Ok, let's try this again. I've done some homework and am looking for advice as to which coil spring compressor is best and cheap, for compressing front springs during upper and lower control arm work. My bushings are torn/shot. The Jag tool cost a fortune. I'm looking at 2 different ones on e-bay. Both OTC, one is similar to the Jag tool with two plates OTC#7045B @ $200+/-, and the other is OTC#27035 with one plate and two hooks @ $50+/-. The cheaper of the two looks as if it will sufice. Any input on what you guys have used to compress your springs....? My concern might be as to whether or not the bolt will clear either the upper or lower hole of spring seats if it needs too. This may be a non-issue.
And possibly more important, is it worth my time and trouble to do this myself(I've got time, and always seem to find trouble), or should I purchase aftermarket control arm pieces with bushings and ball joints already installed(more expensive than if done myself, I know)? I do have access to a basic "H" type shop press, and I could even buy a used control arms and outfit with new bushings/ball joints for less than new ones from Jaguar. This would reduce the stress of having the car down while I fight with everything.
And lastly, what have you been using to press the bushings and ball joint out? Sockets as in the old days.....? Or is there a rental kit I can obtain. Again, the Jag tool is $$$$. I haven't looked at Auto Zone loner kit, but I suspect it would not work on the Jag parts. I'm already planning on doing the stabilizer links and shocks myself. I do know about needed alignment once bushings are replaced. Any advice would be appreciated.
Thank you

 

Hi Ralph,

I recently performed this task on my 00' XJR, and I will say it wasn't one of my favorite projects thus far. First off, it's not for the faint of heart! The springs can be very tricky and potentially harmful, but I may be of some help.

1. I don't believe either tool you listed would work to compress the springs. The springs are installed at an angle and are very tight between the coils. I ended up fabricating a tool similar to the Jag tool and it worked great. If I remember correctly I used a 23" piece of 3/4" all-thread and drilled a hole for a grade 8 roll pin 1" from the top.
2. The bushings are pressed into the arms with such force that a standard h-frame press would not budge them. They actually sound like a gun going off when they are removed.
3. You'll also have to notch the lower ball joints to get a piece of pipe in place to press them out.

I am not trying to scare you out of doing this yourself, but it is a pretty big job. Albeit a very rewarding one when completed. It made all the difference in steering/handling.

I believe there is a write up for the job here somewhere. It's what I used while doing mine.

Also, you may want to take a look at your front bearings while your in there and everything is off.

Good luck.

 

Thanks TN8Shooter for the input. I made up the special tool today, no problem GR5 bolt & 5/16 roll pin. I've been busy in the analysis (cost/effort/trouble) until paralized mode. Ruled out new right away due to cost. I do have a mechanical background, so the job doesn't bother me as long as I'm prepared with proper tools to get it done. I've located access to a 20 ton press, but may use this as an excuse to buy one. Obviously replacing bushings & ball joints is the cheapest, though maybe not, if I buy a press. Then if you throw in the e-bay options for the rear half of lower control arms already fitted with bushing and ball joint, it starts to get questionable as to whether to buy this piece ready to go, and fit the front piece and upper with new parts. So having rambled on, what "special tool" has worked best for everyone to press out the bushings, and ball joints? I have read some of related posts, but have not come across this tid-bit of information yet. I called Welsh the other day regarding shocks and they have the best price 139.00 for bilstiens (I know they're not a sponsor, but I need evey penny for the rest of the job). I plan on seeing what options they have regarding control arms before proceeding as well.
I do appreciate any input on tool used to press out bushings & ball joints. This has still got to be the cheapest way to go.
WILDCARD ?: How many of you have done the lower control arm without touching the upper control arm? My background would indicate to complete entire front end at one time....waste of money & time.....?

 

I actually took the whole front suspension apart and took the control arms to a local machine shop to have the ball joints pressed out.

 

Re: Compressing the springs..... A friend of mine who is a former mechanic told me they used to leave the car slightly on the ground with the springs compressed (i.e. jack it up until the springs are just compressed a little bit) and then wrap heavy duty nylon tie down straps around the spring to "hold" it compressed. Then you could remove the springs in a compressed state. Do whatever you need to do, put it all back together, lower the car to compress the springs back and then take the straps off.

Though this does seem dangerous to me, it doesn't doesn't look any more dangerous than some of the contraptions I've seen to compress the springs.

Use at your own risk... it may take your face off.... (or worse)

 

I actually tried the nylon strap method. My right shin did not like the way the strap broke under pressure...
The springs are loaded with a tremendous amount of force and can do some serious damage to a body (human and automotive).
I would highly recommend staying away from straps. You'll body will thank you...

 

Just for grins, we can estimate how much nylon would be needed to safely hold a spring. (I was a physicist, not a mechanical engineer, but no need to invoke quantum mechanics for this problem!)

Anyway, say the car weighs 5000 lbs and that 1/4 of that weight is on each wheel; that is, 1250 lbs. Now, each spring is not positioned out at the wheel, but inboard towards the pivot point of the control arm. That means there is a mechanical disadvantage seen by the spring: if the spring is (say) halfway between the wheel and the control arm pivot, it is compressed by a force of 1250 lbs x 2, or 2500 lbs when the wheel is just holding up its share of the car's weight. (If that wheel is jacked up to take more than 1/4 of the car weight, the number would go up.) (If the spring is closer than halfway to the pivot, the multiplier becomes larger also)

The yield stress of nylon is a bit more than 10,000 psi, but let's use 10,000 psi as a conservative number. That means that one would need nylon straps with a cross section area of 2,500 / 10,000 = 1/4 square inches. Now, the beefiest nylon strap I own has a cross section of 3/8" wide x 1/16" thick or 0.0234 square inches per strap. So to take the force of the compressed spring with minimal safety margin would require 0.250/0.0234 = about 11 straps. Or perhaps 15 to have a bit of margin. This all assumes that the little metal latch in the strap is at least as strong as the nylon itself.

Any other engineers in the audience to check my reasoning and arithmetic? Also, there may well be more robust straps available, so that fewer would be needed.

 

Looking at my answer, I was a bit hasty. Each strap loops around the spring before being fastened, so there are two sides of the strap taking the stress. And thus twice as much cross section area. So divide the twelve straps by two to get six or about 8 for more margin. On the other hand, if the strap breaks in the area where it wraps around the curvature of the coil, I am not sure what happens. Might need an actual ME to answer that one.

 

I am a ME, and I still dont like the idea of binding that much force with straps. Just build the tool and be done with it. Much cheaper and safer in the long run.

 

You could work it another way. What does it take to equal the tensile strength of the center bolt in the normal spring compressor?

Of course, the nylon strap could be a great comfort if it is deployed as a backup mechanism.

Umm... how many loops of mechanics' wire would be required? Multiple loop systems of course. Not one continuous run because a single failure is a failure of the whole system.

 

To TN8Shooter - I wasn't advocating using straps. I was just wondering whether it was within the realm of theoretical possibility.

The arithmetic for mechanics wire is the same. Look up the tensile strength for (say) mild steel and figure a likely wire gauge, and one could see how many loops of wire it would take. Braided steel cable might be a better choice than plain wire, tho. Not sure how the ends could be secured in a practical way.

The tensile strength of the thick center bolt in the regular spring compressor is undoubtedly way over what is necessary. The failure mode for that type tool would probably be lateral shear of the roll pin.

 

Usually, u-bolts.

 

No value added here other than discussion. But, I find it interesting how threads get on a roll here....I have made the tool out of grade 5 fine thread all-thread, I haven't looked it up, but I would imagine the tensile strength to be 50ksi or better. I conduct work in shipyards, testing steel used for contstruction, and testing welders qualification coupons. There's no way I'd use straps, although I've seen kevlar mooring lines take in excess of 100ksi, too large to use though.....lol!
I still have to check with local machine shop about pressing bushings & ball joints out & in. This will be a 2 to 3 month project, working parts in past the family book keeper. Also, I hate to promote a non sponser, but Welsh has bilstien shocks for 136.00 and all 4 ball joints in a kit for < $90.00. Sure they're not Moog or some other top shelf brand(although I don't know what brand they are), but ought to last the rest of this cars life. I'd be curious to know if Andy (JagTech) has used any of Welsh's parts. Still waiting to hear what you've used to press out parts. It's not a u-joint so I doubt a socket will work...Have a great weekend! Off to the Machine Gun Shoot @ Knob Creek!

 

Certainly won't refute the math here but a couple of thoughts/observations....

With the car just normally sitting on the ground, the spring would be carrying those forces. But with the car mostly jacked up and spring only compressed, say 3/4", it wouldn't be under as much force. i.e. the force to compress the spring 3/4" is much less than it takes to compress it 10".

The nylon straps I had in mind are the "tow strap" kind that are pretty beefy something like 2" wide by 3/8" thick.


I've personally never tried this method... though given some of the DIY type spring compressor contraptions I've seen, I think I would feel safer with the spring compressed ~3/4" with nylon tow straps holding it together. The safest and best approach is to use a hydraulic press to compress the springs - of course....