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2500 disc conversion

You're brakes from factory are 60-40'ish. Do the new kits come with a new proportioning valve? If not, they'd still be 60-40's (front to rear) after the conversion.

Just the 40% would be more a true 40%.

When your brand new rear drums worked from factory, it may have been a true 60/40 system. But as time goes on, and rear brakes lose adjustment fast, and start to suck (IMO) they don't work nearly as well, nor do they self adjust. So instead of losing the 60/40 ratio, you are just losing a direct % of your rear braking power to pedal movement.

No matter how well your rear brakes work, I don't see how they would ever lock up before the fronts with a 60/40 system (unless something is wrong)
 
As I understand it during braking weight shifts to the front so that the rears will therefore have to work less hard. Even with an already 60/40 bias to deal with this and have the fronts do more of the work there is a danger still that with the added rear braking ability from the discs the rears will try to lock up first.

Of course seems as tho Slim has had no issues and I assume from his post that he is not experiencing his ABS coming on all the time.

Slim I assume you have a FF rear axle and are you running the original stock proportioning valve or did you at some point perform the TSB#99-05-24-001A and change out to the 12548265 valve?

Cheers
Nobby
 
nobby said:
As I understand it during braking weight shifts to the front so that the rears will therefore have to work less hard. Even with an already 60/40 bias to deal with this and have the fronts do more of the work there is a danger still that with the added rear braking ability from the discs the rears will try to lock up first.

Of course seems as tho Slim has had no issues and I assume from his post that he is not experiencing his ABS coming on all the time.

Slim I assume you have a FF rear axle and are you running the original stock proportioning valve or did you at some point perform the TSB#99-05-24-001A and change out to the 12548265 valve?

Cheers
Nobby
Click to expand...


The truck has the original proportioning valve, and I have not had any lock up issues or stopping problems. I bought the adjustable proportioning valve from Summit just in case I needed it: I didn't.

The stopping power of the rear brakes is great, hauling a load it really shines. I have a FF rear and changed everything myself. I made my own parking brake brackets and welded them to the rear caliper mount. I bought the caliper mounts from DIY4x4. The brackets are laser cut and fit perfect, they are over engineered, for the big rock crawler trucks they put them on. I am not sure I can post the link. Look up DIY 4x4 and it will get you their web site.
 
Slim Shady said:
The truck has the original proportioning valve, and I have not had any lock up issues or stopping problems. I bought the adjustable proportioning valve from Summit just in case I needed it: I didn't.

The stopping power of the rear brakes is great, hauling a load it really shines. I have a FF rear and changed everything myself. I made my own parking brake brackets and welded them to the rear caliper mount. I bought the caliper mounts from DIY4x4. The brackets are laser cut and fit perfect, they are over engineered, for the big rock crawler trucks they put them on. I am not sure I can post the link. Look up DIY 4x4 and it will get you their web site.
Click to expand...


would you post a pic of your setup?

thanks
 
I'm with Dennis here stopping is improved, parking is less than optimal, Mike to answer your ? I'd be parking on a hill with chocks if you ahd weight, my driveway is on a hill and empty if I don't push down hard to full travel setting parking brake truck rolls back until it locks in park feature of the trans
 
Turbine Doc said:
I'm with Dennis here stopping is improved, parking is less than optimal, Mike to answer your ? I'd be parking on a hill with chocks if you ahd weight, my driveway is on a hill and empty if I don't push down hard to full travel setting parking brake truck rolls back until it locks in park feature of the trans
Click to expand...

does this affect/weaken the trans on the long term ?
 
Matt Bachand said:
I'm with you, especially with weight or on a significan't hill, I can't stand the loud 'THUMP' Of shifting its weight off the trans park pin.
Click to expand...

Yes, precisely.

I'm willing to install a rear disc conversion kit on my truck and for another guy.

I start digging to see if it is almost easy or a nightmare, costly but efficient.
The other point is that here, our rigs come with the 14 bolts/6 lugs semi float rear end. Less easy to find kits for them.

I park my rig down a hill. So, if e-brakes are not trustable, may be I should just change shoes pad and keep the drums...:confused:
 
matuva said:
Yes, precisely.

I'm willing to install a rear disc conversion kit on my truck and for another guy.

I start digging to see if it is almost easy or a nightmare, costly but efficient.
The other point is that here, our rigs come with the 14 bolts/6 lugs semi float rear end. Less easy to find kits for them.

I park my rig down a hill. So, if e-brakes are not trustable, may be I should just change shoes pad and keep the drums...:confused:
Click to expand...

Or as mentined before, the cost of the kits is significantly less without the E-Brake calipers, put that money towards a separate driveshaft E-Brake.

The chockblock idea not only is a hassle, but its too late. The weight is already loaded up on the transmission.
 
One point with regard to drive shaft e-brakes you are relying on your U-Joints as part of the system. No doubt would still be better though than caliper style.

Cheers
Nobby
 
Not a huge fan of rear discs that are also the parking brakes. My boss has a 98 Dodge cummins, and an 03 Dodge cummins. both 3500's manual and 4wd. the 98 has drum rear, and the parking brake on it can keep a 32' tandem dually dovetail gooseneck from moving when loading the tractor, and when the tractor is on, it will hold anywhere. (biggest loads it has had is a 4840 JD with 168 loader, and then another load of a 7520 4wd JD) the 03, with all discs, can't hold shit. flat ground, won't roll, loading, it will move all over, any slope, it'll roll, even empty trailer.

Now the C3500HD GMs are a whole other game. it is 4 wheel disc, but it has a drum brake on the back of the tranny. I personally believe that this is the best setup. no low hanging cables, etc. And, with drums, isn't it if it tries to roll forward, it often clamps harder?

U-joints are tough, so i would trust them fully. the local farmers often run older hyd. braked 2-tons around as seed wheat trucks, and i know of a few that are soley braked by the driveshaft mounted parking brake, as the service brakes are shot. they work well, and that is loaded to about 30-35K on a single axle 2-ton. they engine brake as much as possible, and then use the parking brake.
 
Awesome thanks for the pictures Slim.

The whole parking brake issue is of concern to me though. I have done some research on this to no real avail. I did find that High Angle Driveline had a transfer case brake kit for the 241/243 tho I then realised it was for a fixed yoke and not a slip yoke as on our trucks. OK I said JB Conversions has a kit for that, so all fired up I took a look at my suburban only to find that the crossmember for the torsion bars is slap bang in the way. I have not measured but am fairly certain just by looking that there is not the room for it.

Not much really out there pinion brake wise and the one comment from TSM is that there kits are not enough holding power for trucks anyway.

I did come across one more solution that works in effect as a line lock. It is an e-brake cable operated master cylinder that it is plumbed into the rear brake line so that when applied it holds the rears on.
http://www.texas4x4.org/showthread.php?t=22423 post #7
It is available as a kit from http://www.ceoffroad.com/ and is just the bracket with a list of part numbers for the other required parts. Do not really like the idea of a line lock for overnight parking and I think if I did this I would use a Mico mechanically operated unit. Perhaps go with the eldarado calipers and have the line lock installed as a backup.

Thing for me is catching the Ferries off the island sometimes they have you park on the ramps to the upper level parking and even tho they place a chock under your wheel it's still a bit hairy, requesting them to not go on the ramp because your e-brake is iffy is probably not the smartest question to ask.

Cheers
Nobby
 
doesn't take much of a disc for parking its not supposed to be used for stopping the rig just keep it from moving
 
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