Designed and Built a Spring Compressor

[DougR]

I needed new coil overs for my 2011 4Runner with KDSS. Front suspension had sagged 0.75 inches. A local off road performance shop would not guarantee their work when I requested a 1-inch lift, by citing a potential risk for KDSS lean. In other words, their mechanic doesn’t know how to work on a vehicle with KDSS.

I’m retired and a bit stubborn, so I got it in my head that I could make a spring compressor. It utilizes the 4Runner’s screw jack to compress the spring. Spent $40 on all thread rod and nuts. The rest is steel and aluminum from a metal scrap bin, and parts on hand. Assembled and installed the new coil overs, achieving 1-inch lift and did not encounter any issues. KDSS system is balanced and there is no lean.

 

[AutoMechanic]

Awesome invention. I always just get the quick struts so I don’t have to worry about using the spring compressor and they are just bolt and play lol. Though those probably aren’t available in quick strut.

 

[DougR]

Awesome invention. I always just get the quick struts so I don’t have to worry about using the spring compressor and they are just bolt and play lol. Though those probably aren’t available in quick strut.

The spring is Dobinson's and the shock is Bilstein, so assembly was required.

 

[MattPersman]

Nice! is the sag common in them ?

 

[JimPghPA]

Until you find out if it can be aligned with the extra height and get that done, the job is not over. Sometimes extra height throws off the alignment enough that other things have to be done before it can be aligned if you stay with the extra height.

 

[DougR]

Nice! is the sag common in them ?

I don't know if this is a common problem. There was 115.000 miles on the old springs and a 4Runner is heavy. When it was new, it had almost 2 inches of rake, so any sag becomes noticeable. My 4Runner rolls on stock tires. Many owners install oversize/off-road tires, and lift the front and rear for clearance.

 

[DougR]

Until you find out if it can be aligned with the extra height and get that done, the job is not over. Sometimes extra height throws off the alignment enough that other things have to be done before it can be aligned if you stay with the extra height.

I measured camber and total toe-in before and after Installation. The after measurements are within factory specification. The steering wheel is centered and the vehicle slowly drifts to the right when I let go of the steering wheel. It handles better, so the alignment is good after a one inch lift. AccuTune off road states, "KDSS equipped 4Runners can be lifted, however there are two common issues: KDSS lean and poor ride quality. Based on limitations of the KDSS system we recommend lifting KDSS equipped 4Runners a maximum of 2.5” in front and 1” in rear. With this setup we have not had problems with leaning and the ride quality is fantastic."

 

[ls1mike]

That is pretty slick. Not a huge coil spring, but I like it. Not sure how it would work on something like the Caprice with huge coil springs. Maybe I would need thicker/different material all thread?

 

[ls1mike]

Certainly better than this. I had to used 4 on each of the Caprices front coil springs. Set up for a V8 with police duty, they were the worst I have ever done. I swapped them out to Chevy SS springs. I am glad I have a will.

 

[DougR]

That is pretty slick. Not a huge coil spring, but I like it. Not sure how it would work on something like the Caprice with huge coil springs. Maybe I would need thicker/different material all thread?

The first design iteration did not have a plate supporting the top of the screw jack. It also had 1/2-inch all-thread rod, where each rod has an 1100 lb maximum load capacity. That’s more than enough to handle this spring load, however it lacked sufficient column rigidity when I proof tested by compressing a spring 3 inches (1800 lbs - more than necessary to assemble). I added a support plate 8 inches above the base and changed to 5/8-ths all thread which greatly improved column rigidity and added additional bulk to guard against tip over. The all thread rods are 6 inches apart on each side, which is sufficient clearance for my springs. Perhaps you need ~8 inch spacing to accommodate Caprice springs ( ... I don't know how large they are). Each 5/8-ths rod has an 1800 lb maximum load capacity.

 

[MasterSolenoid]

Nice job.
A good design is using the least amount of material to get the job done / and that's what you did.

Only thing I would have done differently is use Heavy Duty Hex Nuts and Washers.

 

[DougR]

Nice job.
A good design is using the least amount of material to get the job done / and that's what you did.

Only thing I would have done differently is use Heavy Duty Hex Nuts and Washers.

If I was turning nuts and bolts to compress the spring, or if I had to work with a much stronger spring, I would have used heavy duty nuts and washers. In this application, the spring force is 600 lbs/inch, so grade 2 nuts in this size are far more than adequate to hold the static load. Nuts on the base plate are tight, and all other nuts only need to be finger tight, which makes it easy to square the upper plate with respect to the all thread rods prior to compressing the spring.

Sufficient column rigidity over a span of 36 inches and overall fixture weight to balance with the weight of the coil over assembly were the critical design aspects to safely compress this particular spring a little more than one inch to expose the sliding rod threads, install the upper lock nut and compress the top hat cushions.

 

[MRC01]

Certainly better than this. I had to used 4 on each of the Caprices front coil springs. Set up for a V8 with police duty, they were the worst I have ever done. I swapped them out to Chevy SS springs. I am glad I have a will.

I have spring compressors like this, and I like that they grab the actual coils of the spring. That seems secure. When using them I only compress the spring just enough to eliminate tension, which isn't much.

 

[DougR]

I have spring compressors like this, and I like that they grab the actual coils of the spring. That seems secure. When using them I only compress the spring just enough to eliminate tension, which isn't much.

I also have a spring compressor like the style shown by Is1Mike. Unfortunately, the hooks didn't fit between the coils of this spring. Moreover, this spring is powder coated - so the hooks and safety pins would have damaged the finish.

 

[2EHA]

on old jaguars the traditional type compressors are useless for the front springs. one by one you can put 4 threaded rods through the spring pan bolt holes and decompress/compress the spring, kind of an on-car version of your setup.