I have a 1970 FJ40 with a lift kit. It is a hfs kit with leaf springs and shocks. It must be an old kit since the hfs shocks were made in america. I couldn't find a model number but The rear shocks have on the shock 5251 c220y2. the front shocks have 5247 c175y3. I am looking to replace the shocks but I need to know the correct size Bilstein shocks to use. By the shock size can that determine the lift size? 2 " or 4". I am running 31 x 10 tires.
Can somebody tell me what size lift I have by the model of hfs shocks is used for 1970 FJ40? (1 Viewer)
- Thread starter buck toenges
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A10Driver
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Best to measure them flexed out and then use Bilstein website to find a match
I’d run the longest shocks I can fit without them bottoming out at full compression.
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What the previous two guys said x 1000. I have seen WAY too many suspension ‘packages’ sold and installed with the wrong shocks over the last four decades. And when I became a distributor for Ironman, I unwittingly became a reseller of mismatch components myself until I had to install the first ‘package’ in my shop and realized that Ironman was copying over OMEs mismatched specs.
You could end up just perpetuating a PO mistake.
There’s probably something already available in the FAQ on how to measure for droop and compression from static length. A couple of years ago I asked @HKforte to take on a little task for the community, and he assembled a very nice reference table of shock specs you should be able to find with a search of his username and the key word shock.
Thanks again Aris for doing that.
You could end up just perpetuating a PO mistake.
There’s probably something already available in the FAQ on how to measure for droop and compression from static length. A couple of years ago I asked @HKforte to take on a little task for the community, and he assembled a very nice reference table of shock specs you should be able to find with a search of his username and the key word shock.
Thanks again Aris for doing that.
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there's no specific shock manufactured for any single specific truck. A single shock might have 20 or 50 different applications.
For example, a rancho 9000 series for your truck in stock form would take a part number ending in 113 in the rear. That same shock
is a replacement for Samurai, Plymouth vans, ten different jeeps, dozens of Ford , Chevy and GMC trucks, Isuzu trucks and others.
All the manufacturers, aside from the custom builders like Fox , King etc, use common shock bodies then stuff the insides with whatever they believe
are the best parts. You'll notice when shock shopping they all have about the same extended to compressed lengths available.
The compression and rebound rates will always be a compromise which is why some people prefer one manufacturer to
another. The shock companies use the same shock on a 3/4 ton gmc truck as a stock FJ40. Depending which company assembles that shock body will
determine whether it's under damped for the full size truck or over damped for the FJ40.
You probably won't get all the wheel travel in the rear if you're using the stock lower position, above the spring, on the rear. Changing to a stock lower plate
from a later 40 will give you a better option and will let you run a longer shock placing the lower mount below the spring. Limiting droop with a shock generally
won't hurt it but limiting compression with a shock will destroy it so focus on the compressed length. Whatever that happens to be, your extended length will be
predetermined by the shock body. A shock with a compressed length of 10" obviously won't have a 14" body.
You won't have a choice of multiple extended lengths with a specific compressed length. You're limited by the length of the shock body
For example, a rancho 9000 series for your truck in stock form would take a part number ending in 113 in the rear. That same shock
is a replacement for Samurai, Plymouth vans, ten different jeeps, dozens of Ford , Chevy and GMC trucks, Isuzu trucks and others.
All the manufacturers, aside from the custom builders like Fox , King etc, use common shock bodies then stuff the insides with whatever they believe
are the best parts. You'll notice when shock shopping they all have about the same extended to compressed lengths available.
The compression and rebound rates will always be a compromise which is why some people prefer one manufacturer to
another. The shock companies use the same shock on a 3/4 ton gmc truck as a stock FJ40. Depending which company assembles that shock body will
determine whether it's under damped for the full size truck or over damped for the FJ40.
You probably won't get all the wheel travel in the rear if you're using the stock lower position, above the spring, on the rear. Changing to a stock lower plate
from a later 40 will give you a better option and will let you run a longer shock placing the lower mount below the spring. Limiting droop with a shock generally
won't hurt it but limiting compression with a shock will destroy it so focus on the compressed length. Whatever that happens to be, your extended length will be
predetermined by the shock body. A shock with a compressed length of 10" obviously won't have a 14" body.
You won't have a choice of multiple extended lengths with a specific compressed length. You're limited by the length of the shock body
A picture is worth a thousand words!
31" tires would be a good clue once we see what the fender well clearance is. You also didn't mention if you have rear fender well cutouts.
Once we see a couple of pictures I'm sure you will get some better guestimates of how much lift you have; from no lift, 2" neighborhood, or 4".
31" tires would be a good clue once we see what the fender well clearance is. You also didn't mention if you have rear fender well cutouts.
Once we see a couple of pictures I'm sure you will get some better guestimates of how much lift you have; from no lift, 2" neighborhood, or 4".
