Has Anyone Paired the Bilstein 6112 with their 8100 in Back?

Hi all. I'm trying to figure out a reasonably-priced (Under $2K) shock package for my 3rd gen TRD OR and I'm curious to hear if anyone has done this combo - Bilstein 6112 up front with the smooth-body 8100 in back.

I run at speed on corrugated and poorly maintained roads as part of my job and I'm wanting a better ride and more confident handling on dirt/gravel. I carry a few hundred pounds of gear and dudes and the ride can get really jarring at times, I've gotten into the rear bump stops more than a few times, too.

I just feel like I'm running near the limits of what the stock shocks on this truck are capable of reliably handling, but I know I'm nowhere near needing to spend $4k plus on on a full 8112 DSA Bypass setup or King shocks or anything else mega high-end.

I know people generally run the 5160 with the 6112, but I can't really figure out why you'd want to pair a 60mm shock up front with a 46mm shock in the back. The smooth body 8100 matches that 60mm diameter of the 6112 and it just seems like a significantly better shock for only a couple hundred bucks more than the 5160.

I see a million threads on the 6112/5160 or the 8112/8100, but for the life of me I can't find any word online from people who have run the 6112/8100 shock combination or something similar. So if you do, I'd love to hear some of your thoughts. Thanks!

 

I have always wanted to run this set up. I had 6112 with an extended 5100 in the back of my previous Tacoma. 6112 are beefy and soak up big hits well off road. 5160 and 5100 are not in the same league as the 6112. I bet it would handle great! Do it!

 

Yeah that's my thought, too. It seems like a no brainer for just a couple hundred bucks additional spend. I'm honestly a bit stumped as to why the 5160 is the recommended pairing and not the 8100.

 

One thing to make sure is that the valving is the same or similar. I know 6112 are digressive valving. If 8100 are also then should be no issue.

 

Yeah the 8100 is also a digressive shock. The only gotcha I’ve found is a restriction on wheel backspacing to a max of 4.5in, but I’m good there.

I think I’m going to order that setup.

 

Upgrading rear shock without upgrading crap stock mounting point to something like Archive relocation

seems stupid

 

People do it with king and fox all the time. I've installed many. Only reason to do a relocation is if going mid or long travel.

 

Those things seem like massive overkill for the no lift setup and near stock-length shocks I’m looking at.

 

Just found this post from a couple years ago on an 8112/8100 thread.

Posting it here for anyone comes across this thread in the future:

 

Continued:

 

The idea of a "digressive shock" is sort of a misnomer. I almost hesitate to even enter into the conversation because the difference between digressive and progressive can literally be 5% and indiscernible.
Bilstein uses a high flow 60mm digressive piston primarily for ease of assembly, you can tune this piston to create many different overall graph curves. The last 8100 rear i took apart has a directional bleed shim so that the compression can be "linear" and the rebound can be "digressive". King does this same thing with many rear tacoma shocks using a machined preload adapter for the rebound side (but do folks say "king is a digressive shock"?)



If you look at this photo in the center column you can see the circular spring shim, this provides some preload to that large shim above it which creates directional bleed. So if the rebound and compression side had 10mm^2 bleed then compression would have 20mm^2 and rebound would have 10mm^2. This is a cool setup because drilling holes in the piston to create bleed makes equal amounts of bleed for compression and rebound despite rebound events being about 3x the force of compression events, this is also why rebound sides of a piston will typically have about half the holes as compression (the bilstein piston has equal ports, so youll often find stacked face shims to account for that).


This is kings digressive rebound spacer on a set of tacoma shocks i tuned a few weeks ago. There is also a common piston in Kings carli kits or it's setups for heavier trucks that has a groove cut in them for a preload shim... although i usually swap to their standard piston and close some bleed and rely on agressive initial flutters, in my experience firmer initial valving with lots of bleed tends to drive real wack especially with super high spring rates like on the front of a diesel f250.
The worst set of shocks i tested for the tacoma platform where foxes which had a low flow piston that was likely close to digressive... though it felt like not having a shock at all... and ironically the 2nd worst setup which was from dobinson had a very high flowing linear style piston.

I just revalved my personal 8100 series front coilovers and actually went to a "linear piston" however i valved them to behave in more a digressive fashion than the digressive piston that comes in them, so i can be more comfortable towing up and down the mountain where i live (exclusively windy roads), and so i can increase my vehicle speeds offroad when im in the desert for shock tuning... however in doing so i have given up some low speed fire road type driving comfort, which i never do in that vehicle.



Anyways, apologies for all the text. I normally don't chime in on forums but i appreciate you asking these questions.
The reason a 6112 is paired with a 5160 is motion ratio, the rear of your truck is close to 1:1 so for 1" of travel you get 1" of shock movement. This matches with the front which is at a higher ratio, so an inch of shock travel has to control more than an inch of wheel travel. The 6112 is also a non reservoir shock, but it's much cheaper than other companies 2.0 non reservoir front coilover shock options which is insane because I tested those and the ride quality is abysmal, much worse than stock.
Imagine 2 guys trying to lift 100 lbs with a crowbar, the guy with the shorter crowbar is gonna need to put more work in, this directly relates to shock size.
In my blind testing i did find the 5100 much more comfortable offroad at speed than the 5160, however the extra oil volume of the 5160 does help.

I normally rip off these ridiculous large aftermarket bump stops folks put on, however it sounds like you might be a candidate for a more progressive bump stop that engages sooner in travel, just keep in mind they will induce much more jounce into the system which can negatively effect ride quality.

I also don't see much reason to do a shock relocation unless you are willing to do the extra work they don't tell you about to get close to 12" of travel out of the rear... which even at that isn't a huge improvement. It's many thousands of dollars to spend to be passed by a guy with a bolt on bypass setup on the trail lol.

TLDR; 8100 rear will be good, primarily for folks with lots of rear end weight who don't need the performance of a zone specific shock like a bypass.

 

Gosh dang you clearly have a ton of knowledge when it comes to the inner components of a shock and overall suspension knowledge. I'm jelly over here. I read that wall of text and enjoyed it.

 

Hey never apologize for good information. I was an engineer in a past life and I'm always appreciative of real knowledgeable technical information on forums.
I really appreciate all the information, especially right on the heels of your moab trip. I also think that reply covers the email I sent you over the weekend

The motion ratios being different between the front and rear makes complete sense. Can't believe I didn't think of it.
I've thought about replacing the rear bump stops a few times but, like you said, it will induce more jounce. Since I'm planning on upgrading the shocks regardless, I figured start there and feel what changes.

Can I ask you one more question? If I end up deciding to pull the trigger on pairing the 6112 & non-adjustible 8100, do you think I would need to get the rear shocks revalved? Or is this something I could theoretically get a good result with out of the box?

Thanks again!

 

Ah apologies, im pretty far behind on everything so im only dedicating a few hours a day to emails... im almost caught up now though.

The stock bump stop in the rear is essentially a concrete block. We blind tested falcons tacoma kit that comes with a foam rear bump and it was pretty impressive how much better that made the rear end feel... that being said, we've also tested a bunch of aftermarket bump stop setups and while several have made the vehicle much worse, any kind of foam or not too aggressive rear replacement does help a ton.

As long as your use case is what they're designed for the out of the box valving should be very good. For 8112 front coilovers i revalve 90% of them because i feel they are too soft in the ride zone however after one of our old tests i gave a set of 8112/8100 smooth bodies to my friend for letting us use his truck and the ride quality of the smooth bodies is quite good for the factory leaf pack, i can't imagine making many changes unless you're running significantly more weight in the bed.

The bottom piston here is kings piston but if you can tell theres a ring cut out next to the center hole, thats to preload the shims a bit... although i've also seen some folks use it to step off the face shim a few thou which really rides weird and jittery. The piston above it is foxes low flow piston, these actually came out of the worst riding set of tacoma shocks i have personally experienced in my life (even worse than dobinsons), it would be very easy to create a digressive valving curve out of it. I swapped the fox 2.5s to the 9 hole high flow piston with my own valving and they ride great now.