TehRaydarlover's AWD Lover

[FAROYE.MOTORSPORT]

Hi !! Great rebuild for your car !!I follow you

325ix my turbo breaking my two front differential

Remy

[Eskie]

awesom

Absolutely awesome work and engineering in regards to the rebuildable V/C. It is the center correct? Do you think you may be selling these rebuild housings in the future?

I've got a spare blown V/C that I've been toying around with the idea of doing this for a long time but haven't because I lack the skills and machines. I did however rebuild one a couple years ago but cutting it open, replacing the o-rings, refilling it and welding it back together. Been daily driving it in the winter ever since and still functions great. Heres the thread, maybe there is some info that can help: http://www.e30tech.com/forum/showthread.php?t=118249

Excited for more!

[TehRaydarlover]

I added some more detail about filling the VC to my last post on the previous page.

Hi !! Great rebuild for your car !!I follow you

325ix my turbo breaking my two front differential

Remy

Thanks! Curious, what was the failure point in your two broken diffs? I'm guessing the spider gears, but maybe the crown gear?

Ray

Absolutely awesome work and engineering in regards to the rebuildable V/C. It is the center correct? Do you think you may be selling these rebuild housings in the future?

I've got a spare blown V/C that I've been toying around with the idea of doing this for a long time but haven't because I lack the skills and machines. I did however rebuild one a couple years ago but cutting it open, replacing the o-rings, refilling it and welding it back together. Been daily driving it in the winter ever since and still functions great. Heres the thread, maybe there is some info that can help: http://www.e30tech.com/forum/showthread.php?t=118249

Excited for more!

Thanks! Yes this is the center VC, although if you look back at my rear diff rebuild the one of the two rear VC I used had a similar design from BMW, I resisted the urge to open it as it was the one I ended up using so I'm not sure what they used to seal it but I'm guessing some sort of o-ring.

Maybe if work slows down a lot and I finish my build I could make a few, but for now this is a one off.

Nice, yes I saw your thread when doing research for this project. How did you decide on the viscosity of the silicone fluid? There is a car show in Chicago that I go to every year, Windy City - Vintagefest. Its at the ZF plant, Talking with a guy who worked there he was going to try and get me the specs on the viscosity and volume of fluid in the VC. Unfortunately, he never followed through for me :( I ended up following you with the mix of 100,000 cs and 60,000 cs. From your experience it seems to work well

Ray

[Eskie]

Thanks! Yes this is the center VC, although if you look back at my rear diff rebuild the one of the two rear VC I used had a similar design from BMW, I resisted the urge to open it as it was the one I ended up using so I'm not sure what they used to seal it but I'm guessing some sort of o-ring.

Maybe if work slows down a lot and I finish my build I could make a few, but for now this is a one off.

Nice, yes I saw your thread when doing research for this project. How did you decide on the viscosity of the silicone fluid? There is a car show in Chicago that I go to every year, Windy City - Vintagefest. Its at the ZF plant, Talking with a guy who worked there he was going to try and get me the specs on the viscosity and volume of fluid in the VC. Unfortunately, he never followed through for me :( I ended up following you with the mix of 100,000 cs and 60,000 cs. From your experience it seems to work well

Ray

Yeah, I'm curious to know if my rear diff has the welded cover or the snap ring cover. Mine is a '90 so who knows.

As far as the viscosity goes, I was shooting for 88k cst. I used this website:

http://scriptasylum.com/rc_speed/oil_mixer.html

which calculates that you need 75% 100k cst and 25% 60k cst.

I don't know if the volume that I put in it or the ratio was dead on but it is without a doubt stiffer than factory. Its a good and bad thing. You can tell when making tight turns into a parking spot the most. The drivetrain tightens up and the rear diff makes a slight rumble in that situation but its fine otherwise. I just take it easy when i'm parking honestly. It handles great in the snow and does some very interesting donuts in empty parking lots (in snow of course). Around corners you can whip the tail out by giving it gas and then it always wants to pull itself straight again.

That would have been really cool to get the info from a ZF employee, or ex employee. I've emailed them and called them a few times to try and get the info myself and they have no been willing to give it out. I'm probably on their shit-list.

If and when I do the next one I was thinking that I might just use slightly less volume but the same mix. If I recall, air-space in the V/C is key for the lock up characteristics as well as viscosity.

[Eskie]

Ah! I just re-read that you filled it and went back a page to check it out. Awesome!

Did you fill it all the way up to the fill plug or use a specific volume?

[TehRaydarlover]

Yeah, I'm curious to know if my rear diff has the welded cover or the snap ring cover. Mine is a '90 so who knows.

As far as the viscosity goes, I was shooting for 88k cst. I used this website:

http://scriptasylum.com/rc_speed/oil_mixer.html

which calculates that you need 75% 100k cst and 25% 60k cst.

I don't know if the volume that I put in it or the ratio was dead on but it is without a doubt stiffer than factory. Its a good and bad thing. You can tell when making tight turns into a parking spot the most. The drivetrain tightens up and the rear diff makes a slight rumble in that situation but its fine otherwise. I just take it easy when i'm parking honestly. It handles great in the snow and does some very interesting donuts in empty parking lots (in snow of course). Around corners you can whip the tail out by giving it gas and then it always wants to pull itself straight again.

That would have been really cool to get the info from a ZF employee, or ex employee. I've emailed them and called them a few times to try and get the info myself and they have no been willing to give it out. I'm probably on their shit-list.

If and when I do the next one I was thinking that I might just use slightly less volume but the same mix. If I recall, air-space in the V/C is key for the lock up characteristics as well as viscosity.

Yeah, I have no idea what diffs got a rebuildable rear VC. Both of the two I took apart we from '88 and one was and one was not

Good to hear it locks up well! How did you decide on 88K cs? I'm thinking I'm going to let it sit for a while and get all of the air up to the top then take a look at the expansion rate of the silicone and try and determine how much space I need to leave for expansion. I've got another VC cut open that I can measure the empty volume. Then just top off my filled VC and remove whatever I come up with for the expansion.

[Eskie]

If I remember correctly someone found someone send some V/C silicone out to be tested for viscosity and 88k cst is what the lab measured. I'd have to go back and check to make sure, it's been over 2 years since I did it. Crazy.

I'm interested to hear what you come up with volume wise, I measured mine with mineral spirits using the parts washer at work. Again, if my memory serves me I think it was 4.5oz with the plates and spacers in...

Also I don't know if this helps, but here is the link to the post where I referenced the expansion of the xiameter silicone from a pdf file on dow's website:

http://www.e30tech.com/forum/showpost.php?p=1371170&postcount=15

[rzerob]

Subscribed.

[23732]

As I am turboing my iX, I am very interested in the front differential reinforcement. Keep us updated.

Also, you have amazing skills and knowledge. Keep up the good work!

Best regards from us, crazy Scandinavians ;)

[litu]

Not sure are here some info for that upgrade that front diff for all those turbo ix owners who is broken it

http://www.r3vlimited.com/board/showthread.php?t=180631

[TehRaydarlover]

Thanks guys, Eventually I'll give an update with the front diff. Welder got a little happy with the heat and it locked up. In the process of cutting it apart and trying again.

If I remember correctly someone found someone send some V/C silicone out to be tested for viscosity and 88k cst is what the lab measured. I'd have to go back and check to make sure, it's been over 2 years since I did it. Crazy.

I'm interested to hear what you come up with volume wise, I measured mine with mineral spirits using the parts washer at work. Again, if my memory serves me I think it was 4.5oz with the plates and spacers in...

Also I don't know if this helps, but here is the link to the post where I referenced the expansion of the xiameter silicone from a pdf file on dow's website:

http://www.e30tech.com/forum/showpos...0&postcount=15

Cool, I'm glad we have some sort of source for the viscosity.

Nice reference, I think there might also be something in the SDS that came with from Krayden. (edit: nvm couldn't find anything in the SDS) I didn't get to it this weekend (was picking up a very special part :D) but hopefully after work sometime this week.

[TehRaydarlover]

Working on getting the transfer case back together.

I assembled my spare VC and used a syringe to add mineral spirits 10ml at a time. It came out to almost exactly 160ml (or 5.41oz)



Using the coefficient of thermal expansion that Eskie outlined in the link above of 0.00096cc/cc/°C I can calculate the amount of air I should have in the VC to allow for thermal expansion.

160ml = 160cc

160cc x 0.00096cc/cc/°C = 0.1536cc/°C

I'm assembling this at room temperature of 70°F or 21°C. I did a little research on how hot a transfer case should get (mostly coming from jeep forums) and it sounds like they can get over 200°F. That seemed really hot at first but then I thought about it. The engine is right there the exhaust is right there. ~30% power loss to the drivetrain has to go somewhere. Looking at the x profile o-rings they are only good for 230°F. I decided to go with 200°F (93°C)

93°C - 21°C = 72°C

0.1536cc/°C * 72°C = 11.06cc or 11.06ml for me

With this I will open up the fill hole on my VC and make sure it is completely full then remove about 11.5ml of silicone fluid. This should give me enough room for thermal expansion and keep the VC from exploding. :D

[nando]

I don't think the drivetrain loss is 30% - also it's not linear. if you are making 800whp the % decreases quite a bit. it's more like a slope/offset than just a straight percent. most of it is fixed by the drag of the drivetrain (whatever power it takes to rotate everything).

in any case I think you are on the right track with your calculations. I've read anywhere from 40-20% air volume at room temperature. The less air, the more it will lock, but it can also blow up that seal faster.

[TehRaydarlover]

True, my point was just that some of the drivetrain loss goes into friction and heating the parts up.

Yeah, 12.5ml seems logical to me. I might take a little more out just in case. The one write up that Jusso posted the translation of, a few years ago, showed the welded cover breaking. Whether that was from a bad weld job or the vc being over filled I'm not sure but I'd rather not have the same experience.

[FAROYE.MOTORSPORT]

[QUOTE=TehRaydarlover;4563843]I added some more detail about filling the VC to my last post on the previous page.



Thanks! Curious, what was the failure point in your two broken diffs? I'm guessing the spider gears, but maybe the crown gear?

Ray


Thank you for your interest, I have broken two spider gears, and impossible to remove the shaft, I had to cut the casing for disassembled


I can send you a message to improve the diff front ?

thanks you

Remy



Little movie of my Ix snow , e30 lover !!

https://youtu.be/oatRIAcfGqU