Changing caster angle solved problems with G-177 tires

[Aswayze]

I got to thinking about this a bit out there and looked at how everything sat with a 1/8th inch shim stuck under the back of the wedge. By my measurment, that knocks about 4 degrees out of it which would then give me about 4 degrees of caster.

I was about to go post this idea up and discuss it but quickly determined that this is one of those things that's probably faster to do than it is to talk about so I just hopped to it and shimmed both sides right quick.

It's currently a little after 5 and living in the middle of the city like I do I am not eager to test drive in the middle of rush hour so I'll probably take it for a whirl a little later on tonight and see what all that does for us.

Good news is, this is actually a pretty simple process if you've got the tools for it. If I need to do it again, I'll wager I can be in and out of there in less than an hour so if I need to fiddle with it further it's no big deal.

 

[gimpyrobb]

Yes, from the other thread I linked to, it is stated that you should take 5/16ths off the high side.


Mill away!

 

[gimpyrobb]

Figures, I took too long to read what everyone posted!

 

[deathrowdave]

Flip the shims you will be pleased with the results !!!

 

[Aswayze]

Actually the shim trick worked like a charm. 1/4 inch under the low side to split the difference and we're off to the races. Steering wheel returns to center just like before, steering effort is about the same as it was with the old NDCC tires and it tracks good at highway speeds.

Whew...

Now to start flipping some rear hubs...

 

[Flyingvan911]

Glad you got her fixed.

 

[pctrans]

Drop your air pressure to 45, and make sure all your fittings are well greased, front AND rear. Adjust toe-in to spec. Because of the "side-play" in the rears, you will notice more "wandering" on singles, due to having less footprint on the pavement. Mine has duals on the rear, and drives like a dream.

 

[sandcobra164]

Mine's on Firestone T831's with duals on the rear. It ran fine on the old NDC's 9's, I'm going to flip the shims this weekend after reading this and will post my results. Currently, it feels very jumpy when it hits a bump or a depression in the road. I'd like to get back to a more solid feel. I'm running 90 psi in the fronts and 70 psi in the rears. The taller sidewall's seem to take more air pressure to straighten out. I tried on the front's adjusting the air pressure but my best results are at 90.

 

[dburd72]

I swaped to 10 G177's truck was scary to drive at first played with air pressure no real change as the tires warm up it does drive better. When the weathers warms up I will flip the shims.

 

[timntrucks]

my duece is running ndts duals in the rear 1100s and it drives fine. i did not flip the shims either. i have a set of 11 to install on my 818 of those nice looking 177s goodyears. i hope they run good on the 5ton.

 

[MWMULES]

Aswayze glad it worked and if you are hub flipin' this weekend let me know where and when. I was going to put the new shoes on the XM818 this weekend but the guys farm it is on left for the "show of shows" in Louie ville yesterday and didn't leave me the keys to the gate. If you are doing it out at davesgmc I can bring the xl's and finish my duce.

 

[Aswayze]

I was planning on at least starting on them here in my driveway today and tomorrow and probably finishing off at Dave's over the weekend.

BTW, did I ever mention how much I hate people who over torque lug nuts?

 

[Flyingvan911]

Wow.

 

[MikeON]

I put on 10 11R20 G177s and had the same experience - the steering is very touchy and requires constant steering correction. Handled great with the old NDCCs. I tried higher and lower air pressure, to no avail.
I reversed the shims, took it for a half mile drive, and immediately put the shims back to original orientation. Due to rotation of the top of the axle rearward, steering to the right is very limited without a longer pitman arm. It also rotated my Air-O-Matic cylinder down to where it looked vulnerable. It also felt like it was putting a lot of strain on steering components. It did, however, take care of the squirrely steering problem.
My shims have a 4.5 degree angle, so reversing them changed the caster by 9 degrees, which is probably way too much.
I read on monster truck forums that 2-3 degrees makes a big difference, so I am planning to make a pair of 1.5 degree shims (3 degrees different from the original).

 

[ICAT]

I just bought a pair of 3 1/2deg shims from oreillys for $20.00 they need slight modification but it should set the caster at 4deg total.

 

[jesusgatos]

I just bought a pair of 3 1/2deg shims from oreillys for $20.00 they need slight modification but it should set the caster at 4deg total.

Are they steel or aluminum? Would not use aluminum shims if I were you. They tend to crack and fall out, which is not so awesome...

 

[ICAT]

yes their are aluminum but they are for semi trucks. If they crack or fail, i would think they wouldn't use them on heavy trucks though i could be wrong

 

[michigandon]

More crazy caster, thanks to G177s

Just got ten of 'em put on today. The steering in this truck was nice and tight with the 9.00x20 NDTs. Now it feels like it is all worn out and sloppy. The wheel turns back to center in a very slow and lazy fashion, that is IF you can even get it to do it at all (It used to spin back with a wrist-shattering velocity).

Going to go shopping for some shims tomorrow morning. Been up almost 24 hrs now and need to get some rest.


Sure am grateful to the OP for this thread!

 

[jesusgatos]

Just got ten of 'em put on today. The steering in this truck was nice and tight with the 9.00x20 NDTs. Now it feels like it is all worn out and sloppy. The wheel turns back to center in a very slow and lazy fashion, that is IF you can even get it to do it at all (It used to spin back with a wrist-shattering velocity).

Going to go shopping for some shims tomorrow morning. Been up almost 24 hrs now and need to get some rest.


Sure am grateful to the OP for this thread!

Just flip the stock spring perches around like this.

 

[Aswayze]

I wouldn't do that. WAY too much caster angle then. You're going from one extreme to another.

Just pull it apart and stuff some shims in it like I did. Mine drives quite well now.