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#2342475 - 07/24/17 01:49 PM Bigger tires up front, more pronounced hunting on the road
FuryBoy Offline
top fuel

Registered: 01/20/03
Posts: 1720
Loc: Eugene, OR
Went from 235/60r15s to 245/60r15s on the front and 245/60r15s to 255/60r15s on the back. Haven't adjusted the torsion bars yet, but I think the front end could be lowered down a little bit now.

The car has hunted a little bit forever, it has a FF stage 2 steering box, FF seemless HD tie rods, FF 1.06 torsion bars, moog problem solver bushings, new ball joints, pitman/idler arms, new LCA bushings, re-inforces LCAs, factory sway bar and poly bushings/endlinks.

The car feels like it has an inch of slop in the steering and will violently hunt back and forth
when it finds a new set of ruts. Is this bump steer? I have had no luck with local alignment/suspension shops. I thought maybe the return on the steering box needed some adjustment but now I am wondering if I just have some severe bump steer due to K frame issues.

I suppose I should adjust the ride height and have the alignment checked again. What should I be aiming for with the problem solver bushings and 15 inch radial tires(won't be going to larger tires for quite some time)

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#2342671 - 07/24/17 06:37 PM Re: Bigger tires up front, more pronounced hunting on the road [Re: FuryBoy]
Frankenduster Online   content
Moparts proctologist

Registered: 02/15/10
Posts: 14696
Loc: Granite Bay CA
The difference in height can't be much. I'd suspect the tires themselves to be the problem rather than the 1/4" increase in diameter.

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#2342687 - 07/24/17 06:53 PM Re: Bigger tires up front, more pronounced hunting on the road [Re: FuryBoy]
GoodysGotaCuda Offline
5.7L Hemi, 6spd

Registered: 11/23/04
Posts: 23913
Loc: Texas
Changing only tire diameter will effectively change your toe measurement up front.

Have you rechecked it? I am not sure how much a ~1/2" will change it, but it's worth validating.

Bump steer can be checked if you pull the torsion bar, put the tire/wheel back on and cycle the suspension. If the tire steers as the suspension cycles, you have an issue there.
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#2342827 - 07/24/17 09:55 PM Re: Bigger tires up front, more pronounced hunting on the road [Re: FuryBoy]
jcc Offline
I Live Here

Registered: 12/21/03
Posts: 16735
Loc: Trumussia
What wheels do you have, or more to my point, did the offset change with change of wheel from OEM? Reason being, I've always suspected a change of wheel offset, would change tire "scrub, and might lead to wandering, this point I mention it because it is seldom discussed, why (?), because it has no merit, or whatever? Just throwing it out there.

"When the vehicle has been modified with offset wheels, larger tires, height adjustments and side to side camber differences, the scrub radius will be changed and the handling and stability of the vehicle will be affected." Wiki


https://en.wikipedia.org/wiki/Scrub_radius


Edited by jcc (07/24/17 10:02 PM)

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#2343015 - 07/25/17 10:43 AM Re: Bigger tires up front, more pronounced hunting on the road [Re: FuryBoy]
FuryBoy Offline
top fuel

Registered: 01/20/03
Posts: 1720
Loc: Eugene, OR
Straightened the steering wheel when I got home last night and snugged some 2x4s next to the tires. I should have snapped some pictures, but it does appear that the tires are toed out a decent amount.

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#2343198 - 07/25/17 04:25 PM Re: Bigger tires up front, more pronounced hunting on the road [Re: FuryBoy]
TC@HP2 Offline
master

Registered: 01/23/03
Posts: 4754
Loc: Pikes Peak Country
Tramlining. Often happens with wider tires. https://www.tirerack.com/tires/tiretech/techpage.jsp?techid=47

Wheel offset effecting scrub can help or hurt tramming. Added caster can help over come it. Toe out will make it worse. Lower tire pressure can help some.

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#2343480 - 07/26/17 12:09 AM Re: Bigger tires up front, more pronounced hunting on the road [Re: FuryBoy]
autoxcuda Offline
Too Many Posts

Registered: 01/20/03
Posts: 25339
Loc: So Cal
You only went up one side wider/taller tires. The car only rose a 1/4" ( radius of 1/2" diameter change). Your caster and camber will not change. The toe change is insignificant

How does this car's steering feel compared to the other vintage Mopars you've owned?


Edited by autoxcuda (07/26/17 12:24 AM)
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#2343518 - 07/26/17 05:22 AM Re: Bigger tires up front, more pronounced hunting on the road [Re: FuryBoy]
HUSTLESTUFF Offline
pro stock

Registered: 01/21/03
Posts: 1325
Loc: NORTHERN CA
Originally Posted By FuryBoy
Straightened the steering wheel when I got home last night and snugged some 2x4s next to the tires. I should have snapped some pictures, but it does appear that the tires are toed out a decent amount.






That could have been the problem the whole time. You can adjust your toe with the tie rods and your 2x4's. Try that and see if it changes anything. Mike
PS do you still have those headers from like 1999 I sent you? LOL
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#2343732 - 07/26/17 01:44 PM Re: Bigger tires up front, more pronounced hunting on the road [Re: HUSTLESTUFF]
FuryBoy Offline
top fuel

Registered: 01/20/03
Posts: 1720
Loc: Eugene, OR
Originally Posted By HUSTLESTUFF
Originally Posted By FuryBoy
Straightened the steering wheel when I got home last night and snugged some 2x4s next to the tires. I should have snapped some pictures, but it does appear that the tires are toed out a decent amount.






That could have been the problem the whole time. You can adjust your toe with the tie rods and your 2x4's. Try that and see if it changes anything. Mike
PS do you still have those headers from like 1999 I sent you? LOL


Holy smokes, yes, I kind of do! Was that off MoparChat or Moparts? I used the headers on the 318 but eventually put hooker super comps I snagged from the swap meet once I swapped to my 360. Installed the old headers on my grandpa's '4 Plymouth that had a diplomat front end in it. They fit surprisingly well. Mopar people are the best people! Was 15 when you sent me those headers!


I'm gonna lower the front end a smidge as it's riding fairly level right now and then re align it.

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#2345492 - 07/29/17 09:39 PM Re: Bigger tires up front, more pronounced hunting on the road [Re: FuryBoy]
ahy Offline
master

Registered: 01/22/07
Posts: 7364
Loc: IN
Incorrect alignment can cause wandering... sounds like its time to have a look. Toe in promotes stability. Also positive caster. About 1/8" toe in and as much positive caster as you can get up to 5 degrees is bound to help.

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#2345501 - 07/29/17 10:05 PM Re: Bigger tires up front, more pronounced hunting on the road [Re: FuryBoy]
krautrock Offline
pro stock

Registered: 01/27/03
Posts: 1415
Loc: central texas
toe out will make it wander, i would fix that and see how it does...

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#2346846 - 08/01/17 05:30 PM Re: Bigger tires up front, more pronounced hunting on the road [Re: FuryBoy]
Mopar Mitch Offline
super stock

Registered: 01/17/10
Posts: 984
Loc: NW Chicago suburban area
For "pylon" autocrossing (where quick l-r-l-r-l-r responses are needed), a little toe-OUT is actually preferred as it helps quicken the maneuvers, but for street/highway/hi-speed track events a little toe-IN is preferred ... for stability at higher speeds.
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#2351247 - 08/09/17 09:51 AM Re: Bigger tires up front, more pronounced hunting on the road [Re: FuryBoy]
70Cuda383 Offline


Registered: 10/07/03
Posts: 21330
Loc: Marysville, O-H-I-O
Toe out will wander as said.

Wider tires will wander too, but your change shouldn't be enough to change that.

I once had a set of 315 wide road race tires on the front of my Dakota. It wandered over every crown in the road, every rut in the asphalt. I did not like it and changed my wheel combo.

Now with 285 wide fronts, it does not wander


Adjust your toe and report back
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#2382812 - 10/06/17 12:01 AM Re: Bigger tires up front, more pronounced hunting on the road [Re: FuryBoy]
Rob C Offline
mopar

Registered: 03/04/05
Posts: 676
Loc: Earth
Wander???? LOL!

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