vtdds71 Posted March 9, 2010 Share Posted March 9, 2010 My '72 240Z, with less than 30K original miles, is back on the road again after I have made the following "improvements": - New Tokico Illumina shocks, front and rear - new Eibach progressive-rate springs - replaced all suspension bushings with new polyurethane parts, incl. steering damper and steering rack - new tie rod ends - complete suspension rebuild, including all new bearings, ball joints, strut bearings - front bump steer spacers - MSA front and rear anti-roll bars - MSA front and rear strut bars - four new Sumitomo HTR 200 tires, size 205/70 x 14, mounted on "original" 14 x 6 American "slot mags" - front end alignment adjusted and OK'd to specs After all of this, the steering is still not as sharp and precise as I think it should be, mostly on initial turn in. Quick lane changes create a feeling of the rear end "catching up" to the rest of the car, sort of like initial understeer caused by soft tires. Is the problem mostly the old-tech tire/wheel combo? Could I expect a big improvement switching to "plus-2" 16" wheels and tires? Should I try to tighten the large adjusting nut on the top of the steering box? What other mods should I consider? Quote Link to comment Share on other sites More sharing options...
randy 77zt Posted March 9, 2010 Share Posted March 9, 2010 70 series tires dont help-try running more pressure.how is the toe in in the rear suspension?you need to find an alignment shop that has a good laser alignment rack and a tech that knows what he is doing=but this will not be the $29.95 set-the-toe-and-let=it-go alignment.most shops dont like getting involved in this kind of stuff.when i used to be a tech at a dealership i used to set my z up for track days on a $45,000 hunter alignment rack.does the car track straight with out wandering at speed?the adjustment on the rack should not be tightened unless there is too much freeplay in the steering.if it is set tight the steering wont return well if it is too tight.i could not put 50 series or less tires on my car-with the track suspension i use my tires as part of the suspension because my springs are stiff. Quote Link to comment Share on other sites More sharing options...
Administrators SuperDan Posted March 9, 2010 Administrators Share Posted March 9, 2010 - MSA front and rear anti-roll bars Is the rear MSA bar the one that mounts from the front, basically mounted to the floor pans behind the front seats? I installed that that style bar on my car years ago and the binding caused all kinds of screwy handling issues. I replaced it with a rear mount bar and it made a huge difference. Quote Link to comment Share on other sites More sharing options...
Dtsnlvrs Posted March 9, 2010 Share Posted March 9, 2010 Well, I would say your tire choice and size could be causing some of your problems. I would suggest a 225/60/14 until you decide to pony up for bigger wheels. The other issue at play (literally) could be the needle bearings in the steering column u-joints. If you have a bad joint, the car will feel very sloppy. Also ditto on the rear mount sway bar...the fromt mount ones really do suck Quote Link to comment Share on other sites More sharing options...
deja Posted March 10, 2010 Share Posted March 10, 2010 Make sure your steering rack isn't moving sideways when you turn the wheel, test that sitting still. I know it sounds strange but it happened to me and did not get better with new rack bushings. I had to make sheetmetal spacers to weld beside the rack bushings to make them fit tight. Quote Link to comment Share on other sites More sharing options...
roger280zx Posted March 10, 2010 Share Posted March 10, 2010 Well, I would say your tire choice and size could be causing some of your problems. I would suggest a 225/60/14 until you decide to pony up for bigger wheels. The other issue at play (literally) could be the needle bearings in the steering column u-joints. If you have a bad joint, the car will feel very sloppy. Also ditto on the rear mount sway bar...the fromt mount ones really do suck I think that 225's are too wide for 6" wheels. Maybe okay for 7"s but with 6" wheels I'd have 205 60s. They work very well. Just my .02 Quote Link to comment Share on other sites More sharing options...
Drax240z Posted March 10, 2010 Share Posted March 10, 2010 Given the mods you've made, the 70 series tires shouldn't cause "vague" handling. A bone stock restoration running stock tires has very direct steering feel, and actually feels quite good. Do you have the alignment specs after the alignment was completed? I would start by posting those. As mentioned above, a loose steering rack will cause a vague feel. Do you have any freeplay in the steering wheel at all? (ie: can you see the front wheels move with even minute amounts of steering input?) If there is no freeplay, I'd be looking at alignment much more closely. Quote Link to comment Share on other sites More sharing options...
vtdds71 Posted April 17, 2010 Author Share Posted April 17, 2010 Sorry about the lack of timely response to your good suggestions. Car is out of winter storage, so I had a chance to check the front end up on a lift today for the first time in awhile, and did note a very slight amount of play on the right side of the steering rack when the right front wheel was nudged from side to side. Tie rod ends and ball joints are new, but is there something I can do inside the steering rack to eliminate all sources of free play? When I inspected the rack when it was off the car a couple of years ago, it seemed like a tricky piece to disassemble for close inspection, and reassemble correctly. Best to plan on a rebuilt rack in this case? Quote Link to comment Share on other sites More sharing options...
johnc Posted April 17, 2010 Share Posted April 17, 2010 Do you have the alignment specs after the alignment was completed? I would start by posting those. To repeat... Quote Link to comment Share on other sites More sharing options...
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