Project to divert KK coil to KJ

[ikuo78]

This project started by acquiring a used KK strut for $20.

At first, I was thinking of just checking the structure or reusing the clevis.

However, the free length of the spring attached to it was 25mm shorter than that of the KJ.

The wire diameter is also thick.

The number of turns is also small.

That means the rate is high.

KK coil has short free length and high rate.

The set length is probably the same as KJ.

The 1G length is probably the same as KJ.

When I roughly estimated the set load for KK, it was 770N lower than KJ.

Set load is easier to feel than rate and has a greater effect on ride comfort.

Maybe I can get about 2.5 inches of lift without increasing the set load as much as the OME927, and without increasing the strut length as much as the top spacer.

to be continued.

 

[ikuo78]

To begin with, I was considering rebuilding the front struts.
This is because the shock absorber is the same as when shipped from the factory.

In Japan, there are distributors such as ARB, Teraflex, Bilstein, RC, Rancho and H&R.
KYB is a Japanese company.

However, they do not carry KJ parts.
The order price is the order price.

High-pressure gas products are dangerous goods, so Amazon will not ship them overseas.
eBay's shipping costs are too high.
Two Bilsteins cost $450 including shipping.

With Bilstein, the saucer is a separate part, so I might be able to change it to ID65 or 70.
But shocks are consumables, so the cheaper the better.

Once, I was able to get two Monroe shocks for $128 from a private importer.
Inside the package was an Amazon slip from when the importer obtained it in the USA.
Two for $114.
Did he import it for $14?
Apparently he quoted the wrong price, seeing as I only received one at first.

Lucky brings misfortune.
The welding where the clevis is attached was rough, so I smoothed it out with a file.
It was too rough, I shaved about 2mm.

Next, how do I lift it?

to be continued.

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[ikuo78]

From the coil length at 1G,
The force to compress the coil was calculated to be 3350N for the wheel and 6700N for the coil.
A 1G load of about 5050N is applied to the front wheel, so
A force of 10100N is applied to the coil.
The missing part probably depends on the angle.
To avoid complicating matters, the loss was kept constant.

The set load and rate is
KK Stock : 2652N 68N/mm
KJ Stock : 3421N 54.3N/mm
KJ RC Spacer : 5321N 54.3N/mm (As stock length.)
OME926 : 3859N 61.25N/mm
OME927 : 6160N 70N/mm

I would like to attach a top spacer to the KK strut, but
I would like to avoid increasing the strut length by 25mmor30mm.
Re-bump limits will die.
It wouldn't be a Jeep if I couldn't jump off the curb.

Currently I am lifting with a 35mm clevis spacer, but it makes a terrible noise when the tire is floating in the air.
That's the only thing I don't like.
I drive so that my tires never leave the ground.
The shock has also deteriorated sufficiently, so the speed at which it stretches is probably fast.

To obtain lift within the limited suspension stroke, the set load must be increased.
If it is a coil with liner characteristics.
As a compromise, I would like the set load to be at most 60% of 6700N = 4020N.

If I insert a 31.75mm spacer, I can lift it 2.5 inches.

When I try to calculate,
If I insert a 30mm spacer into the KK coil,
The set load will be 4692N.

It's a bit big, so I extended the set length by 10mm,
4012N.

KK coil with 30mm spacer and 10mm set length extension.
Even if I extend the set length, will it hit the suspension limit?

how?

I'll attach the calculations, but don't rely on them.

to be continued.

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[ikuo78]

Daystar.
Is it alright?

Daystar has a spacer for 1.5 inch UP.
Probably a 20mm spacer.

Amazon.com says it does not ship internationally.

How about Daystar2.5UP?
It would be a 31.75mm spacer.
Apparently it can be shipped overseas, so I bought it.

First, the instruction manual is difficult to understand.
The HOW TO introduced in Lost has the washer removed from the rod cover in the wrong direction.
Because the meaning of "bevel down" is not understood,
Most likely everyone has the tip of their shock boot stuck in the stock rod cover washer.
Over time, as the tip of the shock boot creeps, the rod nut loosens.

This is uncertain because it is just an imagination based on seeing the shape, not an experience.
I feel a little sorry for the fact that this is left unexamined.

The spacer was 40mm.
Since it's urethane, it probably dents and shrinks under load.

The same kit is offered with a 2 inch lift for KK.
I'm a little worried, but
KK is a little heavier.

I don't use the kit's mounting plate.
It increases the set length by 30 mm.

How about a 10mm extension?
The suspension won't stretch that much.
Let's measure it.

to be continued.

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[ikuo78]

When I measured it,
The strut extends to a coil length of 333mm.
In the photo, 290 - Isolator 10 + Spacer 53 - Clevis mounting position 10.
The RC spacer was 53mm. I mistakenly thought it was 35mm.
Since the clevis and RC spacer are in close contact, the installation position difference from the stock was set at 10mm.
In any case, it exceeds the stock set length of 296mm.
The stock re-bump limiter is a shock absorber in its stock condition.
That's obvious.
At 333mm, the knuckle was hitting the strut.
306mm would be fine.

When compared with similar lift specifications.

KK 30mm Spacer+Set10mmUP : 4012N 68.00N/mm 2.43in
KJ RC Spacer : 5759N 54.30N/mm 3.38in
KJ 30mm Spacer : 5049N 54.30N/mm 2.36in
OME926 17mm TopSpacer : 3859N 61.25N/mm 2.44in
OME927 22mm Cut : 4620N 70.00N/mm 2.42in

RC spacers have a high load.
It is 1747N lighter than the current KJ+RC spacer, so I will lift it with this.
Considering urethane as an elastic body, the rate when placed in series with the KK coil is 56.5N/mm.
Placing springs in series always reduces the rate.
It's pretty good, isn't it?

This is somewhat contradictory to the difficulty of assembling that can be seen from the HOW TO regarding strut assembly.
I wonder if it can be extended if assembled.
Is it just that the bushing is hard and difficult to assemble?

I have to buy a 10mm spacer.

to be continued.

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[ikuo78]

Oops, I miscalculated.
290-10-10+53-10=313

The rebump limit listed as 333mm in the post above is actually 313mm.


By the way, Daystar 2.5 has a re-bump stopper.
If it works, it will be revolutionary.

The knuckle hits the spacer and stops.
At that time, the spacer tries to push the knuckle outward, applying thrust load to the upper and lower ball joints.
The shock rod is also pushed inward through the spacer.

Is it correct?
I don't really understand.
I feel like the direction to accept it is bad.
There won't be any strange sounds at first.
It's not worse than hitting the strut directly.

I hope it doesn't reach there with a set length of 306mm.

I will wait a while for KJ's stock mount plates and isolators to cross the Pacific Ocean.

to be continued.

 

[ikuo78]

Think about the full stroke.

By inserting a 30mm spacer, the spring reaches its full stroke 30mm before the shock's full stroke.

Daystar probably lowered the top plate to put a bump stop there.
It looks like the mount bush is used as a bump stop.
There is no bump stop in the kit.

I won't be using the Daystar top plate, so I'll have to find a replacement.
I don't think the coil will bite, but it is likely that the stress will exceed the allowable stress.

I'm going to put a bump stop on the shock rod.
50mm soft one.
It says that the hardness is shore A65.
Hits from 30mm up stroke.

Is it a little early?
It should be enough to stop with an upstroke of 50mm.

It's good because it's soft.
It says that the allowable load is 2200N.
There will be no excessive load.
The concern is whether the shocks are made to take such loads.
Monroe's shock doesn't stroke to the point where it hits the mount bush.
Stock shocks move that far.
The Monroe has a catch on the bottom to prevent it from stretching during transportation.
The one you turn to release.
This may cause the catch to hit depending on the rotation position.

Monroe also has an unnecessary protrusion where the Daystar spacer is set.
There is a bulge around the drain hole where the plate and cylinder are welded.
I have to cut it down.

Terafrex's bump stop is short for my strut specs.
Shipping costs are also high.
130 dollars for 2 pieces including shipping.
Higher than shocks.

Currently, the bump stops are stock size, but the tires have probably never rubbed against the fender.
But I don't know if I pushed the stock coil past the minimum height.
The rear gets rubbed a lot on the mogul terrain though.


to be continued.

 

[ikuo78]

I shaved the contact point between the shock protrusion and the spacer.

to be continued.

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[ikuo78]

I added a taper to the bump stop attached to the rod.
The motor screwdriver broke while I was cutting it.
I want to adjust the shape of the bump stop a little more, so I'm going to buy a new motor screwdriver.

Come to think of it, I once saw a Nissan Pathfinder bottom out.
The shock had protruded far enough to destroy the top plate and deform the hood.

The top plate has also arrived.
KK's mount bush is structurally more flexible.
KJ's is quite hard.
The set angle is slightly different, but I guess the body is also different.
For now, I'll use the one for KJ.


to be continued.

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[KJowner]

You need a lathe!
Looks interesting, I'm keen to see the results.

 

[ikuo78]

Thank you.
Sometimes I want to use a file or a saw to sharpen things.
This time I was able to get a good file, so I can easily scrape rubber even at room temperature.
I stole it from the company's FA department.
No, I borrowed it.
I'm doing it slowly, but please stay tuned.

 

[ikuo78]

Now, I have to think about how to easily remove the strut, which has become 43mm longer with the RC spacer.
Looking at the photos the shop gave me when they replaced all the bushings on the front LCA, they used a spring compressor.
The one on the left has a thin tab, so it seems like it was set at 1G and then jacked up.
They probably added a durable spring compressor when the coil pitch widened to a certain extent.
Although the work space is dirty, this shop is the most knowledgeable about Jeeps in my neighborhood.
It's a 15 minute walk from my house.

I can also easily remove the strut by fixing it at 1G length, so I'll buy a cheap spring compressor with thin claws.
It is not used to shrink the coil, and the coil is not in a free state, so it will be okay even if it breaks.
A new strut cannot be assembled unless the coil is shortened by about 70mm, so it can also be used as insurance in that case.

KJ's coil pitch is too narrow.
Although longer wire lengths are advantageous for allowable stress.

to be continued.

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[ikuo78]

I tried assembling the strut.
I tried extending the free length by 10mm using a washer, but I can't tighten the nut.
The condition shown in the photo is 7mm.
Although it is a nut with nylon, it does not touch the nylon slightly.
I decided to make the free length extension 4mm.
The spacer remains 40mm immediately after assembly.
It seems that the set load will be higher than calculated.
It will be about 4692N.
Recalculating the set load of the RC spacer with a free length of 313mm, it is 4833N.
There's not much difference.

Let's look forward to the effect of shortening the strut length.

The bump stop attached to the rod is also a bit long, so I plan to cut it to 40mm.

to be continued.

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[ikuo78]

I have attached a photo of the discontinued KK top plate + full urethane mount.
I tried to make it mainly composed of A90° ether type urethane.
It can definitely lengthen the strut length by 10mm, but the bushing on the extension side is thin, so it's a bit stiff.
The mount angle may also be different.
I'm also a little worried about losing the steel inner sleeve.
Daystar's kit has a full urethane mount, so it seems to be related to the issue of noise over time.
It may work if the rod nut is in a position where it is easy to tighten.

This time it's rejected.

to be continued.

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[ikuo78]

This is what the inside of the rod cover looks like.
Install a bump rubber with OD50mm and 40mm height under the ID11mm, OD50mm, t=4mm washer.
Monroe's rod is slightly thicker than the stock.
The rubber hole drilled with an 18mm drill fits tightly.
The hole is smaller than 18mm.

Even so, the hot days continue.
Hot days usually result in showers accompanied by thunder.
I can't find any time to work.
There are some joints that need to be greased and some parts that need to be polished and painted, so I estimate 7 to 8 hours of work.
I envy air-conditioned garages with roofs and walls.

to be continued.

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[ikuo78]

Finally, a cool, non-rainy weekend arrived, so I assembled the struts to the car body.
It was a bit difficult to remove the old struts that had over 40mm spacers in them.
I was able to easily insert the spring compressor on the right side, but on the left side, I had to redo it many times and spent about an hour.

Assembly was easy as it is the same length as the stock shock.
All I had to do was step on the lower arm with my foot and align the clevis hole.

The boots on the upper ball joint were deformed and grease was leaking from the bottom, so I also replaced the boots.
If I didn't have to do this, I would have been able to work a little more cleanly.

The vehicle height has been lowered by about 15mm.
The RC spacer is 3.5 inches and the Daystar is 2.5 inches, so the coil is for KK, but it was almost as described.

As for the ride quality, thanks to the new shocks, there is no longer a feeling of tire flapping.
The strange sound when the shock is fully extended is also gone.
After driving about 5km, I started to notice that the rear shock was deteriorating.
I have to change the rear shocks as well.

My mistake in this work was when I tried to re-tighten the upper arm mount bolt, I broke the screw that holds the steering shaft bracket in place.
The steering shaft gets in the way too much.
I wonder if the tip of the screw is crimped to prevent it from falling out.
It will need to be repaired eventually.
Also, when I removed the nuts on the left strut upper mount, I cracked the ABS actuator connector.
I think I'll also apply caulk.

to be continued.

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[ikuo78]

Dodge Dakota 4x4 rear shocks.
I learned that it can be used here.
The Rnccho RS5248 I looked for while looking at the SPEC table is for Dakota, so I'm sure.
RS5248 is out of stock and probably not manufactured.
So, I ordered A-premium ones from Amazon.com.
This is a dubious product.
There are no notes regarding overseas shipping, so it doesn't seem to be filled with high-pressure gas.
If the internal pressure is low, there is a risk of oil leakage.
I want it to last three years.

Also, I can't buy rear spring isolators.
Only on eBay.
Shipping costs are high.
I have to find out if the one for Commander or Grand Cherokee can be used for KJ.

to be continued.

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[ikuo78]

The rear shocks arrived and I installed them.
Without removing the tires,
Without jacking,
Crawling under the car,
It was frustrating to put 3 t1 washers in this location.
It is better to use only one t3 washer.
It took about 45 minutes to complete, so it may have been faster than removing the tire.

The right rear shock that I removed wasn't stretched properly, so it's probably at the end of its lifespan.

The front and rear shocks were new at about the same time, so the ride is very smooth.
At the rear, the damping on the compression side may be a little weak.
It feels softer than before.

The screw for the steering intermediate shaft bracket that I broke the other day.
I tried to grab it from the wheel house side with pliers and pull it out, but it was hard and I couldn't.
I should have tried the double nut first.
Currently, it is temporarily fixed with wire in addition to the one screw that was not broken.
Now, what should I do?
I think I'll try driving a drilling screw from the wheel house side.
I'm thinking now.
Why is this screw so difficult to turn in the first place?
It looks like there's nothing on it other than the paint that might bite.

to be continued.

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[ikuo78]

I replaced the front brake rotors, which I had been concerned about for about a year.
It looked like it would last another year, but the edges were rusty and crumbling, so maybe it was the right time.
Even in this state, the pillars held both disks firmly.

to be continued.

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