Brandt Posted June 4, 2015 Share Posted June 4, 2015 (edited) I have 4.42's in my truck and am looking for a bit lower rpm at highway speeds. Is it cheaper to find the diffs with the gears I want (4.17 or 3.86) or to buy an entire rear clip?? I have cammelback suspension and want to keep it. I also have spoke hubs and they could stay or go. It would be nice if I could find a set of diffs with lockers, as I spend a good bit of time off road. I don't know what my current axles have for weight rating, but everything on this truck is built heavy. The build sheet says I have CRDPC92 and CRD93 axle assy. Edited June 4, 2015 by Brandt Quote Link to comment https://www.bigmacktrucks.com/topic/40341-regear-options/ Share on other sites More sharing options...
alex g Posted June 4, 2015 Share Posted June 4, 2015 I would change gears rather than replace a whole clip I have a set of 3.86 if your interested but that is a pretty tall gear to be off road with you could run 24.5s if your not already to drop your rpms a bit Quote Link to comment https://www.bigmacktrucks.com/topic/40341-regear-options/#findComment-292317 Share on other sites More sharing options...
kscarbel2 Posted June 4, 2015 Share Posted June 4, 2015 I like a 4.42 ratio, but 4.17 will accomplish what your want.3.87 (not 3.86) would be to high (low numerically). Quote Link to comment https://www.bigmacktrucks.com/topic/40341-regear-options/#findComment-292323 Share on other sites More sharing options...
RowdyRebel Posted June 4, 2015 Share Posted June 4, 2015 I've got 4.17's and had been contemplating 4.42's when I pulled a dump bucket on mostly 55 mph roads. Now that I'm flatbedding and spending more (still not much, though) time in 70 mph zones, if I HAD made the switch a few years ago, I'd be looking to swap back to 4.17's or even 3.94's. It is all in what you do and where you go, though. I'm running 11R24.5 tires, though, so my 4.17 rears are like having lo-pro 22.5's and 3.73 gears. Quote When approaching a 4-way stop, the vehicle with the biggest tires has the right of way! Link to comment https://www.bigmacktrucks.com/topic/40341-regear-options/#findComment-292327 Share on other sites More sharing options...
Dirtymilkman Posted June 5, 2015 Share Posted June 5, 2015 I run a lot of gravel roads and soft roads with my CL. It has 3.86/3.87 rears and never runs out of power but thats with a 18spd. It runs 1300@55mph 1500@65mph and 1610@70mph 1 Quote Link to comment https://www.bigmacktrucks.com/topic/40341-regear-options/#findComment-292337 Share on other sites More sharing options...
Brandt Posted June 5, 2015 Author Share Posted June 5, 2015 I'm running 11R 22.5 tires and with the spoke hubs a switch to 24.5 is as cost effective as regearing.The engine is an EM7 which peak torque is at 1050 and peak HP at 1710rpm. I'm also running a 1070 12 spd, so with the 2 deep reduction gears, I think I would be OK with 3.87's. However I do think 4.17's are ideal.Are all the Mack gear sets interchangable?? Or do I have to get gears from a set of axles that have the same weight rating and model. Quote Link to comment https://www.bigmacktrucks.com/topic/40341-regear-options/#findComment-292351 Share on other sites More sharing options...
RowdyRebel Posted June 5, 2015 Share Posted June 5, 2015 Would a 12R22.5 tire work? Nearly the same diameter as an 11R24.5 tire, but fits on a 22.5" rim...you'd just need 9" wide rims instead of 8.25" wide. The load rating is also slightly better than an 11R24.5. Quote When approaching a 4-way stop, the vehicle with the biggest tires has the right of way! Link to comment https://www.bigmacktrucks.com/topic/40341-regear-options/#findComment-292357 Share on other sites More sharing options...
Brandt Posted June 5, 2015 Author Share Posted June 5, 2015 I looked into them last summer (before I bought a set of 8 11Rs). I ran into a few hurdles that I couldn't seem to overcome. I don't know if a 315/80/22.5 will work in a "dual" position or not. Quote Link to comment https://www.bigmacktrucks.com/topic/40341-regear-options/#findComment-292366 Share on other sites More sharing options...
bts-4120 Posted June 5, 2015 Share Posted June 5, 2015 there is a many waste management roll off on 315 floats all they way around so yeah yes you can Quote Link to comment https://www.bigmacktrucks.com/topic/40341-regear-options/#findComment-292367 Share on other sites More sharing options...
Brandt Posted June 6, 2015 Author Share Posted June 6, 2015 Are the 315s ran as duals or are they singled up?? Finding rims for singled up Daytons might be difficult.Can any one tell me more about the CRDPC92 and CRD93 axle assy? Quote Link to comment https://www.bigmacktrucks.com/topic/40341-regear-options/#findComment-292456 Share on other sites More sharing options...
6368 Posted June 7, 2015 Share Posted June 7, 2015 The 315s are run as duals. you won't like the price for new but the casings can usually be had pretty reasonably because refuse companies are about the only ones who run em for drives. Yes, they can be put on 8.25 inch rims it is not ideal ( it lowers the weight rating) but you will be fine for drives . The best thing about running them is they are tough. Quote Link to comment https://www.bigmacktrucks.com/topic/40341-regear-options/#findComment-292498 Share on other sites More sharing options...
j hancock Posted June 7, 2015 Share Posted June 7, 2015 Can any one tell me more about the CRDPC92 and CRD93 axle assy?That housing combination could be found in various 34,000, 38,000, 40,000 or 44,000 lbs. bogie models. Some were actually set up without a power divider. 1 Quote JimIt doesn't cost anything to pay attention. Link to comment https://www.bigmacktrucks.com/topic/40341-regear-options/#findComment-292515 Share on other sites More sharing options...
Brandt Posted June 19, 2015 Author Share Posted June 19, 2015 That housing combination could be found in various 34,000, 38,000, 40,000 or 44,000 lbs. bogie models. Some were actually set up without a power divider.Somewhere I got the idea that they were 43K or 46K axles. I don't know where I got that info from. How do I tell w/o tearing them apart and measuring bearings? Quote Link to comment https://www.bigmacktrucks.com/topic/40341-regear-options/#findComment-293929 Share on other sites More sharing options...
j hancock Posted June 22, 2015 Share Posted June 22, 2015 Since you have the build sheet, it should tell you unless you think someone has changed them. Quote JimIt doesn't cost anything to pay attention. Link to comment https://www.bigmacktrucks.com/topic/40341-regear-options/#findComment-294301 Share on other sites More sharing options...
Brandt Posted June 23, 2015 Author Share Posted June 23, 2015 Duh!! Senior moment ;-)It does say SS440C - guessing that means 44K rears Quote Link to comment https://www.bigmacktrucks.com/topic/40341-regear-options/#findComment-294395 Share on other sites More sharing options...
j hancock Posted June 23, 2015 Share Posted June 23, 2015 Yes, 44 on camelback. Quote JimIt doesn't cost anything to pay attention. Link to comment https://www.bigmacktrucks.com/topic/40341-regear-options/#findComment-294409 Share on other sites More sharing options...
rsb502 Posted July 6, 2015 Share Posted July 6, 2015 Youll be cheaper in the long run and more than likely happier to swap to 4.17's, I went from 4.64's to 3.65's and I went too far with 11R24.5's, Im looking at going back to 4.17 or 3.87 myself, if I go to the 3.87 Ill swap to low pro 24.5's for a little more gearing. The CRD 92/93's just unbolt and drop in from one gear ratio to another, the only real difference is there are different splines for the power divider input and the axles, just make sure you know what you have and get the same splines. Quote "Any Society that would give up a little LIBERTY to gain a little SECURITY will Deserve Neither and LOSE BOTH" -Benjamin Franklin"If your gonna be STUPID, you gotta be TOUGH" "You cant always get what you want, but if you try sometimes you get what you need" Link to comment https://www.bigmacktrucks.com/topic/40341-regear-options/#findComment-295783 Share on other sites More sharing options...
Outbehindthebarn Posted Wednesday at 02:41 PM Share Posted Wednesday at 02:41 PM On 6/4/2015 at 7:02 PM, kscarbel2 said: I like a 4.42 ratio, but 4.17 will accomplish what your want. 3.87 (not 3.86) would be to high (low numerically). Can you speak as to why two such similar ratios were offered? Quote Fun is what they fine you for!My name is Bob Buckman sir,. . . and I hate truckers. Link to comment https://www.bigmacktrucks.com/topic/40341-regear-options/#findComment-576132 Share on other sites More sharing options...
kscarbel2 Posted Wednesday at 04:05 PM Share Posted Wednesday at 04:05 PM 1 hour ago, Outbehindthebarn said: Can you speak as to why two such similar ratios were offered? The 4.17 harkens back to a tractor with a 237 and 5-speed. With a 300/5-speed, then a 3.87. The 4.42 was my go-to for a 10-speed T2100, at the bottom of the fuel curve at speed. Quote Link to comment https://www.bigmacktrucks.com/topic/40341-regear-options/#findComment-576137 Share on other sites More sharing options...
Outbehindthebarn Posted Wednesday at 05:16 PM Share Posted Wednesday at 05:16 PM 1 hour ago, kscarbel2 said: The 4.17 harkens back to a tractor with a 237 and 5-speed. With a 300/5-speed, then a 3.87. The 4.42 was my go-to for a 10-speed T2100, at the bottom of the fuel curve at speed. What's your 'go-to' for an E9 12 speed OD with 11r24.5's in a road tractor? It currently has 3.87's, but I've never worked it... yet. Found metal on drain plug on the crdp92, so I pulled it... gear set is toast. Rebuilder is shying away from replacing the 3.87 ratio. He called it a "weak gear set". I have zero experience with that sort of thing. He's steering me towards 4.42 or 4.17. That's the reason I asked about the closeness of the 3.86-3.87. .. and why he calls it a "weak gear set". Quote Fun is what they fine you for!My name is Bob Buckman sir,. . . and I hate truckers. Link to comment https://www.bigmacktrucks.com/topic/40341-regear-options/#findComment-576140 Share on other sites More sharing options...
kscarbel2 Posted Wednesday at 05:42 PM Share Posted Wednesday at 05:42 PM 27 minutes ago, Outbehindthebarn said: What's your 'go-to' for an E9 12 speed OD with 11r24.5's in a road tractor? It currently has 3.87's, but I've never worked it... yet. Found metal on drain plug on the crdp92, so I pulled it... gear set is toast. Rebuilder is shying away from replacing the 3.87 ratio. He called it a "weak gear set". I have zero experience with that sort of thing. He's steering me towards 4.42 or 4.17. That's the reason I asked about the closeness of the 3.86-3.87. .. and why he calls it a "weak gear set". The Mack 3.87 is not weak. That said, I'd consider 4.17 with your specs. Quote Link to comment https://www.bigmacktrucks.com/topic/40341-regear-options/#findComment-576141 Share on other sites More sharing options...
mrsmackpaul Posted Wednesday at 08:32 PM Share Posted Wednesday at 08:32 PM I think the very first thing would be to determine were the metal came from in the oil and what causef it to fail If the diffs have 3 million miles I wouldn't class them as weak If they have only done heavy haulage with half a million miles on them, then they probably aren't If they pulled truck loads of sail boat fuel and have 100,000 miles then maybe they are weak If they were run low on oil or driven by a rough bastard they probably aren't weak With out knowing the history it's pretty hard to make a call Also if your rebuilding one center, I guess now is the ideal time to change the ratio to something to really suit what you want 3.87 would be no good for me, I wouldn't have the power to shift loads quick enough E9, even in it's smallest power size is still a lot more power than me Paul 1 1 Quote Link to comment https://www.bigmacktrucks.com/topic/40341-regear-options/#findComment-576142 Share on other sites More sharing options...
Outbehindthebarn Posted Wednesday at 09:34 PM Share Posted Wednesday at 09:34 PM 50 minutes ago, mrsmackpaul said: I think the very first thing would be to determine were the metal came from in the oil and what causef it to fail If the diffs have 3 million miles I wouldn't class them as weak If they have only done heavy haulage with half a million miles on them, then they probably aren't If they pulled truck loads of sail boat fuel and have 100,000 miles then maybe they are weak If they were run low on oil or driven by a rough bastard they probably aren't weak With out knowing the history it's pretty hard to make a call Also if your rebuilding one center, I guess now is the ideal time to change the ratio to something to really suit what you want 3.87 would be no good for me, I wouldn't have the power to shift loads quick enough E9, even in it's smallest power size is still a lot more power than me Paul The truck is new to me, I have no real first hand knowledge about how it was driven or what it hauled. But when I pulled drain plug found metal (fingernail size pieces). The gear set in it was pitting, flaking, chipping: it was a matter of time. I began to hunt around for a replacement 3.87 crdp92 and nobody had one within a 100 miles.... I actually had a guy tell me he had remanned 3.86 to sell, and that I could just use that... small difference he said. Another guy said he was crazy, totally different .. Which led me to wonder why Mack offered such similar ratios... Then a guy on facebook replied: "I'm sure someone will correct me but from my understanding 3.87 was a weak gear set, most notably the spur gear. Subtle changes were made to make it stronger and the set wound up being 3.86. 4.17 and 3.86 use the same spur gear and 3.87 and 3.65 share the same spur gear, the last 2 being weaker." My rebuilding shop agreed with the above statement at least as far as the "weak gear set" comment. Any truth to this?? I haven't a clue. He can order new parts to rebuild my crdp92 as a 3.87.. total cost around $2000.+ I found a set of carriers with 4.17's in them used for $500.. Quote Fun is what they fine you for!My name is Bob Buckman sir,. . . and I hate truckers. Link to comment https://www.bigmacktrucks.com/topic/40341-regear-options/#findComment-576148 Share on other sites More sharing options...
Joey Mack Posted Wednesday at 11:24 PM Share Posted Wednesday at 11:24 PM Buy the 4:17's. Gear sets are still available Quote Link to comment https://www.bigmacktrucks.com/topic/40341-regear-options/#findComment-576150 Share on other sites More sharing options...
Outbehindthebarn Posted Thursday at 12:09 AM Share Posted Thursday at 12:09 AM 43 minutes ago, Joey Mack said: Buy the 4:17's. Gear sets are still available Because they're better, or just the availability ? Quote Fun is what they fine you for!My name is Bob Buckman sir,. . . and I hate truckers. Link to comment https://www.bigmacktrucks.com/topic/40341-regear-options/#findComment-576151 Share on other sites More sharing options...
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