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Retarder Question

Is it normal when using the transmission retarder to hear air releasing like when braking? When I let up on the throttle I feel the retarder engage, and when I accelerate again I hear air venting just like when I let up on the brakes. I also noticed yesterday on a fairly long downhill with the retarder engaged that my brake temperature rose, even though I never touched the brakes. Is this normal?

Dave & Kathy Bennett
2004 U270
Dave and Kathy Bennett
2004 U270
Build #6253
1600W Solar
700 AH Battle Born Lithium
2015 Jeep Wrangler

No matter what happens, remember you always get the trip out of it.

Re: Retarder Question

Reply #1 –
Yes everytime retarder releases it vents air. Completely normal

Re: Retarder Question

Reply #2 –
Quote from: dsd –
Yes everytime retarder releases it vents air. Completely normal
Thanks. I couldn't find any mention of it by searching the forum and this is my first experience with a transmission retarder. I still don't understand why the brakes would heat up, though.

Dave & Kathy Bennett
2004 U270
Dave and Kathy Bennett
2004 U270
Build #6253
1600W Solar
700 AH Battle Born Lithium
2015 Jeep Wrangler

No matter what happens, remember you always get the trip out of it.

Re: Retarder Question

Reply #3 –
I too have no clue as to why your brakes are heating up nor how you are monitoring them? The brakes should only build heat when they are used and they are not unless you have applied them or you have a caliper hanging up. I do happen to check brake temperature with a hand held pyrometer but nothing while on the fly.
Scott

Re: Retarder Question

Reply #4 –
Are you saying the brake pads smoke or are you referring to the building of heat on the transmission temp gauge?
Dub McBride 1996 270

Re: Retarder Question

Reply #5 –
Quote from: dbennett9 –
Is it normal when using the transmission retarder to hear air releasing like when braking? When I let up on the throttle I feel the retarder engage, and when I accelerate again I hear air venting just like when I let up on the brakes. I also noticed yesterday on a fairly long downhill with the retarder engaged that my brake temperature rose, even though I never touched the brakes. Is this normal?

Dave & Kathy Bennett
2004 U270

You have a temp sensor on your brakes? Are you looking at the transmission temp gauge?  The trans temp will increase when using retarder


Dub typed faster then me.
2014 ih45  (4th Foretravel owned)
 1997 36' U295 Sold in 2020, owned for 19 years
  U240 36' Sold to insurance company after melting in garage fire
    33' Foretravel on Dodge Chassis  Sold very long time ago

Re: Retarder Question

Reply #6 –
Quote from: turbojack –
You have a temp sensor on your brakes? Are you looking at the transmission temp gauge?  The trans temp will increase when using retarder


Dub typed faster then me.
The coach has brake surface temperature available in the information center readout. I don't know how accurate it is, but I was only looking at the fact it changed when I wasn't braking. The only possibilities I can think of are a stuck caliper, as Scott suggested, or the readout is slow to update and was reflecting braking before I started down. Since I don't see consistently high temperatures (they fluctuate depending on the amount of braking) I am inclined to believe it's not a stuck caliper.

Dave & Kathy Bennett
2004 U270
Dave and Kathy Bennett
2004 U270
Build #6253
1600W Solar
700 AH Battle Born Lithium
2015 Jeep Wrangler

No matter what happens, remember you always get the trip out of it.

Re: Retarder Question

Reply #7 –
Since a dragging brake is even a remote possibility you should get a Infrared thermometer and check brake rotor temps when you stop and then you will be sure of  your rotor temps. A stuck caliper will cause heat that can be very expensive and a IR gun is around $20.00 at Harbor Freight. Majority of us carry a IR temp gun.
Dub McBride 1996 270

Re: Retarder Question

Reply #8 –
In my old coach after I had the brakes worked on by a guy that said he knew what he was doing but didn't, I started having brake overheating problems.  After a few coach bucks later and a trip to MOT they found the brakes were not adjusted correctly after replacing the pins and installing helper springs. 

Back to original  question, the brakes and  retard are not connected.  If retard is slowing you down, the temp of transmission oil will go up.  Once you apply the brakes I am guessing it will take a little while before you start seeing that temp go up.

2014 ih45  (4th Foretravel owned)
 1997 36' U295 Sold in 2020, owned for 19 years
  U240 36' Sold to insurance company after melting in garage fire
    33' Foretravel on Dodge Chassis  Sold very long time ago

Re: Retarder Question

Reply #9 –
I don't know about your newer coaches, but the brakes are connected to the retarder if the retard switch is on with my coach. More brake more retarder.
1999 40 ft. U-320 wtfe build 5563 Chuck & Lynda's "Rollin' Inn"  2030 watts solar
prev. mh's 71 GMC 5 yrs. 73 Pace Setter 1 yr. 78 Vogue 5 yrs 81 FTX 40ft all electric 18 yrs. 1996 Monaco Signature 3 yrs.
2014 Grand Cherokee Overland
Dream as if you will live forever. Live as if you will die today.  James Dean

Re: Retarder Question

Reply #10 –
Quote from: craneman –
I don't know about your newer coaches, but the brakes are connected to the retarder if the retard switch is on with my coach. More brake more retarder.
After reading the manual for the transmission, I see that there are a number of possible configurations for the retarder. One increases the amount of retard based on braking force, as you describe. I haven't felt that in my coach, but Foretravel may have changed how they set up the retarder over the years. That wouldn't affect what I was concerned about though, which is the opposite.

Dave & Kathy Bennett
2004 U270
Dave and Kathy Bennett
2004 U270
Build #6253
1600W Solar
700 AH Battle Born Lithium
2015 Jeep Wrangler

No matter what happens, remember you always get the trip out of it.
 

Re: Retarder Question

Reply #11 –
One way the retard works is when you push down on the brakes the retard kicks in to start slowing you down.  As you push harder on the petal the more retard effort you get, plus more effort from the brakes.

Another is where the retard is applied when you take your foot of the gas, once you give it throttle the retard is turned off, let off and retard is engaged again.  Have to watch out for this one since a lot of cruise controls will disengage when the cruise tries to go into coasting.

Third  is manual apply the  retard by the joy stick, the farther you move the joy stick the more retard you will get.  This is good for going down long hills, you can adjust your speed based on how much retard you are applying.  You just have to watch out and keep the transmission temp under control.  You can run the temp up to high if not watching what you are doing.
2014 ih45  (4th Foretravel owned)
 1997 36' U295 Sold in 2020, owned for 19 years
  U240 36' Sold to insurance company after melting in garage fire
    33' Foretravel on Dodge Chassis  Sold very long time ago