Front end wobble after engine swap

i swapped in the Chevy 153 engine and probably Jeep front end probably lost 100 pounds.The front end is now about an inch higher.This Jeep is lifted about 2-3 inches and previous to the swap the back end was a bit higher than the front.So now it sits level.......And now it has a front end wobble at 40 mph.Before the swap it had no wobble at any speed on any road surface.The front suspension had new king pins bearings with the proper preload and the tie rods and steering box are good.Radial tires with about 1/16 toe in.
As a test I added 100 pounds of barbell weights to the front pumper and this lessened the wobble.................So...you think the change in ride height causes the wobble by messing up the castor and toe in?

 

Do you still have the ross box and 2 piece tie rod ends? if so I would say your toe is out since the loss of weight. In my head the jeep sets higher now and that would pull on your rods causing your toe to be out.

 

Yeah,stock steering

 

Get out your measuring tape, gonna say you will see some deviation in your original steering adjustments

 

Yes,probably.The new U bolts should be here today.Then I'll check the toe.Some have suggested a castor issue,castor is supposed to be 3 degrees positive.I see no easy way to check castor ,like no reference points to stick on an angle finder.One Jeep builder says if the bottom of the differential carrier on a Dana 25 is parallel to the ground,the castor will be about 4-5 degrees positive.Mine is tilted up a few degrees like it was before the swap. I put in 2 degree castor shims,the bottom kingpin is now more forwards than it was,positive castor. And the wobble got far worse.....

 

Well,junky U bolts ain't the only problem.I pilled the front springs today figuring to disassemble them and knock off the rust and dirt.What i found under the grease was this mess.One spring pack has 8 leaves,the other 10 leaves. And only one side had a castor shim.The difference in spring arch is about an inch not counting the extra leaves. The best part the Jeep sat pretty level....And last summer I rebuilt the steering knuckles, cleaned up the tie rod ends and adjusted the toe in and never noticed the springs. I better look closer next time

 

3 degrees is where it should be from the factory, everything I have read up on 6 to 8 degrees work the best, mine is 6. I got my degree shims from mcgruff on here. they bolt to the spring with the center pin. As you can see they are quality pieces. I got my center pins from a local welding shop here in town.


Yeah that could defiantly cause an issue

 

5-7 degrees positive is optimum. Any more and accelerated tire wear in turns and high speed instability is possible.
You can measure caster with an angle finder on the top or bottom steering knuckle bearing caps or bolt heads. Not perfect but gives a good idea where you are at and where to go.


Sent from my iPhone

 

A friend of mine bought a former phone company Jeep. It was all over the road. We pulled the springs off and found a caster shim on one side only. There should be no caster shims from the factory - the proper caster is built-in to the knuckle. We put the springs back with new u-bolts and no shim - problem solved.

I'd remove the two extra leaves and put it back together. Spring center bolts are widely available - supposedly Napa stores have them.

 

The one spring is sacked out,junk.......No shims from the factory?.....Then I'll try that first.. I found the bottom kingpin cap to be reasonable true...A small piece of metal to fit inside the nuts,then stick the angle finder to that.

 

Please re-read timgr's prior posting. He's right. Swapping the engine and reducing /re-allocating weight most likely exposed an existing problem rather than causing one. Don't try to re-design the steering -- the odds are stacked against you.

 

All fixed,drives like a Cadillac I installed the new springs with no castor shims.I didn't check toe in .. The angle finder fits ok by holding it onto the nut faces of the lower king pin cap.The castor is 3 degrees like Timgr says it is .....this Jeep has a slight rake so it's probably closer to 2 degrees if it sat level,close enough.No shimmy at any speed up to 50 mph.

 

Good deal......glad ya found the issue and it's fixed

 

Watch your tire pressure, too. Low tire pressure causes my front-end on my CJ5 to wobble at speeds above 40 mph. Put the pressure to 32 psi in all tires and she tracks like on rails, with no wobble.

 

Would one of you guys show pictures of what you did to correct this?
What was the measuring tool?
How did you use it?
I have uneven wear on my drivers side tire for the last year.