Top plate spacer or bump up 5100s? Need slightly more front lift
- Thread starter blairracd
- Start date
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octanejunkie
Elite Member
The distance between the top and bottom of the front suspension doesn't change. Adding a spacer increases preload, and static ride height, whether you add it to the top or bottom.
Adjusting a notch has the same affect as adding a spacer of the same thickness.
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blairracd
New member
So that video was wrong?
Spiker Engineering
official vendor
It was not wrong. Adding a top plate spacer does not increase preload, but does increase the ride height.
Adjusting the notch upwards increases the preload and the ride height, but it also reduces the droop.
Last edited:
Moving the spring perch changes ride height
Spiker Engineering
official vendor
Ugh, I thought one thing but posted another, my bad. I was trying to point out that the extra preload does not change the spring stiffness, one of the common myths that the video busts. I changed my post to eliminate the confusion.
octanejunkie
Elite Member
In the spirit of clarity, I'll repost rather than edit
The distance between the top and bottom of the front suspension doesn't change. Adding a spacer (EDIT: into the coil stack) increases preload, and static ride height, whether you add it to the top or bottom of the stack.
Adjusting a notch to compress the spring has the same affect as adding a spacer of the same thickness into the coil stack.
Adding a spacer ABOVE the coil stack will force the spring assembly down, pushing the LCA down, increasing ride height and reducing droop. Preload is not affected.
I think the other meaningful takeaway from that video (thanks for linking it [MENTION=319302]Bad Luck[/MENTION] ) is HOW lift affects total suspension travel. The Lexus in the video gained the highest amount of total effective suspension travel with 2" of lift (total of upward and downward travel) and lost effective travel above that.
If the 3rd Gen 4runner is the same, anything over 2" may not be optimal. Can we discuss that?
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HiluxSurf SSR-G
Senior Member
Is it possible that the conclusion in the video that 2" is the "optimum" lift is based on the travel lengths of off-the-shelf shocks?
Would it be also possible that if long travel shocks were used, the "optimum" lift amount would go up?
Would it be also possible that if long travel shocks were used, the "optimum" lift amount would go up?
He has a few other videos which are also pretty good. I like this video because he explains the science/math behind different changes and also demonstrates real world measurements to back it up in a way that most people can understand.
Are you referring to longer travel shocks but still stock arms (mid travel) or a full long travel suspension?
HiluxSurf SSR-G
Senior Member
Sorry, I was referring to extended travel shocks paired with aftermarket UCAs, e.g., King shocks that are designed for 3" lift. These shocks are longer than off-the-shelf shocks by about 1.8" so this add to the droop.
phattyduck
Elite Member
Similar to the GX in the video, the gen3 4Runner stock droop is limited by the shock when installed, then next by the upper ball joint when the shock is removed. Extended length front coilovers require new upper control arms due to the increased length. With new upper control arms, the limit to droop will be the axles, just like the GX. The actual travel numbers are different, but the order of limitations is the same. This is all with stock arms, of course.
With 100% stock arms, I ended up with at 3/8" (actually, slightly over that - I think they were actually 11mm thick) top plate spacers to maximize the use stock arm travel (the lower arms get lifted just a bit to get the lower shock bolts in place).
By the numbers, on my 4Runner:
full extension (stock arms, pivot bolts loose): 25.25"
full compression (stock arms, pivot bolts loose, bump stops lifting truck): 16.75"
So, absolute max travel with stock arms/bump stops is 8.5"
I then set my front ride height at ~21.25" to give 4" compression travel and 4.5" droop travel, theoretically. I also went with the softest springs I had available to try and maximize front flex (V6 2WD springs) and verified the shocks don't bottom at full compression. It would be reasonable to go up another 1" if I wanted the look, before starting to lose too much droop.
I feel like I should check this on my ramps now...
-Charlie
octanejunkie
Elite Member
Now we're getting somewhere...
I feel like an Excel spreadsheet with the right formulas could be used to generate a lot of this information plugging in things like shock compressed length versus extended length, spacers and custom arms
I too will perform the ramp test and do some math based on my suspension components specs
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Spiker Engineering
official vendor
Charlie, just to be sure we're on the same page, is this from shock eye CL to bottom of top hat?
phattyduck
Elite Member
No, hub center to fender lip, which allows you to measure with the wheel on or off. I was talking about wheel travel, not shock travel.
Haven't measured the motion ratio, but it should be around 2:1. Bilstein claims 4.61" of shock travel on the 5100's, which would generally confirm that (I had a little less than 1/2" of shock travel left at full bump with no spring when using nearly 8.5" of wheel travel). The OEM shocks are shorter than the 4600s/5100s, which is why those 3" spacer lifts kinda work.
-Charlie
Spiker Engineering
official vendor
Gotcha, thanks.
Romeo1
Member
That’s a super cool video. Thank you for posting it. That guy explains everything perfect too.
