Ridetech Home Forums Tech & Products Setting rideheight 65 mustang 4-link and other issues

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  • #207564
    FordpwrJan Evert Kozala
    Participant

    So, the manual for the 65-70 mustang calls for a 4,5″ spacer between the frame rail and rear axle to get the proper ride height of 14,5″ on the shocks. The rear axle pictured in the manual is an 8″. The 8″ has smaller tubes and are narrower at the end than a 9″. My 8″ has 2,25″ tube at the narrow end, while my Strange 9″ have 3″ tube, which brings me to the question. If I would use the 4,5″ inch spacer on top of the 3″ tube, that would raise the rear of the car 3/8″, and the rideheight would be altered.

    Second issue is that the spring perches also sit lower on a 3″ tube, 3/8″ inch difference  between my 8″ and 9″, that means the LCA bolt-on bracket is sitting lower on the 9″ axle than an 8″ and the 14,5″ ride height of the shocks is further altered.

    If I wanted to maintain the shock rideheight of 14,5″ only, that would push the rear axle closer to the frame rails, and wheel more up in the wheelwell.

    Third issue is that my Strange 9″ have an oil fill cap at the top rear of the housing, so pushing the rear axle all the way up to the original frame rail bump stops would make the oil fill cap hit the cradle before the axle hit the stops. I had to lower the rubber stops on the frame rails to keep the cap from hitting the cradle, but doing so also calls for stiffer springs.

    So my solution is: cut the framerail to axle spacer by 3/8″ (3″ – 2,25″ /2) , to 4-1/8″ instead of 4,5″. Install the lower shock bracket in the two bottom holes to get a shock rideheight of 15″, or move it up one hole to get a shock rideheight of 14″.

    Another issue is that the preset control arm lengths of 21,75″ and 11,75″ seems to be too long for my car, the wheel is set way back in the opening, much more than with the leaf springs. Any thoughts of just shortening the control arms to bring the axle forward?

    Then to the last issue: even with shortening the control arms, setting the ride height (4-1/8″ spacer between axle tube to frame rails) and setting 3 degree of pinion angle, the coil springs are hitting the rear inner corner of the U-bolt plate of the LCA bracket. I have a set of 59120375 (I know, too stiff for this application, just for mock up) and this spring is supposed to be 2,5″ ID, but that is only at the ends, it widens in between to 4″ OD, which makes it hit the bracket corners. I ordered a set of 59120175, I hope these are not as wide??

    Any thoughts?

    #207914
    gfuesler@ridetech.com
    Keymaster

    Technically speaking, yes, it would alter the setting by approximately 3/8″.  However, keep in mind this suspension is adjustable.  If you wanted to go ahead and compensate, it would not hurt.

    On the second issue, the same logic applies.

    Regarding the rest of the rest of the issues, you mentioned some things that we will need to investigate further.  If you have some pictures. that would be great.  Please contact us at 812-482-2932 and our Tech Department can get to the bottom of what is going on.

    Thank You

     

    #208305
    FordpwrJan Evert Kozala
    Participant

    Thank you for your reply.

    I tried to upload some photos here but it didn’t work out.

    I’ll send you some photos by email, my english writing is way better than my english speaking 🙂

    #208537
    FordpwrJan Evert Kozala
    Participant

    UPDATE: The new 150lb springs corrected the issue with springs touching the LCA bracket, the 150lb springs have good clearance to the brackets.

    Now I just need to figure out why the wheels are further back in the wheel opening than with the leafsprings. I managed to move the axle forward a bit by loosening the axle U-bolts and slide the LCA bracket backwards on the perch (centering hole in perch are bigger than the centering bolt on top of the bracket). Wheel is still out of center in the wheel opening. The centering bolt of the LCA bracket should be even further to the front, or the centering hole in the perch further back to correct the issue.

    #208887
    FordpwrJan Evert Kozala
    Participant

    I removed the lower axle mounts on both sides to have them and the spring perches checked and measured, in case there is some errors going on with one or the other.

    I then measured the distance between the front eye leaf spring pocket CL and the centering bolt of the leaf spring and it is approx. 21-3/4″ unloaded, putting load on the leaf spring would most likely raise that to excact 21-3/4″ , same as the lower bars of the 4-link. I guess Ridetechs intention is to put the CL of the lower bar just below the CL of the rear axle, like it is originally. That would center the axle in the correct location.

    However, the lower axle mounts in my kit doesn’t do any of those things, the CL of the lower bars are in front of the CL of the rear axle, no matter how I adjust the lower axle mounts. Why? Because the centering pin of the lower axle mount is not in the center of the hole for the lower bar, it is located more to the rear. And it just got a bit worse; the two axle mounts are not welded together equally, they differ from eachother, putting one side of the axle more to rear than the other side. I guess the two mounts were welded in different jigs, but they should still match up with eachother.

    I can still move the rear axle around on the lower axle mounts, as the centering hole in the spring perches is larger than the pin, but I can’t do anything with centering the axle properly over the lower bar/in the wheelhousing, without cutting off those pins on the axle mounts.

    I also checked the angle on the perches on the axle with pinion at 3 degrees up, car level to the ground, the perches are also level to the ground, centering hole is in the center of perches, no errors there.

    Had the car on all its wheels in the proper rideheight, and it’s easy to see that the axle is not centered in the wheelhousing.

    #208892
    marolf101x
    Participant

    How much different are the two lower control arm axle mounts? I agree, they should be the same, but slight variation is still ok. . .1/8″ (~3mm).

    Can you not adjust the upper and lower bars to center the axle?
    Just as a note, these cars were no where near perfect when new, and were often quite a bit different from one car to the next. Everything will have to be adjusted slightly to fit each car properly.
    Unfortunately, most times you must measure these cars with a yard stick not a micrometer if you wish to keep your sanity.

    #208910
    FordpwrJan Evert Kozala
    Participant

    Well, I’ve had my car for 23 years so I know they are far from spot on from the factory.

    I might be overreacting, I must admit that I do not know much about 4-links and how to adjust them, or if they can be adjusted at all. I have gone through a couple of different leaf springs setup, last installation was mono-leafs from Calvert with a panhard bar from MMI. I did take several measurements before I removed this setup prior to installing the 4-link.

    I’ve searched around the internet looking for answers about adjusting the 4-link, some say the links can’t be different lengths because that will throw off the suspension in let’s say at the dragstrip. Others say they can because that is why they are adjustable. Ridetech doesn’t say anything about any adjustment of any part of the 4-link, except minor adjustment of the upper bars for pinion changes. So this is why I assume that the bars is supposed to be the length they are adjusted to at the factory and what is explained in the manual. No mentioning of any adjustments for setting correct wheelbase or side-to-side movement. I have seen some aftermarket vendors with fixed lower bars, and some with adjustable. I have no idea what is correct.

    Anyway, IMO, I want to get as close to factory wheelbase as I can, without any major correction of the intended length of the bars, so I have cut those pins off from the lower axle mounts, drilled a new hole and rewelded, to get the CL of the axle spot on to the axle mount bracket. Any adjustment of the lower bars will be very minor I guess. Without this modification of the lower axle mount, one of the lower bar would be approx. 1/4″ shorter than the other.

    #208911
    marolf101x
    Participant

    Just so I’m not sounding like a know-it-all, or favoring the Ridetech parts. . .I ran the Engineering department for Ridetech for about 10 years. I absolutely loved working at Ridetech (Air Ride Technologies when I started in 2006), but times change, I moved to Southern Indiana to take the Ridetech job, then I got married, had kids and decided to move back home to be closer to family.
    One might think I’d be biased to the RT parts, but to be honest it’s nice now sitting on the outside, able to say whatever I want.

    I say all that only to make clear that I’ve seen, measured, worked on, designed around, tons of old cars.

    So, when it comes to any suspension under an older vehicle, here’s how it’s handled. . .
    #1-NOTHING will measure perfect or “spot on”. They simply were not built within those tolerances (nor are cars today for that matter. Though they are a lot better, you’ll see up to 1/2″ ride height difference side-to-side in a new vehicle, for example.)
    #2-the wheel openings side-to-side will not be the same (it is typically worse if the quarter panels have been replaced.)
    #3-More than likely the front lower spring perches are not exactly the same side-to-side (they are typically a lot better than the wheel openings though)
    #4-the best you can do is compromise. . .everywhere

    4-link install notes:
    -ideally the lower bars are of equal length
    -ideally the upper bars are of equal length
    -generally the amount of adjustment in the link arms is not enough to throw out the designed geometry
    -ideally the rear is centered in the vehicle (center of the front suspension to the tail), AND has equal distance from the tire edge to the wheel well “lip”
    -ideally the wheel base is the same on both sides, AND centered within both wheel wells
    ***the last two are nearly always the killer. . .most people center the wheels in the wheel well when looking from the side, or center the wheels so they have equal distance from the edge of the tire to the wheel “lip” (as one would think you should), however, the wheel wells are typically not the same side-to-side, so the links are different lengths, and the rear is not centered to the chassis.

    So, in most situations, you adjust each bar as best you can to get an overall compromise you can live with. How far off each bar can be from the others depends on length. The longer the bar, the more they can be off (overall percentage remains the same) Typically 1/8″ is really good; 1/4″ is decent, and 1/2″ is about as far as I like to go.

    #208956
    FordpwrJan Evert Kozala
    Participant

    Thank you for your input and advice, that makes more sense.

    #208145
    FordpwrJan Evert Kozala
    Participant

    Thank you for your reply.

    I’m going to check to see if the new springs I just ordered from you have the same issues with hitting the LCA bracket, there will be another week passing by before they are delivered to me here in Norway.

    Here are some photos of the setup with the 375lb springs.

    IMG_20210705_200113 IMG_20210705_195955

    #208144
    FordpwrJan Evert Kozala
    Participant

    Thank you for your reply.

    I’m going to check to see if the new springs I just ordered from you have the same issues with hitting the LCA bracket, there will be another week passing by before they are delivered to me here in Norway.

    Here are some photos of the setup with the 375lb springs.

    IMG_20210705_200113 IMG_20210705_195955

    IMG_20210705_195942 IMG_20210627_182354

    IMG_20210615_172117

    #208143
    FordpwrJan Evert Kozala
    Participant

    Thank you for your reply.

    I’m going to check to see if the new springs I just ordered from you have the same issues with hitting the LCA bracket, there will be another week passing by before they are delivered to me here in Norway.

    Here are some photos of the setup with the 375lb springs.

    IMG_20210705_200113 IMG_20210705_195955

    IMG_20210705_195942 IMG_20210627_182354

    IMG_20210615_172117

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