Lightweight Flywheel Gear Rattle Lash Noise on BMW

[Jeron]

A solid fly in place of the dual mass fly is a common "upgrade" for BMW's but causes gear rattle at idle. In my case, I also have noticeable gear noise during engine braking.

ATF is the spec fluid for my tranny. There is no idle gear noise when my RP Syncromax is cold, 35.3 Cst@40c.

Common solutions to thicken the tranny oil are:
Redline (50/50) D4 ATF and 75W-140ns
Redline MTL90

I'm concerned about unknown side effects of mixing ATF and Gear Oil. Also the mix of ATF and 140 seems to yield a cST@100c that is only slightly thicker than MT90 so I think I would rather use MT90 to avoid the "unknown" of blending.

cST@40c cST@100c
35.3 7.7 RP Syncromax (in there now)
34.5 7.5 RL D4 ATF
90 15.6 RL MT 90
179.2 26.9 RL 75W140ns
83.7 13.8 Amsoil 75w-90 GL4

Any suggestions of how best to thicken my tranny oil, retain protection and retain decent cold (30F) weather shifting would be appreciated.

 

[Whimsey]

I would strongly advise against using gear oil in a manual tranny UNLESS the manufacture specifically calls for it. Which is probably only on heavy duty equipment at best. Contact MolaKule at Specialty Formulations, a site sponsor. They have a great line of tranny and gear fluids that are top quality. I'm using their SynchroGlide MTF and I believe it's around 9.3 "ish" cST @ 100*C instead of ATF which the manufacture calls for. And to be fair to our other site sponsors check with Pablo concerning Amsoil's selection also. In fact just check out the site's sponsor section. OH! and

! Happy hunting.

Whimsey

PS. I'm in northern NJ and the SynchroGlide shifted just fine this past winter in single digit temps.

 

[unDummy]

Why mix?
There are a bunch of fluids that are thicker to try. If you have to mix, stay with the same brand.
Plus, since you're in Texas, you probably don't need to worry too much about the cold performance.

To thicken RP Syncromax, use their GL4/GL5 Maxgear.

Besides Amsoil and SF, here are other fluids to try alone or blend with same brand ATF:
Pennzoil Syncromesh
Redline MTL
Torco MTF
BG Synchroshift II

 

[e36'n]

from another thread from bimmerforums.com

M3 UUC LTW Flywheel "magic mix"

* The "magic mix" is something we recommend no matter what: 1 full bottle of Redline 75W140NS, the balance (about 4/5ths of a bottle) of Redline D4 ATF. We use this mixture in the notoriously louder 6-speed gearboxes and they go dead-silent. If anybody wants to stop by UUC and hear my car, feel free.

 

[Craig in Canada]

Have they/you tried MTL or MT-90 and compared it to "magic mix"? MT-90 has a pretty high cSt, pretty much equivalent to 75W90 but GL-4 and with friction modifiers for the synchros. Also, there's the GL-4 vs. GL-5 issue. You wouldn't want that 75W140NS to be corroding your synchros or something. I know there's debate on whether GL-5 is actually corrosive to soft metals, but I've heard enough that I wouldn't run it in my transmission.

cSt data:

D4-ATF 7.5/34
MTL 10.6/56
MT-90 15.6/90
75W90 15.6/94
75W140 26.9/180

Personally, I'd try MT-90 before 'magic mix'.

Craig.

 

[Jeron]

Thanks for the responses. The UUC "magic mix" from BF.c is what I was referring to. I should have contacted Redline to see if they agree with that blend of their oils.

I wanted to try Redline MT90 but Redline is not as easy to get, so I purchased Amsoil 75w-90 Gl-4 Manual Tranny Lube to use straight up. The Amsoil is slightly thinner than the MT90 but still twice the rating of ATF.

 

[e36'n]

Go for the UUC mix. They specialize in BMW's and deal with the chatter all the time.

Contact Redline to see if they are compatible and if so do it.

 

[MolaKule]

quote:

---

Any suggestions of how best to thicken my tranny oil, retain protection and retain decent cold (30F) weather shifting would be appreciated.

---

Try our SynchroGlide before trying to do any amateur blending:

http://specialtyformulations.netfir...alog/product_info.php?cPath=21&products_id=33

 

[e36'n]

Why do you recommend syncroglide over MTFglide?

 

[MolaKule]

Because it has a higher viscosity and "tends" to dampen vibrations in the tranny.

Any fluid thicker than SynchroGlide will probably yield slougish shifting in cold weather.

 

[e36'n]

Thanks. Could I get your input on this thread I started
http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=get_topic;f=16;t=002918

Much appreciated.

 

[madmax420]

Jeron, There's a little company called SWEPCO in your backyard,up the road from the stockyards on n.main. They've got a tranny fluid next to nobody!!!!!they call it 714-20. Works great.swepcousa.com