BP-51 Preload Struggle (1 Viewer)

[DesmoPilot]

I have finally found the time to install the BP-51 suspension and have hit a wall on setting preload on the front. ARB recommends 10mm preload for gas with bumper and winch. They are currently at the factory 20mm of preload. The spring compressors that I have are not getting the job done for compressing the springs enough that I can get the preload collar to rotate.

What tools and/or methods have others used for setting the preload on your BP-51s?

 

[Nola622]

They are definitely more difficult to adjust because of how large the preload collar is (it has an inner section that goes inside the spring) vs. other coil-over designs. Easiest option is to find a shop / friend that has a wall or floor mounted spring compressor. Of the cheaper compressors, I believe this design works better than the two-piece kits on BP-51s: Eastwood MacPherson Strut Tool & Coil Spring Compressor - https://www.eastwood.com/fairmount-tools-interchangeable-macpherson-strut-compressor.html
(there are other brands available, probably all Chinese, but this basic design)

I have been able to adjust BP-51 preload with the basic Harbor Freight 2 piece compressor bolts. If the compressors you have are fitting in between the coils and doing some compressing, maybe you just need to carry on with a bit more squeezing to free the collar. It will be night and day with how easy the collar will be to spin once the spring is compressed enough. Don't beat on it and damage the holes obviously. It will spin freely when the tension is off. I use an impact with the harbor freight compressors, which is probably not recommended. Be sure to oil the threads of both compressor bolts if that is the type of tool you are using.

You could also hit a few local auto parts stores to see what design of spring compressor they rent out. There may be some variety there.

Do you have a photo of the current tool / state of compression on the BP-51s?

 

[GreatestDane]

ARB recommends 10mm preload for gas with bumper and winch. They are currently at the factory 20mm of preload...

This doesn’t answer your question but more of a clarification. I think the 10mm setting is for no accessories and the 20mm is for winch and bumper. How-To Adjust BP-51 Preload | Blog Post | ARB 4x4 Accessories

I also suck at mobile posts

 

[WesSiler]

Leave it at that factory 20mm setting if you have a bumper and winch.

 

[DesmoPilot]

I ended up ordering a different spring compressor today. I will work on it again at the end of the week.

ARB instructions call for 10mm for gas engine with bumper and winch. I don’t know the weight difference be Toyota’s gas and Diesel engines. But, has to be at least a couple of hundred pounds if it is anything like other manufacturers.

 

[4wheelgreg]

20mm seems to be the sweet spot for a gas with a bumper , winch and if you do bud built skids and rock sliders , not forget about a extra battery for the winch , also possibly a compressor .
So 10mm or 15mm could be your sweet spot with out all the other stuff .
Thats one reason I am still gathering all my parts and going to wait til this up coming winter and just do it all at once .

 

[DesmoPilot]

Just for reference, here are the instructions that came with my set. I have seen on the ARB site, the reference to setting it at 20mm. However, seems that is related to diesel. Anyways, I will get these setup later this week when I receive the new spring compressor and report out. Thanks for all of the help!

 

[kcjaz]

OP, FWIW, I had originally intended to set mine 10 mm per the instructions but failed to communicate effectively with the install shop and they did not adjust it from factory and I ended up at 20mm preload. I had a TJM bumper w/o winch at the time. I liked the height and ended up dead level empty (2721's on the rear). I ended up putting 30mm spacers in the rear to get back a little rake empty rather than dropping the front by adjusting the preload. I went that way because 1. adding spacers to the rear is easier that uninstalling/reinstalling the front just to adjust the preload. 2. I liked the height (though wife's not not exactly on the same page as me here). 3. I was planning on adding a winch and BB skids and maybe a 2nd battery latter anyway. My point is that there is nothing magic about the 10mm. It is just an approximate starting point.

 

[DesmoPilot]

Quick update:

I ordered a compressor like @Nola622 recommended. Nice unit that I will certainly use on other projects. Unfortunately, doesn't work for the BP-51. With the progressive rate spring, the compressor can't compress enough to fully take the tension off. Therefore, will need to use a shop style that compresses from the end cap to effectively make the adjustments.

I decided to take a chance and see what the 20mm preload looks like, so installed them as-is this weekend. Keep in mind, I don't have the bumper/winch installed yet. That will be this coming weekend, however, my confidence level is very low that it will be enough weight to get the front end into a good position. As of now, I ended up with 4.75" of lift. The frontend compresses zero when setting it back on the ground.

I will install the bumper/winch this weekend and see how it changes things. But, honestly, I don't see it coming down enough. I will plan on pulling the shocks right after installing the bumper and will take them to a shop to have the spring removed and adjust the collar.

I will give another update this weekend after the bumper install.

Thanks for everyone's help, I appreciate it.

 

[Nola622]

My apologies if I led you astray - I've never had an issue with that type of compressor unless the included spring "cups" or whatever they are called do not fit the coil. Even the cheap Harbor Freight compressors work but you can't obviously grab the entire coil with either style - just the section with gaps big enough to insert the compressor. Here is a visual of the HF compressors for reference:
#50

On the HF "Maddox" compressors, like pictured in the link above, sometime you have to find a gap to get the compressor in and then rotate it around to the position you want for even pressure. Even pressure is important in this case or the collar won't spin freely. The set screw on the collar obviously needs to be slightly loose as well. And all threads benefit from some lube, on the BP's and the compressor.

If the compressor fits in there I wonder if you are just not compressing hard enough? Does the machine stop squeezing?

Good luck to you. That spring is 700 lb (I believe) and I've found it quite stiff for my rig. Kings used 600lb for my stock weight front end and zero preload.

 

[DesmoPilot]

My apologies if I led you astray - I've never had an issue with that type of compressor unless the included spring "cups" or whatever they are called do not fit the coil. Even the cheap Harbor Freight compressors work but you can't obviously grab the entire coil with either style - just the section with gaps big enough to insert the compressor. Here is a visual of the HF compressors for reference:
#50

On the HF "Maddox" compressors, like pictured in the link above, sometime you have to find a gap to get the compressor in and then rotate it around to the position you want for even pressure. Even pressure is important in this case or the collar won't spin freely. The set screw on the collar obviously needs to be slightly loose as well. And all threads benefit from some lube, on the BP's and the compressor.

If the compressor fits in there I wonder if you are just not compressing hard enough? Does the machine stop squeezing?

Good luck to you. That spring is 700 lb (I believe) and I've found it quite stiff for my rig. Kings used 600lb for my stock weight front end and zero preload.

No apology necessary. It will get use on other projects.

I also tried with the Harbor Freight style, but no luck. I have had one of those compressors break before and I felt like I was getting close to that point again and backed off.

I did rotate the compressor around as far as I could get it so that it was compressing as many coils as possible. And tightened as far as I could muscle it. No luck.

I am just going to pull them out and do it in one of the more commercial style devices.

Update will be coming