M42club.com - Home of the BMW E30/E36 318i/iS
DISCUSSION => Engine + Driveline => Topic started by: BlackBMWs on February 13, 2010, 07:30:37 PM
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Sunny day, good day to play. Dropped the top and drove around enjoying the great weather.
I noticed a sound after making a right turn at an intersection, thinking it was a beater next to me, only to find it was me. I pulled into the nearest parking lot and found that I was hearing a clunk every 1/2 rotation of the rear wheels.
I had it put on a AAA flatbed and now the vert is in my driveway. Raised the rear on stands, crawled under and visually inspected. Guibo, center bearing and nuts to driveshaft all look good. Axle boots are cracked, but looked normal otherwise. spun the rear wheels and I'd get a slight clunk, whick I've always associated with about 1/4" or so play in the diff when rotating the wheels from forward to reverse and back. No holes in the diff case, no signs of any leaks. I run Redline Gear oil in the diff itself. All bolts/nuts I could see are intact. Diff mount is intact.
Rear universal joint on the drive shaft looked intact. I could not see the forward universal joint closer to the CSB. Nothing really looks out of place visually. Dropped the vert back down and moved it foward under power. Clunk, clunk about every foot. (Only moved 2 ft). It sounds like the CSB is loose/off.
I'll get the car back up tomorrow and see if I can pull the heat shield to inspect the CSB. I did just replace it and the Guibo last week, so that the first place I'm suspecting...
Just posting here in case someone else had any similar experiences that they had not posted yet. (I did search, no clear match)
Thanks!
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I did just replace it and the Guibo last week, so that the first place I'm suspecting...
I'm not a gambling man, but if I was I'd bet on something related to that work being the culprit. If you did it yourself go back and check everything - you must be able to better determine whereabouts the sound is coming from. Allow your eyes to be led by your ears, but don't rush. Get under that wretched vehic with your tools and investigate.
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I've heard of pre loading the csb . Did you do that ?
good luck
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Thanks guys. I'm thinking the CSB nuts worked loose. While I torqued them down, I don't think I applied any locknut as I usually do. I applied locknut to the new Guibo and driveshaft nuts. :mad:
I did preload the CSB forward 3/8" from it's neutral position. Two worse cases, 1 of the universals on the driveshaft has failed or, My diff is going.
I'll see after I finish up a short job on the 533i. :cool:
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Well, I found the source of the clunking.
(http://i402.photobucket.com/albums/pp105/BlackBMWs/318ic%20-%20DIY%20Differencial%20replacement/DSC01952.jpg)
I wonder if I can just JB weld this back on. :D
(http://i402.photobucket.com/albums/pp105/BlackBMWs/318ic%20-%20DIY%20Differencial%20replacement/DSC01958.jpg)
The fresh fluid is on the right. Fine Metallic particals in the current fluid along with the one big chunk.
(http://i402.photobucket.com/albums/pp105/BlackBMWs/318ic%20-%20DIY%20Differencial%20replacement/DSC01955.jpg)
The driveline to the diff was just fine. There's a 33% off parts at the yards so, I'm off to see if I can find a donor...
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Is that part of the ring gear? Sorry to see those pics. Time for a 3.73 medium case LSD upgrade! I found mine in an '88 325is. I highly recommend it, especially for fuel mileage and prolonging the engine's lifespan.
It didn't make as much of a performance difference as I thought it would, but I'm only running 14" wheels so your mileage may vary.
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Nice feedback! It looked like a 1 inch piece of the ring gear. Was the medium case you put in a bolt in upgrade or was there other mods necessary to fit it in? I'd be interested in the same setup. There are many E30's at the yards out here and I bet I could find one.
I found a donor 91 318i sedan with a intact 4.10 diff, CV and half shafts. $59.00 for all. Drained nice clean diff fluid out of this one, not like what I drained out of mine yesterday. While I used Red Line 75/90, anyone recommend a superior fluid for general use?
As a bonus, found another basketweave as a spare for $12.99.
(http://i402.photobucket.com/albums/pp105/BlackBMWs/318ic%20-%20DIY%20Differencial%20replacement/DSC01961.jpg)
The rubber on the CV boots are in better shape than mine, so I'll swap those in next week.
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Looking at RealOEM, the cases between the small 4.10 and medium 3.73 look identical, however, neither look like it has the same rear cover diff bushing mount. I suspect the drawing is off. :confused:
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Found and read a few good articles on BMW diff swaps and gear ratios. I better understand now and have a good idea of what to look for. I'll take a quicklook around the yard for a few potential candidate vehicles and perhaps find a LSD in either a 3.73 or a 4.10. If no luck, I'll put in the non-LSD 4.10 I picked up on Monday.
It also described the difference between BMW fluids for LSD and non-LSD final drives. It mentioned that Redline 75/90 would work for either, but is the BMW fluid actually optimum?
Thanks for the lead... :cool:
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The diffs absolutely swap right up. The medium case is bigger but has the same mounting holes. The diff bushing is much stouter than the small case (thus the different part number..it's nearly solid rubber), so I considered that an upgrade as well. I still have pics up if you're interested, but you got a great deal at the salvage yard...http://s729.photobucket.com/albums/ww299/desktopdave/Diff%20Job/ (http://s729.photobucket.com/albums/ww299/desktopdave/Diff%20Job/)
The only difference in e30 diffs is the speed sensor. Earlier (pre-'88) cars have a different plug on the diff. I had to cut & splice mine after I stripped the lower bolt head. They're only 8mm or 10mm and catch a lot of road salt. I'd have preferred to swap the speed sensors, but it didn't work out that way.
I'm not sure if the ix and M3 oddballs are the same, but you can also even swap e36 diffs from the Ti and Z3 with some parts swapping. I'm told that the same diff was installed in e12s and maybe e28s too. I know my e34 had the same ring & pinion but in a very different case.
I had a lot of trouble with the mounting process. I'm sure you've found it's a PITA to get at those upper mount bolts. The diff snout seemed to be slightly longer when installed (FWIW the two measured exactly the same). I ended up pulling the heat shield and exhaust, then loosened the drive shaft collar nut. The drive shaft can compress or expand that way. I also pounded out the rear drive shaft studs. Then I jacked the diff up, caught the top bolts, re-installed the drive shaft studs & tightened them down. I had to bend the ear mount slightly back for it to fit perfectly. Finally, I reinstalled the half-shafts and put the heat shields & exhaust back together. Took me an afternoon without air tools and lots of rusty bolts. I'll bet I could do it in half the time now.
I use Valvoline synthetic gear oil in the diff, but I'm figuring any synthetic gear oil without too many friction modifiers would work well. Redline makes great stuff. BMW fluids are excellent too.
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Thanks Dave! I had a tranny jack with me so, once I disconnected the diff bushing bolt, I lowered the diff about 2" and used a 17" 3/8" breaker on the top bolts from the passenger side of the diff. No problem.
I did spray all the fasteners with PB Blaster the day before, so that probably helped.
Armed with a bit more info on diff options now, I'll head back and take a look at the 89 and 90 e30 is I saw this weekend and check their diff types/ratios.
among the yards within 20 miles, there are prolly 20 or so E30's to check. Perhaps, I'll run into a good find.
How signifant was the 3.73 swap for you in terms of gas mileage?
Thank you for the pics and feedback! Rich :cool:
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It wasn't too significant in terms of mileage, at best (on summer tires, low-alcohol fuel, high humidity, cruise control, 70mph-ish highway driving) maybe 2-3 more mpg.
I expected the car to feel slower, but it really doesn't. It's only a 5% difference IIRC. I'll bet a racer would notice, but I don't track the car.
The big difference is how much more useful 3rd gear is. I just don't have to shift between about 20mph and highway speeds. RPM at typical highway speeds dropped 400-500rpm too, makes for a nice difference especially over 70mph.
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Related question; what size allen wrench would I need to take off the drain and fill plugs on the diff?
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I don't recall. It's big, like maybe 10mm. Some other BMWs have huge 17mm plugs...
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I have a set that goes up to 10mm and it's loose so it must be a tad bigger. 12mm perhaps...just wanted to know if anybody knew of the top of their head. Thanks for the reply though Dave.
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I have a set that goes up to 10mm and it's loose so it must be a tad bigger. 12mm perhaps...just wanted to know if anybody knew of the top of their head. Thanks for the reply though Dave.
I've used 10 and 14mm IIRC for the various cases I have. 17mm I believe used on a E36 auto tranny plugs. I purchased a set of allen sockets at Harbor Freight for like 12 bucks. 5mm to 17mm. Worth the $12. :rolleyes:
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Find a bolt head that fits the hole. Weld the nut to the bolt, or double nut it and use that.