JMortensen Posted January 17, 2015 Share Posted January 17, 2015 (edited) I can't say I have ever had an emergency lane change or handling issue that was caused by bouncing the car (up or down). Once I put the race car back together later this spring (engine, tranny and diff) I will corner balance, align and check the bump steer I should clarify. It wasn't just a bump on the track. It was a short hill. You come over a hill around a left turn, then track out at the bottom. This is followed by a maybe 10' rise onto a short straight. With my z being under sprung and over tired, I'm sure I had a lot of lean going on, then it was kind of a g-out situation where the bottom of the hill was followed by the rise. My issue happened going up the little hill. The car would jerk hard right. Scared the crap out of me the first time. There is also a long right sweeper and I really would saw at the wheel on that turn. Adjusted the pivot height and both issues were resolved. Edited January 18, 2015 by JMortensen Quote Link to comment Share on other sites More sharing options...
gnosez Posted January 17, 2015 Share Posted January 17, 2015 Jon, other than having a heim joint snap going down the straight doing 90mph, the suspension and front end has been without issue through the last 10 years. It is regularly aligned, checked and rechecked. The bumpsteer was checked last year but I confess it might not have been as accurate as say the ones down by John Coffey. I had JR Mitchell, a former BSR crew member and the builder of the 280ZTT V8 race car drive it and all he said was add an 1/8-inch to the rear toe and that it either needed another 50 hp or less weight. So, if I have not had an experience like you, what would an adjusted bumpsteer front suspension (if it actually needed to be adjusted) do for my current ride? What would I feel different about the turn in or under braking? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 18, 2015 Share Posted January 18, 2015 The difference will be less corrections to hold a line, in theory you might have less tail wagging under braking, I never noticed that though. You might not notice at all. Quote Link to comment Share on other sites More sharing options...
gnosez Posted January 18, 2015 Share Posted January 18, 2015 I have no problem holding a line (even less when I get to use the 15X10 wheels and Hoosiers) and my tail doesn't wag which could imply I'm not pushing myself hard enough, so I'm going to concentrate on other things first. Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted January 18, 2015 Share Posted January 18, 2015 Which heim joint snapped? I'm about to convert from stock outer tierod ends to DP outer tie rod ends. I'm doing it because I don't like the kink in the stock tierod ends and how it puts the inner tierod at an angle on a modestly lowered car, and I seem to go thru those hard to find inner tie rods faster than I think I should. My concern with raising the inner control rod pick up point is that with the big rod end that is on a TTT front LCA, I don't see room to raise the pickup point even a full bolt-hole width. So it seems like too much sugar for a dime to me. My car is twitchy in the rear because I sonetimes fail to get my steering wheel straightened up before piling on the brakes just before turn-in. Probably not you, but so far, every handling problem I have had (I am very, very inexperienced), has been traceable to the driver. I used to laugh at guys who thought a Z needed power steering, but now that I have tracked a car with 10" of sticky rubber on each corner, I'm a believer. Quote Link to comment Share on other sites More sharing options...
gnosez Posted January 18, 2015 Share Posted January 18, 2015 We got a prototype set from someone we trust and then we made a set of our own. Both failed within 5 laps under heavy braking. I have the TTT LCAs on my street Z which sits at under 6 inches (less than 3 inches at the edge of the AZ Z oil pan) and have not had Any issues with it at all and it uses the raised pickup point which the race car is not allowed to use. The race car uses a stock LCA with the delrin adjustable bushing. I have one of the original BSR modified LCAs and they gusseted the top and bottom plus pressed in a ball bushing. It weights nearly 5 lbs per side more than a stock part. Considering they drilled 3/16th holes in the inner door pulls that 10 lbs was worth it to them. Both the race car and the street Z have the heim jointed outer tie rods as I had the same problem with the geometry/replacing the inners. Over 30 track days and 15,000 on the street Z without an inner rod replacement. Quote Link to comment Share on other sites More sharing options...
G-E Posted January 18, 2015 Share Posted January 18, 2015 gnosez: which type or series of rodends did you use? I've seen a lot of people snap cheapo rodends in tierod applications, mainly because they can't tilt enough, and if they bind, they snap. Often exacerbated by using poly bushings on one joint, and rodends on the other... the poly allows movement putting 100% of the load on the other joints, namely the rodend. This shouldn't be as common where you have a big chunky rodend placed mostly in rotation, as you would on a control arm, or radius/tension/compression rod... again assuming you have all pivots converted to bearings/rodends. Quote Link to comment Share on other sites More sharing options...
gnosez Posted January 18, 2015 Share Posted January 18, 2015 Not sure who's rod ends we used for the custom LCAs but it wasn't some cheap knockoff. I'll look when I get back home. Quote Link to comment Share on other sites More sharing options...
RebekahsZ Posted January 19, 2015 Share Posted January 19, 2015 So the rod end that failed was at the inside pivot of the LCA where it bolts to the crossmember. Quote Link to comment Share on other sites More sharing options...
tube80z Posted January 20, 2015 Share Posted January 20, 2015 Pictures of the parts would be interesting too. Cary Quote Link to comment Share on other sites More sharing options...
gnosez Posted January 20, 2015 Share Posted January 20, 2015 When I get back this weekend I'll get the one arm that broke out of storage and take some pictures along with the BSR LCA Quote Link to comment Share on other sites More sharing options...
gnosez Posted January 25, 2015 Share Posted January 25, 2015 I have added a photo of the LCA we built (failed) and a few of the BSR LCA I have. Note on the BSR LCA it has been opened up to allow the end link to be attached. The front sway bar was inserted in a tube that was welded into the engine bay rails. The gussets and connections added 5 lbs more to each side. The end at the crossmember pivot point was cut back and the front lip was trimmed to avoid hitting the rotors. Quote Link to comment Share on other sites More sharing options...
G-E Posted January 25, 2015 Share Posted January 25, 2015 Where's pics of the carnage? Anyway looks like you used 5/8"-ish 3-piece rodend, but the rest of the hardware is unclear, did you weld a nut to the arm for a double adjuster? As for the added strengthening parts, that is way overkill, you should have stuck with 2mm sheet laterally supporting the bolt tubes, with maybe some bead rolled X's on the flat bottom plate... Quote Link to comment Share on other sites More sharing options...
gnosez Posted January 27, 2015 Share Posted January 27, 2015 No carnage. That's the one that didn't snap. The rod end was the same one used in the restoration of the 1991 Ferrari IMSA car and it held up just fine. As to the added strengthening parts, that particular LCA was built in the South St. Datsun dealership which was also the home of Bob Sharp Racing. Those LCAs saw service in the C- Production and GTU S30 body race cars. I figured while it may have been overkill, it was them not me that the added 5lbs per must of seemed worth it at the time. The front sway bar was likely in the 1.25 to 1.5-inch range. I have several of them in labeled tubes. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 27, 2015 Share Posted January 27, 2015 (edited) Looks to me like they wanted a longer end link and double shear mounting. The extra 5 lbs seems awful "extra" to me, but then again, I'm not using a 1289 lb/in swaybar (that's what calculates out for a 1.5 in bar). Edited January 27, 2015 by JMortensen Quote Link to comment Share on other sites More sharing options...
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