Jesus Gatos wheel center flip

[RANDYDIRT]

Hey Guys, I did the "Jesus Gatos" center flip on the wheels. Here is what I found. After a test drive I found that the handling was terrible. It wandered all over the road. I also found that even a little axial wheel runout causes a steering shake. The added scrub radius is causing the wandering as it loads the tie rod and creates a "toe-out" situation. I jacked in a complete turn of toe-in but can't check how it does because I had a front wheel cylinder blow out during the test run.

I hope I handled the wheel shake by putting the straightest wheels on the front. I won't be able to test this out for a week or so.

I first thought that my front end and steering linkage was worn. There is no slack anywhere. Period.

Just a heads up for anyone doing this, and I will update this with my findings.

Dirt

 

[Jake0147]

Axial runout isn't such a bad thing, but I would imagine it's hard to get that without getting a little radial runout as well. .060 is pretty much where they consider it unable to work satisfactorily with modern tires and suspensions. I think most of the NDT's have more than that built into them, but it gives you an idea of how close this stuff needs to be.
Scrub radius is a big deal in and of it's self. It's probably exaggerated by the enormous caster angle built into these trucks. If there's ANY play in your kingpin bushings, I'd venture to guess the truck would be all but undriveable.
All in all, I'd expect it to be a good modification (if you need a wider stance), but everything wheel, tire, and suspension related will have to be 100 percent exact from start to finish.

 

[jesusgatos]

Sorry to hear that you're having problems with those wheels. What tires are you running? With 11.00's the scrub radius isn't THAT bad. If I remember right, I think G calculated that it should be about 2 3/8"? Nothing I was too concerned about because I'm adding full hydro steering. Haven't put more than a handful of miles on Mah Deuce since mounting the new wheels/tires, but it rode/drove smooth up to about 50mph. How much runout do you have? What about 'hops'? I had to knock the centers out of several shells, rotate them, and then press them back into the shells, in order to get them to run true.

 

[RANDYDIRT]

Here is a pic of the truck with the wheels. Tires are G177 1100r20's. I do feel that increasing the toe will help with the wandering. I checked the runout of the wheels with a pointer they were all within 1/8 of an inch. I checked with the tires mounted and at the tread I had one that was on the front that wobbled 1/4". So I found 2 that were within 1/8" and mounted them on the front. Still can't test drive it yet though.

Dirt

 

[jesusgatos]

Looks sharp! Hope switching those tires around does the trick. 1/4" is a lot. I wasn't able to get many of my rims better than within 1/8" either. Mostly because the rim shells weren't perfectly round/straight. If you're not planning on adding any type of PS, you might notice the extra scrub (I didn't), but I just can't see how that amount of scrub would be causing the problems you are/were having.

 

[RANDYDIRT]

In theory the extra scrub seems to be causing a toe out condition. It wasn't an issue with the original wheels but seems to be now. You being a suspension man will know that toe out causes wandering. I'm thinking that if my toe in was set to neutral or "0" before the wheel mod that the scrub is loading the tie rod etc. thus causing a toe out condition???

Dirt

 

[RANDYDIRT]

BTW Jesse I really like your ideas and am bound and determined to make this one work.

Dirt

 

[jesusgatos]

My toe is set at just a little bit more than 1/8" (43" dia. tires), and I didn't notice any handling problems (wandering, shimmying, etc.), but like I said - I haven't put more than a few miles on the truck since mounting the new wheels/tires. I didn't measure the runout of any of my tires. Didn't balance them either. Just put the newest ones up front.

Where did you install the center-sections? How much backspacing? I don't remember off the top of my head, but I think I set mine at 6"? If I was building full custom wheels, I would have added about another inch, but didn't have that option.

That's the one downside to having the tie-rod behind the axle. Tie-rods are much stronger under tension, but I wouldn't guess that the additional scrub is causing the tie-rod to deflect by any measurable amount.

By the way, thanks for the compliments, but I don't think I was breaking any new ground here. Pretty sure I found out about flipping the center-sections on here, while researching wheel/tire options. Don't know who deserves the credit for coming up with this idea, but it's not me.

 

[RANDYDIRT]

Well, I didn't check the toe before I did the mod, so I don't really know where I am with that.

On the wheels, I had my machinist friend cut the wheels on his HUGE lathe just next to the weld. I didn't have enough riveted wheels to completely follow your exact description, but I feel mine have just about the same offset as yours.

I will get this figured out, it's just another lump in the road.

You said "Tie-rods are much stronger under tension, but I wouldn't guess that the additional scrub is causing the tie-rod to deflect by any measurable amount."

OK, I see where you are coming from... I am saying not so much about the tie rod deflecting, but the cumulative "slack" tied to the unknown toe in that I started with being used against me in this situation.

Dirt

 

[jesusgatos]

The toe-in hasn't changed. That's totally independent of the wheels. I'd be curious to know how much offset/backspacing you ended up with if it's not too much trouble to measure.

The 'slack' having to do with the tie-rod could then only be coming from either of those two ball-joints. Slack in the drag-link TRE's or in the steering box could certainly cause problems too, but that's not what I thought you were talking about.

 

[gimpyrobb]

(In my best Bob and Tom "Donny Baker" voice)

Goddammit Randy, your gonna make me build a bobber!

 

[RANDYDIRT]

Here's another one for ya Gimp

Dirt

 

[MO MV man]

I found my drag link was adjusted improperly causing a horrible wandering problem that was amplified with the installation of my 395 tires.
I took it apart, adjusted it per the maintenance instructions and she's a whole different truck to drive now!

It's not that my ball-and-sockets were worn in the drag link, it was how they were preloaded-WAY TOO LOOSE!

Anyway, it's a thought.
That little fix made a WORLD of improvement in how my bobber drives.
She's a "one hander" most of the time.

 

[Wildchild467]

Wouldnt having the center of the wheels farther out from the kingpins make the bushings wear faster? expecially on a winch truck? anybody have any experience with this? i just grease mine about every 500 miles just because it makes me feel good to know they have plenty or grease.

 

[jesusgatos]

Yes, increasing the scrub radius will put some additional strain on those parts. How much? Meh, I'm not too worried about it.

 

[JOAT 0311]

Randy that is a sharp truck put more pictures up.

 

[RANDYDIRT]

Well to update this thread. I all but removed any wandering I was having by adding one round of Toe to the tie rod. I found that the wheel/tire with the 1/4" runout actually had a flat spot on it. It is now my spare. Drives like a different truck!
Thanks guys for your input on this problem and the compliments on my Bobber. It's been a lot of work so far, but it's coming along fairly well.

Dirt

 

[jesusgatos]

Glad to hear you got that all sorted out!

 

[R Racing]

for some reason the pic's are gone ?