AEV JK suspension testing photo from today!

[Root Moose]

Which all means that the on road performance is not going to leave you stuck on the trail because it won't articulate.

Agree 100%

Comparing these systems my final judgement would be based on the on-road handling. That is something that I am really sensitive to. I have no interest in being a "ramp king". I'm building my XJ to go places, not to "be someone" so I understand your point.

That said, I always want it all.

It hasn't been discussed yet... The lifted short arm TJs kind of had a reputation for jacking the suspension when turning and applying power. A wheel would lift.

Is this much of an issue with the JK? I have yet to hear anyone mention it but then I don't follow the JK stuff as closely as some of the other Jeep stuff. My gut says the longer arms would reduce the amount of lift and if the arms are at less severe angles that would reduce it even more.

 

[Cole]

.....ya'll are making some VERY extreme generalizations about the Geometry of both of these models of suspensions that I don't think can be boiled down to simple ratios and SOHCAHTOA principles with right angle triangles. There is quite a bit more to them. .

I was about to come on here and point out that we are making too big a point of the control arm angle all by itself. There is so much more that is different between the TJ and JK suspension that focusing on a single variable makes little sense. The control arms are mounted in different spots, springs in different spots (frame is wider, spring pearches narrower, springs shorter, etc etc). In the reality they are different supensions and can't be compared based on a single angle.

Agree 100%

Comparing these systems my final judgement would be based on the on-road handling.

It hasn't been discussed yet... The lifted short arm TJs kind of had a reputation for jacking the suspension when turning and applying power. A wheel would lift.

.

I used to love lifting my wheel in the TJ:bike_rider: The JK shows no sign of this trait.

That being said. Jim did get a tire to lift on the slalom. He was pushing it REALLY hard, off line (as you can see by the picture), His Jeep was a 5.7L Hemi 6 speed. What you should really note is look how distorted the passenger front tire is:Wow1: That should give you an idea how hard it was being pushed. To push it that hard and only get a few inches of lift is pretty good.

 

[Root Moose]

What kind of tire pressures was he running? Given the type of tire that's not that terrible.

For racing on street tires in auto-x we typically run anywhere from 5-15 psi more than recommended to get the tires to not roll over too much. Just curious if anything like that was done during this testing. I've started running the same types of pressures on my Jeep (~40 psi, XJ) for less sidewall flex and to help the MPGs a bit. The suspension works well enough that the ride does not seem to be that affected.

This kind of thing is exactly why I'm a fan of 16-17" tires on a 4x4. A ~33"+ tire on a 15" wheel has a LOT of sidewall. Depends on what you are trying to accomplish of course.

 

[Hilldweller]

One of these things is not like the others...

I would've loved to hear those K-MTR's howling in the slalom. Neat.

Can I have your Krawler kit now, Cole?

I think I ran 38 psi in the Mini tires that day; about 80 degrees ambient temp and the tires were running about 170 degrees and not getting greasy. Fun stuff those track days.

 

[Cole]

Not sure what Jim had his pressures at. It should be noted that he towed a Brute to the track, unhooked it and then did the slalom.

I had about 25psi in the Toyos on my Jeep that day. We started out higher on mine and it just slid way too much, had to drop the pressure to get some grip.


Here is a shot of the side of my Toyos after some play time.

(and FWIW to you auto-X guys. My Auto-X car is a Porsche 951, which is what is in the blury backgound, not mine, but an identical one)

 

[Root Moose]

Here is a shot of the side of my Toyos after some play time.

Feather, feather.

Which Toyos are those? I'm thinking about buying some "street tires" now that I'm on the Toyo Racing program (got my R888s for the S2K at ~40% off!). IIRC their truck tires are eligible too.

 

[Cole]

Toyo mt

 

[Hilldweller]

Which Toyos are those? I'm thinking about buying some "street tires" now that I'm on the Toyo Racing program (got my R888s for the S2K at ~40% off!). IIRC their truck tires are eligible too.

Ooooo. I'd like a set of R1R's in a 205/50-16 ---- really cheap, please....

 

[Cole]

TJ LCA length is 18.75" vs 22.5" for the JK, so 20% longer. .

I hate to bring it up again because of all the other reasons posted above.

I just happen to talk to a Jeep engineer buddy of mine today over email and this topic came up. Here is the quote from him on the factual matter of the subject.

The TJ arms are only ~16" long, and JK is 22.619" (from my CAD model from Jeep!), so the % is: +41.4%

Not that it matters at this point. But you know how those engineers can get about numbers

 

[Root Moose]

Ooooo. I'd like a set of R1R's in a 205/50-16 ---- really cheap, please....

Sign up with Toyo's racing program. You'll need to prove membership with a car club but if you are auto-x'ing that's probably not a problem. Then find a local vendor that works with the program.

 

[winkosmosis]

I hate to bring it up again because of all the other reasons posted above.

I just happen to talk to a Jeep engineer buddy of mine today over email and this topic came up. Here is the quote from him on the factual matter of the subject.



Not that it matters at this point. But you know how those engineers can get about numbers

My bad. It does matter, because it means you can lift 40% more and have the same LCA angle! Holy crap! I was right that they're the same as XJ arms, but the site that I got the 18.75" number from was wrong.

 

[Hilldweller]

Sign up with Toyo's racing program. You'll need to prove membership with a car club but if you are auto-x'ing that's probably not a problem. Then find a local vendor that works with the program.

I had to stop racing after the heart attack; I keep hoping to get back...
That's why I bought a Jeep; something fun to do that's slow.

 

[Cole]

I had to stop racing after the heart attack; I keep hoping to get back...
That's why I bought a Jeep; something fun to do that's slow.

You may not ever want to wheel with us then. We go slow, but I'm not sure it would be good on your heart. :coffeedrink:

 

[Hilldweller]

You may not ever want to wheel with us then. We go slow, but I'm not sure it would be good on your heart. :coffeedrink:

I only had palpitations once while wheeling; bad spot at Tellico.

You can keep Black Bear Rd and that stuff though; I get all sweaty when there's a drop and no trees around. It just looks bizarre to me.
Here in the east, the drops are just as nasty but at least there are trees around to make it look gentler...

 

[Cole]

Couple of quick pics from wheeling the TJ. Replaced this rig with the JK, just have not had the time to put much wheeling on it yet.

But this should give you a little idea.

.....oh and I tested those on the street too!