How to use the retarder in the 1988 FC

[Rick]

Sean, Have you read the ZF Retarder Threads? Your "Lever" moves up and down not forward and rearward. With the lever up and the Retarder in the on position, when you apply the brakes the Retarder is in the full on position. Try this: As you apply your brakes reach over and turn the retarder off or on. You should feel a change in the braking effort.

[Bill Pape]

Originally Posted by seanbirm01

So if I am foot braking with the retarder lever in the full forward position and the rocker switch in the on position - is the retarder actually functioning or does the lever.need to be pulled back some for the retarder to engage?

Yes it is a little confusing, but it works great with a little practice.
Re-read John McG posts,
Pull Lever "up" this is Off & leave it up, retarder rocker switch "ON", green light will illuminate when foot brake is on or lever is pushed down then tail lights will illuminate. Rocker on all the time lever up unless descending a hill.
If lever is forgotten and remains in a down ON position, the retarder will release with throttle pedal, but reactivate when off the throttle.
Drive it and practice.
Another way is to turn the rocker Off, push the lever down about 1/2, get up to speed , then turn the rocker ON, toggle Off/On/Off/On. you will catch on quick.

[Bill Pape]

Opps, did not see Rick's post , my post is more of the same.

[Clueless]

Originally Posted by birds_first

I think #5 may be an incorrect statement, with the rocker switch (power switch) on your retarder is functioning with the lever engaged in any position regardless of the use of the floor brake pedal.... With the rocker switch on the retarder will engage either with the foot brake or the lever; with the use of the lever only you have no mechanical brakes at the brake drums, if that make sence, but you are braking through the transmission.

I think you still have mechanical brakes available with the brake pedal, you just aren't using them if the lever is down.

[seanbirm01]

Practice makes perfect so that's what I'll do. Thanks everyone!

[birds_first]

Originally Posted by seanbirm01

So if I am foot braking with the retarder lever in the full forward position and the rocker switch in the on position - is the retarder actually functioning or does the lever.need to be pulled back some for the retarder to engage?

With the retarder power switch (rocker switch) in the on position the retarder will activate without you touching the mechanical retarder lever when using the foot brake pedal; also in the on position you will get retarder braking power but no mechanical brakes at the brake hubs when you use the retarder lever only. That is one of the main purposes of the retarder system to reduce the wear on the meachanical brakes. Go try it out and tell us what it does I have been averaging about 10K a year and I learn stuff in the coach everytime I hit the road. So will you Next you need to learn to activate the Horton Fan switch to help you decend a long grade. This in conjunction with the retarder and a lower gear selection can help reduce your decent by 10mph or more. As we said it takes practice, good luck and safe driving...

[Steelwheels]

Originally Posted by seanbirm01

Kiki - I picked up a 1988 FCRB last week from Somerset, KY and drove it home to Chandler, AZ. It's got about 130K on it. New hardwood flooring, new 8.0 diesel generator, new shocks, new alternator, new ac compressor, 3 year old tires all around, 3 year old batteries all around, all the hoses and belts replaced in the past 3 years, new water tank valves, many gaskets replaced throughout the engine and other systems, and good maintenance records in the blue box. I'm the third owner. The first owner had it for about 18 years. The second owner did most of the recent work. He stored it in a climate controlled garage for the duration of his ownership and spent a small fortune replacing and maintaining items that weren't necessarily going bad but he wanted replacing for piece of mind. He hated to let it go but wasn't using his bird due to health issues.


Pictures follow...

Thanks for the pictures and history. It seems like everyone likes buying they're bird on one side of the country and driving it to to other. Good way to do it.
Sounds and looks like you have a nice bird.

Does anyone know how the retarder is applied when you depress the brake pedal, I mean how is it triggered, does it go through the PMMI box relays and then where how does it send the signal, and how much force is applied when the brake pedal is used with the retarder on but lever off. ?

[FredNewell]

The BB manual in the blue box doesn't provide enough info.

There are some official ZF (from the tranny manufacturer) Operating Instructions for the tranny and retarder somwhere on this board. I downloaded it and emailed it to my ipad. I'll read it again in prep for each trip until it is second nature.

I Bought my bird last week, then took it across the Rockies to CA on I-40. The steep downhill concerned me. Bad visibiliy, heavy rain, night driving, my inexperience. I should have read up and practiced more.

It is very easy to heat up the transmission. Use the fan. Go downhill at about the same speed as uphill. Keep distance between your BB and the next vehicle ahead - like 7 to 10 seconds in my opinion.

With the retarder toggle "on" there is some hydraulic tranny braking on typical freeway offramps and long slow city stops, that works very well as you feather the brake pedal.

The little lever - push it down (As I recall), not up to increase braking.

Remember the energy removed from foward motion is going to the transmission fluid, which is why you have to monitor the tranny temp.

There's a buzzer and idiot light in case you approach the red zone on the gage. I only buzzed once, and immediately shut off the retarder.

With the retarder on, it stops retarding when you press the accelerator, then resumes when you soft-peddle the brake a little.


The Operating Instructions have drawings of a foot on the brake pedal at differenet positions and a description, in German, of what is happening in terms of braking.

Here's my main error, which resulted in a little too much use of brakes: I didn't shift down before starting the big downhill. I was assuming the transmission was programmed to take care of it. That's how my Honda Accord works, but I'm not sure of the ZF.


I really think some hands on driving instruction would be beneficial for any new BB owner. Just my opinion.

[Rick]

the ZF tranny is not as smart as your Honda. It's big and strong not like your Honda that way. You will have to let it know when your headed down a hill by down shifting yourself.