Jump to content

saturn rack swap


Recommended Posts

ok, after months of reading and ridiculous amounts of research on how to correctly make a McPherson strut steering set up correctly i kept coming back to the same conclusion. Some caster is good, anything more than 5 degrees of camber is for show and bump steer is bad. the factory set up really isnt too bad but you cant modify much (easily) for more steering angle other then shorten the knuckles, which in turn adds bump steer and incorrect ackerman. our lower control arm pivot point on the cross member is about 22 inches hole to hole. the pivots on the stock tie rod set up are at 20 inches and parrellel with the control arms vertically and horizontally with the wheel straight. that means the knuckles have an inch of offset of the ball joints for an ackerman effect while turning. theory suggests that the control arms and tie rods be same length and angle(s) so that means that the rack and pinion must have pivots at 20 inches. one of few cars that have that is a geo metro, and that rack looks pretty pathetic to me. there is almost nothing that has a rack that is of decent steer ratio, strength and powered that is 20in or less (you can make anything longer). after looking at tons of cars in the pick and pull and measuring and checking and comparing i noticed the same thing on every vehicle i looked at. none of them use the theories ive read. not a single car had the rack at the same tie rod angle as lower control arm angle while looking at it from the top. they did how ever have the same angle while looking at it from the front. on some cars this changes with suspension movement because the tie rods are a DIFFERENT LENGTH then the control arms (honda pilots are about 6 inches longer on each side). that means that some manufacturers are intentionally adding some kind of bump steer to the steering for normal road handling.

 

this basically got me thinking. people are using 240 racks (with success) and i know the pivot points are wider than the quest cross member pivots, but narrower then the 240 cross member pivots. ive heard of honda racks being used and none of them i found (darn near all yr civics and accords) are under 22 inches for pivots and the control arms are close to 24in pivots on the cross member. 99-03 grand ams and related plateforms are at 23.75in for racks, 25.5 for cross members. 98+ sl/sw/sc saturns are 23.5 at the rack pivots and 25.5 cross member. this list could go on forever but the gist is is that the quest is narrow (ironic to wide body owners i know ;) the fact is is that if we want to use a super common rack on our car we have to figure out more than how we are going to attach a rack to the cross member, we must figure out tie rod angles, lengths, and adjustability but above all there will be two things we must deal with. some amount of bump steer and the amount of ackerman you want while turning. these two things go hand in hand and are important, but i will not be explaining all of this here, you have the internet and i believe in you :) instead i will show you what i used and why i used them. if there is anything here needing correcting i am more then happy to change what had been written

Link to comment
Share on other sites

i used a power rack out of a 00 saturn sc2 because its somewhat narrow, extremely common and the way it mounts is oh so simple (and super easy to take out of the car). some pictures are crummy and im sorry..

 

//i first used a piece of 1.5x1.5 angle iron to mount the rack too. its just two holes for some 9/16 bolts. the rack holes were enlarged too. this is it clamped to the cross member

http://i668.photobucket.com/albums/vv44/skunkworks_1/conquest/CAM005381.jpg

 

i was using bolts to center the rack TO THE LOWER CONTROL ARM HOLES, NOT THE CROSS MEMBER. the cross member is not centered in our cars for those who do not know.

http://i668.photobucket.com/albums/vv44/skunkworks_1/conquest/CAM005411.jpg

 

weld that baby on to the top of the pinch weld and make sure its at a 15 degree angle or so. this will come in later.

http://i668.photobucket.com/albums/vv44/skunkworks_1/conquest/CAM005441_1.jpg

 

the gap at the top should be filled with a chunk of metal and welded in place too.

http://i668.photobucket.com/albums/vv44/skunkworks_1/conquest/CAM005431.jpg

Edited by clow340
Link to comment
Share on other sites

(the car gets oiled every year before putting it away so its supper dirty, just fyi)

 

make sure it all looks right before you weld everything up, here i have the arms and lower knuckles on the wrong sides and i caught it before i made any mistakes :)

 

http://i668.photobucket.com/albums/vv44/skunkworks_1/conquest/CAM005451.jpg

 

i probably cut off a good 1.25 inches off the inner tie rod and an inch off the ball joint to get the length close. i will be getting a die and running the threads up higher on the inner tie rod so i can use an unmodified ball joint but for now, i made due.

http://i668.photobucket.com/albums/vv44/skunkworks_1/conquest/CAM005471.jpg

 

this is the first test fit. it worked pretty good but the rack is too close to the lower control arm mounts and causes negative ackerman. its also too high and causes negative bump steer(its literally less than a quarter inch too high for my liking). these are both cured with a spacer.

http://i668.photobucket.com/albums/vv44/skunkworks_1/conquest/CAM005531.jpg

 

no spacer, just more pics

http://i668.photobucket.com/albums/vv44/skunkworks_1/conquest/CAM005541.jpg

 

a couple different sizes, never know what you need till your down there. i made some 1 inch, some half inch and some quarter inch and figured id mix and match till i found the settings i liked.

http://i668.photobucket.com/albums/vv44/skunkworks_1/conquest/CAM005891.jpg

 

with the spacers. this is where the 15 degree angle comes in, not only are you spacing it out but your moving the rack down, thus correcting both the ackerman and causing some positive bump steer. positive is the lesser of the two evils, but both kinds of bump steer are bad...

 

http://i668.photobucket.com/albums/vv44/skunkworks_1/conquest/CAM005921.jpg

 

http://i668.photobucket.com/albums/vv44/skunkworks_1/conquest/CAM005931.jpg

 

http://i668.photobucket.com/albums/vv44/skunkworks_1/conquest/CAM005971.jpg

 

http://i668.photobucket.com/albums/vv44/skunkworks_1/conquest/CAM005881.jpg

 

here is what the length of the inner tie rod came out to after cutting

http://i668.photobucket.com/albums/vv44/skunkworks_1/conquest/CAM005981.jpg

Edited by clow340
Link to comment
Share on other sites

i will have to get pictuers of steering angle on wednesday, for some reason i didnt take any. but the set up is all done and works good, had to completly grind the stops off of the knuckles, and that made me happy. its very smooth and takes up about the same amount of room as the stock set up does underneath but far less next to the frame rail, because theres nothing there anymore. im also using the UNMODIFIED steering joints out of the saturn with the stock steering column shorted (that will be another post). hope this helps someone with their own project.

 

on a side not, the lower knuckles are made of steel and can be shortened like what the 240 guys (and many others) like to do, but its safer, because its steel, not iron. steel. which can be welded safely. unlike iron. which isnt steel. welded iron scares me. ok im done.

 

 

p.s.can someone please post a pic of stock steering angle lock to lock to compare? i was a dummy and didnt take any before shots. thank you

Edited by clow340
Link to comment
Share on other sites

 Share

×
×
  • Create New...