1.5” rear blocks with no other mods?

I just installed 1.5” rear blocks (stock springs), and 5100 rear shocks on my 2020 TRD off-road short bed. Is there any other mods that needs to be done to run that set up safely? Drives fine as is with no noticeable vibrations.

 

Not an absolute, but i would install a carrier bearing drop, its cheap and easy.

 

if over 2" of lift in the front youll want UCAs as the OEMs will likely bind out or not give proper alignment specs, needle bearing replacement on drivers CV is done too depending on how high the lift or how heavy offroad you plan to go.

 

I’d check the length of the brake lines.

 

5100s are the same exact length as the stock shocks, unless you bought an extended length model of 5100.

 

Did you get the longer shocks? One inch is generally ok, but anything more, the shock will top out and affect extended travel.

 

I got the 5100’s that say for up to 1” lift. (I think). I’m only a half inch more with 1.5” blocks and I figured my stock leaf springs with 70k miles are probably sagging at least a half inch by now.

The next extended shock up is for like 2-3” lift I believe.

 

It is not the compression side, it is the extension side. You lose extended travel. With one-inch blocks, I got the extended travel shocks for 2-3 inch lifts.

 

Ok, gotcha. So are the 2-3” extended shocks still able to compress down to 1”-1.5” block fully compressed? If yes, what’s the 5100 model number, or would that be a different number like 6150?

 

I do not recall any specs, nor the model. They ere Bilstein but not 5100. I’m sure there is a trade-off.

 

With a 1.5" block inserted between the leaf spring and axle, the upper shock mount is roughly 1.5" higher and further apart from the lower shock mount on the axle. If you wish to make this gap back up to maintain the same amount of downtravel as the stock situation was (assuming leafs can droop down as far as shocks can extend) the replacement shock would have to be 1.5" longer.

Herein lies the difficulty finding a match: Stock OR rear shocks and Bilstein 5100 are the about same 23" extended length. A 24.5" extended length shock is going to increase compressed length from 14" stock OR/Bilstein 5100, to around 15". This is because a longer shock body is needed for the longer shaft, all of which ia housed between the upper and lower shock mount locations. Not only has no absolute space really changed (1.5" longer but lose 1" compressed length), you'll also need slightly longer bump stops that can stop the frame's downward motion prior to the new longer shock shaft compressing on itself.

Most people get a slightly longer shock between 23-24" that keeps the compressed length close to 14". The additional lift then goes toward uptravel. If for example, you were to add the long 5100 Bilsteins at 16.3" compressed length, you would need about a 4" or so bump stop instead of the approx 2.5" stock bump stops. In that case, your bumps are close to always engaged by being so close to the frame, especially at only 1.5" lift.

Rear lifting does increase shock size that can be fit into the stock mounts, but it is far from 1:1.

 

Thanks for the detailed post. It seems I couldn’t find the “perfect “ length shock for a 1.5” block. It’s either a 1/2” too short, or over an inch too long, so I went with the closest possible being a 1/2” too short. I ran my stock OR shocks with a 1” block previously with no noted problems. So if the 5100’s I have now are rated for stock up to 1” lift, (I even read on a few of the websites that sells them), that the 5100’s are good from stock to 2” lift, I should be good. The picture posted is the same part# I have for the 5100’s.

 

5100's are fine for a 1.5" of lift or 23.5" center of hub to fender. Once you get closer to 24" then the 5125 is a better fit, but you might want to extend the rear bumpstop then too.

The stock suspension with a block doesn't droop as much as an aftermarket leaf pack either.

 

Using the stock mount locations in the rear works similar to the front IFS in that the range is pretty much fixed at around 10" total travel. The difference is where the ride height (lift) is set, and the resulting division of travel range between up and down.

Bilstein 5100s are good and will work fine with 1.5" block or even more. The total travel range (22.94-14.02=8.92) is basically the same as the stock offroad shock. Other than being stronger, what changes is the ride height point within the shock travel range and the division of up travel, limited by the bump, and down travel, limited by the shock extended length (so long as the leafs droop to match).
Adding the 1.5" block moves the ride height in the shock travel range downward 1.5" from where it used to be. You thereby gain 1.5" of up travel and lose about the same amount of down travel. Many people want this extra up travel for high speed and jumping, hence, many published lift ranges.

The next longer Bilstein rear shock, non-reservoir and non-bypass, is the 5125. It is 24.38" extended length, but compressed length is now 15" instead of 14", which pretty much requires a slightly longer rear bump stop. The 5125 has .45" more total travel than the standard 5100. With a 1.5" block lift instaled, 5125 gives back 1.38" of down travel. Up travel gained now is just .12", assuming a slightly longer bump stop.

Given the total travel space constraints of the stock mount locations and work involved to relocate and weld new mounts, the longer bump stop install work, and desire of many for additional up travel, most people will be happy with 5100 rears with a lift, or 5160s with wide bodies and reservoirs, at 14.2"-23.6" travel, well within stock fit parameters, unless you specifically want max down travel, i.e. slow, rough offroad/ rock crawler users.

 

did you do any lift to the front, or am I understanding that you just put 1.5 in blocks and 5100 shocks in the rear? if this is the case you rear end is now around 3 in higher than the front?

 

Sorry, I should have clarified, front is lifted 2”. I originally had a 1” block in the rear, but just went to 1.5” just to have the slightest bit of rake.

 

Thank you for schooling me. Appreciate the detailed response.

 

Ha, I just write up long form because it takes more than 3-4 sentences to explain all angles. I rearranged different leafs, blocks, AALs, and shocks, multiple times, on my 2016 OR last year, trying to dial in a 1" lift with max flex, running mostly empty bed offroad, with 400 lbs suspended armor and bed cover weight. 1" is harder than 2" lift as most 3rd Gen products are geared to 2". Yes, I have a collection of extra parts in my garage now.

My ride is a Frankenstein of different manufacturer parts to get what I wanted, keeping my bed as low as possible for in and out work use, yet still offroad worthy. My front hub center to fender is 22" and my rear hub center to fender is 23.25". Both about 1-1.5" give or take, over new stock height.
I run General Spring HD leafs right now, cheap but effective, and keeps my rear low, yet high enough to give my neg offset 33s room to sneak up into the fender wells I run rear Fox 2.0 shocks, 24.8" extended length, in the stock mounts. My rear bumps plus flip bracket are about 3.5". This gives me about 4" up travel and 5.5" down travel at the shock, both ends being maximized by just enough bump stop to prevent overcompression and leafs with droop more than 24.8" down.

Now if I didn't use my truck rear for work and I was taller, I'd spec everything for 2" lift front and rear, and saved myself alot of time and money, and ease of measurement and fit.