EVC Posted August 30, 2023 Share Posted August 30, 2023 Has anyone had experience with an offset version of the front upper control arm shaft ? I'm trying to set my castor alignment to get into the positive range of 3 to 5 degrees without screwing up the Camber or changing the upper control arms. I've also seen versions of offset bushings, but don't care for the idea. Any help would be appreciated. I'm in the learning stage and have access to a complete alignment machine at our military hobby shop. One of the members suggested I change the upper control arms to achieve the increased positive castor. After doing some research I found that offset shafts are available. Looking closely at the upper bushings they appear to be perfectly centered, but after looking more closely it appears the passenger side bushing may have slipped backwards a bit. My first order of business will be changing the upper bushings and see if it makes a difference in the settings. I replaced the lower front bushings and springs about 8 years ago and they appear to be good. The bushings in the rear control arms are also about 8 years old and still good. The toe is within specs with a 3/16 overall,,, but the car seems to favor the right slightly. I'm thinking this may be the lack of positive castor or the upper right bushing. Thoughts and suggestions would be appreciated. Ed C. Quote Link to comment Share on other sites More sharing options...
Blackhawk Posted August 30, 2023 Share Posted August 30, 2023 The offset shafts are more for fixing the effects of frame sag, where the upper control arm mounts are pulled toward each other. They affect the front and rear stud evenly, while you need to pull the rear of the control arm in to get positive caster. Anything more than 2-3 degrees of positive caster will probably be tough with stock control arms. 1 Quote Link to comment Share on other sites More sharing options...
EVC Posted August 30, 2023 Author Share Posted August 30, 2023 Thank you Cody. That makes a lot of sense to me… I hope the new upper bushings will help, otherwise I'll dig deeper and sort this thru. Your information has helped my understanding. I think the Monte's are stock with almost zero castor, so going into the negative side has me concerned. I'm going to recheck those numbers. The car drives great and the tires are wearing good, but all I get from most alignment shops is setting the toe and out the door I go with less money. Even the numbers from each shop vary widely, so I'm not certain of their accuracy. I've been to the guy, "who knows a guy, that is friends of a guy," and he was dumber than a rock. Without breaking the bank, I'm considering aftermarket or GM stock style upper arms to achieve the goals of positive caster.. Any recommendations will be appreciated. Ed C. Quote Link to comment Share on other sites More sharing options...
stangeba Posted August 30, 2023 Share Posted August 30, 2023 This is old (Muscle Car Review 1990) but it may help. (Click link to read) https://1971montecarlo.wordpress.com/2023/08/30/front-end-alignment-information-2/ 1 1 Quote Link to comment Share on other sites More sharing options...
TheBMan Posted August 31, 2023 Share Posted August 31, 2023 @EVC Hey Ed, I've done this on two Monte Carlo's (72 and now my 70) and didn't use the offset shafts. You can get at least 3° of positive caster with the stock setup (including stock control arms). If you're lucky, you can get 5° or so. I started an entire thread about it here with lots of feedback and tips from the guys here. This also talks about replacing the stock steering gearbox with a Borgeson unit, which I also did after the alignment, and it added even more stability and road feel. Night and day. Ideally you want as much positive caster as you can get, -.5° camber and 1/16" to 1/8" total toe in. With these settings, you car will drive like a dream; far better than when it was new/with the factory alignment specs. I hope this helps! Bryan 1 1 Quote Link to comment Share on other sites More sharing options...
EVC Posted August 31, 2023 Author Share Posted August 31, 2023 1 hour ago, TheBMan said: @EVC Hey Ed, Ideally you want as much positive caster as you can get, -.5° camber and 1/16" to 1/8" total toe in. With these settings, you car will drive like a dream; far better than when it was new/with the factory alignment specs. I hope this helps! Bryan Thank you Bryan, My goal is to keep the stock arms and get as much positive castor as possible…. Anything north of 3 degrees The steering box is on my list as well. Somewhere I must have done something wrong…. My castor readings are in the negative 7 and 8 degree range, making it impossible to get into the positive range without an excessive amount of shims and therefore making it impossible to reach a good camber number. "Hence the idea of an offset shaft"…. The car drives very well. Numbers that far into the negative range would make the car almost impossible to drive. I plan to put her back on the alignment rack next week. I've had the car aligned many times at other shops. Those wild castor numbers never appeared before and were always in the green. The camber has also remained stable over the years and still is. Any sudden change in the castor would most likely have shown up in the camber relationship. My camber numbers are currently ,, .4 and .1 respectively… I called Scott at Globalwest yesterday and he agreed, castor numbers that far in the negative would manifest itself in terms of drivability meaning, in his words "almost impossible". It was interesting , but he actually asked me if my control arms could possibly be on the wrong side? I doubt this…… but ,,What If ??? LOL Apparently it's possible and he said he's seen it before and it would give those wild numbers. I'll remove the wheels next week and send him some photos.. I think the upper arms are stamped with a "D" for driver and "P" for passenger side. The upper bushings all appear well centered, but the upper passenger arm may have slipped back a little on the shaft…. .. not sure just yet… The rubber between the washers is gone and the rear washers are touching…. Hoping it's that simple and new upper bushings will do the job. I can then go about the business of getting as much positive castor as possible with the shims. I may try the offset shafts in the event there has been some frame sag. I also want to fine tune the camber for mountain driving and curvy roads. Open to suggestions…. Thoughts and ideas… Are there any negatives to using the offset shaft to achieve better Castor numbers ???? I know nothing about alignment,,, but for an 82 year old I'm learning very quickly… I really appreciate your info and help… Ed C Quote Link to comment Share on other sites More sharing options...
TheBMan Posted September 1, 2023 Share Posted September 1, 2023 @EVC Ed, I agree that -7° caster would make your car almost impossible to drive so that means that I also agree that something odd is happening. Perhaps the arms are on the wrong side as the Scott mentioned - I wasn't aware that was possible but I guess it could be. My advice, especially since it sounds like your bushings are shot: replace the arms with new assemblies (pre-assembled with shafts and bushings). It's cost effective when compared to pressing your own bushings into old arms and the time and effort it takes to do that. All of the parts houses carry upper and lower control arms pre-assembled with new shafts and bushings. This is what I have done on both of my cars and it was easy-breezy. OPGI has the uppers here. And the lowers here. Again, these are easy to find at the various parts places. Get those new arms installed and find an alignment place that will set your car to your desired settings (some places won't do that). Sounds like you might have that taken care of already. Last piece of advice. If you want a natural ride, stick with rubber bushings. Don't be tempted by the hype around urethane bushings unless you want a stiffer, noisier ride. My car had urethane when I got it. It rode like a tank. Going back to rubber bushings and regular ole hydraulic oil shock absorbers (about $35 ea at NAPA) returned it to a nice comfy ride. I'm sure some of the other guys will have advice, too. There are a lot of smart, experienced men around this place. P.S... If your car drives "very well" as you said with -7° caster, it makes me wonder if you got erroneous readings from your alignment machine due to a problem with the machine or perhaps it wasn't setup on your car properly. I just can't imagine the car would drive anywhere near nice with that much negative caster. Should be all over the place. 1 Quote Link to comment Share on other sites More sharing options...
EVC Posted September 1, 2023 Author Share Posted September 1, 2023 Excellent advise. Thank you Bryan… 7 to 8 neg castor degrees is impossible, especially if the car drives extremely well. Been reading about the rubber bushings and agree. We have and still drive this car all over the US… Going to Florida from Calif is done at the turn of the key and a few road chips along the way is normal for us. The tire wear was very slight on our last trip and minor toe adjustments corrected that. I stored the original motor in 1992 and used a nicely built 350 for about 80, 000 miles. Rebuilt and installed the original a year or so ago. I promised her I'd give her original heart before we part. Her original engine now has about 13,000 on the rebuild and purrs like a cougar in heat. She is getting close to 200, 000 on her old body and frame, but she can hold her own in any show. May not win, but who cares… She's an American road car and has always brought us home safely. She's an elegant lady and does what she was designed to do. Really looking forward to the upgrade of positive castor and possible steering box you recommended… The shocks have about 100,000 miles and will change that too… Ed C.. . Quote Link to comment Share on other sites More sharing options...
EVC Posted September 6, 2023 Author Share Posted September 6, 2023 On 8/31/2023 at 5:14 PM, TheBMan said: @EVC Ed, I agree that -7° caster would make your car almost impossible to drive so that means that I also agree that something odd is happening. The odd thing was me (the dummy) using alignment adapters on the wheels to slide over the Rally caps.. Today I removed the Rally caps and didn't use the plastic alignment adapters… Now I have sane numbers and will be able to shim into the positive 3degree side using the stock arms and shafts… All steering parts, bushings etc are in great shape except for the passenger uppers and some wear on the drag arm. The steering box, ball joints, tie rod ends etc, and all other bushings front and rear are in excellent shape. Apparently those two upper bushings took a beating or were improperly installed and the arm slide back just enough to cause the car to slightly favor the right side of the road and create a slightly negative castor reading…. It was almost impossible to see because they appear perfectly centered. I'll replace these parts and see if I can improve the castor and camber with the stock arms and shaft. No offset needed now.. I'd like to see how she drives with a positive 3degree castor and then perhaps go to the offset shaft…. She currently drives great at the near zero castor numbers, so another 3 degrees will be fantastic for me. Thanks for the help .. Ed C. Quote Link to comment Share on other sites More sharing options...
EVC Posted September 15, 2023 Author Share Posted September 15, 2023 Bryan, Yesterday, I installed the new center link and the passenger side upper arm bushings… I reused the original shims as they were and didn't mess with bushings or shims on the drivers side. My time on the alignment rack was limited, so I made some quick adjustments to the toe and called it a day. I didn't have time to play with the caster and camber, but will return next week to experiment with the shims. I was impressed with the out of the box numbers... It now appears to be an easy reach to the positive caster range. Thank you for the help… Your thoughts on these numbers will be appreciated. Ed. Quote Link to comment Share on other sites More sharing options...
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