misterp Posted October 8, 2006 Report Share Posted October 8, 2006 (edited) OH MY GOD. What a difference. If you have both 2" drop spindles -and- 1" lowering keys on your truck you are going to want to seriously consider this modification. I've got a lot to say so bear with me on this. Six months ago I installed the McGaughy's 2" drop spindles and 1" drop torsion bar keys, giving a total suspension drop in the front of about 3". Along with the install I followed best practice of the time and shortened the front rubber suspension rebound bumpers by cutting off 1 'nub' (pic). The resulting ride was definitely stiff, dare I even say jarring on broken pavement. Now I actually prefer a firm ride, I've driven 650-lb road racing coil springs in my prior F-body and really liked it, but after this suspension drop I dreaded driving the truck more than three to four hours, it was doable but would just wear your body out. To borrow a quote from Posi12Bolt, it was like driving a huge skateboard. I reached under the front of the truck (at rest) and judged the gap between the modified front bumpers and the lower control arms with my fingers, there was only a whisper of clearance; the two were not touching but there was about 1/8" of daylight between them. I suspected that I was riding on the front bumpers during normal driving and that it was transmitting a lot of road harshness into the truck, but I did not want to just hack another 1/2" off the bumpers before doing a little research. The function of the front bumpers is largely misunderstood; they are not just there to prevent the frame from slamming down metal-to-metal onto the lower control arms, but they are important active parts of the suspension. The torsion bar keeps the truck sprung off the ground, but it is not a progressive rate spring like modern coil springs, it is a linear rate spring. To give the driver a progressive rate feel GM suspension engineers made the little rubber bumpers of special material and configuration so that as they compress their resistance rises in response to the force applied against them, like a progressive coil spring. In fact these rubber bumpers act as progressive secondary springs in addition to the main steel torsion springs; and it makes more sense now why they are roughly conical and corrugated in shape. By cutting off the first 'nub' of the factory rubber bumper, one sacrifices progression of spring rate for increased suspension clearance; this is a bad tradeoff as the moment the lower control arm moves towards the frame and loads against the now firmer rubber bumper the spring rate quickly goes from spongy to very hard, as that rubber is not as compressible/forgiving as one might think. The result is that when traveling in a straight line you have a very harsh ride on anything worse than a dead calm surface; when dropping into a quick dip in the roadway the front suspension will land pretty hard on the front rubber bumpers. But the worst symptom of this problem is seen when cornering hard enough that the outside rubber bumper will not compress anymore and the suspension *stops* (binds) - in this very dangerous moment the outside front suspension has gone solid (infinite spring rate) and the front end plows off the side of road; I've experienced this in the SS. The front suspension becomes very unpredictable. I reasoned that trimming even more off the rubber bumpers to make additional clearance would make things worse rather than better; I might achieve more clearance and smoother ride but when the lower control arms finally did contact them I would go skidding off a corner again. So what I did instead was to actually weaken the top 'nub' of the bumpers by drilling six 1/4" holes. I'm sure the front-end is still riding on the rubber bumpers, but I have weakened them to restore the desired gently progressing spring rate. After a quick test drive I am VERY pleased, and not only do I now have the best ride I've ever had in the SS to date (I'd drive it cross-country now) the truck's cornering behavior is greatly improved. The SS is now begging for better sway bars but is not plowing off the corner like it was before today. Mr. P. Edited August 18, 2008 by Mr. P. (see edit history) Quote Link to comment Share on other sites More sharing options...
ItsJac Posted October 8, 2006 Report Share Posted October 8, 2006 (edited) Would this make any difference with just the spindles? And why could you not post this info yesterday when I was lowering my truck... J/k When i go back in next weekend to check all my torques I might be up to it... Edited October 8, 2006 by ItsJac (see edit history) Quote Link to comment Share on other sites More sharing options...
Posi12Bolt Posted October 8, 2006 Report Share Posted October 8, 2006 Would this make any difference with just the spindles? Quote Link to comment Share on other sites More sharing options...
misterp Posted October 8, 2006 Author Report Share Posted October 8, 2006 Would this make any difference with just the spindles? THIS IS AN EXPERIMENT, but with that said yes, if you are riding on the front bumpers and can feel it in your kidneys then drilling 4 or 6 holes will give you a lot of relief. Other variation to try is the size of the holes (I just guessed and may have gone too large). I may try to find another set of stock front bumpers and experiment with four 1/8" holes, then increase to eight 1/8" holes, then maybe even drill the original four to 3/16", etc. The trick is to get the spring to react uniformly in a turn, you want to feel the weight compress the bumper in a predictable fashion. Hogging out the bumper with a dozen large holes would be the same as just cutting another 1/4" off the bumper meaning that it will have loose travel for a 1/4" then suddenly bind again. Mr. P. Quote Link to comment Share on other sites More sharing options...
Blk06Limited Posted October 8, 2006 Report Share Posted October 8, 2006 Interesting theory.. Might have to give that a shot Quote Link to comment Share on other sites More sharing options...
r8rs4lf Posted October 8, 2006 Report Share Posted October 8, 2006 (edited) Might have to try this out. My front end sure does ride like @$$ especially when I happen to drive over a speed bump faster than I want, but I wonder if it's because I turned the torsions a bit to get the rake I wanted. Also, are those the factory shocks? I wonder if the ride would get even better with some aftermarket shocks? What do you think? Edited October 8, 2006 by r8rs4lf (see edit history) Quote Link to comment Share on other sites More sharing options...
04CHASE Posted October 8, 2006 Report Share Posted October 8, 2006 sp yu have uncut bump stops now with drilled holes?? why are your shocks blue?? when i pulled my stockers they were all black Quote Link to comment Share on other sites More sharing options...
misterp Posted October 8, 2006 Author Report Share Posted October 8, 2006 sp yu have uncut bump stops now with drilled holes?? why are your shocks blue?? when i pulled my stockers they were all black No I drilled holes in my modified (cut) bumpstops. I got another pair hoping to use them instead but they were the wrong ones. Shocks - those are the factory ones, they've about lived their useful life, time for new ones... Mr. P. Quote Link to comment Share on other sites More sharing options...
kelleyperformance Posted October 19, 2006 Report Share Posted October 19, 2006 yea mine are red.... GM prob goes from korean sweat shop, to bilstein, to mexico, then to china LOL i cut my stops as low as possible as to not tuck my big ass tires, and i have like 2 inches of travel without stops. i cant begin to explain the ride difference, it rides fantastic. its really stiff tho, and corners pretty damn well too..... why am i the only one who did this? i noticed it rides on the bumps from GM Quote Link to comment Share on other sites More sharing options...
gs430 Posted October 23, 2006 Report Share Posted October 23, 2006 Got any pics of your ride with your drop? Quote Link to comment Share on other sites More sharing options...
SS_bnoon_SS Posted October 23, 2006 Report Share Posted October 23, 2006 yea mine are red.... GM prob goes from korean sweat shop, to bilstein, to mexico, then to china LOL i cut my stops as low as possible as to not tuck my big ass tires, and i have like 2 inches of travel without stops. i cant begin to explain the ride difference, it rides fantastic. its really stiff tho, and corners pretty damn well too..... why am i the only one who did this? i noticed it rides on the bumps from GM <{POST_SNAPBACK}> Dude, you've got to be bouncing around like a kid in a candy store without the bump stops in there... it's a torsion bar suspension and supposed to ride on the bump stops just a bit. With a lowered suspension, it's important to some people to restore the progressive rate of attack on the upper control arm... without it, the main torsion bar has free reign. I'd be sicker than a dog in something like that... Quote Link to comment Share on other sites More sharing options...
drako Posted January 11, 2007 Report Share Posted January 11, 2007 Bump to the top, any update P? Quote Link to comment Share on other sites More sharing options...
misterp Posted January 11, 2007 Author Report Share Posted January 11, 2007 Bump to the top, any update P? <{POST_SNAPBACK}> Not really - what kind of update were you looking for? I like the modification, it rides much nicer and handles far better when you pitch it in the corner. I will be getting more info in a couple weeks after I see a stock SS and take some comparision measurements. I have also made the decision to throw out the dropped spindles and install DJM control arms, so I am not doing any more suspension work until I install this and the Hotchkis bars. Mr. P. Quote Link to comment Share on other sites More sharing options...
drako Posted January 11, 2007 Report Share Posted January 11, 2007 Bump to the top, any update P? <{POST_SNAPBACK}> Not really - what kind of update were you looking for? I like the modification, it rides much nicer and handles far better when you pitch it in the corner. I will be getting more info in a couple weeks after I see a stock SS and take some comparision measurements. I have also made the decision to throw out the dropped spindles and install DJM control arms, so I am not doing any more suspension work until I install this and the Hotchkis bars. Mr. P. <{POST_SNAPBACK}> keep me updated, the ride for me is ok, but Im a big lover of a better ride. I was gonna do your recommendation when I add my Nitro shocks probably on sunday. So do you think I should just leave it at stock (dont cut of a nub) and drill the holes. Thats what I was thinking about doing. Like I said before tell me how the control arm handle, and how much did you get them for? PM if youd like thanks again P as a fellow left hander my left hand can only dream of your left's legacy Quote Link to comment Share on other sites More sharing options...
r8rs4lf Posted January 11, 2007 Report Share Posted January 11, 2007 Bump to the top, any update P? <{POST_SNAPBACK}> I have also made the decision to throw out the dropped spindles and install DJM control arms, so I am not doing any more suspension work until I install this and the Hotchkis bars. Mr. P. <{POST_SNAPBACK}> I don't know about that P. I've read some things about those DJM control arms from people that have them and they say they are junk. I was just reading something about that yesterday. I don't know, he had a 4/6 with those arms and he hates driving his truck now. Maybe it is the fact that it's soo low now. I'm sure you've done your research though, good luck. I'll see if I can dig up where I read that. Quote Link to comment Share on other sites More sharing options...
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