Actual measurements on 5100's.... you are not using all the suspension!

Alright so this weekend i threw on some lightracing UCA's (sweet product btw) While i was there i decided to cycle the suspension without a spring to see how much of the 5100's shock travel was actually being used. I expected it to be pretty close to bottoming out the shock when the stock LCA hit the stock bumpstops on my truck.

I ran the shock without the dust cover so i could mark travel, noting that the dust cover accounts for a decrease in 3/8ths of an inch of shock up travel due to how its positioned on the upper shaft.

I did a full cycle with the bumpstop in place smushing the stock bump as much as i could with the static weight of the truck , obviously limited by the bumpstop.Then a full cycle without the bumpstop, and stopped traveling up just before the UCA hit the inner fender, which was JUST before my 3/8ths of an inch mark for the dust boot that was not in place.

The result, there was right at 1.25in of shock travel not used with the bumpstop in place!!! thats a solid 2in of wheel travel that is unused.

This leaves credence to why the Baja / TRD pro's come with shorter bumpstops, and also why it is not a concern with the Baja / TRD pro / 6112's slightly longer collapsed length ( compared to the 5100's ) when running said shorter bumpstops. After doing measuring this got me to thinking, shorter bumpstops and or, space the top of the shock down via a top plate spacer. Idealy id like to use about 7/8's of an inch more of the shock stroke, to leave some extra wiggle room for suspension movement / super smushing of the bumpstop.

So maybe a 1/2in top plate spacer and a shorter bumpstop ala 4th gen 4 runner (or... remove some of the material above the flange on the stock bumpstop)

the ideas are flowing.



NOTE: these measurements were done on my driver side that ALREADY has a 1/4in top plate spacer (so i could see the worst case scenerio on my truck), so if you are not running a 1/4in top plate spacer you are actually not using about 1.5in of shock travel.


A question for the masses. Can someone measure the space between 2 of the adjustment notches on a 5100 body? i wanna say its right around 5/8ths?

 

Not the best picture but you can get an idea.

 

"The result, there was right at 1.25in of shock travel not used with the bumpstop in place!!! thats a solid 2in of wheel travel that is unused."

OP, how did you do the math to figure out the loss of travel? Keep in mind bumpstops compress much more under dynamic loads. Also, by slowing down the final amount of travel and eliminating the shock from bottoming, you are saving your shock from being damaged.

 

@nd4spdbh Nice work on spending the time trying to figure all of this out. One thing to consider would be the Wheeler's Superbumps and how much more they compress than the factory bump stops.

This is a good video of the superbumps in action:
https://youtu.be/YRmK_NkU8Rs

 

Oh yes, one last measurement was the minimum thickness for a bumpstop which was 3/4 of an inch before the uptravel of suspension was limited by the UCA hitting inner fender / shock bottoming.... those super bumps look like they get pretty close to that.... HMMMMMM


still looking for the measurement between each adjustment notch on the body of the 5100's

 

well you never want the shock to be the limiting factor, no?

 

this is true, you never want the shock to be the limiting factor. but when there is 1.25in left of shock travel unused, id like to have that down around .5in to gain 3/4 of an inch at the shock or right around 1.5in of wheel travel!

still toying with various ideas on how i want to go about this. with the idea of making a 3/4in spacer for just the shock shaft, then getting a long sleve nut, or do a standoff on the top of the shock with a bolt down into the standoff to capture it. Im trying not to mess with my lift height as i like it where it is.

 

What's even more interesting to me is that the 4600 is only a hair longer collapsed than the 5100 meaning you should be able to safely use a 1" thick spacer(giving you 2" of lift) with no worry of your strut becoming the bump stop.

I think tomorrow I'm going to measure a 4600 with a 1" spacer to see if there is still shaft left after the control arm hits the bump.

 

If you do please report back your findings. Make sure to take into consideration the thickness of the dust boot collar as you will likely cycle the suspension without it on so you can get measurements. (or hell cycle the suspension with the dust boot collar on and just make your measurement marks on the body of the shock)

 

I got curious so....

This is with a 1" spacer on the stock Bilstein TRD shock.
You can see there is still about 1/2" of shock shaft showing. The weight of the truck is resting on the bump stop.

I left the dust boot and just cut a window. These are just high mileage spares I use when my Icons need rebuilding.

With a 1" spacer I really don't see how you could bend or snap a shock considering it's NOT being used as a bump stop.




Looking at the bump stop you can see I've smashed it a few times and it will probably compress a bit more during a big bottom out. 1/2" worth of squish? I suppose...

 

I'm going to tie a zip tie around the shaft and repeat to see exactly where it compresses to.

 

Interesting...so this is essentially an argument that reasonable spacer lift (say, for leveling) does not negatively impact ride quality and does not put the strut in danger?

 

I suppose so. At 1" I really don't see the harm. Unless you REALLY slammed down on something hard enough to compress that bump stop into oblivion?

I'm not saying spacers are badass or the way to go by any means. I did this out of curiosity because you hear so much talk about how dangerous they are and how they can snap/bend shocks.

 

Not sure if it relates but with ATV's the bump stop a huge part of the suspension and you need to take into account for that being nearly fully compressed. The last thing you want is that shock to be metal on metal when taking a huge hit.

 

Based on this, I can see issues for large spacers (such as for 3 inch lift kits). A leveling kit though may not be bad.

 

I'm curious to know how far it can physically be compressed. With the weight of the truck on it you can hardly notice any compressing. Mine are a decade old now so maybe they've hardened a bit over the years.

 

those numbers are right inline with what i found... about 1.25-1.5in of extra shock not used when the truck hits bump. Actually its exactly what i found as i took my measurements on the driver side that already has a 1/4in spacer!!!

with .5in of shock shaft left, that should be plenty to allow for stock bumpstop compression. The stock bumpstop is hard, and the big flange you see is the start of the compressable rubber (so only the lower half actually compresses) This is also why the TRD baja / pro kits come with a bumpstop that has a shorter top half (above the flange) to gain some up travel.

Idealy id like to find some spacers that are the same thickness as the distance between the notches on the 5100. Then run that spacer above the top plate, and lower the coil one notch. This will net the same lift height but allow more droop.

Or fab up some new top plates... hmmmmmm, can anyone with a spare top plate take a measurement of how much further up the center hole is from the studs? A flat top plate would be VERY easy to cut out, but i have a feeling that would be too much spacing down of the shock stem. (something like this )

 

Is it the tequila, or is this happening? I'm making another drink...