F42 RPO Code

[da_raabi]

My truck has no codes for anything related to an HD suspension. I see that there are a bunch of options on parts sites for control arms and coil springs related to the RPO codes F41 and F42, which I do not have. Can anyone explain what these codes mean/what parts they apply to? I know F41 is "Firm Ride" and F42 is "Heavy/Severe Duty" but other than that I've got nothing.

I am also curious if swapping out my non-HD suspension/springs with F42 Severe Duty suspension/springs will give me any front-end lift. I cannot find ANY info on the specifics of these RPO codes, so I'm hoping someone here might know more about it. Thanks!

 

[chengny]

I would not get too excited. here are the parts list and dwg for 85-86 2WD front suspension (C10, 20 & 30).

It looks like the "Heavy Duty Front Suspension" package as shown here, consisted of a heavier steering knukle to control arm U-bolt. Most front suspension parts that can be upgraded to Hvy Duty are listed as "see catalog". I don't have that catalog so, that's all I could find:

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Heavier duty springs don't provide additional lift - they might maintain the original curb height for a longer time - but the original height is the same.

 

[da_raabi]

Hmm... Very interesting. I wonder why all of the parts sellers have specific "HD F42" parts including control arms (upper and lower) as well as springs rated waaay higher than stock. Is this an aftermarket thing?

 

[chengny]

No, no there are lots of parts that can be rated as hvy duty. Look at the parts list. Nearly all the components require reference to "the catalog". I think it's a safe assumption that the catalog parts are the ones that get upgraded with a hvy duty package. I was editing my post - read it now. It is more clear.

 

[da_raabi]

Ahhh I see. So the weight capacity increases but the sprung/unsprung dimensions stay the same. So the ride gets stiffer, but the ride height is the same. Damn... Here I was hoping a spring upgrade would give me some lift, otherwise I seem to have ZERO options for a 2wd BB truck.

As far as the rest of the "HD" parts, is there any reason to use them of the other standard duty parts? Know of any overall design differences?

 

[chengny]

As far as the rest of the "HD" parts, is there any reason to use them of the other standard duty parts? Know of any overall design differences?


If you want to maintain the truck's one ton rating you may want to use the parts that were originally spec'd.

Another thing to consider is that if you start to "mix and match" STD & HVY duty components, there may be fitment issues as they relate to connected components.

It probably should be an all or nothing decision.

I wish someone else would step in and offer some real advice. I am making this stuff up as I go. Check my syntax. Full of probably's, assumption's, might's, looks like's. You ever heard the expression; "the blind leading the blind"? That's us on this issue.

 

[da_raabi]

As far as the rest of the "HD" parts, is there any reason to use them of the other standard duty parts? Know of any overall design differences?


If you want to maintain the truck's one ton rating you may want to use the parts that were originally spec'd.

Another thing to consider is that if you start to "mix and match" STD & HVY duty components, there may be fitment issues as they relate to connected components.

It probably should be an all or nothing decision.

I wish someone else would step in and offer some real advice. I am making this stuff up as I go. Check my syntax. Full of probably's, assumption's, might's, looks like's. You ever heard the expression; "the blind leading the blind"? That's us on this issue.

heh heh, LOVE IT. I am still doing some research on it, and actually just found a pdf of the original dealer fact book, so I'm going to have a looksie through that and see if it details the available options.