mackmb212 Posted September 23, 2015 Share Posted September 23, 2015 So I have pulled the rears out of my truck for several reasons. While I'm at this point I am thinking of faster ratio. I have 7.49's now and from what I read and was told that was the fastest ratio available at the time. A friend of mine keeps telling me to find dm800 rears for the faster ratios and for having 30/30 brake chambers. Dose anyone know if gear sets are still available for these older carriers I have crd113 stamped onto the hogshead. I'm 99% sure I have a double overdrive quadbox and I'm looking to get up to 65 mph Quote Link to comment https://www.bigmacktrucks.com/topic/41915-b-model-rear-end-ratios/ Share on other sites More sharing options...
Brian Blaylock Posted September 23, 2015 Share Posted September 23, 2015 The bigger the number the slower the gear ratio for example a 7.49 gear ratio is going to be way slower than a 4.17 Quote Link to comment https://www.bigmacktrucks.com/topic/41915-b-model-rear-end-ratios/#findComment-304906 Share on other sites More sharing options...
j hancock Posted September 23, 2015 Share Posted September 23, 2015 Better ratios for that would be 5.02, 5.32, 5.73, 6.34 or 7.00 to replace the 7.49. Quote JimIt doesn't cost anything to pay attention. Link to comment https://www.bigmacktrucks.com/topic/41915-b-model-rear-end-ratios/#findComment-304909 Share on other sites More sharing options...
Freightrain Posted September 23, 2015 Share Posted September 23, 2015 With a double over, the 5.02 will likey be really close. My single over triplex with 4.62 would go ~65 flat out with 22.5" rubber. If you have tall rubber, it will gain a couple more. Quote Larry 1959 B61 Liv'n Large...................... Charter member of the "MACK PACK" Link to comment https://www.bigmacktrucks.com/topic/41915-b-model-rear-end-ratios/#findComment-304914 Share on other sites More sharing options...
Vladislav Posted September 23, 2015 Share Posted September 23, 2015 There were at least 2 styles of diff housings on B's.Earlier ones had 10 bolts all around the flange to be fitted to the axle banjo.Actually 10 bolts (2 big and 8 small) and two studs wich you can't see from the top but two nuts at the bottom side. No matter though.Later ones have multiple bolts around the mounting flange and they fit the same as CRD92/93 of R-model and other newer style trucks.The difference in late B's and R's is the length of the interaxle diff (power divider) housing. B's had longer divider and R's are shorter. This fact means a R model gear set (of the CRD92/93 style wich are pretty common) has short drive pinion on a FR than B model has. So you can put B model style gear set or use a newer one together with complete short body power divider. Need to correct the prop shaft lenght as a follow.I myself am looking for a pair of gear sets of a long divider style with a ratio about 6-6.5It doesn't look easy to find but you know my location isn't perfect for such the entertainment and I need no housings, gears only to ship them overseas for reasonable. Quote Никогда не бывает слишком много грузовиков! leversole 11.2012 Link to comment https://www.bigmacktrucks.com/topic/41915-b-model-rear-end-ratios/#findComment-304920 Share on other sites More sharing options...
daveigou Posted September 24, 2015 Share Posted September 24, 2015 Rudy, here is some info that may be helpful. The CRD 112 / 113 carriers were made until relatively recently, although there may be some differences. I know the ratios are different, maybe the axle shafts, maybe the way the torque rods mount. Other model carriers may be interchangeable, I don't know, maybe somebody else on here would know.Our Superliner (1988) was built with 112 /113 series carriers (4.64 ratio) and were replaced by lower GCWR 92 / 93 series.doc348.pdfdoc349.pdf Quote See my Flickr photostream page http://www.flickr.com/photos/96692978@N05/ Link to comment https://www.bigmacktrucks.com/topic/41915-b-model-rear-end-ratios/#findComment-304951 Share on other sites More sharing options...
mackmb212 Posted September 24, 2015 Author Share Posted September 24, 2015 Thanks for your input guys. Quote Link to comment https://www.bigmacktrucks.com/topic/41915-b-model-rear-end-ratios/#findComment-305061 Share on other sites More sharing options...
Gmerrill0516 Posted September 25, 2015 Share Posted September 25, 2015 I've got the same set up I believe with the double over quadbox, 7.49's and the lot. So, to get the "right" set of parts to maintain stock appearance we would need to find rears off of a B and not an R. Is that right? Otherwise we can make a set of parts that works at whatever ratio we pick up but the power divider is a newer style and we would potentially need the R intermediate shaft (or whatever you call it) to make it work right...Is that accurate?I haven't driven mine on the road yet but I know it's gonna be a tad slow even with the 24's.Thanks Quote Link to comment https://www.bigmacktrucks.com/topic/41915-b-model-rear-end-ratios/#findComment-305071 Share on other sites More sharing options...
j hancock Posted September 25, 2015 Share Posted September 25, 2015 Most tire manufacturers prefer to have their tube type 24 inchers stay around 55-60 mph so don't make your B's too speedy. 2 Quote JimIt doesn't cost anything to pay attention. Link to comment https://www.bigmacktrucks.com/topic/41915-b-model-rear-end-ratios/#findComment-305072 Share on other sites More sharing options...
Maddog13407 Posted September 25, 2015 Share Posted September 25, 2015 id look for a heavy R or Dm and swap the rears out, even if you have the shorten or lengthen the driveshaft, its worth it and only cost a hundred bucks or so to have a shop to it. least that way you end up with the newer style hogs heads and the ability to put maxi cans on Quote Link to comment https://www.bigmacktrucks.com/topic/41915-b-model-rear-end-ratios/#findComment-305097 Share on other sites More sharing options...
Gmerrill0516 Posted September 25, 2015 Share Posted September 25, 2015 There sure is a lot to learn on this topic...so I've got maxi cans on my old rears that appear to be close to correct. I believe if I get offset slack adjusters I'll be legal...Is that not possible or just difficult? I do know that the cans sit real close to the sidewall of the tires. The clamps are all rotated so that the draw bolt and nut are inboard and not out as they would make contact for sure. Is that too close for comfort? I know the prior owner ran a triple cylinder Donaldson dump body on it and had lengthened the frame a foot or so to accommodate its length. He definitely worked the truck in its current axle/brake configuration for a long time.MACKMB212 how are your brakes set up on the old rears? I'd love a picture of it (oh and don't throw those away...)ThanksGreg Quote Link to comment https://www.bigmacktrucks.com/topic/41915-b-model-rear-end-ratios/#findComment-305115 Share on other sites More sharing options...
Vladislav Posted September 25, 2015 Share Posted September 25, 2015 So, to get the "right" set of parts to maintain stock appearance we would need to find rears off of a B and not an R. Is that right? Absolutely. Quote Никогда не бывает слишком много грузовиков! leversole 11.2012 Link to comment https://www.bigmacktrucks.com/topic/41915-b-model-rear-end-ratios/#findComment-305135 Share on other sites More sharing options...
mackmb212 Posted September 26, 2015 Author Share Posted September 26, 2015 There sure is a lot to learn on this topic...so I've got maxi cans on my old rears that appear to be close to correct. I believe if I get offset slack adjusters I'll be legal...Is that not possible or just difficult? I do know that the cans sit real close to the sidewall of the tires. The clamps are all rotated so that the draw bolt and nut are inboard and not out as they would make contact for sure. Is that too close for comfort? I know the prior owner ran a triple cylinder Donaldson dump body on it and had lengthened the frame a foot or so to accommodate its length. He definitely worked the truck in its current axle/brake configuration for a long time.MACKMB212 how are your brakes set up on the old rears? I'd love a picture of it (oh and don't throw those away...)ThanksGreg Quote Link to comment https://www.bigmacktrucks.com/topic/41915-b-model-rear-end-ratios/#findComment-305169 Share on other sites More sharing options...
mackmb212 Posted September 26, 2015 Author Share Posted September 26, 2015 I was told if I had 65k rears the stock brake chamber mounts are bigger and a new style can will fit. I have a maxi chamber that I tried fitting on my rear but there is no clearance for it to fit. Quote Link to comment https://www.bigmacktrucks.com/topic/41915-b-model-rear-end-ratios/#findComment-305170 Share on other sites More sharing options...
Gmerrill0516 Posted September 27, 2015 Share Posted September 27, 2015 I need to look at my truck and my paperwork to see what I have, i'll grab some more pictures and share what I find. Thanks to all...So I checked my paperwork and I have 50,000 CDDP112/CRD113 rears with 7.49 ratio. The speed indicated on the sheet is 57/58 mph. It does have maxi's on it now so there must be a way to do it without the 65,000# rears. I'll get info off the cans if I can this weekend. Also says I have the TRQ7220 trans and I have 24" rubber again from Mack. Originally the 864 V8 as well.Don't know if that helps any but its more info for the mix.Thanks Quote Link to comment https://www.bigmacktrucks.com/topic/41915-b-model-rear-end-ratios/#findComment-305355 Share on other sites More sharing options...
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