E39 (1997 - 2003)
The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki
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Topaz m5 diff build part 3- copied and moved over here
Many moons have gone by since this projected had started but it is still underway. Doing it my way requires much extra effort for all of the cleaning, prepping, and misc parts replacement that many people might typically skip.
As some of the more observant may notice something is different this time. As you can see I just got my differential case back from the jeweler after having it plated in 18k gold purely for corrosion resistance. 24k would have been to soft for this application.
I also had my m5 chasis rods painted red in a mixture of clear lacquer and wolve's blood for animal spirited driving. Unfortunatley i lost those pictures so you will have to wait until the install to see them.
i will now show you how to change the pinion seal in less than 10 minutes if you already have the differential out. It will probably take more time to read this than it took to actually do.
First take your bmw v8 fan clutch tool set fan clutch holder and attach it to the input flange through the creative use of various bolts, washers, and nuts. I would swear this tool was made for this.
Now that you have a way to stop the input from turning your can break the pinion nut loose. Keep in mind that the pinion nut is on the end of the pinion shaft and sets the preload against the pinion bearings so it is super critical to put back on exactly the way it came off.
There are 3 theories as to how to achieve this putting back the way you found it problem
method 1. use paint to mark the nut before removal so you know when you have turned it far enough when reassembling.
method 2. measure the peak torque required to break the nut loose then use the same torque to reinstall.
method 3. measure the turning resistance of the pinion shaft. Put a super lightweight torque wrench capable of measuring in the super low range of 10-20 inch pounds not foot pounds. Measure what the lightest setting is that you can put your wrench on without clickign while using it to spin the input. It should take somewhere in the neighborhood of 20 inch of force before the pinion spins. The correct amount is unknown.
I used method 1 and 2 at the same time. I originally planned to use method 3 but my 1/4 inch drive inch pound torque wrench wouldnt go low enough.
I painted the nut and bolt with a paint pain after thoroughly cleaning the surface with brake cleaner. I made two marks in case one got wiped.
Using my digital torque adapter set to peak mode (trace will only take live readings while peak will lock in the highest achieved. good for when you cant see the screen).
btw, before you try turning the nut remove the lock ring with needle nose pliers. Using a breaker bar in one hand and the fan clutch tool in the other i was able to break the nut loose with a recorded peak torque of 134ft-lbs before the nut came loose.
Using a three jaw puller i was able to easily snatch the input flange off of the pinion shaft. It actually came off so easily i wunder if it would have came off by hand. i never even tried.
The next picture is a view looking into the input end of the diff after removing the flange and shaft seal. You can see the roller of the the first set of pinion bearings. I drove the new seal in by flipping the old seal upside down so that it was face to face with the new seal. Doubling up the seals will help strength it from distortion while driving it in. I used a 6 inch length of schedule 40 pvc that i had laying around. It was approx 2 inch diametere. I laid a wood block on top of the pipe and knock the new seal in with a mallet because i didnt feel like carrying the whole thing upstairs to my hydraulic press.
I then slid the output flange back on and snugged up the nut. The nut went on by hand and only required tools for about the last third of a turn. Using my digital torque adapter set to peak again I turned the nut checking it every few millionths of a turn until the paint lines were exactly perfect. The adapter only measured a max torque of 114 ft-lbs to achieve this. In my experience it takes way more force to take a nut off than it does to put it on in the first place. Ever notice how much more force it takes you to take lug nuts off than when you put the wheel on?
anyway i considered the paint line method superior because the paint doesnt lie. The nut had to be in the exact same position it was before so i left it alone at the 114ft lbs measurement.
My camera also erased the pics of the spool and flanges being reinstalled.
What i did was first put the spool back into the differential and lay the diff case on its right side. Be careful not to let the spool slam around or you could damage the bearing or chip the gear teeth. I then put the left side flange about half way in.
I had to tap it with a wooden block to get it in. I then flipped the case on its left side and put the right flange in. Working back and forth i careful got each flange fully into place without smashing the bearing rollers on the ends of the spool. The outter bearing race in in the flange so that as the flange slides in it will cup the bearings and lock the spool in place.
some reused pictures:
The flanges have a certain orientation that was marked early with a chisel so that the oil drain ports are in the correct location.
Next I reinstalled the rear case cover. The cover is made of sand cast aluminum and has many interior and exterior heatsinks to shed the extra heat created by the friction disk style differential.
I would recommend new wave washers for all of the bolts. Wave washers are a type of lock washer. Instead of being clipped and twisted like the kind your used to, wave washers get their springy-ness from being twisted like a pringle. The clipped washer kind would most likely dig into the soft aluminum as it spun.
Not all of the rear cover bolts are the same length so hopefully you made a map of where they go.
good thing i tried out my paper gasket from pelican before applying the sealant. Everything was perfect except for the bolt holes on the left side making the gasket useless. Most people that take the cover off dont use this gasket anyway.
i was able to acquire a small tube of the realoem.com specified "flange sealant" made by loc-tite. It came in a really nice syringe but was probably not worth the $25. It appears to be silicone gasket maker like the permatex in a tube at autozone for a 1/5 that price.
I made a very small opening and put a very thin bead the whole way around the cover carefully circling the bolt holes after thoroughly degreasing it.
i did the same for the case. Only a little is needed because once you crank the cover down most of this will squirt out anyway.
Im not sure how long it takes to dry but i wont be putting the oil in for a few weeks so it wont matter.
after looking over my rebuilt driveshaft i noticed that the centering bushing on the transmission end might not be new so i replaced it. TIS procedure is to pack the end with grease then use a special tool to pound the grease in. The grease will provide pressure from behind and pop the bushing out.
I made my own special tool by wrapping 2 layers of electrical tape around 3/8" socket extension. After retopping off the grease about 20 times it eventually came out but it was a bit harder to do than i thought it was going to be.
here are 2 random pics of the finshed product
ESS Tuning m60 version software
m60 intake manifold
3" obx catback
full powerflex urethane setup
m5 rear sway bar
M5 chassis rods
M5 3.15 lsd
Bc-r coilovers w/ swift springs
ss braided brake lines
Last edited by Topaz540i; 01-02-2013 at 06:56 AM.
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