I want to go to 3rd gen brakes on my truck. I've gotten pretty good at rebuild calipers. Wondering about getting some used calipers for the price of core charge. 

While were here, and CSM is starting on our Free Body Diagram.... 

 

Lb for Lb,  changing Rotor diameter will not effect the MPG like tires will.  It comes back to the inertia, not just the straight weight added...   The radius of the mass change of the tires is much further out when compared to the radius of the mass change of the calipers.  so the inertia  will be completely different.  The distances for calculating inertia are squared functions, so you get a parabolic relationship of radial factors in the equation.   

 

In simple terms, mass added near the axis of rotation has a exponentially smaller effect on inertia, than the same mass added evenly a a longer radius.  ( It is very similar to the ratchet and cheater bar used earlier....  except that is direct ft*lb.... inertia is ft^2*lb...)

 

I am going to make some popcorn too....

 

Merry Christmas!!!!

 

Hag

30 minutes ago, Haggar said:

While were here, and CSM is starting on our Free Body Diagram.... 

 

Lb for Lb,  changing Rotor diameter will not effect the MPG like tires will.  It comes back to the inertia, not just the straight weight added...   The radius of the mass change of the tires is much further out when compared to the radius of the mass change of the calipers.  so the inertia  will be completely different.  The distances for calculating inertia are squared functions, so you get a parabolic relationship of radial factors in the equation.   

 

In simple terms, mass added near the axis of rotation has a exponentially smaller effect on inertia, than the same mass added evenly a a longer radius.  ( It is very similar to the ratchet and cheater bar used earlier....  except that is direct ft*lb.... inertia is ft^2*lb...)

 

I am going to make some popcorn too....

 

Merry Christmas!!!!

 

Hag

 I know I slept thru that part of school.  My millage now is pretty good even with my truck near 8k. 20 mpg on pure interstate runs and a couple runs a little over 20. That is on 265's the truck came with.

Edited December 6, 20168 yr by dripley

Let's just put it simple. When some one with 3rd Gen brakes and oversized tires (GPS verified) can beat my MPG high mark I'll start listening... So far it has not happened yet. When it does happen I will be asking all kinds of questions. 

I've already got the 17" 3rd gen wheel and tires. Doubt I'd add much more weight than I already have. Recently put new studded winter tires on. Snowing now. Don't look like a fool now. Lol. 

 

I replaced my pads and rebuilt front calipers recently, but I didn't address rotors (which need to be replaced). So being the cheap @$$ I am I thought I'd look for some core returned 3rd gen calipers. Rebuild them, get the 3rd gen rotors and caliper hangers. Do the front for now, as the rears have had new rotors done a while back. 

 

Do the 3rd gen rears work like the 2nd gen? Little drums for parking brakes? Are the 2nd and 3rd gen parking shoes the same? Parking brake cables same?

9 hours ago, Mopar1973Man said:

Let's just put it simple. When some one with 3rd Gen brakes and oversized tires (GPS verified) can beat my MPG high mark I'll start listening... So far it has not happened yet. When it does happen I will be asking all kinds of questions. 

Let's put it this way... if ANYONE changes to 3rd gen brakes (brake change only) and loses mileage, I'll personally send @Mopar1973Man whatever it costs to purchase your favorite liquor.  

 

7 hours ago, joecool911 said:

I've already got the 17" 3rd gen wheel and tires. Doubt I'd add much more weight than I already have. Recently put new studded winter tires on. Snowing now. Don't look like a fool now. Lol. 

 

I replaced my pads and rebuilt front calipers recently, but I didn't address rotors (which need to be replaced). So being the cheap @$$ I am I thought I'd look for some core returned 3rd gen calipers. Rebuild them, get the 3rd gen rotors and caliper hangers. Do the front for now, as the rears have had new rotors done a while back. 

 

Do the 3rd gen rears work like the 2nd gen? Little drums for parking brakes? Are the 2nd and 3rd gen parking shoes the same? Parking brake cables same?

3rd gen rears are just like the second gen. You use all 2nd gen parking brake hardware though as no one knows if the shoes and mounting on the axle are the same. 

 

No need to change anything other than rotors, caliper brackets, and shoes.

No need to touch anything 3rd gen with respect to calipers or emergency brake. 

Edited December 7, 20168 yr by TFaoro

5 hours ago, Mopar1973Man said:

Let's just put it simple. When some one with 3rd Gen brakes and oversized tires (GPS verified) can beat my MPG high mark I'll start listening... So far it has not happened yet. When it does happen I will be asking all kinds of questions. 

I dont think anybody with over sized tires can touch you. I would just wonder how much difference there would be between say my 2nd gen converted to 3rd gen brakes. How much weight difference between 3rd gen tires and wheels compared to 2nd gen tires and wheels with the 3rd gen tires be of the similar diameter as the 2nd gen. I know the wheels would weigh a little more but maybe the 17" tire is a little lighter? I dont know.

4 hours ago, TFaoro said:

Let's put it this way... if ANYONE changes to 3rd gen brakes (brake change only) and loses mileage, I'll personally send @Mopar1973Man whatever it costs to purchase your favorite liquor.  

 

3rd gen rears are just like the second gen. You use all 2nd gen brake hardware though as no one knows if the shoes and mounting on the axle are the same. 

 

No need to change anything other than rotors, caliper brackets, and shoes.

No need to touch anything 3rd gen with respect to calipers or emergency brake. 

 

This is awesome info! Thanks!!!

Stock wheels/tires 2 gen...265/75-16

3rd gen 265/70-17. 

Overall tire diameter and width the same on both. So just a little more rim and less rubber. But does allow for needed rotor/caliper clearance. 

 

Mike is spot on if you have an exhaust brake like he does. For us automatic transmission owners the exhaust brake is not realistic. So the additional braking potential is desirable. 

Stock wheels/tires 2 gen...265/75-16

3rd gen 265/70-17. 

Overall tire diameter and width the same on both. So just a little more rim and less rubber. But does allow for needed rotor/caliper clearance. 

 

Mike is spot on if you have an exhaust brake like he does. For us automatic transmission owners the exhaust brake is not realistic. So the additional braking potential is desirable. 

I did this a while ago to the fronts, just a few weeks ago for the rears. The 3rd gen calipers are the same part numbers, iirc, what you do is get new caliper brackets, rotors, and pads (with 17" wheels) and bolt them up. Easy as that. Traffic near Philadelphia means my truck eats brakes, and if you leave 1/2 car length in front of you people will force their way in. I have an HO with 4.10 4x4 so… yeah I never see great MPGs. My best trips are up to then NY mountains where doing 75 on the highway and going up and down steep hills for miles would make you think your mileage would lower. I got 19.9MPG each trip /shrug

19.9 at 75 is pretty darn good mileage. My HO 4X4 with 3.55 will barely do that. What size tires are you running?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

275-85r17, I think what helps is miles of downhill where I coast in gear… That trip is the only times I can get that high, otherwise it's in the 17-18 range.