June 8, 2015 at 11:48 am #1101662cutlassconvertParticipant
I am going through the front suspension of my car and need to set up the control arms. The service manual says upper arms are centered on the pivot shaft and the lower arms are positioned on their shaft using a factory tool, a spacer between the control arm and the pivot shaft threaded boss in the subframe. Size of the spacer is not given, only the tool number. All the spacings front to back for uppers and lowers were different on the arms prior to dissassembly. Car and subframe do not appear to be damaged or bent.
The procedure for the lower control arm spacer is to use it on one side of the arm, tighten the bushing and then tighten the other bushing. So I am not clear if the bottom control arm has equal spacing front and back or not since I do not know the size of the spacer.
Service manual notes alignment is achieved through typical spacers on the upper control arm shaft. No mention of movement of the upper or lower control arm front to back. Spacing of the control arms can only be changed by removing both bushings, repositioning the control arm, and re-threading the bushings.
1. Is the spacing for the lower control arm to the pivot shaft boss equal for front and rear, or…?
2. Is it acceptable and can I achieve more positive Caster with movement of the upper control arm. Purpose would be to firm up steering and road feel from the typical 60’s feel.June 9, 2015 at 1:24 pm #1101763cutlassParticipant
I believe that fig. 5-108 in the manual shows that the shaft is equal in length on either side of the lower arm, It looks like tool J-8808 locates the shaft centered in the arm, but I’m by no means an expert in front suspension work of the 61 to 63s.
As far as getting more positive caster, yes, moving the top control arm straight back by changing how the shaft is centered in the arm, should result in tilting the top of the steering knuckle back, thus increasing the caster. Looking at the service manual, factory caster specs at curb height are -3/4 to -1 3/4 changing to +1/8 to +1 1/8 degrees at full load (4 passengers). Changing that to a positive 3 or 4 degrees at curb height would help a lot in road feel and wandering.June 9, 2015 at 2:00 pm #1101862cutlassconvertParticipant
Thanks for jumping in on this issue-lots of views but no answers. Yes, the lower shaft is to be centered-ie same exposed length from the boss in the subframe to the end of the shaft on both front and rear positions-manual says about 1 11/16″ from the boss to the end of the shaft both front and rear. But I believe once the shaft is installed in a centered position, the tool J-8808 locates the control arm spacing from the boss to the inside of the arm. So is the set-up to center the arm front to back or is that spacer used in only one location to give specific spacing to one side while the other side has a resulting space which is not equal?
Is that movement of the upper arm acceptable to do and apprx how far off center is a good starting location for the alignment shop?
Thanks again for the help.
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