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Jag front end question

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Old 09-02-2012, 10:59 AM
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Jag front end question

I am back in shop trying to get this ride on the road. I am in the process putting the jag front end back together and trying to remember how it goes the light is coming on but I did have a question about the lower a arms or control arms.I read where some have put spacers to get about another inch lower. Has any one here done that and was it worth it or did it have any effect on the handling.I could put some stock in the lathe and turn some nice 1 inch spacers to put in. Any comments ? Thanks George in Texas
 
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Old 09-02-2012, 11:10 AM
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Changing the pivot points on the A arms would change the excellent Jag steering geometry. Some make changes by the seat of their pants engineering, for convenience or because another clueless builder did it or recommended it without understanding the ramifications. I can guarantee it won't do anything to improve the design. IIRC the Jag will be pretty low, but there are dropped spindles available if you want to scoop up road kill.
 
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Old 09-02-2012, 11:11 AM
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I can't help with your question, but I will say "Welcome to FTE".
 
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Old 09-02-2012, 02:19 PM
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Originally Posted by AXracer
Changing the pivot points on the A arms would change the excellent Jag steering geometry. Some make changes by the seat of their pants engineering, for convenience or because another clueless builder did it or recommended it without understanding the ramifications. I can guarantee it won't do anything to improve the design. IIRC the Jag will be pretty low, but there are dropped spindles available if you want to scoop up road kill.
Pivot points will not be changed only the spring will extend lower. On the jag the plate that holds the spring in has bolts that hold the spring in place. I am no engineer by any means but I do like input to decide if in fact I will even do this. thanks for your input.
 
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Old 09-02-2012, 03:04 PM
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Originally Posted by barrnone51
Pivot points will not be changed only the spring will extend lower. On the jag the plate that holds the spring in has bolts that hold the spring in place. I am no engineer by any means but I do like input to decide if in fact I will even do this. thanks for your input.
That would still impact the geometry since the lower control arm would then angle upwards rather than be parallel to the ground at rest. The suspension is designed to add camber as it compresses (control arms angle upwards). I'm kinda the suspension guy around here.
 
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Old 09-02-2012, 03:38 PM
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Lower the ride

I recall reading that if you discard the white spacer under the spring it will lower the ride some.
Thomas
 
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Old 09-02-2012, 05:28 PM
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Originally Posted by AXracer
That would still impact the geometry since the lower control arm would then angle upwards rather than be parallel to the ground at rest. The suspension is designed to add camber as it compresses (control arms angle upwards). I'm kinda the suspension guy around here.
Lowering the plate that attaches to the lower control arm does not change the angle of the lower control arm. The plate is attached to the bottom of the control arm, by adding spacers you lower the spring ONLY. This is like cutting a coil out of the spring but better. Check out this link if you want to lower the Jag IFS. http://www.tunersdepot.com/Jaguar_XJ...ng_Springs.htm

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Old 09-02-2012, 07:31 PM
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Check with Jeff and Nichole. They have been doing this swap for a while.
 
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Old 09-02-2012, 08:00 PM
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48 Steel is who I followed with the JAG IFS. He is the man to follow! But I also have spent countless hours reading about this JAG thing.

I do remember reading that if you lower the spring pockets, for example, 1 inch....it will lower your ride ht. about a half inch.
The spring pockets are bolted to the bottom of the lower control arm with several bolts. I don't think you will gain much drop because you can't really lower them too much....they are only a few inches from the pavement to begin with. But you could try it pretty cheap, you would need longer bolts and spacers. I thought about trying it, but not for a long time. I am so far from worrying about that, at this point...
I will have to wait and see for sure, but my lowers are not anywhere close to parallel to the ground. I have had my engine/tranny/sheetmetal on the front along with me standing on the frame ends.(225 lbs) And still not parallel, but again, I will play with that later.
 
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Old 09-02-2012, 08:21 PM
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Originally Posted by barrnone51
Pivot points will not be changed only the spring will extend lower. On the jag the plate that holds the spring in has bolts that hold the spring in place. I am no engineer by any means but I do like input to decide if in fact I will even do this. thanks for your input.
We have one in the shop under a 70 GMC were building for a customer ill gladly check and write you back tuesday noonish. Would a picture help as well?
 
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Old 09-02-2012, 10:30 PM
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Thanks to all for the input with the front end.I would like to see a photo.
What I did was to rubber mount the front end. I made some new mounting plates that are the same level as the lower part of the frame so if I was to weld or mount like I did it would end up the same height.I think at this point I will finish putting everything and test fitting the body to see what I have.I do have a lot more to get this truck on the road so the ride height can always be changed at a later time.I thought at this point since everything is apart might as well do the lower A arms. Thanks again to everyone for the help.
 
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Old 09-02-2012, 10:49 PM
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Barrnone51 welcome to the forum! I have some pics in my albums here and my build thread link is at the bottom of my posts. Feel free to ask questions or comment. Good or bad. well maybe not bad...
 
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Old 09-02-2012, 10:57 PM
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Originally Posted by 48 Steel
Lowering the plate that attaches to the lower control arm does not change the angle of the lower control arm. The plate is attached to the bottom of the control arm, by adding spacers you lower the spring ONLY. This is like cutting a coil out of the spring but better. Check out this link if you want to lower the Jag IFS. Jaguar XJ6 Lowering Springs, XJ6 Lowering Kit

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You can't possibly lower the truck with the springs without changing the control arm angles at rest unless you use dropped spindles or move the control arms up on the frame. The frame has to go down relative to the spindle height to lower the truck which lowers the inner control arm pivot points relative to the ball joints. That also changes the steering tie rod angles. It's simple high school geometry and angular displacement.
 
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Old 09-02-2012, 11:33 PM
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Originally Posted by AXracer
You can't possibly lower the truck with the springs without changing the control arm angles at rest unless you use dropped spindles or move the control arms up on the frame. The frame has to go down relative to the spindle height to lower the truck which lowers the inner control arm pivot points relative to the ball joints. That also changes the steering tie rod angles. It's simple high school geometry and angular displacement.
Ax you are right. In my case, and maybe others, my lower arms are not level, as well as the rack-n-pinion arms. They angle downwards from the frame.
they should be parallel to the ground right?
Mine wont level out with the engine/tranny/front clip and my wieght on the front. I will have to deal with that when the time comes, and it may just be the tires keeping it from flattening out. I don't know, but maybe that's what he is dealing with.
 
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Old 09-03-2012, 11:04 AM
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Jeff, Yes, the lower control armsand tie rods should be parallel to the ground at rest. The obvious solution to your case would be softer springs. Is you IFS from a J6 or J12? If I misunderstood his original purpose then I apologize.
If the reason he wants to go lower is to level the lower control arms, then I withdraw my comments and offer him the same suggestion to put lighter springs in it, Dropping the perches on too stiff springs is not the right way to go, You want the lightest springs that will support the weight at the right height. But he won't be able to see what's needed until he gets the full front end weight on it: engine/tranny, radiator and fluids, front sheet metal. Changing the springs or adding spacers after that won't be a major job. Every install is going to be different so going by someone else's experience isn't going to be a help unless they have the identical setup.
 

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