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| transmission / rear diff question https://slantsix.org/forum/viewtopic.php?t=33207 |
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| Author: | rock [ Tue Jan 13, 2009 6:20 am ] |
| Post subject: | Mopardean, I was after low end feel and 3.91 was fine |
Mopardean, I run 235 70 15's and a 3.91 suregrip. I put in a 833OD and found it to be a greaat combination! In 4th at 75 I was turning about 2400 rpm. I built my d100 for low end torque and with that 3.91 the application of that torque to the road produced very satisfying fun in any gear. I never found enough road to find out the top end on the highway. I never had a 3.55 but I can make you feel comfortable about a 3.91. As to shifter rebuilding, it is easy, easy. Just a Sunday afternoon task on a clean table top. I took a whole sequence of pics of the process and shared them with Argentina (Juan) who wrote up the process and used the pics and it was published in a Mopar world publication in Spanish. I can send you the link to it if you want to see it, and the pics are so clear stepwise that you don't need to read Spanish. rock '64d100 |
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| Author: | mopardean [ Tue Jan 13, 2009 7:14 am ] |
| Post subject: | |
sounds great Rock i will pm you with my email address thanks again dean |
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| Author: | tlrol [ Fri Jan 16, 2009 6:11 pm ] |
| Post subject: | A 3.9 will work better in a truck |
Yes is the answer to your question Quote: aside from the savings assoc with not repairing the rear diff on the truck now, will the 3.91 still help me?
The A833 O/D isn't what I would consider geared for a truck. 1st gear isn't low enough and the O/D is too "tall" at 0.73. With 3.5ish gears you don't really have the depth of gears that make a truck work like a truck. Using that 3.91 gear will help you actually make good use of the power band of the motor. Why don't you wire up a cheap tachometer and make note of what RPM's your rig is most peppy at...that should help in figuring out if you want to use the 3.91 or maybe even a 4.1. If you had a torque monster of an engine you could probably stick with your current gearing.
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| Author: | rock [ Sat Jan 17, 2009 6:24 am ] |
| Post subject: | Mopar Dean, yes |
MoparDean, In a word. yes. My 3.91 sure grip with 833OD was as nearly ideal for combo racing and daily running as I can conceive of having. I use an engine built for low end torque and an exhaust system designed and custom built to match. But even stock with a 1bbl carter and a stock engine and a A745 3 speed, the 3.91 rear end was perfect for work and road because of the ratios. Stock was a '64 with a 244 cam and the huge clutch. I can't even imagine how wimpy any ratio down from 3.91 might feel! A wonder you aren't having to slip the clutch all the time. I did change axles, housing, and all adn used Green bearings, just to try them and I have no problem with them. Much better not using the tapered axle to drum setup! rock '64d100 |
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| Author: | mopardean [ Mon Jan 19, 2009 9:44 am ] |
| Post subject: | |
the 3.91 goes in as soon as it warms up a little and i have a free weekend thanks to everyone for the advice dean |
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| Author: | mopardean [ Fri Apr 24, 2009 8:24 am ] |
| Post subject: | |
I finally got around to installing the new rear end and what a difference in driveability and performance. Many thanks for all the excellent advice. One issue i discovered: the gearing turned out to be 4.1 not 3.91 and i now need a different speedometer pinion. I found Doc's post on calculating the proper pinion tooth size and if i calculated this correctly with a 235 75 15 tire size i need part number 2538938. If this is correct that number does not align with the part number Dan provided earlier (5206 8157) with a 3.91 set up. So i am wondering if i calculated this correctly and / or maybe the part numbers have changed or something. I thought about asking the parts guy at the Chrysler dealer but he is busy looking for another job. Pretty sad what's happening right now to Chrylser and GM...But i digress. thanks for the help Dean |
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| Author: | rock [ Sun Apr 26, 2009 1:06 pm ] |
| Post subject: | yeh, the 3.91 is a match made in heaven |
I put a 3.91 sure grip behind my 833 and run 29 inch tires, the widest that will clear fenders in front on a sweptline d100. I don't have my tire chart on this computer but think it is 275 60 15 tires. Had I know how hard it was going to be to get 15 inch tires I probably would have gone down the 16 inch rim path. I had a set of mopar 15 inch cop car rims I had powder coated so wanted to use them. At 70 to 75 mph you will be turning 2400 rpm. Now that is loafing. Send me a PM and I will email you a scan of an article Juan (Slant Six Argentina) and I put together about the Hurst Comp Plus shifter cleaning and rebuilding. Great closeup pics, takes a lazy late Sunday afternoon to do, absolutely worth the effort. If you think the linkage is worn out, it may not be. Most likely the cup washers, bushings, and or cotter pins are worn out. You can still get them a Chrysler place. I have also made rods from other rods, but that is a lot of effort. On ebay you can buy bundles of rods cheap and with a picture of how things should look, make your own. rock 64d100 |
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| Author: | mopardean [ Mon Apr 27, 2009 8:23 am ] |
| Post subject: | |
Rock, thanks for your offer but you have already sent me this article and it was great. I took your advice and perfomed all these recommendations when i changed the clutch out simultaneous to my rear end swap. Many thanks to you and all the others for your advice. Dean |
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