E39 530i5 Crunchy shifting - Old trans, bad driver, or wrong fluid? (ZF S5D 320z)

[computiNATEor]

I just finished overhauling my clutch and transmission assembly, and I'm having issues with crunchy shifting. I can't rush the transmission into any gear, especially 2 or 3. This is a replacement transmission from a junkyard car; I'm not sure of the mileage, however, the car was in fairly decent mechanical shape.

I have a 2002 530i with the ZF S5D 320z 5-speed manual transmission. I'm using a UUC B1 lightweight flywheel paired with an OEM E34 M5 clutch, Genuine BMW E34 M5 throwout/release bearing, new F.A.G. pilot bearing, new FTE slave cylinder, new FTE clutch master cylinder, Genuine BMW new clutch fork/arm, new Genuine BMW pivot pin and spring clip. I have replaced the transmission twice now. I had a spare trans that I replaced the shift detents in, but it leaked from the input shaft seal like crazy and had odd first gear whining. I junked the OE transmission because it was popping out of 3rd gear at high loads/speeds, and it was completely covered in oil from 213k miles and 40k miles of oil pan gasket leaks.

This transmission I just installed came from a junkyard 528i. It's an "orange sticker" unit that I pressure washed clean, then lubricated the key points and installed in my car with the parts listed above. The shift detents seem a little looser, likely because I did not replace them.


I used some Valvoline 75w140 gear oil that I picked up from AutoZone in the transmission. The 75w140 is designed for differentials and has limited slip friction modifiers. I chose 75w140 to try and lower the volume of gear rattle that comes with a lightweight flywheel. I still hear gear rattle, though it is quieter than previously. If I'm going to have gear rattle even with this ultra-heavy oil, I think I'd rather have better shift quality.

But the bigger issue is how crunchy the syncros seem to be. I don't think I'm a bad manual driver now; I've put 22,000 miles on this 530i5, and I think I'm pretty smooth, but I can't get this trans to be smooth. And I don't think it's the transmission; at least, I hope it's not. I had the same issue with the last (now dissected) transmission.


Because of the UUC lightweight flywheel, RPMs drop very quickly when the clutch is pressed in. When I try to shift quickly at higher RPMs, like 2nd-3rd at about 4500, I get a quick "scrunch" grind before it goes into gear. Shifting at higher speeds and RPMs only works if I'm very careful and deliberate in moving the shifter. It's fine for street driving, but for performance driving it's quite frustrating.


Does this sound like the gear oil is too heavy? Too light? What's the deal here? The other transmission, the car's 2nd, had a blend of Redline MT90 and 75w140NS in it, and suffered from similar characteristics.

All thoughts/advice/helpful comments from the peanut gallery would be appreciated.

Thanks!

[djb2]

I just finished overhauling my clutch and transmission assembly, and I'm having issues with crunchy shifting. I can't rush the transmission into any gear, especially 2 or 3. This is a replacement transmission from a junkyard car; I'm not sure of the mileage, however, the car was in fairly decent mechanical shape.

A rule of boneyard parts: if the car looks in great shape, you don't want the engine or transmission. A car with a crushed front or rear was running great until its final millisecond.

But it's installed now. Try the proper viscosity fluid, with the right specs. The orange sticker should say "ATF", which is much lower viscosity than the syrup you have in there now. Put in the cheapest DEX-III ATF you can find and see if it improves. If it does, drain and fill with a full synthetic DEX-VI fluid.

[Mike WW]

I agree with the above, the oil in it is waaaaaaay too thick. And the wrong kind, it's a GL5, designed for diffs and has very sticky properties which make it bad for your tranny, at least synchros and shifting. Yes, ATF seems too thin, but it's not. I shake my head whenever I use it, but it works.

[dannyzabolotny]

Yeah, I'd try using the manufacturer-specced fluid to try and rule that out. Transmissions are not something that I would want to experiment with when it comes to fluid.

When sourcing transmissions I always try to get them from running cars... you never know how a car was driven when it ends up in the junkyard. That's why I bought a whole 540i/6 parts car for my 6-speed swap, so that I could verify the transmission was 100% good.

[computiNATEor]

A rule of boneyard parts: if the car looks in great shape, you don't want the engine or transmission. A car with a crushed front or rear was running great until its final millisecond.

But it's installed now. Try the proper viscosity fluid, with the right specs. The orange sticker should say "ATF", which is much lower viscosity than the syrup you have in there now. Put in the cheapest DEX-III ATF you can find and see if it improves. If it does, drain and fill with a full synthetic DEX-VI fluid.

There was a big dent in the LF fender and some big rear quarter panel damage, plus no rear bumper. I bet that's what did it in; it was an M52, non-sport 528i.

I have a half gallon of Valvoline Maxlife ATF that I've had for a while now for power steering and for my old 530is. I'll pump it in and see how we get on.

I agree with the above, the oil in it is waaaaaaay too thick. And the wrong kind, it's a GL5, designed for diffs and has very sticky properties which make it bad for your tranny, at least synchros and shifting. Yes, ATF seems too thin, but it's not. I shake my head whenever I use it, but it works.

Thanks!

Yeah, I'd try using the manufacturer-specced fluid to try and rule that out. Transmissions are not something that I would want to experiment with when it comes to fluid.

When sourcing transmissions I always try to get them from running cars... you never know how a car was driven when it ends up in the junkyard. That's why I bought a whole 540i/6 parts car for my 6-speed swap, so that I could verify the transmission was 100% good.

Understood, but I wasn't going to buy an entire E39 for just one part. Definitely easier to justify if you have a swap coming up.

[geargrinder]

Yoiks, yeah puttin' the diff stuff in is NOT the right move unfortunately. That very well might be hurting the shifting, not helping (and over time might hurt the parts as well).

If you want to try a Gucci fluid, on an ATF-spec'd box, the route to go is Redline (D4) or RP (Max) ATF's , but after putting that thick goo in, I'd flush w/ the Valvoline first. Run it for a week or something, then dump it for your final choice.

W/ the more finicky 420G tranny some guys find fresh RP or RL changes improves the shifts, although RP has the biggest impact, it also seems to 'wear out' so after a while you're back to ground zero.

Some of the BMW tuners / vendors also suggest using a moly-boost additive cocktail... see below.
I admit I have tried this in the box in my 540.... It shifts great for the most part although on the other hand come winter 2nd gear will undoubtedly be a bitch on freezing mornings, which seems an incurable condition, and so indeed its not a cure-all that's for sure.

http://store.uucmotorwerks.com/lubro...ive-p1189.aspx

Re: gear noise etc. that's just the game your into now, I'd not try to change it, as its' 'normal'.
If you get your idle boosted up a little in your tune that does help a bit. That should be an easy fix as long as you're on a version of the M54 tune that is publicly mapped.

[computiNATEor]

Cool, thanks for your insight GG. Going to fix that now.

I could change the idle, but I'm coming up on a road trip and I just want the car to be reliable for now. I might play around with it afterwards; I have a Shark injector tune at the moment, but the throttle mapping is tricky (and the OE map is superior, IMO). I may try to delete the idle control valve and use the electronic throttle body only, but that'll be a fairly large project.

[computiNATEor]

Update: put in Valvoline Maxlife ATF. Immediately the shifts are crisper and smoother. I can now rev match without grinding! YAY!

Thanks guys!

I also swapped out the trans mounts; the junkyard trans mounts were ok on inspection, but I was feeling some odd vibrations in the shifter assembly. I reinstalled my Lemforder bushings I had previously, and the vibes went away.

Took me about 90 minutes, including jacking the car up on to jack stands, draining and pumping fluids, and supporting the transmission to replace the mounts. EZ PZ.

[computiNATEor]

I'll report back if I have any further issues, but initial impressions are very positive. Didn't get the transmission fully heated up, so we'll see how loud the rattle is in a bit.

[djb2]

Another issue with diff fluid in a transmission: most GL-5 fluids have sulfur EP compounds at a concentration that will eat copper-bearing parts when activated. Synchronizers are often bronze (i.e. copper alloy) and activate the EP additives at every shift. That's why GL-4 fluids still exist -- it isn't an obsolete spec, it's a different spec.

We are glad to hear that your problem is solved, and that you reported back.

[f355spider]

Synchos do not like the slippery stuff in the differential fluids optimized for limited slip diffs. Synchros will crunch, when using that stuff...at least that was my experience with Ferraris I've owned. If I used diff fluid in a tranaxle without the limited slip stuff, shifting was crisp, no crunching.

[Santaclaus4]

Years and years (30!!!) ago I put regular gear oil in my manual transmission Ford Escort instead of the recommended ATF. It shifted horribly and after a few days I drained it out and installed ATF. The shifting immediately improved. As a side note, the gear oil that had only been in the transmission for a few days, drained out with a lot of brass "sparkles" in it. I do indeed believe it was corrosive to the transmission.

[computiNATEor]

Years and years (30!!!) ago I put regular gear oil in my manual transmission Ford Escort instead of the recommended ATF. It shifted horribly and after a few days I drained it out and installed ATF. The shifting immediately improved. As a side note, the gear oil that had only been in the transmission for a few days, drained out with a lot of brass "sparkles" in it. I do indeed believe it was corrosive to the transmission.

I didn't notice any sparkles, but then again, I just drained it directly into a drain pan. The fluid that came out was clean and clear. Could've probably gone back in the bottle, honestly.

[geargrinder]

Modern synchros should be steel not "yellow metal", so, the fears of damage shouldn't be quite as bad in past. I bet there's still some yellow metal in there someplace but in such a short time, any damage would be more from the physical 'grinding' you experienced from the fluid not supporting the synchro action properly.... not from the corrosive effects of the fluid. Should be 100% fine.

[blarf]

Modern synchros should be steel not "yellow metal", so, the fears of damage shouldn't be quite as bad in past. I bet there's still some yellow metal in there someplace but in such a short time, any damage would be more from the physical 'grinding' you experienced from the fluid not supporting the synchro action properly.... not from the corrosive effects of the fluid. Should be 100% fine.

Pretty sure the 420G uses brass syncros, which is why you have to be careful about which fluid you use.

[computiNATEor]

Pretty sure the 420G uses brass syncros, which is why you have to be careful about which fluid you use.

The 420G might, but I have a ZF S5D320z.

[geargrinder]

Pretty sure the 420G uses brass syncros, which is why you have to be careful about which fluid you use.

In the pix I've seen of them pulled apart, (one example below) I've never seen yellow... although I'll grant you for sure it could be "hidden"...

https://www.m5board.com/vbulletin/e3...ml#post6861617

My bud has a dead 420G lying around we keep saying we'll get some beers and take it apart some day for fun just to figure out how they come apart.

There are dire warnings about not being able to disassemble/reassemble without special jigs and tools out there (old LSCman threads IIRC) however there are also a number of threads like that one where people have pulled them down pretty far and put 'em back together. I do know one of the tricks is that the gears are pressed on with an interference fit and require crazy pressure to assemble (and the right jigging presumeably) but seems like if you're not trying to pull gears off shafts then they'll tear down OK, just with some tricks and jiggling required to put the cases back on...

Sorry for TJ Nate.

[TerraPhantm]

FWIW, this is what one of the synchros on a 320Z looks like:

[geargrinder]

mmmmm... looks like maybe yellow metal inside? Or maybe that's just some kind of treatment/coating.

[computiNATEor]

Either way, the “wrong” fluid was in there for less than 3 day and ~100 miles before being drained out.

[blarf]

There are dire warnings about not being able to disassemble/reassemble without special jigs and tools out there (old LSCman threads IIRC) however there are also a number of threads like that one where people have pulled them down pretty far and put 'em back together. I do know one of the tricks is that the gears are pressed on with an interference fit and require crazy pressure to assemble (and the right jigging presumeably) but seems like if you're not trying to pull gears off shafts then they'll tear down OK, just with some tricks and jiggling required to put the cases back on...

I was thinking more about the warnings to be careful with which fluid you use vis-a-vis synchros in the 420G (and the Supra 6 speed). Good to know people are having more luck pulling them apart... would be better to hear people are having more luck finding parts.

[TerraPhantm]

mmmmm... looks like maybe yellow metal inside? Or maybe that's just some kind of treatment/coating.

Yeah I'm really not sure. This is a synchro out of a Getrag 260 (e30), which is obviously yellow

[pelikot]

Sorry to interrupt the topic. This message is for TerraPhantm. I sent you a pm some time ago but never received a reply, just want to make sure that you received it. Thanks

[blarf]

Yeah I'm really not sure. This is a synchro out of a Getrag 260 (e30), which is obviously yellow

You linked to a webp image which only renders in Chrome/Opera (and maybe Safari).

Here's the jpeg:



After doing some digging I learned a few things. 1.) GL-4 still has the corrosive components (namely sulfur) and 2.) it looks like some manual transmission manufacturers go so far as to recommend GL-5 and GL-4 oils even though they (especially the GL-5 oils) will shorten the lifespan of the synchros. As to why some synchros are more susceptible to damage, they probably have more copper in the brass alloy.

[pleiades]

Those are 24K-gold synchros ...

Anywayz, if you have a 320z synchro on hand, magnetize a small needle and see if it is attracted to the metal. I'm actually surprised a soft copper alloy would still be used in a modern tranny. Learn something here every day.