Wheel to Wheel width... what do you think? - Off-Road Forums & Discussion Groups
Jeep-Short Wheelbase All discussion of short wheelbase Jeeps: CJ, TJ, YJ and JK

 
LinkBack Thread Tools Display Modes
post #1 of (permalink) Old 12-11-2002, 11:59 AM
thejunker
Guest
 
Posts: n/a
Wheel to Wheel width... what do you think?

I am getting ready to order some new tires and wheels for my CJ. I will be using 37x12.5 MTR's on 17x8 Allied Beadlocks. I can get any backspacing I want for the wheels, so I drew up some pics of the new axles with different backspacing wheels on them. The wheels I used in the drawing are at their standard backspacing option, just used that for reference.

The axles I am going to be using are from a waggy, the drawing shows the rear HD AMC20.

I do not want the tires sticking out a whole lot, but I also do not want to be super tippy. What do you think the ideal width would be for this?

The CJ has 4.5" suspension lift, SUA, and 1"body lift. There will be lots of fender trimming, and the front axle will be pushed forward about 4", the back one will move back about 4" for about a 101" wheelbase.

Thoughts, opinions, etc, on what width will be best for stability without having the wheels stick out too far (I know that is subjective, so tell me what you think).

Sponsored Links
Advertisement
 
post #2 of (permalink) Old 12-11-2002, 02:17 PM
Way Outta Control
 
Join Date: Sep 1999
Location: The Palouse
Posts: 13,432
Thanks: 1
Thanked 3 Times in 3 Posts
 
Re: Wheel to Wheel width... what do you think?

There are lots of things to consider...
1. How wide's the trail you usually run on.
2. Will you be widening fenders or putting on wider flares.
3. Which do you like the looks of better? (IMHO ... Wide).
4. How much stability do you want.
5. A wide wheel, with less backspacing puts extra stress on the bearings and seals, etc, etc..
6. This is because the center of the tire is farther away from the hub.
7. A wide wheel with less backspacing can also cause more rubbing on the control arms and a reduced turning radius.
8. I think I'd favor the Middle option, the Allied Beadlock Baha.
9. Think Stress = Broken/Breaking parts. [img]images/graemlins/mad.gif[/img]
LEVE is offline  
post #3 of (permalink) Old 12-11-2002, 03:45 PM
thejunker
Guest
 
Posts: n/a
Re: Wheel to Wheel width... what do you think?

Thanks for the thoughts Leve!

</font><blockquote><font class="small">In reply to:</font><hr />
1. How wide's the trail you usually run on.

[/ QUOTE ]

Usually run my XJ on the same trails, and never had a width problem. The CJ will be going to essentially the same width, give or take a few inches.

</font><blockquote><font class="small">In reply to:</font><hr />
2. Will you be widening fenders or putting on wider flares.

[/ QUOTE ]

No to both. I know this will throw mud at me from the back, but I really do not like the look of the big flares, plus, I am choping the back, kinda like jeff has his.

</font><blockquote><font class="small">In reply to:</font><hr />
3. Which do you like the looks of better? (IMHO ... Wide).

[/ QUOTE ]

I like the wide look, but I hate the look of the rigs with the entire tire sticking out from under the jeep.

</font><blockquote><font class="small">In reply to:</font><hr />
4. How much stability do you want.

[/ QUOTE ]

Enough not to have to change my pants [img]images/graemlins/wink.gif[/img]

</font><blockquote><font class="small">In reply to:</font><hr />
5. A wide wheel, with less backspacing puts extra stress on the bearings and seals, etc, etc..
6. This is because the center of the tire is farther away from the hub.
7. A wide wheel with less backspacing can also cause more rubbing on the control arms and a reduced turning radius.

[/ QUOTE ]

This is why I am leaning toward a wheel that is close to centered, ie, one with 4 - 4.5 backspacing.

</font><blockquote><font class="small">In reply to:</font><hr />
8. I think I'd favor the Middle option, the Allied Beadlock Baha.

[/ QUOTE ]

Me to, so what does everyone else think? Anyone run widths near these with 35-38"tires? Would you do anything different?
Sponsored Links
Advertisement
 
post #4 of (permalink) Old 12-14-2002, 09:41 AM
Can't Get Enough
 
Join Date: Sep 1999
Location: Cotopaxi, Colorado
Posts: 1,036
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: Wheel to Wheel width... what do you think?

I think yoiur main concern should be "scrub radius". Scrub radius is the root cause of the famous "death wobble". Here is a link that explains it. Scroll down to scrub radius and read it. This article is good, but could be better with a diagram showing scrub. It also dosn't cover death wobble and the implications of having improper load on the wheel bearings. The load is carried in a straight line through both ball joints.

http://aligncraft.com/terms/terms.html#FrontCaster
dorfs is offline  
post #5 of (permalink) Old 12-14-2002, 04:13 PM
Enthusiast
 
Join Date: May 2002
Location: College Station , TX
Posts: 338
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: Wheel to Wheel width... what do you think?

So now that I know what scrub radius is. How much of it should there be? That article says that you need some, and it doesn't matter is it is + or -, but says nothing about how much it should be.
ryankopecki is offline  
post #6 of (permalink) Old 12-14-2002, 05:37 PM
Can't Get Enough
 
Join Date: Sep 1999
Location: Cotopaxi, Colorado
Posts: 1,036
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: Wheel to Wheel width... what do you think?

??? I was tought that anything over 1 inch could lead to trouble. Ideally, I think you want the S.A.I. line to be 1 inch below the center of the tire. Most high speed sports cars like Porsche's use neg. scrub. I don't think that applies to a Jeep. I personally have never felt squirm, and again that mostly applies to high speed. I would shoot for 0, and if anything funny happens, use wheel spacers.

I see posts on the por board all the time about death wobble. Those guys use 10 inch wide wheels with 3 inch backspacing to clear those big dana 60 calipers. That is why I am going with 17 in. wheels. I am looking at a set of 8.5 inch wheels that have 4.5 inches of backspacing. When I get it up and running I will let you know.
dorfs is offline  
post #7 of (permalink) Old 12-14-2002, 07:04 PM
Enthusiast
 
Join Date: May 2002
Location: College Station , TX
Posts: 338
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: Wheel to Wheel width... what do you think?

To make sure I've got this right, scrub radius is the horizontal distance from the ball joint (or king pin) centerline to the center of the tire?

Maybe the death wobble and squirm are not related. All the death wobble problems I've heard of were with wide tires and rims too.

But for shooting for zero, the article says this:

"Squirm
Squirm occurs when the scrub radius is at zero. When the pivot point is in the exact center of the tire footprint, this causes scrubbing action in opposite directions when the wheels are turned. Tire wear and some instability in corners is the result."

It says some cars use -, and some use +, so I guess that doesn't matter. I'm sure there is some "ideal" amount. Anybody know it?
ryankopecki is offline  
post #8 of (permalink) Old 12-14-2002, 07:52 PM
Can't Get Enough
 
Join Date: Sep 1999
Location: Cotopaxi, Colorado
Posts: 1,036
Thanks: 0
Thanked 0 Times in 0 Posts
 
Re: Wheel to Wheel width... what do you think?

I know. If I shoot for 0, I probably won't hit it. And if I do, I can change it by installing beadlocks and widing the wheel or using spacers.

The whole point of the post was to let people aware that wheel off-set shouldn't be used to determine the width of the axle as much as setting the proper scrub. An overlooked design angle that is criticle to proper handeling and load stress on the bearings.
dorfs is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Off-Road Forums & Discussion Groups forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome