OEM Rear Brake Hose Length

[MoparGuy68]

After installing a new “Right Stuff” FH85 rear brake hose on my 1971 Charger (8.75” rear), I’m concerned about it being too short in length. When the rear leaf springs are almost completely unloaded, the hose appears to be pulled taught like a rope. It’s pulled tight enough that I’m concerned it will weaken the hose, resulting in it bursting/breaking in the future.

DoctorDiff has assured me that FH85 is the correct replacement hose for my car. He said if I wanted a longer hose I could get the hose meant for a 1970 Dodge van.

I’m most concerned about the differential shop I’ll eventually be taking the car to. They will be putting the car on a four point lift, which will allow the rear end to completely unload, hanging down as low as possible.

Have you guys had any problems with the OEM rear hoses getting over stretched when the suspension is totally unloaded? This is something I never paid any attention to, until now, doing this brake system replacement. When I was lowering the rear end, while jack stands were under the rear frame rails, that’s when I noticed the hose getting pulled tighter than I expected it to.

Do any of you run a longer than stock hose back there on your cars? The stock length hose just seems short to me.

Unfortunately, I didn’t take a photo of the new hose when the suspension was nearly unloaded. I’ve attached two photos of the old hose, but the the suspension was mostly loaded. Only have one of the new hose connected to the holding bracket.

I guess if this “short” length is stock, it is designed to handle the stretch? Maybe I’m worried about a non issue??

 

[493 Mike]

Take out the vent bolt and tape over the hole while it is away from home. That will give you some slack.
Mike

 

[hyde-park]

I put a C-body rear brake hose in my B-body for just the same reason. Rockauto lists lengths for brake hoses in the specs. Van and pickup ones are longer yet if you prefer.

 

[MoparGuy68]

I put a C-body rear brake hose in my B-body for just the same reason. Rockauto lists lengths for brake hoses in the specs. Van and pickup ones are longer yet if you prefer.

This afternoon DoctorDiff told me he thinks the 70 Dodge Van hose is only about 1” longer in length than the stock B-Body hose. I was hoping an alternate hose would be more than only an inch longer. Though even one extra inch would be better than what is on there now.

I’m wondering if either Chrysler engineers were asleep when they specified hose length for this application, or a bean counter in the company requested the shortest possible length to save a few cents on each B-Body car they produced.

Maybe old leaf springs allow the rear axle to drop lower to the ground when unloaded, and this wasn’t an issue when the cars were new. It’s another head scratching Mopar moment..

 

[dadsbee]

Everyone seems to make them too short... been down this road on the Bird and Roger bailed me out and sent me a hose all the way from New Zealand!

 

[MoparGuy68]

I did not measure the Right Stuff FH85 hose before installing it on the car, but based on your photo I assume mine must be 12.25”. So that’s .5” shorter than OEM.

Now I’m wondering if there is a similar issue with the front hoses…. I have not put them on the car yet, so I was able to measure them tonight.

I still have one of the old front hoses. This is how it it compares with the new front hoses that DoctorDiff sent me.

Old front hose overall length = 13.75”
New FH84 hose overall length = 14.25”

So the new fronts are .5” longer than the old ones. At least they aren’t shorter!

Are the metal fittings on the front hoses the same as the fittings on the rear hose? I don’t know if the threads in the calipers are the same size as the threads in the brass Tee block.. If they are the same, I could just obtain a third FH84 front hose and install it in the rear.. That would be 2” longer than the FH85.

Who is Roger, in New Zealand?

 

[dadsbee]

Pretty sure the front hoses thread is smaller than the rear... can't remember.

 

[MoparGuy68]

The plot thickens..

Cass (DoctorDiff) has stated that the FH84 (front) and FH85 (rear) hoses have the same size threaded fittings on both ends..

This morning I found the other two hoses I had cut off the car. I put them back together and carefully measured them.

My old hose lengths:
Drive side front = 13.75”
Passenger side front = 14.5”
Rear = 13.125”

Inside diameters of the two hoses I cut off the car are different!!

In the attached photo you can see the old rear hose is significantly smaller inside diameter (on left side of photo) than the old passenger front hose (right side of photo).

I do not know if the rear diameter should be the same or different.. Nor do I know if the new FH84 and FH85 have different inside diameters..

 

[MoparGuy68]

Cass just told me he thinks both front and rear hoses should have the same inside diameter, but doesn’t know for sure. Regarding my old hoses, he thinks maybe the larger ID front hose has swollen..

The smaller ID rear hose looks significantly older.. That rear hose looks to have been on the car for a minimum of 20 years, maybe even 30. The front hose looks like it was replaced more recently. Maybe the rear hose was higher quality and held up better under pressure than the younger front hose..

This weekend and I’m going to attempt to look inside the new hoses with a light to see if I can tell if the diameters are the same. It’s tough to see what the IDs are without cutting the hoses..