Hello! I've been reading many old posts about caster, but wasn't able to get any definitive information on a few things: How much caster on average with the strut rods give you without binding? How much caster will a single 1/8" shim on the front of the upper control arm give you? How much caster will moving the control arm shaft forward (arm backwards) give you? I was planning to do the shim and shaft modifications to get more caster, but I don't want to do more than I need to. Currently I have close to 0* caster...and as most of you know it sucks with radials.
I have 2 dergees caster on my manual steering...its awsome very directionally stable. I hear 3 degrees on power steering cars .. more caster is harder for turning the wheel at parking speeds.
Im pretty sure thats how its done; I had a experienced shop make mine to my desires specs. Check posting #8 here: http://mmb.maverick.to/threads/how-is-caster-measured.97959/ Also, there are many posts on this.. I search by typing into google... site://mmb.maverick.to caster you can search very well with this
Oh yes I've read every single one actually, it was the specific questions that I posted that have not been answered in any of them. The problem with getting to 2 to 3 degrees caster with the strut rods is it begins to pull the lower arm too far forward, thus creating binding with the bushing. I just need to know how much caster can be gained through the control arm shaft mod, and shimming, separately, so I know whether to do one or the other, or both. I'll have the front suspension completely apart and want to do it all at once when I do.
Was easier for me to stay on point by inserting red responses into your quote below. You should be able to reach pretty close to mack's spec's mentioned above by just using shims and strut rod adjustments alone. Offsetting the shafts within their end caps will help a bit more too. Just remember that as caster goes up.. so shall your camber in the process. Due to the angles involved it's not a 1:1 ratio but it does add up in cumulative fashion so just be sure to readjust the LCA to compensate. PS. I looked at my Comets front suspension in greater detail last week and it SUCKS for the amount of room available at the cross shaft nuts and arning drops over the 1" would surely need to torch some clearance holes. Then you could run centered zerks on the end caps to be greased under the hood. Had a few old Fords like that.. works well.
captainmack- that's actually very helpful, it's nice to know I could (most likely based on your results) get 2 degrees out of the stock setup. groberts- I should have worded it as "excessive binding", or perhaps excessive deformation of the bushing due to the arm being pulled forward too far. 1/2" (4 1/8" shims) sounds like a LOT of shims, I don't know how accurate the information is I've read, but some mustang guys say the old 1/8" spacers can give anywhere from .5 to 2 degrees caster difference, such a big difference in information... If I can put in a 1/16 or 1/8" shim, and adjust the strut rods fully to get over +2.5* caster I'll be pretty happy
I was able to get almost 2 deg. positive on my car w/o shims. 1-31/32 right --- 1-9/16 deg left. The rods are out farther than I like, but they made a big difference in improved steering/tracking after I did Borgeson PS conversion. I plan on going to Pacific Thunder struts in the near future.
Hi Phil: We "mocked" up a quarter inch shim behind the front Upper A-Arm bolt in CAD software . The result was that the Upper Ball Joint was moved REARWARD by .540 of an inch . Hope this information helps. The car has yet to be "aligned" on the rack so we're not sure what the Caster Gain would be. However, in the CAD software, it appears that the 'spindle' angle will change by approximately three degrees . The on the rack alignment will tell the final story. ( This information was gleaned by Dr.Bill here at C.A.M.E.O. ) Cometized (Chip)
improving the caster on these cars at the UCA is more advantageous to keeping a centered wheel than relying only on the LCA/strut rods adjustment alone. Always best to do both for greatest overall effect. Puts more anti-dive geometry into this old suspension too. Albeit at slightly increased bushing/balljoint wear rates. And yeah, Phil.. although those numbers seem overly large, they were right which is why I pointed out the need for angled washers and longer bolts. The added benefits are cumulative in nature if you do several things to complement one another and avoid pushing any single point of adjustment too far out from its original designs parameters. The UCA on these cars seriously needs to be dropped to help fix the very poor camber curve if handling ever becomes a bigger concern. That added camber curve also increases castor rise on turn in too. EDIT.. just wanted to avoid confusion here, Phil. My previous response was aimed at your original question about how much shims could be used. Not implying that you SHOULD use a half inch of shims and install longer bolts.. only that many have done it and that's the way the first gen Mustangs were adjusted. In this case you're simply adding things up(past and present techniques) in cumulative manner as I mentioned above. I looked at my Comets suspension in much greater detail today and will be doing much of what you're doing here plus throwing some homemade parts into the mix too.
Ah, I'm glad you posted, I meant to give an update. Yes I was! My buddy and I set the caster to 2.75 using just the strut rods. We were able to go over 3.25* (discovered by accident because when I replaced the suspension, it's what it was set at on one side when I drove it into the shop). I have a lot more adjustment left, I wouldn't doubt I could easily get 3.5-4* of caster with the strut rods alone, however I would probably start running into rubbing issues with the tires on the front valence. Also I had to replace the one strut rod, because it was bent, and that seems to have a lot more thread area to adjust than the stock piece, just thought I'd mention that as well.
Here is some great info regarding alignment spec's, also read up on their FAQ section, more info about our suspension and what improvement can be done. Contact John if you have any questions, he will be more than helpful in answering all you questions! David http://opentrackerracing.com/technical/
