Help me figure out what is on this XJ I just bought!

[irish44j]

i actually mean that NASTY peice of plastic below the front bumper....
its kinda a pet peive of mine, soooo damn ugly....

btw, i wouldnt touch that thing, i assume you got it dirt cheap.

people on here are very anti-blocks(rear blocks), and for a good reason (it will wrap your leaf springs), however, id rock that till it started to sag, then just get junkyard leafs to replace them (OR if you find yourself driving it more then you thought, you could allways do bastard rear leaf springs.... which is gonna be beyond your interest right now.....

anyway, taking the lift out will probably require you to find some OEM suspension parts.... but the question becomes why are you wanting to remove the lift? because of the rubbing?

no, as I stated I haven't experienced any rubbing to date. I don't necessarily have to remove the lift, only talked about doing it because I had heard that blocks were not good to have and frankly just don't want to invest any money in a "better" suspenion setup (as my other two cars already ate up about $10k of suspension/brake/chassis bracing work already). So if it was cheaper to bring it back to stock height with smaller tires, that would be an option. There is little to no off-roading going on here in the Washington D.C. metro area, I can assure you

Aside from the blocks and the plastic air dam, might i inquire as to why you "wouldn't touch" it for a utility beater? I got it for a decent price I think, and it has a ton of new stuff under the hood (radiator, fans, all belts, water pump, all emissions equipment, front brakes, diff seals, etc) so I figured it to be pretty good for what I was looking for....and it runs well overall with relatively low miles for an older XJ, from what I've found in this area.

And almost no rust. Most of the XJ's i lookd at had rust all over the place....we here on the east coast have to deal with road salt and such. You cali boys wouldn't know about that

 

[lancey3]

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.

 

[irish44j]

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.

ah, rgr that....I wanted to make sure you didn't mean "warp" the springs...

if you were in my position with wanting to do away with these blocks in the back (and doing minimal changes elsewhere), what route would you go? the blocks are 2" thick, so what specifically could I use to replace this and maintain a similar/slightly lower lift in the rear, in your opinion?

I'm still trying to sort through all the tons of jeep aftermarket distributors and brands out there, so any links you can provide to a specific component would be much appreciated - if you care to do so :yelclap:

 

[lancey3]

http://www.jeepinoutfitters.com/scripts/prodView.asp?idproduct=557

 

[Gaius]

Me, I would remove the block, and insert a few S10 leafs to create the 3 inch lift. Search around here for "S-10 bastard packs" and you'll get some good info.

 

[tclapp_88]

you can just get 2 inch lift shackles from rough country for 40 bucks shipped, i think. and then you wont have the 2 inch lift blocks. pm GRIMUS99XJ on here, he works for rough country.

 

[balloo93]

As mentioned, search "bastard pack". That set up is using S10 leaf springs under the stock XJ main and a few XJ leafs.

If I were you I woudl get some S10 leaf springs. Use only the S10 main under the XJ main and then the rest of the XJ leafs under the S10 main.

You will cut the eyelets off the S10 main. I took mine to a leaf spring shop and had then drill out the S10 main and add antifriction pads on them. Then assemble the packs.

Find a 1" boomerang shakle like this one :
http://www.jeepinoutfitters.com/scripts/prodView.asp?idproduct=556

Or a set of MJ shakles. That combo will give you a firm ride and around 2.5-3" of lift. It will flex well and outlast a block setup. It will also outlive a 2" lift shakle on stock leaf springs.

For the front, look for junk yard ZJ (93-98 Grand Cherokee) coils from a V8 equipped one. Those front coils offer about 1" of lift. Throw on a 1 3/4" spacer and you have a firm riding rig with a bit more compression travel up front.

 

[Gojeep]

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.

Actually the leverage that causes the springs to go into a S shape and causing axle tramp is the distance from the ground contact patch to the spring mount. So you are correct in that the blocks increase this distance by most dont take into account that the bigger the tyre the greater the leverige factor as well.
Personally, for what this is going to be used for, just make sure that the bumpstop have been lowered the same as the height as the blocks on the rear as this will stop the spring being over compressed the 2" beyond what they were designed to do. This will kill the springs probably faster than any spring damage from the blocks themselves.
Rubbing up the front most likely only occurs with the swaybar disconnected. For what you are doing I don't see this being a problem as just leave it connected.
Maybe just level out the lift with lower steel blocks. I have even just cut some down to suit a height or angle I was after.
Might what to think about smaller tyres if you want more torque to tow with which looks like a primary roll for you.
The rear pack looks to have an add-a-leaf and where the extra 1" over the block came from.
See my site for ideas on different lifts etc done cheaply. http://www.go.jeep-xj.info/

 

[TRCM]

Actually the leverage that causes the springs to go into a S shape and causing axle tramp is the distance from the ground contact patch to the spring mount. So you are correct in that the blocks increase this distance by most dont take into account that the bigger the tyre the greater the leverige factor as well. http://www.go.jeep-xj.info/

You are correct in saying that the tire size can change leverage, but incorrect in saying that it is the distance of the tire contact patch to the spring is the only cause.

The distance between the center of the axle and the spring mount is what will determine axle wrap initially. The tire size is what will determine how easily it happens once momentum has been established.

You can take a stock axle with a 35" tire and no block, and still have some degree of axle wrap. You want also take a 15" diameter tire (not rim, tire) with 8" of block, and get the same axle wrap problem.

We all know a longer wrench will make breaking a stubborn bolt loose easier, right ?

Everything pivots on the axle centerline. As you make the distance between the axle centerline and the spring greater, it has the same effect as getting a longer wrench to break that bolt loose. As the wrench gets longer, the force on the bolt increases a lot even tho you are putting the same force on the wrench. This is due to leverage.The same thing happens with the axle and the spring, as the distance between them gets bigger, the leverage on the spring increase substantially even with the same force being applied. And at some point, the force will overcome the spring and cause it to bend.

Think of the axle/spring/tire as a see-saw. If the distance from the axle centerline to the ground is lets say, 20", and the spring to axle centerline is lets say, 1", then you have a ratio of 20-1. When the tire tries to walk forward, if it moves 20", the spring will only move 1" backwards due to the ratio (numbers are an exaggeration). BUT, if the spring to axle distance is 5", the tire will only have to move 4" to get the spring to move 1, because the ratio is no longer 20-1, but is now 4-1.

The FORCE required to make this happen with a large tire is much less than with a small tire because of it making the ratio larger faster. Just like the longer wrench puts more force on the bolt with the same INPUT from you, the greater distance between the axle centerline and the spring will put greater force on the spring to wrap with the same INPUT force.

In the above see-saw scenario, if there is 100 ft lbs of force at the axle, then there will be 5 ft lbs of force on the spring and 100 ft lbs on the tire (remember, there is a 20-1 ratio centred on the axle). But if the same force is at the axle with the spring 5" away, the spring will have 25 ft lbs of force on it, which will make it easier to move, in fact, 5 times as easy.

Now, as Gojeep said above, the reaction forces from the ground will also have an effect. As the tire size goes up, the 5 ft lbs from the axle will be diminished at the tire. So, if the axle has a force of 5 ft lbs, and the ground is 20" away, then the force there will be 1/20th at the ground as at the axle. Yes, a shorter tire will give you more torque at the ground. A bigger tire will have more speed for the same torque input, but will provide less motive force (which is why a vehicle takes off slower with a big tire (sassuming no tire spin). A big tire is heavier, and therefore takes more force to get it moving, and while this is trying to happen, the forces from the axle will act on the spring, which tends to wrap the spring up. Since the tire isn't moving, ALL the force from the axle will go to the spring (or break the axle shaft).

Imagine the see-saw example, if you hold the long end down to simulate trying to get the big tire moving, and you rapidly keep piling on weight at the short end to simulate the axle continuing to try and turn, you could conceivably bend/break the seesaw before the long end moves. Once the long end does move, the forces will settle out according to the ratio of the long-short ends

Where the big tire gets it's real power in wrapping springs up is once it is spinning, it has a lot more momentum to provide force to act on the springs. If the big tire is spinning, and suddenly finds traction, it will wrap the spring up in a heartbeat because of the momentum it has developed.

A small tire will give you more torque for the same input, but a large tire will give you more speed.

These axle wrapping characteristics are slightly different when the axle is above the spring, but will still happen.

Again, as Gojeep eluded to, the distance from the ground to the spring does have an effect, but a more important effect is the ratio of ground to axle vs axle to spring. Mainly, axle wrap when starting, is from the ground to axle vs axle to spring ratio, but once moving, the ground to spring distance will become more important since the momentum and speed of the tire now becomes a big factor.

 

[irish44j]

For the front, look for junk yard ZJ (93-98 Grand Cherokee) coils from a V8 equipped one. Those front coils offer about 1" of lift. Throw on a 1 3/4" spacer and you have a firm riding rig with a bit more compression travel up front.

Thanks for the info. I was planning on hitting a junkyard next weekend so I'll look out for the springs from the ZJ.

Personally, for what this is going to be used for, just make sure that the bumpstop have been lowered the same as the height as the blocks on the rear as this will stop the spring being over compressed the 2" beyond what they were designed to do. This will kill the springs probably faster than any spring damage from the blocks themselves.
Rubbing up the front most likely only occurs with the swaybar disconnected. For what you are doing I don't see this being a problem as just leave it connected.
Maybe just level out the lift with lower steel blocks. I have even just cut some down to suit a height or angle I was after.
Might what to think about smaller tyres if you want more torque to tow with which looks like a primary roll for you.
The rear pack looks to have an add-a-leaf and where the extra 1" over the block came from.
See my site for ideas on different lifts etc done cheaply. http://www.go.jeep-xj.info/

thank you sir!

you guys have been very helpful, much appreciated!

 

[Ray H]

If you're not going to off road it, I would just remove the front spacers, remove the rear block and get some 30s on stock wheels. Sell the blocks, spacers and wheels/tires and disconnects and you will probably come out ahead on money in the long run and you will have a better DD to show for it. I doubt the PO regeared it when he/she lifted it and put the big meats on. It'll run and ride better with 30s on it than it does with the 32s.
PS: while you're at the junkyard, look for some rear bumpstops, yours are missing.

 

[Mudfrog]

I know i'm not hardcore as some of you out there but i have to weigh in about the blocks.

I agree that axle wrap is definitely more apt to occur when using blocks but i've had them on my 94 XJ running 31x1050s for well over 10 years and have never experienced any problems. The blocks are 2" in height and i'm using them in conjunction with Rusty's 3" spring pack so i guess that could possibly make some difference. The Jeep has been through alot, including doing a fair bit of heavy trailer pulling. It's still my favorite daily driver and to this day i haven't noticed any sagging on either the front or the rear.

In otherwords,,, i wouldn't worry about the blocks any. However, i would think about going smaller on the tires!

 

[Gojeep]

You are correct in saying that the tire size can change leverage, but incorrect in saying that it is the distance of the tire contact patch to the spring is the only cause.

The distance between the center of the axle and the spring mount is what will determine axle wrap initially. The tire size is what will determine how easily it happens once momentum has been established.

You can take a stock axle with a 35" tire and no block, and still have some degree of axle wrap. You want also take a 15" diameter tire (not rim, tire) with 8" of block, and get the same axle wrap problem.

We all know a longer wrench will make breaking a stubborn bolt loose easier, right ?

Everything pivots on the axle centerline. As you make the distance between the axle centerline and the spring greater, it has the same effect as getting a longer wrench to break that bolt loose. As the wrench gets longer, the force on the bolt increases a lot even tho you are putting the same force on the wrench. This is due to leverage.The same thing happens with the axle and the spring, as the distance between them gets bigger, the leverage on the spring increase substantially even with the same force being applied. And at some point, the force will overcome the spring and cause it to bend.

Think of the axle/spring/tire as a see-saw. If the distance from the axle centerline to the ground is lets say, 20", and the spring to axle centerline is lets say, 1", then you have a ratio of 20-1. When the tire tries to walk forward, if it moves 20", the spring will only move 1" backwards due to the ratio (numbers are an exaggeration). BUT, if the spring to axle distance is 5", the tire will only have to move 4" to get the spring to move 1, because the ratio is no longer 20-1, but is now 4-1.

The FORCE required to make this happen with a large tire is much less than with a small tire because of it making the ratio larger faster. Just like the longer wrench puts more force on the bolt with the same INPUT from you, the greater distance between the axle centerline and the spring will put greater force on the spring to wrap with the same INPUT force.

In the above see-saw scenario, if there is 100 ft lbs of force at the axle, then there will be 5 ft lbs of force on the spring and 100 ft lbs on the tire (remember, there is a 20-1 ratio centred on the axle). But if the same force is at the axle with the spring 5" away, the spring will have 25 ft lbs of force on it, which will make it easier to move, in fact, 5 times as easy.

Now, as Gojeep said above, the reaction forces from the ground will also have an effect. As the tire size goes up, the 5 ft lbs from the axle will be diminished at the tire. So, if the axle has a force of 5 ft lbs, and the ground is 20" away, then the force there will be 1/20th at the ground as at the axle. Yes, a shorter tire will give you more torque at the ground. A bigger tire will have more speed for the same torque input, but will provide less motive force (which is why a vehicle takes off slower with a big tire (sassuming no tire spin). A big tire is heavier, and therefore takes more force to get it moving, and while this is trying to happen, the forces from the axle will act on the spring, which tends to wrap the spring up. Since the tire isn't moving, ALL the force from the axle will go to the spring (or break the axle shaft).

Imagine the see-saw example, if you hold the long end down to simulate trying to get the big tire moving, and you rapidly keep piling on weight at the short end to simulate the axle continuing to try and turn, you could conceivably bend/break the seesaw before the long end moves. Once the long end does move, the forces will settle out according to the ratio of the long-short ends

Where the big tire gets it's real power in wrapping springs up is once it is spinning, it has a lot more momentum to provide force to act on the springs. If the big tire is spinning, and suddenly finds traction, it will wrap the spring up in a heartbeat because of the momentum it has developed.

A small tire will give you more torque for the same input, but a large tire will give you more speed.

These axle wrapping characteristics are slightly different when the axle is above the spring, but will still happen.

Again, as Gojeep eluded to, the distance from the ground to the spring does have an effect, but a more important effect is the ratio of ground to axle vs axle to spring. Mainly, axle wrap when starting, is from the ground to axle vs axle to spring ratio, but once moving, the ground to spring distance will become more important since the momentum and speed of the tire now becomes a big factor.

Thankyou for going to the trouble of explaining this out. I found the way you explained it better than the way it was shown on a web site on the subject. Was good to see just how much more tyre height you need to get the same effect as a block of X height. Most still dont realize that tyre height does still have an influence on the leverage that causes the spring warpage.
Spring over axle is far more prone to it than under as well. You will find that spring over axle have their centre pin further forward as well. This is so they can still get the better ride from a longer springs without increasing the ease by which the front part of the spring can bend under acceleration force. Those that turn their springs around to extend their wheels base wonder why, without any other changes, they have axle wrap where they didn't before. You will also find less stagger in the springs towards the front as well to help reduce the wind up. The rear is staggered more to increase ride comfort and is not as effected by the forces as much.

 

[ChuckstrPT]

My other project is going to be taking the bulk of my time and car money

Now yer talking.....I miss my TR8 Coupe....and ya know I was think, not to long ago...how kewl it would be to build a GT6.....got any specs? You restoring? or gonna have some fun with it???

:cheers:

 

[irish44j]

Now yer talking.....I miss my TR8 Coupe....and ya know I was think, not to long ago...how kewl it would be to build a GT6.....got any specs? You restoring? or gonna have some fun with it???

:cheers:

combination....some restore, but going to "improve" alot of things about it to make it track-ready and a miata-killer for autocross, lol.

actually, the GT6 restoration is one of the main reasons I bought the XJ in the first place - needed something to haul parts to the sandblasters, haul doors and body panels to be painted, and to tow the thing eventually to the paint shop.

Here's some more info that I posted on another forum in case you're interested:
http://grassrootsmotorsports.com/board/viewtopic.php?id=29622

my other project, more or less complete, is my DD 2000 Maxima, with all kinds of goodies

but I digress.....