WHY THE C-DORY GODS MADE TANDEM TRAILERS!!

BrentB":2b9ox4li said:
guestimate - an estimate that combines reasoning with guessing
Click to expand...

Thanks Brent. There's also a SWAG. A Shixxy Wild Ass Guess... BTDT!

Merv, thanks for the link, I'll go review my Calculus of Variations and Complex Differential Equations Books and think on it.

Mike, as usual, a practical solution. Just don't know when I'll have that thing back on the trailer again. I think I'll move it back 6" and try it. As for Side to side, not much leeway on the TC with the tunnel on the rack of the trailer. only about an inch or so to move if adjusted right. In the meantime, having fun with the best (Arguably) TC255 on the East Coast and maybe any Coast.

Charlie
 
Charlie, from a guy that's moved a lot of bow stop/winch stands . Go no more than a couple inches at a time . That will make a substantial difference . The height of the hitch to level the trailer is also important to get an even load on the axles. Put a level on the frame .
Try to get the bunks even with the end of the sponsons .
Marc
 
I tried to find out what a sponson was so I searched on Google. The second result was "interesting". You could spend all day reading it, but then you'd be bat s**t crazy. PM me if you're curious and can't find the site.

Sorry for the tangent!
 
Charlie, My boat is 11,300# on the trailer... The factory calculated the position of the king post during the design phase aiming for 10% on the tongue (this was their first Ranger Tug)... The weighed the tongue and it came out to 970#... The trailer engineer called that good enough... The boat has been pulled some 5000+ miles at that tongue weight since then and it seems perfect..

I don't see where fifty or a hundred pounds one way or the other in your tongue weight makes a real difference in the tandem tire loading since that is an approximate one percent shift ***It may make a difference for the suspension and tires on the tow vehicle*** but I doubt that 100# overloads one tandem axle compared to the other... Your tire failure was dry rot in the tires...
 
I had some how missed Charlie's reply on this---and he was kind enough to send it via a PM.

My feeling is that one of the critical issues is the levelness of the trailer. Yes, the tongue weight is a bit more than I would like to see. One of the lessons of all of this is that TORSION Axel trailers do not equalize the weight. Thus, there most likely more weight on the trailer's front axel. I don't know how much, since the two axels were not weighed.

When I went to the weight distribution hitch on the C Dory 25, one of the goals was to make sure that the trailer was absolutely level. The equalizer hitch is adjustable, so that the ball height can be raised, but also when the spring bars are chained up,it brings the trailer to level--by raising the rear of the truck and putting more of the truck weight on the front wheels (and a little on both trailer wheels (in leaf spring trailers)--with the Torsion axels, I don't know, if keeping the axels level will tend to equalize the weight, or if there will be even more weight on the front axel when the equalizer hitch is used.
 
Torsion axle trailers must be level when towed.

Another trick from when I was in the RV business (is there anything he hasn't done, you ask?)-

measure the top of the frame between the two axles. Since the pivot point is about there, it should be very close to the same at various angles when the trailer is close to level.

Then measure the hitch height on the truck, taking into account where the hitch on the trailer is in relation to the top of the frame.

We always guess at about 2" higher on the ball than the trailer to account for tongue weight. Your mileage may vary. If this dimension is off, use a different hitch stinger to get the correct height.
 
Just read about weight distribution hitches and blow outs. How about air springs, I installed them on my truck, and it is easy to level the truck when the weight of the trailer depresses the rear. This also keeps your head lights from being to high with the trailer attached.

ED on "Rambler"
 
Thanks ED. I don't think air springs are the answer, the "truck" doesn't go down more than an inch or two when the tongue weight is on it. The tires all have 85psi in them (max listed on the sidewalls of both trailer and "truck" tires) when towing. I think it was just a combination of too much weight on the front of the trailer and the age of the tires.

The latter has been corrected (new tires) and the former will be prior to loading the trailer again.

Charlie
 
So do most people run higher pressure in rear truck tires when towing? Or is it only when the tongue weight is very high?

I haven't checked ours since we got the truck a little while ago (2004 Silverado 1500 4wd) and didn't realize it was safe to go over what I was used to (35-40 psi).
 
Don't know about "most" people but I do and I know Dr. Bob does. And to quote myself, the two best rules are:

1. Dr Bob is always right (at least in my book)
and
2. See rule #1.

I think it's "safe" up to what the tire says on the side for Max pressure. After the tow, I lower mine to what is a "comfortable" and softer ride.

Charlie :mrgreen:
 
As Charlie noted, I always run higher pressure on the rear truck tires when carrying a load. If it is a SUV, or cross over, then probably not, unless there is excess load in the rear.

For my Road Trek I ran more in the rear tires, because of the increased weight with the RV conversion of the 3500 series van. There are graphs or tables which will tell you how much air you should have in tires (and singles vs duals) for each specific weight range. Also the pressure is adjusted for speeds run. I just purchased a new air compressor, because the old one was not really up to the 110 lbs I run in the rear duals of my RV. (Max rated at 120 PSI, but for the weight I run, the 110 is correct--100 PSI in the front tires However these are 22.5 load range H tires rated at up to 6700 lbs each).

Here are light truck tables for Goodyear tires:
http://hmcclub.homestead.com/Goodyear_Tire_Inflation___Load_Charts.pdf
 
Just towed a CD-22 Cruiser 225 miles. Half freeway and half 2 lane hiway. Checked axel temps several times at stops. Front axels were in the mid 70's and rear in the low 90's, simular at each stop, with little variation. Trailer frame is measured 2 inches higher at the tongue than at the end of the frame, under the transom. Is that 2 inches what is making that difference? Sees like a lot but the tandems are new to me I am working on getting the trailer level. Just having a hard time procuring the correct hitch hight.

Harvey
SleepyC :moon
 
Harvey, as far as I know it is important that the trailer be level, especially if the suspension is a torsion arm type rather than leaf springs. Apparently an off level trailer of that type can affect the wheels in some way. I don't know more, sorry.
 
Harvey-

Simple mechanics: lift the tongue, more weight transfers to the rear axle, and the bearings take more load and heat up more.

From the mid-70's to the lower 90's isn't a lot of difference to a bearing or grease, but I'll bet if you level the trailer out, the temperatures will come closer together, if not equal out.

Is all you have to do is to change your drawbar and ball height?

Joe. :teeth :thup
 
Thanks guys. I Should have noted it is a leaf spring trailer. I am going to get it level for and aft and then see if that takes care of the difference. If not, I may need to move the post, but hope to not have to do that because the transom is sitting right about where I want it. I could move the boat forward, maybe an inch if I have to but I am liking the ball and hitch height adjustment first.

Harvey
SleepyC :moon
 
Thanks. Just brought the boat home. Front of trailer is 1.5" higher than rear. Temps were ~15 to 20 degrees higher on the rear hubs. Temps were 65 - 70 front and 80 - 85 rear. Next pull will be with a level trailer.

I am working on a level stinger set up. Should have it soon.

Harvey
SleepyC :moon
 
Just put new tires on the trailer. Went up one size, so the tire height is taller, and raised the axle about 1/2 inch. This should make the trailer level. Will be towing this week and will be checking temps, bearings and tires.

Harvey
SleepyC :moon[/b]
 
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