omega 24 v6
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| posted on 20/5/06 at 05:26 PM |
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Bump steer
I picked up my mark2 escort rack last night and have cleaned and dry fitted it.
I was drawing up the mounts etc to try and get all the ball joints in line (bumo steer) and have come across a problem.
Hope you don't mind me using your drawing James
The dimension from inner ball joint to inner balljoint on the rack is as far as I can see is 585mm. split this in half it's 292.5mm. The top
wishbone mount is 297mm so in order toget them all in line the rack is very high.
Comments and advice are required please.
 
The plans
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zetec7
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| posted on 20/5/06 at 05:32 PM |
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If you get the rack that high, the tierods will droop down to the steering arms on the uprights - that will also cause bumpsteer. We looked for
shorter racks, and couldn't find any short enough to eliminate this problem. We're having our racks cut down by 4" to solve
it...
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mark chandler
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| posted on 20/5/06 at 05:49 PM |
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Cut 3 inches out of the tube, 4" out of the rack to sort mine out !
Had to to remake the rack mountings but when I move the hub from full droop up to the bump stops not a sign of bump steer.
Regards Mark
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omega 24 v6
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| posted on 20/5/06 at 06:10 PM |
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Mark did you do the cutting yourself or what? if i cut the tube as well it would help the downlink clear the fu tube as well.
It's a standard rack and I thought the escort was supposed to be a straight fit. Also if its shortened I'd need to use track rod
extensions as well. Ho hum problems problems AGAIN.
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Bob C
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| posted on 20/5/06 at 06:47 PM |
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similar to above - I cut 3.5" out of rack and 3" out of tube. The rack itself is machinable (only the teeth are hardened) without
difficulty. If you cut more off the tube you may find the rack mounts end up worryingly close together, mine are 7" apart. With all mods as
above everything fits together nicely - steering UJs & column miss everything.
cheers
Bob
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mark chandler
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| posted on 20/5/06 at 07:49 PM |
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Yes, cut it myself.
Used a hacksaw to cut the tube, an angle grinder to cut the rack up by the threaded end.
I then knocked 3 1/2" out of the rack, then using my angle grinder cut 1/2" deep slot in one end and a female match in the other. Wel it
together, quick clean with a grinder and away you go.
The tube was just a 90 degree cut, butt welded.
Although this sounds horrible I,m sure my weld is much stronger than the the weakest part (the tiny ball joint which fits in the rack end) and where
its cut it cannot foul the bush in teh tube as it does not reach in that far.
Yes I needed rack extensions, but then I made my bones 2" wider anyway.
I,m not saying thats the way to do it, probably better getting a new thread cut on the cut end, its just how I did it.
Regards Mark
[Edited on 20/5/06 by mark chandler]
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JoelP
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| posted on 20/5/06 at 08:58 PM |
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it seems to be an internet myth that the nk2 one fits as is. I got told it once, couldnt make it work and then got a sierra one shortened. Can anyone
confirm they have fitted an unmodified mk2 rack and not suffered bump steer?
ps my car came with a rack that i think is escy mk2, and it had dreadful bumpsteer, it was about 3 or 4 inches too long.
[Edited on 20/5/06 by JoelP]
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RichardK
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| posted on 20/5/06 at 09:13 PM |
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I'll let you know in about a year 
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Peteff
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| posted on 20/5/06 at 11:16 PM |
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Mine's got a mk2 rack
What's bump steer?
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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DIY Si
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| posted on 20/5/06 at 11:22 PM |
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Mine'll be a mk2 rack, but I'm running a +4.
Bump steer is the effect of the rack moving the steering arm in/out as the 'bones move up/down, ie as one side compresses, that wheel steers
away from the car. Most production cars do it, but most don't notice it.
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JB
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| posted on 21/5/06 at 09:19 AM |
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Narrowing Steering Racks
I too narrowed my first rack by cutting and welding. And has been stated the weld is probably stronger than the weakest part of the ball joint on the
end........but..........it still scares me to think about the consequences of anything not being done correctly.
If welding the rack I think you need a deep V to ensure penetration of at least 10mm, a gentle pre heat of the area then quite a few runs of weld to
fill the V and then let everything cool down nice and slow.
Then pray the rack is still straight and if not try to straighten it.
A straight rack is important.
I would never cut and weld a rack again but get a new thread cut and the correct holes bored in the end.
I kmow this is a Locost car building forum but a custom made rack to your dimensions can be had for around £200 (or it was when I bought mine some
years ago) from Titan.
Remember if your brakes fail at least you can pick which tree you are going to hit, if your steering goes..........
John
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omega 24 v6
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| posted on 21/5/06 at 10:04 AM |
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No disrespect to anyones workmanship but I don't favour the cut and shut way.
What threads are on the rack end and do you cut the 3 or 4 inch from one end only??
If I went this route the steering downlink would clear everything. Failing that I do the same as Richard K and 2 years down the line wonder if I need
to redesign the thing or put up with (possible) bump steer??
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JoelP
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| posted on 21/5/06 at 10:49 AM |
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pete, without sounding cheeky, any chance of a photo of the front of your car? I cant understand how your is different to mine.
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Peteff
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| posted on 21/5/06 at 02:31 PM |
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If it ever stops raining I'll take some . It's outside under a sheet at the moment and somebody's cat is living in it.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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