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Axle Alignment
rasbury
Member Posts: 8,242 ✭✭✭✭✭
I had a previous thread on this but was kind of mixed in with someone else's so I thought I'd start my own. My 270 has a twin axle trailer and the front two tires are getting really chewed up, rear tires show no weird wearing at all. From the previous thread, it was mentioned that the axles were not tracking with each other. So, I looked at the boat and although not very scientific way to measure, I have a large T square for drywall and I laid the straight edge from left to right against the front tire to get a sense of where the rear tires are in relation- it was over an inch difference easily. I understand depending on the weight distribution, this is not entirely accurate and would need to pull the tires off and probably align with the calipers. At first I thought this would be to large of a task but since there is no front to back adjustment, it is only from left to right one of the axles needs to move- is this a task that if I do it myself and line them up with a straight edge with which ever axle is centered on the trailer, will that be good enough or is there some much more scientific what to do it?
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PC BYC, Holland, MI
PC BYC, Holland, MI
PC BYC, Holland, MI
get weight of trailer off tires- jack stand the frame in four places, posting where a square can be drawn within the frame, and a fifth stand on the tongue if required.
from a fixed position- say, on-center of the mast, measure to your leading edge of the leading wheel lip. do the same on the other side. they should match precisely. there is enough room to loosen shackles (if equipped with leaves) or punch up the torsion bar (if equipped with torsion) the difference... measure other axles same way, adjust same way...
you are not concerned with camber, you are not concerned with castor, and you are not concerned with toe. these are not steer wheels. they are fixed solid axles... the axle manufacturer should have produced an axle that when properly constructed, and based on it's rating, is set in a non-adjustable manner to accommodate camber... toe in isn't relative and castor isn't relative.
as mentioned before, the biggest place people screw this up is when bushings start to fail, and the hinge that exists on leaf spring axles hangs. it will make measuring accurately next to impossible. hit them with some silicone lubricant spray, and whack them with a mallet while the tires are off the ground.
see that hinge in the front?
it can be a bit of an aggravation, especially if it has been dunked in salty drink and not maintained. you gotta make sure they're matching in position from side to side.
this, is a torsion bar trailer axle (not like a vehicle torsion bar axle)
they, too, are fixed. Check the key for wallow. replace spindle/key assembly if needed.
heat was mentioned... heat will tell you alignment in a heartbeat... an IR temperature gun is invaluable in this use... once inflation and balance has been addressed and confirmed, the offending wheel/tire will run a lot hotter than the true tracking one. measurements across the contact patch will tell you what needs to be adjusted and where.... if its measurements match up as addressed above, it's your camber you're having issue's with, which means it's most likely an issue with your wheels/tires and not the axle.
if you're wearing **** one tire across the tread, and it's a braking axle, i'd want to get a look at the condition of the braking mechanisms.... that temperature gun comes in handy again here, too.
More to follow, sounds like @212rowboat is our resident trailer expert!
My thoughts exactly, my trailer is due for a tune up as well, but it ain't happening this weekend!!! I have put over $5K worth of new parts and work into this trailer. if you were local, I have a guy I could send you to, he is awesome. That is all they do is boat trailers. He took my broke down trailer and basically made it new again. New torsion springs, new brakes, bearings and tires, plus the trailer wasn't supporting the weight of the boat very well, so he bolted in two 1/4 inch thick, 16 inch long, and 8 inch wide plates of stainless steel. used many bolts, trailer is rock solid now. I just need a new winch, strap and bow stop.
6 lugs is around 5000#
GVWR of trailer is 9990, payload of 8600. Read a post from @Alswagg on the same subject and boat that the boat should be around 8300 #, fuel about 700 and 1400 for the trailer. So that puts the weight at around 10400. A little over, axles estimated at 5000# each. Wish I had a little more to work with but I would think marginal at worst. I am posting pictures of the tires and also a view of the suspension that looks like it is leaning a little to the rear. With regard to the tongue wight, I have an adjustable hitch. So if I lower the hitch a notch, that will level the rear suspension some I assume and would be the same effect as pulling the boat forward on the trailer. My transom is already past the end of the bunks so I don't know how much further up I should try to pull it- is lowering the hitch the same effect as far as the tongue weight? Once I get that suspension leveled out I will make the venture to the truck scales and see what that tongue weight is as well as confirm
it isn't, though...
is it a torsion setup or leaves? I can't tell on this screen by the pictures... if it's full axle, and it's one of those shaped ones, it may stand to reason that the V isn't plumb.
if you've been dragging it around unloaded, and with a trailer brake engaged even slightly, I could see that kind of wear, too. it wouldn't take long for that kind of wear either if the brakes are dragging.... are both axles braked or just one?
leaves.... full axle...
but is it a drop axle? meaning, does the center cap center on the axle, or is the axle's center below the wheels center by use of an offset plate/bar?
break out the chalk....
draw a line on the pavement/concrete that runs the length of the unloaded trailer from ball hitch to a foot or two behind the furthest back frame brace. draw four more exactly parallel to the first- the inside lines the measurement of the inside of the tire, the outside lines the measurement of the outside width of the tires.
use your chalk and a carpenters square to make 90* line through all the parallel lines that match where your axles would be.
mark your axles dead in the middle with the chalk... mark your rear most frame brace dead center with the chalk.
roll your trailer directly on top of your art work- with the hitch splitting the center line, and the middle mark of the rear most brace also spitting it.
your tires should be dead in between your parallel lines.
the perpendicular lines should align to the center caps of the wheels.
if not.... adjust it.
now... load your boat.
park it atop the same drawing, and see if it still aligns.
you could have a bent axles and you could have bent spindles. I can't tell by the pics on this screen if your wear is scalloped or smooth- scalloped could be something else altogether.
the weight on the wheels is not resting on the spokes from 3 oclock to 9 oclock as it would seem- weight is actually hanging from 9 oclock to 3 oclock.. as it is, when weight hangs, it works something like a plumb bob and hangs vertical which makes seeing any offset, as a result of deterioration, hard to see.
i'd rec you lay under the frame right before or after the axles and look carefully at the wheel, and maybe even run a fingernail down the spokes and feel for a little ridge. if there is a consistent ridge there is bad things in store for you and those wheels. the metal is fatigued and about to go. maybe it will give you further warning, or maybe it won't before it pops the rims free of the face plate (if that ridge is present)...
for a saltwater rig that sees a lot of dunking and load, aluminum wheels are a must... balancing steel is almost a fools game, as they deteriorate and shift constantly.
what you call scoop is scalloping- it is indicative of either bad balance, or play in the wheel bearings allowing lateral movement inside and out while moving- it's almost imperceptible to a naked eye, and only needs maybe five to ten millimeters of play to scoop them right up... if what i'm saying is correct, the spokes loading and unloading from hanging the weight to being driven into the ground (with the rim/tire in between) would force the outside edge to bite. it would also stand to reason since all wheels match and are presumably the same age/exposure to same use, they would all be having the same issue.
if you need to move the weight further back to eliminate tongue weight, you're only going to want to move that tower an inch or so. geometry isn't my strong suit, but experience tells me that an inch forward or back is worth at least 10% of the total hitch weight. looking at your rig attached, you may want to consider bagging the rear axle on your tow pig.... you can pick up some good bridgestone pneumatic bags for less than $200, or add an onboard compressor and control for around $500... it may seem like a needless expense, but once you use them? you'll wonder why you haven't before- and you'll want to tow everything in sight.
get away from surge brakes if that is what you have (can't tell by pics on this screen)... electric and a controller is the only way to go.
if you must use those axles (5k#) instead of bumping to 7k# axles and 8 lug, add another... it isn't as expensive as you'd think. the axles may be capable of the weight, but those six lugs wheels, unless heavy cast or spun aluminum, won't for very long. the axles are under tremendous stress, too. for trailers, they say that 10% margin east of the rockies is required, and 20% west... for a salt water trailer, I'd guestimate you want at least 25% margin due to wear.... you may wash them well after every use, as do I, but..... you dunk your boat and then park your rig at the ramp? the damage is done while you're out on your boat and long before you get home to wash it.