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General Forums => The Mess Hall => Topic started by: huntingbuck101 on June 29, 2007, 07:28:26 PM
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got done doing my dana 35 gear swap from 4.10 to 4.88 and wanted to check if it was getting hot. after a 20 min. drive at about 2800 rpms I checked it with an infrared heat gun and it ranged around 198. I did the front that still has stock gears and got around 100 but it's not be powered like the rear. I cant hear any howling but with my tires who knows ( jacked it up and still really couldn't hear anything). I would think 4.88 would run a bit hotter then 4.10 because they turn faster but dose 200 sound to hot?
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I'm thinking your backlash is too tight.
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.013 backlash
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.013 backlash
how many points did you check?
You might as well tell us what the other specs you measured, too.
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it must take a few miles for the gears to set in. I just went for a 30 min ride and checked the temp again and the hottest it got was 165.
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it must take a few miles for the gears to set in. I just went for a 30 min ride and checked the temp again and the hottest it got was 165.
Gears will settle a bit. The reason why you need to get them within spec. is because they were put on a machine that runs the gears so they are matched. The break-in is a continuation of the process. The peening will help harden the gears.
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so do you think around 165 degrees is acceptable?
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If everything is within spec and it's not making any weird noises then it should be fine. There is a bit of leeway when setting up gears. They don't have to be prefect, just close enough.
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bad news, just drove it again today and checked it after 10 miles and it was 145. had lunch and then drove it another 30 miles and it was back to 198. Stop for about 30 min. and drove back about 20 miles and it was 182. all driving is between 60 to 65 so around 2800 to 3100 rpms. other then the heat every thing seems fine when I change the fluid in 500 miles I will put a good synthetic in and see if it will bring it down a bit.
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bad news, just drove it again today and checked it after 10 miles and it was 145. had lunch and then drove it another 30 miles and it was back to 198. Stop for about 30 min. and drove back about 20 miles and it was 182. all driving is between 60 to 65 so around 2800 to 3100 rpms. other then the heat every thing seems fine when I change the fluid in 500 miles I will put a good synthetic in and see if it will bring it down a bit.
If it's not making noise then I'd probably say it's normal break-in.
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Doesn't sound bad to me.
I know several gear installers who will not warranty work if you use synthetic fluid. I can't say why, but they're the pros and they don't recommend it for ring and pinions.
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got done doing my dana 35 gear swap from 4.10 to 4.88 and wanted to check if it was getting hot. after a 20 min. drive at about 2800 rpms I checked it with an infrared heat gun and it ranged around 198. I did the front that still has stock gears and got around 100 but it's not be powered like the rear. I cant hear any howling but with my tires who knows ( jacked it up and still really couldn't hear anything). I would think 4.88 would run a bit hotter then 4.10 because they turn faster but dose 200 sound to hot?
I saw this off-road magazine piece on a the hy-tec diff cover that might give some perspective on diff. heat following a new gear install: http://chevy.off-road.com/chevy/article/articleDetail.jsp?id=200783. Read about 3-4 paragraphs in to it. Mentions 500 mile break-in period, etc. Nothing conclusive, but it might shed a little light on your heat issue.
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I wish I new what was considered hot. If 200 is to hot I would change my oil, in case the heat broke it down.
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Based on the information out there, it doesn't look like you'll have any problem with 200F+ diff. heat during the break-in period.
Here's an exerpt from an article on diff. temps apparently done by SAE:
"Further evidence of stress and increased temperatures during the differential break-in period is documented in a 2005 SAE paper entitled The Effect of Heavy Loads on Light Duty Vehicle Axle Operating Temperature. A light duty GM truck towing 14,000 pounds was driven from Orange County, Calif. to the Nevada state line. The test was conducted with both a new axle and a broken-in axle. Over level ground towing, oil temperature was measured at 230 degrees F in the new axle and 203 degrees F in the broken-in axle. Oil temperature over the most grueling portion of the trip, during which a maximum 6% grade was encountered, revealed the new axle was operating at 350 degrees F and the broken-in axle was operating at 300 degrees F. Laboratory dynamometer test results simulating a truck hauling a trailer provided similar results, with level ground towing temperatures recorded at 266 degrees F with the new axle and 194 degrees F with the broken-in axle and towing temperatures (at a 3.5% grade) recorded at 370 degrees F with the new axle and 295 degrees F with the broken-in axle."
However, that looks like diff temps on light-duty truck (maybe 5000lbs) towing 14,000lbs. In your case, we are talking a 3000-4000lb Jeep though. Your unbroken-in axle is running 200F and their truck pulling 14000lb load with an unbroken-in axle is running 230F (presumably both on level ground). Your new gears are 4.88 which are said to raise temperatures. They are towing which is also said to do the same.
What is impressive is that their truck's diffs are said to be running 350F when towing uphill (Holy Cow :smokes:). And they were apparently doing this with standard gear oil (which supposedly starts exhbiting negative wear characteristics at 200F)! It looks like the gears, if not the gear fluid, have pretty (high) reasonable operating temp limits. So take a look at fluids -- the likely weak point.
Personally, I think you are making a good move if you run synthetic gear fluid, especially during the break in period (AMSoil seems to even make a special synthetic break-in gear oil, specifically for this type of thing) -- go with Mobil 1, Redline, Amsoil, etc. The break down temp on these oils is apparently between 300-375F degrees, likely 100+ degrees more than your standard gear oil. Also, they will likely produce less gear friction meaning less heat, so you'll probably see temps drop right there. Don't off-road, tow, low range for 500-1000 miles. Then change the synth fluid between 500-3000 miles to clean out any gear particulates in the fluid.
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Probably unnecessary, but you could just find somebody with the D35 and 4:10s and stock gear fluid and a heat gun to run at highway speeds for a while. Then get them to check the temp. on their axle. If it tests at 160F (+/- 10 or 20 degrees) or so after a highway run, then your 200F test is about right for a new axle. The ratios on the SAE test only seemed to show that a new axle would run about 15-20% hotter than an older one. If you have a heatgun, you should give a mate with a D35 and the aforementioned setup a call
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after my first run when I noticed it felt hot I put about 5 ounces of Prolong in it. I hope this will not effect the brake-in.
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It sounds like you'll be alright as is. Still, I'd personally want to go with synthetic from mile one on new gears. Then just change it out fairly often, early-on
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It sounds like you'll be alright as is. Still, I'd personally want to go with synthetic from mile one on new gears. Then just change it out fairly often, early-on
You do not want to go synthetic for the break-in. First off, you want the gears to finish the peening process. This is why gears run hot when breaking in. You'll get small flakes of metal in the oil and it's normal. The other issue is that you'll be changing the oil within 500 miles. Synthetics will make the break-in take longer and you'll be wasting the oil since it gets changed soon after. Once the break-in is done, then you can go with synthetics if you want. If you don't finish the hardening process you'll end up with soft gears and could shear them under stress.
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It sounds like you'll be alright as is. Still, I'd personally want to go with synthetic from mile one on new gears. Then just change it out fairly often, early-on
You do not want to go synthetic for the break-in. First off, you want the gears to finish the peening process. This is why gears run hot when breaking in. You'll get small flakes of metal in the oil and it's normal. The other issue is that you'll be changing the oil within 500 miles. Synthetics will make the break-in take longer and you'll be wasting the oil since it gets changed soon after. Once the break-in is done, then you can go with synthetics if you want. If you don't finish the hardening process you'll end up with soft gears and could shear them under stress.
Sure, what synth. oil manufacturer in their right mind would want you to ruin your gears from day 1 by introducing any kind of synthetic into the diff during break-in? http://www.turbobits.co.uk/acatalog/redline_lsd_friction_modifier_additive.html.
Diff additive or gear oil, they're still synthetic, just of apparently different composition and viscosity and partial or full-fill
If synth. manufacturers don't promote synth. gear oil from day 1, it does a couple of things potentially, financially positive for them a) doesn't make GM, Ford, Chrysler look like a$$holes for factory-filling their vehicles with regular gear oil b) gives synth manufacturers an opportunity to sell a "specialized" synthetic for the new gear installers out there. :lol:
Yes, you want to finish peening. You'd just want to finish peening with fewer metal wear particulates circulating, as might be created when running regular oils causing higher friction.
Keep in mind, Jeeps don't get any lighter running synthetic -- either oil, your gears are still under load "pushing the same pig." Run synthetics from Day 1 and minimize unnecessary gear wear.
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I would use regular oil for the break in period, as I am actually doing just now. The old gears with about 85,000 miles on them looked just perfect and they were never used with synthetic oil. Gears last a long time with either oil so there is no harm in running it with regular oil for maybe 500 to 1000 miles and then switching over to synthetic for the long run.
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I was told my 04 Silverado comes with synthetic in the diff. from the factory.
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If the gears are quiet just run it and stop worrying, if you set everyting to spec it will work and last no need to fuzz over it
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If the gears are quiet just run it and stop worrying, if you set everyting to spec it will work and last no need to fuzz over it
Even if the pattern isn't perfect, too! I have 40K on a set that that had an OK pattern but not 'prefect'. Didn't bother checking backlash either. Pattern looked good and went with it. No noise, no worries.
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thats just it, I wasn't relay happy with the pattern the drive side was just OK and I relay didn't like the coast side but I ran out of shims sizes .174 on driver side and .145 on pass. side ( the biggest and smallest in the pack). I wanted to push the ring gear a little further from the pinion to get a better pattern. I also couldn't get the preload on the crush sleeve as I wanted it. but got it tight enough so it would stop as soon as you let go if you spun it by hand. I had a new Mac 800# froward 1000# reverse impact and over 140# line pressure and it took 1 1/2 to get it that far.
Like Jeffy said there is some leeway they don't have to be perfect just close. Mines not perfect but it's quiet and the temp is coming down each day I drive it so I must have done it close.
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Once the spacer collapses it gets actually easier to collapse it further. getting the shim packs right can take patience and a lot of measuring. I have never bothered to check temperatures on the diff after rebuilding them.
Big rig differentials often have temp gauges on them but for car to medium duty trucks temps stay below critical for the oil. Just glad you got it back together and running. Even if it eventually fails you now know what needs to be done.