Lift Blocks

[53guy]

Ok, I searched and found a ton of stuff with "lift blocks" in it, but very little describing why everyone says dont use them. I've got a full traction 6" lift and want to push it up to 7" for a bit more clearance for 35's. Is 1" blocks a big problem? Why are blocks so horriable to add to a lift? And if it is such a big deal, what are my options to get another inch out of the rear? Front doesn't seem to be so difficult, just add spacers, but is that a correct assumption as well? Thanks for the help.

[xjj33p3r]

If you don't add a traction bar, they will warp the leafs. You'll really want something else like a shackle to add more lift.

[rockwerks]

If you don't add a traction bar, they will warp the leafs. You'll really want something else like a shackle to add more lift.

you are talking out your hiney....I ran em for 4 years on my last xj without any problems and no traction bar..I ran 2",

Hell 84 rangers use 4" block from the factory!

[53guy]

hmmmm, longer shackle? I've never read anywhere about how much lift the shackle in the FT kit has or what the rear leaf packs have as far as lift goes. Any idea where i can get a good idea? Are too long of shackles a problem as well?

[RKBA]

I doubt that you will experience any spring wrap with a 1" block added to the already stiff pack that you have. It's not like you are using a sagged out factory spring pack. I would run a short block without hesitation in your situation.

You might consider bolting the block to the spring pack with a longer center bolt instead of relying on u-bolt clamping pressure to hold it in there.

[xjj33p3r]

you are talking out your hiney....I ran em for 4 years on my last xj without any problems and no traction bar..I ran 2",

Hell 84 rangers use 4" block from the factory!
I ran 2" blocks for a couple of months and my leafs sagged 1.5". They were 4.5" springs for reference.

[rockwerks]

I ran 2" blocks for a couple of months and my leafs sagged 1.5". They were 4.5" springs for reference.

Let me guess rustys right? or rancho?

[53guy]

I doubt that you will experience any spring wrap with a 1" block added to the already stiff pack that you have. It's not like you are using a sagged out factory spring pack. I would run a short block without hesitation in your situation.

You might consider bolting the block to the spring pack with a longer center bolt instead of relying on u-bolt clamping pressure to hold it in there.

Yes, I had planned on using the supplied shackels, packs, then getting either a 1" or 2" block, then whatever degree shim I need, then using Rubicon Expresses center pins to bolt them all togeather then use the U-bolts to hold all that to the axle. Anything wrong with that set up? I do have an AA SYE so no problems there.

[Harvo]

They will put more leverage on your springs. Your springs will loose some of their sproing over time. You might get axle wrap. For a cheap inch, I suggest add a leaves... but not the shortys. The full length kind.

[RKBA]

Yes, I had planned on using the supplied shackels, packs, then getting either a 1" or 2" block, then whatever degree shim I need, then using Rubicon Expresses center pins to bolt them all togeather then use the U-bolts to hold all that to the axle. Anything wrong with that set up? I do have an AA SYE so no problems there.

I suspect that you will be fine like that.

One thing that I like to do when bolting together leaf springs is to replace the spring center bolt with a socket head cap screw. It will locate the spring in the perch just like a traditional spring center bolt, but its a heck of a lot easier using an allen wrench to fasten than a pair of vice grips. Most good hardware stores carry them in the grade, size, and thread pitch that you will need.

[OT]

Hell 84 rangers use 4" block from the factory!
Why do you think they stopped at 85?

I doubt that you will experience any spring wrap with a 1" block added to the already stiff pack that you have. It's not like you are using a sagged out factory spring pack. I would run a short block without hesitation in your situation.
Ditto
In this case, shorter is more pleasurable.

[FELIX]

Well I was one who thought that Blocks were no problem. Had run them on several different truck over the years, & 6 years on the XJ no problem. Had heard stories of people breaking them, but never saw a broken one so I kind of discounted it. Then came the day that I broke one :explosion Rotating the rear axel towards the sky & taking out the drive shaft in the process :mad: . I have since pledged :lecture: to never ever run them again.

Rob $.02

[Gil BullyKatz]

Based on experience killing my leaf packs...

I would not go over 1" blocks...

http://img.photobucket.com/albums/v465/bullycatz/ghettoblock.jpg

[gtpolkus]

Here goes some Statics!! Torque=Force*Distance

When you hit the gas and begin to propel your vehicle forward, the axle wants to twist just as badly as the tire does, the forces are equal and opposite. The distance between the Force of the axle twisting and the spring are small, so the torque on the spring is small(or theoretically nothing because the axle and spring are directly in contact). Put a lift block between the axle and leaf spring, and you now have a distance between spring and axle....The force or the axle twisting is still the same, but the distance is greater. This torques the leaf spring and twists them up. The smaller the block, the smaller the forces

[53guy]

One thing that I like to do when bolting together leaf springs is to replace the spring center bolt with a socket head cap screw. It will locate the spring in the perch just like a traditional spring center bolt, but its a heck of a lot easier using an allen wrench to fasten than a pair of vice grips. Most good hardware stores carry them in the grade, size, and thread pitch that you will need.

i've never messed with center pins, do they have to be threaded? do they screw into anything other than the nut? i was under the assumption that the pin just holds the packs/blocks/shims togeather. is that correct?

[rockwerks]

Well I was one who thought that Blocks were no problem. Had run them on several different truck over the years, & 6 years on the XJ no problem. Had heard stories of people breaking them, but never saw a broken one so I kind of discounted it. Then came the day that I broke one :explosion Rotating the rear axel towards the sky & taking out the drive shaft in the process :mad: . I have since pledged :lecture: to never ever run them again.

Rob $.02

Rob 6 years on the same set? Lift blocks are like any other part on the rig they need to be inspected periodically and replaced if needed. also never use hollow .they will fail under the stresses. solid steel or solid alum blocks only, ony the pin spot should be drilled out, from every failure I have seen has been caused by neglect, lack of inspection and lack of retightening the u bolts. and I would not go over 2" either.

[FELIX]

Rob 6 years on the same set? .

Yep. never noticed any cracks until one broke in 1/2 & ejected causing the pinion to rotate skyward. Good thing is it won't happen again to me. running RE 4.5 springs now :) .
Yeah, I usally go thru the truck pretty good each run, but never really noticed anything w/ the blocks, but I also never really paid that much attention to them either :doh: . I guess chock it down to another "sader but wiser investment" that once again proves you can do it right or you can do it again :sunshine:

Rob

[xjj33p3r]

Yea they were Rusty's leafs.

[RKBA]

i've never messed with center pins, do they have to be threaded? do they screw into anything other than the nut? i was under the assumption that the pin just holds the packs/blocks/shims togeather. is that correct?

A spring center bolt is just that, a bolt - it just has a different head than a hex bolt. Automotive leaf springs generally use the spring center style instead of a regular bolt as the round "head" of the bolt is used as a locator on the perch. Take a look at a set of leafs out of a vehicle and you will see exactly how it works.

[Dirk Pitt]

and I would not go over 2" either.

But why, Rangers had 4" from the factory.

[rockwerks]

Yea they were Rusty's leafs.

nuff said LOL, The quality of the spring packs make a world of difference also. I ran 10 leaf national's with my blocks, RE springs also would be fine ( they come with a block in some of the kits 1 1/2" I believe


But why, Rangers had 4" from the factory.

personal preference....the higher you go, with the block the more leverage, we all understand that. I feel 2" will dnot do any damage if you retighten adn check them from time to time

[53guy]

so where do FT springs fall into the mix? they look solid as anything, but i do not have them installed yet. how do they compare to RE springs or Rustys springs? i'm feeling pretty comfortable with 1" to 2" blocks. anyone have any issues running spacers in the front? are there any big problems with running 2" spacers in the front? I was thinking that the ACOS system would be ok, but 200+ dollars is a bit pricy for spacers, I think.

[rockwerks]

so where do FT springs fall into the mix? they look solid as anything, but i do not have them installed yet. how do they compare to RE springs or Rustys springs? i'm feeling pretty comfortable with 1" to 2" blocks. anyone have any issues running spacers in the front? are there any big problems with running 2" spacers in the front? I was thinking that the ACOS system would be ok, but 200+ dollars is a bit pricy for spacers, I think.


My ladies has a 2" BB onit, blocks in the rear and spacers inthe front. the only difference is a little front coil prelaod, so it rides a tad harsher

[Lawn Cher']

My ladies has a 2" BB onit, blocks in the rear and spacers inthe front. the only difference is a little front coil prelaod, so it rides a tad harsher

The coil isn't preloaded with a spacer. The coil gets compressed farther to reach the same tire stuffing point as without the spacer, so it provides more resistance in that respect since without altering the bumpstops you are providing more up-travel. But static coil height and spring rate aren't changed. The harsher ride comes from the increased control arm angles.

[jfiscus]

I personally know of a guy that went through 2 sets of stock leafs and a set of HD leafs in 1.5years with 2" blocks. His springs looked like a "W" eventually.

For a cheap/easy 1" get some stock comanche shackles.

[2xtreme]

nuff said LOL, The quality of the spring packs make a world of difference also. I ran 10 leaf national's with my blocks, RE springs also would be fine ( they come with a block in some of the kits 1 1/2" I believe



Obviously you do not know who makes Rusty's or RE's spring packs!!


As a general rule of thumb lift blocks are not a good way of lifting any truck with any spring pack. However, we all have to make compromises and the cost of a new spring pack is obviously a negative. So if you have a currently good spring pack with reasonable lift and the correct length shackle for that spring pack then a short block is probably a reasonable way of getting that extra lift. An AAL could work but if you have a spring pack with a lift then it might not provide much lift and make the pack significantly stiffer (again depends on the pack and AAL).

If I was to add a 1" lift block I would only do it with a solid lift block and a tapper as part of it (not a seperate taper as well as the block) but that is just me.

for the tires you are planning I would forget the 1" and trim.

Michael

[cal]

Rob 6 years on the same set? Lift blocks are like any other part on the rig they need to be inspected periodically and replaced if needed. also never use hollow .they will fail under the stresses. solid steel or solid alum blocks only, ony the pin spot should be drilled out, from every failure I have seen has been caused by neglect, lack of inspection and lack of retightening the u bolts. and I would not go over 2" either.

Interesting. My Ford truck came from the factory with 3" hollow steel blocks under 17 leaf's.. (10 + 7 overload leaf's).

I've gone through two ford 9"'s and a dana 60.. the truck is 43 years old now. I -do- get some axle wrap out of it, but the blocks have held find and the leaf's do not sag at all.

That said, I am all against lift blocks. Go add-a-leaf, longer shackles, new springs, trim more, smaller tires, whatever is necessary. I carry a set of lift blocks with me as trail spares for peeps who break theres, but I dont suggest running them.

[rockwerks]

Obviously you do not know who makes Rusty's or RE's spring packs!!


Michael

So enlighten us learned one

[cal]

Obviously you do not know who makes Rusty's or RE's spring packs!!


My talk with RE about my failed RE leafs (they were 4 months old!) three weeks ago lead me to understand every batch comes from a random different manufacturer, and that its a constant fight to make sure everyoen gets two leaf packs that are the same.

With that knowledge in my head, i'd have to say .. neither do you?

[sacem]

I've been running 2" blocks on the back and 2" spacers in front in order to be able to fit 31x10,5 tires all around with out too much tire rubbing, but after reading this thread I'm beginning to worry and would like to know if anyone has the lenght of rear springs that are needed to raise the same 2" and delete the blocks.
I'm in Peru (south America) and finding an after market raising kit for the XJ is not possible and importing one would be out of my budget but I sure can get a local manufacturer to prepare or adapt a set with the specs , if I can get them.
I do have been feeling the rear axle warp specially under heavy braking situations, so that and this thread has made me change my mind about the blocks.
SACEM

[cal]

I've been running 2" blocks on the back and 2" spacers in front in order to be able to fit 31x10,5 tires all around with out too much tire rubbing, but after reading this thread I'm beginning to worry and would like to know if anyone has the lenght of rear springs that are needed to raise the same 2" and delete the blocks.
I'm in Peru (south America) and finding an after market raising kit for the XJ is not possible and importing one would be out of my budget but I sure can get a local manufacturer to prepare or adapt a set with the specs , if I can get them.
I do have been feeling the rear axle warp specially under heavy braking situations, so that and this thread has made me change my mind about the blocks.
SACEM

You can find leaf's out of the leaf pack of a chevy s10, if those are in your junk yards, and make your own set. use the 'search' tab above and you can find a write up on it.

[scottsxj]

You can find leaf's out of the leaf pack of a chevy s10, if those are in your junk yards, and make your own set. use the 'search' tab above and you can find a write up on it.

or really any leaf that is the same width as your xj leaf, which is 2.5 inches, iirc.

[2xtreme]

My talk with RE about my failed RE leafs (they were 4 months old!) three weeks ago lead me to understand every batch comes from a random different manufacturer, and that its a constant fight to make sure everyoen gets two leaf packs that are the same.

With that knowledge in my head, i'd have to say .. neither do you?


I do not have a clue who makes either of their spring packs.
As you said, it would not surprise me if it changes regularly.

The coment I was responding to made it clear that it is ok to put blocks under RE's and Nationals spring packs and not Rusty's due to the quality difference of the spring pack. The quality of the spring pack has nothing to do with useing lift blocks. The stiffness, arch, number of leaves, and ability to withstand axle wrap do.

[cal]

The coment I was responding to made it clear that it is ok to put blocks under RE's and Nationals spring packs and not Rusty's due to the quality difference of the spring pack. The quality of the spring pack has nothing to do with useing lift blocks. The stiffness, arch, number of leaves, and ability to withstand axle wrap do.


That was not how it read - but if thats how it was meant, I extend an apology for flaming you. :)

-Cal

[Bender]

If the torque a leaf spring must resist to prevent axle wrap is simply a calculation of the moment about the leaf spring and spring perch connection then you can estimate the added torque applied to the leaf spring fairly easily.

Assuming the spring perch to leaf spring mounting surface is approx 4" above the axle centreline.....

% increase = Spacer thickness / (Loaded tire radius in inches + 4")

So putting a 1.5" spacer on a setup with 32" tires having a 15" loaded diameter will increase the axle wrap by 8%. Doesn't seem like much really.

Considering swapping from 3.55 gears to 4.56 gears will increase axle wrap by 29%. To get that sort of increase from lift blocks they'd have to be about 5.5" tall!!! :D

Like most things I'd say moderation is the key.

[rockwerks]

If the torque a leaf spring must resist to prevent axle wrap is simply a calculation of the moment about the leaf spring and spring perch connection then you can estimate the added torque applied to the leaf spring fairly easily.

Assuming the spring perch to leaf spring mounting surface is approx 4" above the axle centreline.....

% increase = Spacer thickness / (Loaded tire radius in inches + 4")

So putting a 1.5" spacer on a setup with 32" tires having a 15" loaded diameter will increase the axle wrap by 8%. Doesn't seem like much really.

Considering swapping from 3.55 gears to 4.56 gears will increase axle wrap by 29%. To get that sort of increase from lift blocks they'd have to be about 5.5" tall!!! :D

Like most things I'd say moderation is the key.

well said

[sacem]

Sorry to disagree with you Bender but the torque that the leaf spring has to absorve (torque = force x lenght of arm or radius of gyration) has it pivot point at the center of the axle not at the floor.

So: if the axle tube is lets say 4" and it has a 1/4" thick support plate then the radius of gyration or torque arm will be:
r = 1/2 diameter + plate thickness = [1/2 x (4")] + 1/4" = 2 1/4"

If we assume that the force applied to the axle is 1000 lbs thrust

The torque that the leaf spring will be resisting is:
t = force x r = 1000 x 2 1/4 = 2250 lbs-in

If we put a 2" block the new radius of gyration would be:
r1 = 1/2 diameter + plate thickness + block height = 1/2 x 4" + 1/4" + 2"
r1 = 4 1/4"

Then the torque WITH A RAISED BLOCK (2") will be:
t1 = force x r1 = 1000 x 4 1/4 = 4450 lbs-in

thats almost double the initially applied torque.

Sorry for all the numbers but that's how we can figure it out.

SACEM

[red91]

TYLENOL...please.

[Bent]

On The Other Hand,
there are those who run an inch block in the rear as a method of producing a closer spring rate to that of a 1" taller coil up front.
Keep in mind that longer shackles can have their own set of issues too. It's always a trade off, one way or another; whatever it is that gets changed.

[sacem]

To RED91inWA:
I was just trying to be relevant
SACEM

[Red97XJ]

I am not a math wiz. But that is only like 371ish pounds trq. ? right?

If using the 1000lbs starting off with that is an extra 37% right?

How much does gears add? what about the diff between 31" tires and 35" tires? I honetly have no idea, I am asking so I can compare!


Thanks,
Jason

[OT]

Mmmm.
Strong the tech in this thread is.

http://www.formfunctionemotion.net/mt-static/images/yoda.jpg

[Bender]

Sacem,

I still think I am correct.

The axle produces torque about it's axial centreline which for these purposes we can consider constant. This torque creates a force between the pavement and the tire which propels the vehicle in the desired direction. This is the thrust that you speak of....it is not acting at the axle but rather down at the pavement. The only thing that restrains the axle is the leaf spring so the torque on the leaf spring is the forward "thrust" down at the pavement multiplied by the moment arm between the spring perch and pavement.

Since for this comparision we can assume the torque output of the axle is constant and the tire diameter is constant the force down at the pavement or "thrust" is also constant. The only thing changing with the addition of lift blocks is the moment arm which increases the leverage of the "thrust" (force down at the pavement) about the spring perch......increasing the axle wrap.

[Bender]

On another note....

A lift block will have no effect on the spring rate. The only thing that can change the effective spring rate is the shackle angle. The more the shackle is angled rearward the less vertical load it takes to compress the leaf spring.

[Bent]

On another note....

A lift block will have no effect on the spring rate.

Correct. That can be the purpose.

[53guy]

Ok after doing some research, I've come to the decision to get 1.5 or 2 inch blocks and then cut the angle I need into them netting about 1 inch of total lift from blocks. Now the questions is, where do i find SOLID blocks in 2 inch type? Anyone know where I can get them?

[fryed_1]

Most of your truck shops should have them. Pepboys had them around here for like $10 or something.

[53guy]

Pep boys in Northern VA? I may be new to northern va, but darned if I can't find any decent truck shops. Any help? Locations?

[cal]

Ok after doing some research, I've come to the decision to get 1.5 or 2 inch blocks and then cut the angle I need into them netting about 1 inch of total lift from blocks. Now the questions is, where do i find SOLID blocks in 2 inch type? Anyone know where I can get them?


Get them already angled, and you can get them online. If you dont cut the -exact- same angle into them, you can cause yourself a lot of problems.

-C

[fryed_1]

Pep boys in Northern VA? I may be new to northern va, but darned if I can't find any decent truck shops. Any help? Locations?
Head south. Get off at the falmouth/warrington exit and go towards falmouth. When you get to the light at rt1, go straight onto butler rd about 5miles. About a mile after the Wawa in stafford, you'll see protrucks. I get my small stuff from there usually, but they're pretty expensive on labor if you need anything done.

[XJ_ranger]

ha ha


i run 1/2" plates that are 7" long on top of my perches...

kind of an anti-wrap spring perch...

no issues yet..

[Dookie]

meh. as long as they're SOLID STEEL BLOCKS (absolutely NOTHING aluminum), they're fine. i've had blocks on my XJ for as long as i've had an XJ. no sag, no noteworthy axle wrap... keep in mind that most XJ's perform differently. yours may have negative effects. but, a block is SO EASY AND CHEAP to do, why not give it a try on yours?

[cal]

meh. as long as they're SOLID STEEL BLOCKS (absolutely NOTHING aluminum), they're fine. i've had blocks on my XJ for as long as i've had an XJ. no sag, no noteworthy axle wrap... keep in mind that most XJ's perform differently. yours may have negative effects. but, a block is SO EASY AND CHEAP to do, why not give it a try on yours?


Yeah. I have a 1962 ford F100 4x4. When they added the four wheel drive front axle, it lifs the front of the truck 3" (the height of the tube), so the truck comes from the factory with a 3" lift block in the rear.. factory. I got the truck in about 1991, and at the time it got no axle wrap at all.. with 33 year old springs. I get a lot of wrap -now-, but I beat the truck pretty hard..

With good springs blocks do seem to be ok.

[cal]

ha ha


i run 1/2" plates that are 7" long on top of my perches...

kind of an anti-wrap spring perch...

no issues yet..


Got a picture of that?

[53guy]

Head south. Get off at the falmouth/warrington exit and go towards falmouth. When you get to the light at rt1, go straight onto butler rd about 5miles. About a mile after the Wawa in stafford, you'll see protrucks. I get my small stuff from there usually, but they're pretty expensive on labor if you need anything done.

awesome! i hear great stuff about a place down south of me, but never seemed to get the name. i'm gonna give them a call and see what they have. Thanks for your help. and also, do you know a good gear shop or a good guy around the area who does gears for low cost? that'd be cool too. thanks