Rear disc brake conversion

[martin300662]

Looking for some input on benefits and any experience in installing a rear-disc brake conversion on a small Argosy.

The brakes on my 20ft work, but you have to stand on them, and then for about 80% of the pedal travel there is not a lot, but they are able to lock the front wheels in the last 10%.....so only the band from 80-90% is useful.

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I'm looking for something more progressive and that seems to mean a different hydro-boost unit (mine has been tested and is working to spec) or different brakes.

I have the parts guys looking at bigger/modified hydroboosts (to get the power curve altered), but also I want to get something better in terms of brakes on the back. There are plenty of disc brake conversion kits for 10 lug dually axles, almost as many for 8 lug with either a 14 bolt or a Dana70 rear axle and 19.5" wheels, but to fit the little 16" wheels on my 20ft (and I have already established bigger wheels wont fit without changing the frame) it seems only TSM have a kit (2830 - TSM Mfg. Co., Inc.). Anyone tried it?

[mayco]

Martin,
I had about the same curve on my 310 with four wheel disc. New pads, flex lines, master cylinder, and brake flush. Still had a good deal of travel in the pedal before real engagement of the brakes. I was told by two different mechanics that I needed to get used to it, its just the way they are. I started snooping around looking at the brake linkage for some adjustment or something to take some of that travel out and sure enough found a cure....for mine. There is a vertical rod on the front side, towards the grill, that has several inches of thread on the end and a coupling with a through pin. (I cant remember the name of that coupling, U shaped end with a female threaded end that threads onto the vertical rod. Through pin with a cotter key) But anyway, I started threading that coupling up the vertical rod a little bit at a time and eventually it took the travel out of the brake pedal. There wasnt "slop" in the linkage, it just needed to activate the push rod into the master cylinder higher in the stroke of the pedal. Sure enough, I got it adjusted up and it made a WORLD of difference in the brake pedal. I had one fron wheel jacked up off the ground while adjusting it so I could check for any drag in the brakes. I realize we have a didderence in our brake system but the linkage may be similar, dont know. But its sure worth checking out before you go much further. You may want to go ahead and do the rear brake conversion which is understandable but if you have that same adjustment capability in your linkage it could solve all or part of the pedal travel problem.

I hadnt seen anything mentioned here on the forums about that adjustment when I searched for all the threads regarding the brakes. It sure worked for me and Im pleased as punch now with how my brakes feel. That rod is pretty easy to spot when tracing the brake linkage, easy to get to from underneath the front end. The hardest part was just braking it loose to start threading that coupler up the rod, I used plenty of PB BLASTER and it broke loose without too much fiddling. If I can find a drawing Ill send you a link

Mike

[martin300662]

I will have to read this whilst actually looking at the hydroboost Mayco, because I think you are describing the output rod and shortening it (moving the coupler up) will increase the drag on the brakes, vs lengthening (moving the coupler down) will reduce the drag. But all the pictures I have seen don't have a thread on the output shaft there are just 3 or 4 locations for the circlip and you can shorten and lengthening to one of those positions only...I am just working for pictures though - reality could be totally different!!!

[mayco]

Clevis coupler is what thats called I think. Ill get underneath and see if I can take a picture that makes sense.

[mayco]

Sent from my iPhone using Airstream Forums

[martin300662]

Thanks Mayco, I will check when I get in from work

[mayco]

Well, obviously my memory kinda stinks but, the top couple pictures show the rod coming down and threads on to the connecting device. In the last pictures you can just make out the boot and push rod. What I did was thread the male end further up into that connecting rod which pushes on the push rod going to the hydroboost/master cylinder. So the brakes respond higher in the pedal travel. Good thing I dont write instructions for a living, Id be starving. Hope this helps, it really did the job for my brakes. Now when I press my brake pedal I can feel the brakes start to engage in about the upper 1/4 to 1/3 of the pedal travel. Worth a look anyway Martin.

Mike

[martin300662]

From the 1975 chassis manual there is a similar linkage the translate the pedal stroke to the input rod.... let me see if I can find it!!!

[bpg_austin]

This is interesting! I've got the same pedal feel in my '78. Good pedal, but toward the bottom and this is after a brake job, (which they bled the brakes for me). Keep us posted Martin.

[martin300662]

I definitely have a similar setup at first glance.



But on closer inspection the input rod is not threaded, and there is a fixed rose joint at the end of the rod.



Trouble is I can't see if there is any adjustment on the pedal rod from below and the grill is in the way from the front/above....and the 1975 grill is riveted on.

Think it is going to have to go up on a ramp to get a better view.

[bkahler]

Martin,

Here's a view of the rod/clevis if you were looking down from the floorboard where the brake pushrod exits the floor.



This would be a side view from where the radiator would be. Since my radiator isn't installed I can get a clean look at it.



The threaded end in the picture above is shown in Mike's picture below.

[martin300662]

Thanks Brad. I will take another look at the weekend, as I ran out of daylight this evening.

The down side of poking around under the front is the Airstream guys may have given everything a once over but I think the is a set of SuperSteer bell cranks/arms, rod ends and urethane bushes in my near future.

[bkahler]

I put a supersteer on the drivers side of the old 310 and it made a huge difference in steering. My Argosy has new bushings in the original units so I should be good for a while.