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Bumpsteer elimination


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#1 Enzo

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Posted 11 April 2007 - 08:08 PM

Hi Guys,
A bit over a year and a half ago when I was rebuilding my 260z I installed the alloy bumpsteer correctors to the bottom of the struts. These helped the problem of wider wheels but I still had to change to a tyre with more rounded edges instead of the Hankook Ventus K102 that I had bought at the time. This Ventus style of tyre puts more rubber on the road with it's squarer sides causing the car to track over the bumps and ruts in the road. I finally got fed up, even though it was a minor inconvenience and removed the crossmember over the weekend for redrilling. Leaving the alloy correctors installed, ment I only had to move the control arm mounting hole up 13mm. I also moved it out 4mm for a touch of negative camber. Because I only had to go up 13mm I didn't have to modify the control arm to clear the top of the crossmember. I got a wheel alignment today to correct the toe-in after the operation and couldn't believe the difference. It drives like a sports car should. You can release the steering wheel over a rough surface and the car travels straight. I would recommend this simple alteration to anyone with Bumpsteer problems. All the best to you all for 2007. David.

#2 ZD44TT

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Posted 11 April 2007 - 09:45 PM

thanks.............would have loved it if you got some shots.

#3 Toecutter

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Posted 12 April 2007 - 04:23 AM

I really need to do the same thing, thanx. Yer some pics of how it now looks would be good.

#4 Enzo

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Posted 12 April 2007 - 08:06 AM

Hi,
I will be away for the next 7x days. When I get back I will take some photo's . Regards David.

#5 620Z

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Posted 12 April 2007 - 08:57 AM

Well done David. I did a similar thing to my car and man it drove like a different machine or like you say as a sports car should. I think most Zed owners don't fix this problem and never really get the full enjoyment out of driving their car.

#6 nat0_240_chevZ

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Posted 12 April 2007 - 12:49 PM

YEA SPACERS JUST mask the problem, redrilling up and out is the go always,

cant help but say, i told u so, just like anna nicoles babys father!!!


but i would use next time up 17-20mm and about 3-5 out!!!

didnt have to remove the cross member but!!!

nato

#7 Mr240z

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Posted 17 January 2009 - 06:42 PM

Hey enzo250GTO, mate can you post some pics and maybe go into more detail for me.

I need to do the same but dont know where to start.

Thanks mate
                                            Pauly

#8 reverendzed

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Posted 17 January 2009 - 07:42 PM

Like Pauly...I'm real keen :o  After my trip around the great ocean road a few weeks ago I got fed up with how the car was tracking...so I'd definitely like to have a go!
Rev.

#9 Enzo

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Posted 17 January 2009 - 09:07 PM

Hi Rev and Pauly,
                      I already had fitted alloy bumpsteer correctors to the bottom of the struts, but these were not doing the trick. After a bit of research I removed the cross member and used a cold chisel to remove the washers on the inside of the holes for the control arm. I then used a centre punch to mark the location of the new holes. I welded up the original holes and drilled the new locations on the centre punch marks. I then fitted the control arm bolts with the new washers on the inside of the crossmember and held them in place with clamps, and spot welded them with the electric welder. Prior to removing the washers I had measured the gap between the holes. After welding the gap was a couple of mm closed up so I just fitted a bolt with 2x nuts and used this to spread the sides. I only had to drill the holes 13mm higher and out 4mm to make the control arms and steering arms parallel on my car. Then a tidy up with a file to get rid of any sharp edges and dags, and hit it with a can of paint. Off to the wheel aligner for a toe-in adjustment and hit the road. Hope that this helps. Photos to follow. Tried once but it didn't work.
Regards David.

#10 Enzo

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Posted 17 January 2009 - 09:20 PM

Hi Guys,
          I can't post the photos because it tells me the files are too big (over 256mb), but if you look in my gallery the photos are there. By the way Rev, you and the boys are a bad infuence. I gave my 260z a christmas present and put the triple Dellortos back on after reading about everyone else playing with theirs. ( Dellortos that is ).
David.

#11 PeterAllen

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Posted 18 January 2009 - 05:49 AM

I think this is the modification David is referring to.

Note: you may have to remove some metal from the lower control arm as well (see arrow) so first check that it does not contact the crossmember before driving the car.


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#12 Mr240z

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Posted 18 January 2009 - 07:08 AM

Thanks guys thats great help. Now i have to find someone in sydney to do this for me.
looks a bit to hard for me.

p.s To Peter Allen sorry for being a total tool the other day.(36 and acting like a 16year old)

                          Pauly

#13 Enzo

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Posted 18 January 2009 - 07:58 AM

Good photos Peter. I only had the photos of when everything was back on the car. I didn't have to move the hole as far as yours because I had the bump steer spacers on the bottom of the struts. David.

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#14 stevo_gj

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Posted 21 January 2009 - 12:43 PM

Pauly let me know what you are quoted for this job, as I am going to have to ask my suspension place to do it as well (when they finally return my emails).

So by using bumpsteer spacers (I've already bought from MSA) and redrilling the holes for the control arms then you will pretty much cure any bump steer problems I may encounter in my 2 seater 260z?

If its OK with you guys I'll send those photos to the suspension place when I describe the job.

#15 Lurch ™

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Posted 21 January 2009 - 01:19 PM

Only one or the other Steve. Either fit the BS spacers or redrill the LCA pivot point.

#16 620Z

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Posted 21 January 2009 - 02:52 PM

Lurch is correct Steve. Make sure you understand what and why you are doing it.  :)

#17 stevo_gj

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Posted 21 January 2009 - 03:16 PM

Thanks for pointing that out guys! I was confused by what I had read on hybridZ bumpsteer FAQ where a member was stating that some people prefer to raise the roll centre (spacers) and redrill the LCA pivot point.

Well here is a helpful diagram comparing the two methods, courtesy Blackbeaut on HybridZ.

Since other members have stated that the LCA pivot relocation is a better option than spacers I think I might get a quote to see how much redrilling the LCA pivot point will cost. If its reasonable I will sell the 14" bumpsteer spacers that I bought from MSA at cost price.

Here is the HybridZ bumpsteer FAQ page: http://forums.hybrid...ad.php?t=103886

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#18 NZeder

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Posted 21 January 2009 - 04:59 PM

Raising and moving the LCA pickup point does appear to correct the issue. We (as in me and a mate while working on this race car) found some very interesting results with a bumpsteer measuring device that was created to see the changes in bumpsteer with different setups.

My mates race car had raised point etc and I had some of the MSA spacers. The standard tie rods were replaced with a rod end and tapered bolt. This allowed us to move the steering arm up or down in relation to the LCA. Now I know I am talking about moving the steering arm location and not the LCA like most do (this is due the race car setup and rose joint steering arm setup) but we found interesting results when installed with spacers moving things up and down.

The result (well that is a close guarded secret) but let put it this way - what you read about in the US is not the true and correct solution to the bumpsteer issue - yes moving the LCA or installing the spacers does give the feeling of correcting the issue but it does introduce other issues (roll centre changes etc).

To fix the issues correctly on a lowered zed means $$ sorry guys or major changes to the steering setup. Again best to either play with different setups like we did and use a tool to measure the bumpsteer while you make the changes, learn and understand what is going on.

The answer has been posted on this site before - so I will leave it to you to search and do the research. Again there is a well known Datsun shop in that land of yours that does know the correct fix and it is not what you see on the net about moving the LCA location or those spacers - infact they avoid the spacer like the plague and recommend against them. Again depends on your budget and use of the car - me I just wanted the bumpsteer solution fixed once and for all without spacers and what not.

#19 zzzzed

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Posted 21 January 2009 - 08:03 PM

now thats just cruel???

#20 Lurch ™

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Posted 21 January 2009 - 08:17 PM

I'm pretty sure I know what Mike is referring to - it's the oldest method in the book.
Get a hold of a book buy 'Fred Punn' & all will be revield...





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