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With Scott Rossow
Time for Bumpstops
 When you install YJ springs on a Zuk you need bumpstops. The YJ
springs are so flexy that they invert and damage to springs.
Also, if you have shock hoops the tire will rub on both the hoop
and the shock. Then there are the fenders to worry about.
 Stock Zuks have bumpstops; they mount at the frame and probably
work perfectly. It has been so long since I had any on my
tintop that I don’t even remember what they looked like.
Bumpstops didn’t really matter with the overly stiff spring pack
that I was using before the YJ’s. There was no way in the world
those springs were ever going to invert—or flex much either for
that matter, but now I need to fab up some new ones.
I
measured the distance between the axle and the frame and said to
myself “No problem”. Little did I know the aggravation I was
getting in to. The length and placement has to be figured out
so that they will work correctly. I had 8” between the axle and
the frame in the front so I figured that one half that would be
about right. I dug through the spare parts bucket and found not
one, but two sets of stock front stops. I took that as a good
sign, everything I needed right there at hand. The stock ones
were 2” tall and had bolt holes and everything.
Next,
I dug through the scrap metal pile and found some flat stock and
some 2” square tube. I cut a 2” long piece of the tube and then
traced the mounting part of the stock bumpstop onto the flat
plate twice and cut out two pieces, one for the top and one for
the bottom. Then I drilled mounting holes in both to match the
stock stop and finally I welded them both to the piece of tube.
Then I bolted the stock stop onto my new bumpstop. Looked
pretty good, so good I made another one, no test mounting or
anything. When they were both made and painted I took them out
to the zuk to mount them up to see how great they were going to
work.
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 This
is where the cussing started. When I mounted the long travel
shocks last month I trimmed a very little bit of the bumpstop
mount to clearance the shock body. Unfortunately that very
little bit was where one of the original bolt holes was. Since
it did not really look like it was going to line up bolted on
like that anyway I turned it about 45 degrees and drilled a new
hole and then bolted it in place. Time for a test drive into my
favorite ditch.
Well, 4 inches was too darn short, everything still rubbed, I
mean everything, the tire was on the shock and mount and the
bumpstop was not even touching the axle yet. And from the looks
of it, even if the bumpstop did reach it would be in the wrong
place on the axle. It would be hitting the outside u-bolt on
the backside, not centered up like I would want.
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 I
had two problems to figure out. First, it had to be longer if
it was going to work and second the stock mounting point was way
wrong because of axle re-location from the YJ install. I did
what I should have done originally and jumped on-line to see
what everyone else was doing. It seems that 3 inches was a
better distance between the axle and the bumpstop. It also
seems that most of the time the bumpstops were being welded
either to the frame or, more often to the top plate holding the
spring to the axle. I am not confident enough in my welding
abilities to weld to the frame yet and there was no way I was
welding anything to my still “shiny” new Sky top plates
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 I
pulled the front wheel off to look everything over. Holding my
too short first attempt in different places I observed that the
rear of the u-bolts were in about the right place to mount the
stop. So I re-sized the two mounting holes to fit over the
u-bolts and bolted it to the axle. Problem one solved, now it
was going to line up with the axle frame just about right.
Next, to deal with the length I went back to the scrap pile and
pulled out some flat stock 2 inches wide and a half inch thick.
I used the factory bumpstop again to mark it in the right shape
and then cut it out and drilled the mounting holes. 4.5 inches
long and in the right place. It’s going to work this time so
back to the ditch!
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 All new cuss words this time. It still rubbed in all the wrong
places, but at least when the bumpstops almost hit the frame
they were in the right place. Time to make them
longer...again. For a simple task this was taking way too
long. I kept telling myself any job worth doing and all that.
I dragged the half inch stock back out and cut two more pieces,
this time to go under the bumpstop, I drilled holes for the
u-bolts and bolted everything back together. The current setup
was, from the bottom: spring plate, ˝ inch spacer, 2” of tube,
1/2” spacer, rubber stock bumpstop, for a total of 5” of
bumpstop leaving only 3” of space between the stop and the
axle. Back to the ditch.
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 ALL NEW CUSSWORDS! It was still hitting on the shock hoop mount
and the shock. Time to re-think this mess all together because
the 5 inch bumpstop should be all the bumpstop I need, why was
it still hitting? I was starting to think I needed wheel
spacers to push the wheels out further when the light finally
dawned on me, an epiphany of sorts! I was doing all this
fabbing and testing with my 33x12.50’ AT’s and 15x8 aluminum
rims, with 4 inches of back spacing. The rubbing had been so
severe with the smooth sided street tires that I had been
hesitant to put the swampers on because I just knew one of the
oversized lugs was going to grab the shock mount and blow up a
birfield.
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 Now that the bumpstops were in place I put the 33x13.50 swampers
and headed back to the ditch. EUREKA! The tire barely touched
the shock when fully stuffed into the wheel well after I drove
it into the ditch. Success! I guess the 15x8 rim with only 2.5
inches of backspacing made all the difference. I sure wish I
had thought of it earlier.
 After all that experimenting with locations and sizes it was
easy to make the rear bumpstops. I measured and cut the pieces
out of the same material as the fronts, drilled the holes and
bolted them in place. One build, one test ride and everything
was just right. No more inverted springs, no more rubbing in
the wrong places. Bumpstops are a good thing, once you figure
them out.
 The good news is the bumpstops are built, mounted and working
perfectly. The bad news: I saw that my front driveshaft was
seriously hitting on the transmission mount cross member and
that my rear brake line was way too short. Tune in next month
and find out how I fixed this one. Hopefully I will know by
then…
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