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Julia - Scottsdale, AZ

When I first drove my Nissan Sunrader shorty its brakes seemed worthless. But then I discovered that someone had put cinder blocks (!) in the rear box and once o removed them it stopped just as well as my Toyota Sunrader shorty.?

Could it be that yours has some extra weight somewhere? (Especially bad if that weight is "unsprung" behind the rear wheels!)

unsprung would indicate the weight is on the axle itself
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rz

I had the rear storage box removed (hard to do, cos bolts were all rusted and the ends were behind the dinette paneling, took handyman over an hour).? Nothing heavy was inside.? I don't see extra weight.? I don't use the gray and black holding tanks, and fresh water tank only has about 3 gallons.??
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Julia - Scottsdale, AZ

There is no reason for your brakes to be that weak if they are in good working order.

I don't know if it's a national standard, but I remember from my Callifornia Drivers License test years ago that, by law,
the brakes on a vehicle HAD to be able to lock up the tires. If your Sunrader brakes do not do this, there is something
not working right.

One static test you can try is (with the vehicle not moving and the engine off) pump the brake pedal a few times
then hold steady pressure on it. It should not move, or barely move over a long time. If the pedal starts to sink,
the master cylinder has an internal failure.

Other than that, you could have air in the system (is the brake pedal "spongy"?), restriced brakes lines or hoses,
stuck calipers/wheel cylinders, or small leaks in the system that don't let out enough fluid to be obvious.

This is basic mechanical stuff. Any competent mechanic should be able to figure out why the brakes are
giving you grief. The fact you have a great big fiberglass box on the back of the chassis doesn't change that.

Good luck,

Buzz L.
Phoenix, AZ
Former '86 Dolphin 500 owner (once changed the front brake pads at a scenic overlook near Kamloops, British Columbia)

i find two different size master cylinders listed for these trucks.? 1 inch and 7/8 inch. if the larger one was put on by mistake, the pedal would be hard with less stopping power
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rz

The D21 has huge rear brakes but the R/V's are built on the 1 ton chassis but it has huge rear brakes as well. I owned a 1995 D21 and it had rear Anti-Lock brakes. You might want to investigate that. The ABS module is under the drivers seat.

Nothing to add for a solution beyond the good recommendations. ?My 1984 Nissan Sunrader stops just fine so it’s NOT NORMAL and you need to find someone to take a real look. ?Be safe!

Lots of things to check, but most need special tools.
A simple check for the brake booster. Engine off get in and pump the brake pedal several times. Hold the pedal down and start the engine. If you feel the pedal move thats good. No movement?? Maybe a bad booster.

Yeah, if your motor home "brakes" as you describe, it is not an idiosyncrasy or design shortcoming. YOUR BRAKES HAVE FAILED!?

Don't drive that thing on the public streets until you have fixed your brakes.

We can't diagnose it sight unseen. It could be the vacuum booster, the proportioning valve, pad contamination, or whatever, but it is absolutely not "just the way they brake."

You should be able to panic stop and throw the dishes out of the cupboards. These motorhomes are heavier than an unladen pickup truck, but they are not THAT heavy. The underlying pickup truck and its brakes are mature technology and not some weird jury rig.

When you get it fixed, you will say, "Hey, I have brakes!" It won't be a minor improvement.

Mike.

Julia, did your brake problems get resolved? If so what fixed them??
thanks for the info

Update to my subject line.? Thanks to your posts, I did determine that the brake booster was behaving as you described it should be.? But the brakes did not lock up.? I did drive it to the very small annual Quartzsite Rally (6 rigs) and Steve White took it for a drive, and brakes did not lock up for him either, on pavement and the unpaved RV park grounds.? Steve said "There is something definitely wrong with the rear brakes, take it to a brake place or truck repair.? It may cost me $800 but it will be done for the rest of my life".? I already got turned down by many shops, who refuse to deal with RVs, and those that would, refuse Nissan trucks (claiming too much trouble and hard to work on, but accept Toyota trucks).??

Last week I called my local 5 Yelp star rated Brake Masters.? As soon as I said 3 words to Paul who'd been working there almost 20 years, he knew who I was and my little Toyota RV I'd taken there over 10 years ago.? Sadly Paul said he no longer works on RVs, even one as small as mine, cos "We lose money EVERY time on RVs, because they never seem to get fixed, full of complications.? Tell you the truth I wouldn't do another RV even for my own best friend!!!"

? Last Wed I drove my 1995 Corolla wagon to my second home in San Diego, where I have a much larger problem with my 1982 Toyota Sunrader, which I will post here after I post this.? ?So I won't be able to take Nissan Sunrader to a truck repair place till I get back to AZ maybe in May.? I am going to print out all your diligent speculations and responses to my brake problem on this forum, and take to the willing shop.? Thank you all who posted about my brake problem.? I will report results found.

Meanwhile the other problem with the Nissan is that it won't start on occasion.? When I was 30 miles before reaching Quartzsite, I stopped at a Pilot truck stop to get gas.? After I pumped gas, the Nissan would not start.? It was in the afternoon, and maybe 60 degrees.? Well, long story short I had to spend the night at that gas pump, cos as I posted, "it always starts on another day".?

Next morning wouldn't start by 11 am so I called tow truck to tow me to Quartzsite.? Took another 3 hours to find me a provider willing to tow small RV, who had to drive 70 miles from California to come get me.? I told him "Wait before you hook up, lemmie show you what happens when I try to start it".? ? Well, Murphy's Law, it started immediately!!!? I got out of having to pay the $90 for extra miles over 15 by filing dispute with my credit card company.? Steve White looked into No Start issue too, and he posted update what he did under subj "Nissan D21 hardbody Sunrader won't start."
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Julia - Scottsdale, AZ

One thing that comes to mind for me is a power brake booster failure. I*t causes the brake pedal to be hard to push than if it was strictly manual brakes. However, I am not sure the Nissan had such a booster. My 89 Toyota has such a booster.

i just replaced the booster on my 84 dolphin.? old one just didn't seem to work well.? now i have to add a proportioning valve for the rear brakes since i bypassed the load sensing proportioning valve (lspv) because the brakes are so powerful
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rz

p.s.? ?the old booster passed the tests for proper operation
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