forum we tend to over think things. 

57 ford, Day and all.
I am posting to admit I was wrong.  If you were to run only a LCA the torque during acceleration would pull forward, twisting the LCA around to the front. So if you were to run one coil over it would be best to the rear . I think it was Jim B  that was trying to correct me. The force would be generated from the center of the half shaft I figure. Correct me if I am wrong again?

Day, I do think it is important if you were to have a setup such as Heidt's. http://www.hotrodhardware.com/cartimages/prd_lp_258.jpg  Using only a LCA with one coilover. You mention a sway bar as an aid. However on hard acceleration the sway bar will not offer any resistance and that is when the hub is being brutalized.  I'm answering to 37ford's question, "What would be the better side to have a single shock?  Front or rear?"

Also to 37, I would say, once you ground (fasten) the top side of the hub, you remove almost all the twisting stress.
The nicest Jag aftermarket setup I can think of is built by http://www.cobraracing.com/. 37ford a lower A arm will remove the forward movement below the half shaft making rigid. However the twisting is still there. So an upper link such as a watts removes the twisting. It's a one two punch.

Here is the LCA. http://www.cobraracing.com/IntroZooms/XK2001Zoomed.html

Back to coilover location, once you ground the suspension such as CobraRacing did the shock can really go front or rear. From what I have seen racers prefer front. My thought on that is racers are looking for any edge. Most if not all chassis flex. The further you move the mount toward the bumpers the greater the distance vertical of a given flex. So the closer to center you get, the more usable the motion will be sent through the coilover.  Realistic? I think for the average guy location is not going to help us once you get past the physical correctness. But if your trying to make a correct look or your a true racer, location counts. What say you?

There are guys running a Jag setup with only the lower is it Dog Bone? And both coilovers. I have seen a few myself here in ATL. But what I read, they suffer wheel hop and breaking.

Last edited by Ralphy (11/14/2011 7:11 am)

Ralphy wrote:

Day, I do think it is important if you were to have a setup such as Heidt's.

Using only a LCA with one coilover. You mention a sway bar as an aid. However on hard acceleration the sway bar will not offer any resistance and that is when the hub is being brutalized.

I should not have said it that way.  it is important, however I do not think it is a critical as other things.  I still believe that most of the twisting happens where the hub meets the LCA and so the spring is not going to have much effect on that.  Think of it like this, as big and strong as the Jag wish bone is, if there is enough force in the system to twist it, the little bit of resistance provided by the coil over is not going to have much effect on stabilizing the system.  Even a 300# coil spring will compress a little bit if you push on it by hand, so thinking of something that is "sprung" as a stabilizer is kind of splitting hares don't you think???   As to the sway bar reducing the twisting caused by only running one coil over, I was not thinking about the fact that the sway bar provides no resistance when both sides of the car are doing the same thing, so you are correct it will not apply when accelerating, I was wrong, my bad.  Kind of funny I had written a full paragraph talking about how the rear suspension will compress a bit during a hard acceleration and how that would add more force through the sway bar, and then I realized what a dork I was.  That what I love about a good debate.  you learn more about a subject by defending your position than you ever do trying to advocate it.

Ralphy wrote:

Also to 37, I would say, once you ground (fasten) the top side of the hub, you remove almost all the twisting stress.
The nicest Jag aftermarket setup I can think of is built by
http://www.cobraracing.com/
37ford a lower A arm will remove the forward movement below the half shaft making rigid. However the twisting is still there. So an upper link such as a watts removes the twisting. It's a one two punch.

And I think that is the key to a great IRS, upper watts.   That upper whats eliminates most wheel hop, stabilizes the hub, and eliminates twisting.  You said in another post  "if you break a half shaft your car is bound to do more damage when that corner collapses"  I think the watts link even solves that.  if the half shaft fails the links will hold the wheel some what upright.

Ralphy wrote:

Realistic? I think for the average guy location is not going to help us once you get past the physical correctness. But if your trying to make a correct look or your a true racer, location counts. What say you?

There are guys running a Jag setup with only the lower is it Dog Bone? And both coilovers. I have seen a few myself here in ATL. But what I read, they suffer wheel hop and breaking.

for a street car I still don't think the coil over location will make much difference.  Good news for me is I will have the opportunity to do some real world experiments on the subject.  The way I put my set up together I can run the my coil overs on the front or the back.  (there is a host of reasons why I chose the front which I have already stated)  any way I will be able to set the car up one way and go for drive then change and run the same "course" with the coil over at the rear.  my prediction is that it will not make any difference for a street car

37ford wrote:

So, it seems to me that, if I want to start with a JAG unit, all I need to do is add some LCA stabilizers like the orange ones in Daze's sig pic, an upper watts link, and a sway bar.

yes and no.  What you have listed is a fantastic set up and probably one of the best configurations available for a DIY system, but the need for the upper watts is  more dependent on application.  For over 40 years Jaguar put out IRS units in millions of cars.  today those cars are street driven, raced, and everything in between and 99.9% of those aren't going to have an upper watts.  I am not trying to negate the importance of an upper watts.  It is a performance upgrade that becomes more necessary as HP goes up.  I just want to make sure that you and others who may read this post  know that a quality IRS system can be put together with out it.

37ford wrote:

I'm considering making a spreadsheet with all the characteristics of an IRS, how each one is addressed, and somehow assign a level of importance based on the different applications.  I could post it here let everyone contribute and argue endlessly.

I am all for it, especially the endless arguing part

I new what it was similar to as soon as I saw it.  question is what are you trying to tell me by showing it??

Day,
I remember you saying you liked that cantilevered yellow design. I saw the other design without the cantilever and though you would like it. I love the easy toe setting!

Hey Mongoose, you now make two Cobra guys here.

Last edited by Ralphy (11/18/2011 5:39 am)

Ralphy wrote:

Day,
I remember you saying you liked that cantilevered yellow design. I saw the other design without the cantilever and though you would like it. I love the easy toe setting!

Hey Mongoose, you now make two Cobra guys here.

OK that makes sense. a lot of times the pictures you post are to illustrate a point or concept so I was trying to figure out what you were trying to tell me with the other pic.

LOL! ,
They would have a field day roasting me. You have guys at Club Cobra doing the same. Trying to replicate their cars to look like an original and wanting to poo poo any original different idea. They make me somewhat laugh, see because maybe the gauges are correct and the seats look exact. No race Cobra had that perfect paint and the shelby had a unique leaf spring suspension that no replica has. Most of these cars were very rough looking, so? Anyhow I enjoy the Brit's and Austrailians, they write their own rules. I enjoy every idea I see. It may not be my cup of tea, but I see the beauty. As you know I throw all sorts of ideas out there, by doing so and investgating I also have learned lots about the how and why's. So in the end I wonder, how much do you think many of the purists know the why's of their own suspension?

Now take it a step further. I origanally became interested in buying a car. I knew a individual who had a Cobra, so I tried to befriend him and ask questions. I recieved very little input and a lot of lip. So I went on my way. Low and behold after I bought my car, now this person wishes to have his nose up my (sorry) ass. Always looking to add some negative comment. I talk to this person as little as possible. Why are some people like this?

Last edited by Ralphy (11/18/2011 12:15 pm)

JEM wrote:

Y'know, I just found this comment, and I have to say...based on my limited experience, you're being very, very kind to the Jag community with that remark.

Indeed, one of the things that always held me back from any thought of Jag ownership has been the relative lack of technical expertise and mechanical curiosity in the Jag 'net universe.    Compared to the BMW community there's just nothing there, and what is is too often based on wives' tales and in some cases - as you noted - the fantastical belief that somehow the factory way is always the best way.

At one point I would have agreed with you fully, but then I found Jag-lover forum.  Yes there are some extremists there and true it was the members of Jag-lovers  who told me my "one coil-over" idea was crazy but there are also some really helpful guys there.  After I spent a little time at Jag lovers I realized that they were just guys who really love their cars.  Most were all about originality but there were a few that wanted to "improve" things, and even the purists were helpful when I asked a question that they has specific knowledge about.  In some ways I almost feel bad for them, they do not have the luxury that we in the Mustang community have of such a large following and forum options.   

JEM wrote:

Just eyeballing the rear arms it appears to me that the biggest limitation in running a single spring/shock assembly (after all, the XJ40 does) is the single-shear mounting of the coil-over to the arm.

I don't like the single shear even with two shocks.  that is something I am planning on fixing on my set up.  the top and bottom will get "modified" double sheer.

Ralphy wrote:

LOL! ,
They would have a field day roasting me. You have guys at Club Cobra doing the same. Trying to replicate their cars to look like an original and wanting to poo poo any original different idea. They make me somewhat laugh, see because maybe the gauges are correct and the seats look exact. No race Cobra had that perfect paint and the shelby had a unique leaf spring suspension that no replica has. Most of these cars were very rough looking, so? Anyhow I enjoy the Brit's and Austrailians, they write their own rules. I enjoy every idea I see. It may not be my cup of tea, but I see the beauty. As you know I throw all sorts of ideas out there, by doing so and investgating I also have learned lots about the how and why's. So in the end I wonder, how much do you think many of the purists know the why's of their own suspension?

I am sure a similar thing is going to happen in the Mustang community, now that dynacorn is making full Mustang bodies I am sure there are those that will turn their noses up at them.

Digz wrote:

"It's important to understand why an OE would do something a certain way - usually is is in fact the right way, or at least a right way - but cost, manufacturing considerations, or other factors can sometimes get in the way of the factory doing it better."
I figured this out looking at the cast hub design on the one Im refitting. A little more material in the right places could go along ways.

The factory was is always a good way but almost never the best way.

Links for above post:

http://www.erareplicas.com/427/shorten.htm#axle

http://s350.photobucket.com/albums/q401/acmjg/?action=view&current=MOV04917.mp4

Hi Daze,

Thanks for the clarification on the single versus double sheer set-up.  Also, I started to check out your re-build process and found it very interesting.  I will be spending a lot more time on your website.

I have a line on a 94 XJ40 set-up that would give me the outboard disc brakes that I want.  I will be working with Mickmate to come up with a bolt on Watts linkage for the top of the hubs. 

I  was hoping that you could give me some advice with regards to forward trailing arms or radius arms - sorry, still learning the lingo.  In short, I want to stabilize the bottom of the hubs by running a rod from the hub or LCA forward to a point on the frame.  Any thoughts on this would be greatly appreciated.  I went to some of the popular IRS sites but didn't see where they sold a trailing arm setup.

Also, I would be happy to post a link to your site on Club Cobra if you have no objections.

Thanks.

That makes perfect sense.  Now that I look at your signature drawing, I see exactly how the arc is removed when the suspension travels in the vertical plane.  I take it these are usually fabricated or does someone sell brackets, bushings, rods, etc? 

Thanks so much - this really helps.