Community Forums

Bob_C · 12-20-2018, 07:53 PM

We used to have brake machines that had a grinder attachment for arcing....haven't seen one in years...also have tapped the backing of the shoes with a hammer to reconture .....not perfect, but better...

mobilemike · 12-20-2018, 09:07 PM

Quote:

Originally Posted by hclarkx

Yes, but don't forget, my axles are a bastard Dexter 4000# model. Etrailer had to special order the backing plates and drums from Dexter. That took over a month. The $190 per wheel complete (populated backing plate, drums, and bearings) seemed in line with the more common 3500# units listed on their site so I didn't quibble. I think the price was the same direct from Dexter. I didn't find another source for this limited edition axle.

My biggest gripe was that the shoes were apparently not ground ("arced") correctly because my controller was on 10 with weak brakes the first 1000 miles and didn't get down to 5 until 2000 miles. Next time I'll check to be sure the shoes are ground properly.

I really thought Dexter should be able to spec a 5200# axle pair that would give me a loaded torsion bar deflection as the original 4000# axles but they said they could not.

Yes right!!!!
I remember your brakes are bastards. And expensive bastards at 200 per wheel. That is too bad. There are other axle manufactures than dexter you might try. At your price for brakes I would try really hard for a swap.

I may be thick but explain again what the impediments to changing axles is?

Sorry in advance if I am being dumb. I am trying to help.

mobilemike · 12-20-2018, 09:16 PM

Quote:

Originally Posted by hclarkx

but nobody could tell me how high my rig would sit with the new axles. Dexter doesn't provide enough data for me to calculate the required torsion bar unloaded angle to stay close to my level ride height. Several phone calls to Dexter didn't help.

Got it!!!!!!!!!
You will need to call an installer and trailer fab shop to get the unloaded and loaded measurements of the torsion style axles.

In motorcycle suspension terms we call that static sag.

They should be able to tell you where they set the unloaded angle of the hub to axle for a specific load. Mybe a secondary supplier like Potter Webster will be be able to give you that info.

Bob_C · 12-20-2018, 09:19 PM

Go to the Alko site...

hclarkx · 12-21-2018, 04:39 PM

Quote:

Originally Posted by mobilemike

They should be able to tell you where they set the unloaded angle of the hub to axle for a specific load. Mybe a secondary supplier like Potter Webster will be be able to give you that info.

Yes, should. Dexter apparently does not have software (or look-up charts) to design a system so I set it up in a spreadsheet. In the end I didn't have quite enough data. As I recall, the key missing piece was the torsion bar angular stiffness (spring constant). Having that would let me determine the angular deflection for any given starting angle and load. I tried to back calculate the spring constant from other data with no luck. The performance brake guy said he could not get ride height out of Dexter either. Other's might be able to determine this but I'd need some confidence since three's no gong back once an initial unloaded arm angle is selected (it's welded to the torsion bar and thus can't be changed). The saddle brackets on the 5200# axle are taller than on my 4000# axles so I could end up with the 5er too high and no easy way of lowering it other than chopping down the saddles. Doable but messy.

It's a tricky design task because the horizontal component of the arm length is different for each of the five starting angle options and it changes as load is applied. My spreadsheet took care of this but I needed the torsion bar stiffness. I asked Dexter for this specifically but they didn't know it.

For sure somebody could not do this correctly. When my 5er arrived, I had only 1.75" between tire and the plywood above (5er unloaded) when Dexter specifies a minimum of 3 inches. My tires did hit a few times before I added 3 inches between the frame and axles to get the 5er level. I don't know if that was a FR or Dexter miscalculation. I think the proper 5200# no-load angle would make me very close to level without the lift kit. I had to make my own lift kit since Dexter does not have one for the 4000# axle that I have.

Thanks for the help. I might tackle this problem again before needing new brakes. Dexter did put me through to an engineer. Maybe next time I'll get better help; or maybe they will have software or charts to do the job.

hclarkx · 12-21-2018, 04:50 PM

Quote:

Originally Posted by bob caldwell

Go to the Alko site...

Thanks. Interesting. Dexter now owns Al-Ko. AL-KO

I did not look beyond Dexter last time. I may have new options now.

One other issue I had with the 5200# axles was a 6-lug pattern while may wheels are 5-lug, so I would have needed new wheels in addition to $3000 in disk-equipped axles. Though Performance Brake called Kodiak and there was prospect of a special order 5 lug disk for the 5200# axles.

Maybe Al-Ko will have a solution. Thanks again.

IC2 · 12-22-2018, 05:28 AM

Quote:

Originally Posted by hclarkx

Thanks. Interesting. Dexter now owns Al-Ko. AL-KO

I did not look beyond Dexter last time. I may have new options now.

....and now both owned by Lippert (LCI)

mobilemike · 12-22-2018, 10:38 AM

Does Dexter list suspension travel loaded?

If this were summer I would have at least one boat trailer usually more with torsion axles here at the shop. I could do some measuring for you with specific weights and angles.

Bob_C · 12-22-2018, 12:17 PM

4000 lb ones, the standard unloaded angle is 22 degrees...

LargeMarge · 12-22-2018, 07:38 PM

My buddy in Nevada modded her Deuce-and-a-half to disc brakes after she bobbed it. She went through a lot of trial-and-experimentation, for example she needed to mod the booster for correct blow. She says it stops ten-times better but would never go through it again.

IC2 · 12-23-2018, 05:28 AM

Quote:

Originally Posted by mobilemike

Does Dexter list suspension travel loaded?

If this were summer I would have at least one boat trailer usually more with torsion axles here at the shop. I could do some measuring for you with specific weights and angles.

No. Suspension travel is dictated by the trailer manufacturer and how he placed the actual trailer 'box' on the frame which is now more often then not, a Lippert. Our 12,000 pound 5er, 38' long used to bottom out on the 'box' since Keystone was dumb enough to spec 5200 pound axles. First I added a 1" spacer then when that only just helped, installed a 6000 pound set of springs which then did the job, I also kept the spacer since the RV would tail drag occasionally. That too seems to have (mostly) worked

mobilemike · 12-23-2018, 10:26 AM

Quote:

Originally Posted by IC2

No. Suspension travel is dictated by the trailer manufacturer and how he placed the actual trailer 'box'

Suspension travel is dictated by how far the rubber cushions will allow the hub stub to rotate in the axle tube.

If keystone screwed up and installed the axle so it hits the trailer that is on them.

hclarkx · 12-23-2018, 01:48 PM

Quote:

Originally Posted by mobilemike

Does Dexter list suspension travel loaded?

Dexter and Al-Ko both list unloaded and loaded suspension travel, but neither tells you at what loading that is. Al-Ko says "rated load" which suggests 4000# or 4400# (U or H model) which is probably close enough for my purposes since I'm at 3750# (85% of travel on the 4400# axle if the travel is linear). Dexter 5200# axles cover 4000# to 5200# so who knows at what their "loaded" weight is (they don't).

I could adjust my lift during the install if I know where I'm going to land, but having to install the axles and put my weight on them and then take them off to add lift would be a pain.

Interestingly the Dexter torsion axles are actual torsion bar with rubber inserts for damping (according to Dexter). Al-Ko says the rubber inserts are the spring in their axles. This makes me wonder how linear they are or whether they will sag a bit after a while. But, again, predicting height with 3750# on 4400# axles should be much safer than estimating height with 3750# on 5200# axles.

I wonder if the Al-Ko axles will continue to be available? Maybe Dexter is buying market share and will toss the designs. Or should I say Lippert. Though Lippert did not have torsion axles before the merger, right? So they will keep one or both.

IC2 · 12-24-2018, 05:40 AM

Quote:

Originally Posted by mobilemike

Suspension travel is dictated by how far the rubber cushions will allow the hub stub to rotate in the axle tube.

If keystone screwed up and installed the axle so it hits the trailer that is on them.

You are 100% correct for a torsion axle. !00% incorrect on a leaf spring axle which our 5er and probably 90+ percent of all towable RVs are equipped with and pretty well explained in my post. There are NO 'rubber' parts in a sprung axle assembly unless you have a Morryde, Dexter or similar equalizer.