Lift Block Material
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85_Ranger4x4
Well-known member
Well made ones will have an angle to them to keep the pinion angle in spec, you can't just drop a slab of steel in there. If you want to go slab of steel route you can get pinion angle shims but you will need to do some figuring on getting the pinion angle back in spec.
The factory ones on my trucks are hollow cast iron. I deleted the ones on my Ranger to reduce spring wrap and axle hop.
Do not stack them and really IMO at the end of the day if you can find springs that do the same thing... swap springs instead. If you are replacing the factory blocks most stock ones have a tab built into them to catch the bump stop so you need to address that too.
The factory ones on my trucks are hollow cast iron. I deleted the ones on my Ranger to reduce spring wrap and axle hop.
Do not stack them and really IMO at the end of the day if you can find springs that do the same thing... swap springs instead. If you are replacing the factory blocks most stock ones have a tab built into them to catch the bump stop so you need to address that too.
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D
Deleted member 9101
Guest
I have always used steel ones, never had a problem.
Hillbilly Heaven
Explorer
Just say NO
1stDeuce
Explorer
Actually, I'd not overlook a poly block for some applications, particularly lighter trucks.
Cast blocks have their place, but in some applications they can actually be worse than poly blocks. The main issue I see is that the most cast blocks are huge, and the hollow void is often too large for the spring pad size of half ton or smaller trucks. The block ends and sides overhang the spring pad on the axle, rather than resting on it. This leaves all the load going through the center web of the cast block, with the axle kept from rocking only by the u-bolts. Under load, or wheel hop, the u-bolts are prone to stretching, and the block becomes loose, with the axle rocking until something gets spit out our destroyed.
Poly blocks, as well as welded and billet blocks have flat surfaces that interface with the smaller spring pads of lighter trucks to prevent this rocking. Though I wouldn't consider poly blocks for a 3/4 ton or 1 ton truck, I wouldn't hesitate to use them on a half ton or lighter pickup. Glass filled nylon is the normal material for a "poly" block, and glass filled nylon has excellent compressive strength, which is very applicable to how a lift block is used.
If you're looking for a slight boost, I'd also consider something like ORD's "zero rate add-a-leaf" as a good idea. It's basically a ~1" block that you bolt to the spring pack with the spring center bolt. Keeping the block short is always a good idea to reduce the amount of axle wrap and stress that goes into a spring pack, particularly with the 2 leaf packs of today's half ton trucks. Bolting the block to the pack just adds that much more protection against it getting spit out if something goes wrong.
Finally, the idea that a lift block must be tapered is just plain wrong for most applications. If you drop one end of the driveshaft via a parallel lift block, and do nothing to the powertrain angle, the u-joint angles on both ends change by the same amount, which is exactly what you want. Rotating the pinion up via a tapered lift block will actually induce a torsional vibration due to mismatched u-joint angles if the powertrain angle is not also changed. So where are tapered blocks actually a good fit? On vehicles with a short driveshaft, the operating angle of the u-joints becomes extreme, which causes inertial vibration of the driveshaft. On these vehicles, the transmission crossmember is dropped, which angles the transfer case output down, reducing the angle at the upper end of the driveshaft. A tapered axle block rolls the pinon up, reducing angle by a matching amount at the lower end of the driveshaft. The pinion angle is kept in line with the powertrain, and the overall operating angles of the u-joints are reduced. This keeps the inertial and torsional vibration to a minimum.
Great video about driveline angles for a one piece driveshaft:
Cast blocks have their place, but in some applications they can actually be worse than poly blocks. The main issue I see is that the most cast blocks are huge, and the hollow void is often too large for the spring pad size of half ton or smaller trucks. The block ends and sides overhang the spring pad on the axle, rather than resting on it. This leaves all the load going through the center web of the cast block, with the axle kept from rocking only by the u-bolts. Under load, or wheel hop, the u-bolts are prone to stretching, and the block becomes loose, with the axle rocking until something gets spit out our destroyed.
Poly blocks, as well as welded and billet blocks have flat surfaces that interface with the smaller spring pads of lighter trucks to prevent this rocking. Though I wouldn't consider poly blocks for a 3/4 ton or 1 ton truck, I wouldn't hesitate to use them on a half ton or lighter pickup. Glass filled nylon is the normal material for a "poly" block, and glass filled nylon has excellent compressive strength, which is very applicable to how a lift block is used.
If you're looking for a slight boost, I'd also consider something like ORD's "zero rate add-a-leaf" as a good idea. It's basically a ~1" block that you bolt to the spring pack with the spring center bolt. Keeping the block short is always a good idea to reduce the amount of axle wrap and stress that goes into a spring pack, particularly with the 2 leaf packs of today's half ton trucks. Bolting the block to the pack just adds that much more protection against it getting spit out if something goes wrong.
Finally, the idea that a lift block must be tapered is just plain wrong for most applications. If you drop one end of the driveshaft via a parallel lift block, and do nothing to the powertrain angle, the u-joint angles on both ends change by the same amount, which is exactly what you want. Rotating the pinion up via a tapered lift block will actually induce a torsional vibration due to mismatched u-joint angles if the powertrain angle is not also changed. So where are tapered blocks actually a good fit? On vehicles with a short driveshaft, the operating angle of the u-joints becomes extreme, which causes inertial vibration of the driveshaft. On these vehicles, the transmission crossmember is dropped, which angles the transfer case output down, reducing the angle at the upper end of the driveshaft. A tapered axle block rolls the pinon up, reducing angle by a matching amount at the lower end of the driveshaft. The pinion angle is kept in line with the powertrain, and the overall operating angles of the u-joints are reduced. This keeps the inertial and torsional vibration to a minimum.
Great video about driveline angles for a one piece driveshaft:
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shade
Well-known member
I'm assuming this is applies to the truck in your signature.
If not, please specify the vehicle.
- What do I want to do with my truck?
- Why do I believe that a proposed change will be an improvement toward that end?
- What are the drawbacks to the proposed change?
- If the proposed change still makes sense to me, how much am I willing to spend?
That's how I usually approach these things.
Answering those questions might focus the responses.
For example, if you want to lift the rear 1" without spending much money, and you're already happy with the performance of the rear suspension, lift blocks might be fine.
Otoh, if you want to lift the rear 3", you don't mind spending a fair amount, and you already dislike the way the suspension works, new springs or air bags may be a better choice.
I'll add that it doesn't take much lift to exceed the extended limit of some shocks, so that may be a factor in your budget.
Ozrockrat
Expedition Leader
I used billet 6061 aluminum on the last Freightliner. Machines to suit the profile of the smaller block it replaced. No issues.
On this 22,000 lb truck I have 3” billet 6061 blocks on the front. Very minor axle wrap when loading up with the brakes applied but nothing noticeable when driving/stopping.
Because it is unsprung weight you need to keep it as light as possible. (Says the guy who may of saved 5 lbs bolting on an axle that weighs 1750 lbs
)
On this 22,000 lb truck I have 3” billet 6061 blocks on the front. Very minor axle wrap when loading up with the brakes applied but nothing noticeable when driving/stopping.
Because it is unsprung weight you need to keep it as light as possible. (Says the guy who may of saved 5 lbs bolting on an axle that weighs 1750 lbs
)
85_Ranger4x4
Well-known member
My factory cast blocks are tapered and even marked with arrows which way they are supposed to be installed. According to the angle finder thing on my phone it is about 2* but I didn't exactly sandblast them for exactness either. They also call out the wheelbase before the part number (std cab longbox (Long Wheel Base) was as long as they came in '85, Supercabs didn't come out until '86) and 2wd's didn't have any blocks at all... but used the same springs, axle and transmission crossmember.
I guess I don’t get your description of a cast block, they seem strong enough as Ford seems to put them in everything and I have never heard of one failing unless stacked. My F-150 has pretty much the same thing as my Ranger and so did dad's old F-350.
I had no issue with my factory blocks until I applied 2x factory horsepower/torque to worn springs in 2wd. 114” wheelbase so while not real long it isn't real short either, one piece driveshaft with plain ol' u-joints both when new and it’s current state.
Yes it's for my 2016 Silverado
I already bought rear shock extension brackets that allow for a taller block
1stDeuce
Explorer
Ok, you're talking about the cast blocks that the factory used, not aftermarket stuff. Even for aftermarket stuff, the strength of the block is not an issue, it's the "fit" on lighter trucks. Notice that your cast blocks actually have a flat part that sits on the spring pad, and that the spring sits on. That's an excellent design.
Unfortunatily, that is NOT the design used by most aftermarket cast blocks...
here's a pic of some aftermarket blocks to show what I mean...
The part with the hole is the top of the block, and the bottom looks exactly the same, excepting that it has a short pin that sticks out where the top has a hole. The issue I have with these is that for lighter trucks, the spring pad is usually both shorter and narrower than the outline profile of the block, meaning the center boss of the block sits on the pad, but the fore, aft, and sides of that profile hang over the spring pad. That is No Bueno.
As for the taper, you can bet that Ford used a block that provides the correct u-joint angles. Just because they used a block with a 2° taper doesn't meant that every truck needs a block with a 2° taper... My contention is that most trucks that didn't come with a block probably need a block with NO taper, unless you're dropping the t-case to reduce driveline angles.
So the difference is that you're looking a a very well made factory block, and I'm talking about aftermaket stuff, and the two are NOT the same.
billiebob
Well-known member
this ^^^^My factory cast blocks are tapered and even marked with arrows which way they are supposed to be installed. According to the angle finder thing on my phone it is about 2* but I didn't exactly sandblast them for exactness either. They also call out the wheelbase before the part number (std cab longbox (Long Wheel Base) was as long as they came in '85, Supercabs didn't come out until '86) and 2wd's didn't have any blocks at all... but used the same springs, axle and transmission crossmember.
I guess I don’t get your description of a cast block, they seem strong enough as Ford seems to put them in everything and I have never heard of one failing unless stacked. My F-150 has pretty much the same thing as my Ranger and so did dad's old F-350.
I had no issue with my factory blocks until I applied 2x factory horsepower/torque to worn springs in 2wd. 114” wheelbase so while not real long it isn't real short either, one piece driveshaft with plain ol' u-joints both when new and it’s current state.
There are a bunch of considerations beyond just thickness or lift height. Chevy likely has a few choices for different applications.
Personally I'd find a reputable after market supplier who has a specific wedge, not block, for your truck.
If you get the angle wrong you create stress on the driveline joints.
My Superlift lift kit arrived and after looking at the instructions I am surprised it says to use the kits 2" blocks and STACK the block on top of the factory 1-1/4" block
I am not keen on this idea of stacking blocks and want to find a single block
Does anyone know of a company that sells a direct fit 3.50" tall rear lift block? I have found 3" and 4" only
I am not keen on this idea of stacking blocks and want to find a single block
Does anyone know of a company that sells a direct fit 3.50" tall rear lift block? I have found 3" and 4" only
I found a 3.5" by Skyjacker, but some say it wont fit...…..
www.rockymountainsusp.com
Block & U-bolt Kit
Skyjacker Rear Block Kits include a pair of ductile iron blocks with 4 u-bolts, Nylon insert lock nuts and washers. Skyjacker blocks are high quality ductile iron (not gray iron) tapered and are 1-piece construction with axle pins built-in.