slight crunch in bmw manual transmission

[ticktockdock]

I have a 97 328i with a 5-speed transmission. It's the ZF transmission, same one that comes in the m3s. From the factory it calls for ATF. But many runs other fluids to obtain more desirable shifting. I'm running royal purple synchromax right now. The only gear I have a problem in is 4th gear. It feels like a VERY slight grind upshifting into 4th, so slight you can't hear anything, just feels like you nick something going into the gear. Downshifting it doesn't grind but it hesitates a little bit more than other gears (takes longer to go in). When the car is cold(first ten min or so) upshifting into fourth gear is very smooth, once fully warm it has the slight crunch. Does the temperature change and how it shifts changing with the temperatures suggest I should run a different fluid? Overall the car shifts better with the synchromax than it did with the atf it came with.

 

[d00df00d]

The fluid may have sheared and become too thin for smooth shifting when hot.

How many miles on the car, and how many miles since you put in the Royal Purple?

 

[Steve S]

Check clutch adjustment.

 

[d00df00d]

Originally Posted By: Steve S
Check clutch adjustment.

Yes, that too.

 

[mechtech2]

It sounds like new or slightly thicker lube would help.
And like the guys said, bleed the system, and make the pedal height and pushrod freeplay adjustments.

 

[d00df00d]

IMO:

- Change transmission fluid
- Flush and bleed clutch hydraulics

Then see if the problem still exists. You probably won't have to mess with the clutch pedal at all, which would be a good thing on that car from what I've heard.

If the problem is simply that the old fluid sheared, then fresh fluid might do the trick. However, if you're looking for something a little thicker, you might want to try to track down some Motul Multi ATF. It's a little thicker than most ATFs.

 

[double vanos]

Try Redline D4 ATF or MTL. Both great fluids for BMW transmissions that spec atf. Mine loves the MTL.

Cheers!

 

[double vanos]

Try Redline D4 ATF or MTL. Both great fluids for BMW transmissions that spec atf. Mine loves the MTL.

Cheers!

 

[Doug Hillary]

Hi,
ticktockdock - It may be wise to check the filler plug. Colour coded labels were installed to equate with the gearbox fluid to be used. These range from some special formulation lubricants to ATF and a 75W-90 lubricant. A Dealer will have the key to the codes

Castrol's recommendations range from VMX80 (75W-90), thru Castrol R Synthetic 10W-60 (Edge, TWR) engine oil to an ATF and a special fluid SMX-B

I had a Z3 2.8 and mine took ATF (Castrol Transmax Z)

 

[sprintman]

What is the ambient temperature where you live? Redline is the oil of choice for most BMW owners worldwide (Group V POE basestock). I have straight MTL in mine but a tad to thick for a Canberra winter. I'll be changing to a Redline MTL/D4ATF blend in a few weeks as we are in Autumn/Fall and cooling down. The MTL is so much better than the OWM junk it isn't funny.

 

[ticktockdock]

the fluid is fresh with about 1000 miles on it and it is full, I will try bleeding the clutch

 

[ticktockdock]

anybody? I was thinking of draining a little bit and putting a quart of mobil 1 synthetic 75w90 back in to make a thicker mixture. I can't afford to keep draining two quarts of expensive fluid every weekend. I spent $30 last weekend on the dam royal purple but its to no improvement. I bled the clutch slave cylinder to make sure there was no problems there but its the same afterwards, maybe a little better clutch feel but shifting has not changed. Do you forsee any problems mixing royal purple synchromax with mobil 1 75w90?

 

[d00df00d]

That's a gear lube. It's formulated very differently. I wouldn't recommend using it.

Why not get Mobil 1 Synthetic ATF or dealership fluid? Either one should cost you a sight less than $30 for two quarts.

 

[mva]

There are number of BMW owners reporting very good results with Amsoil 5W30 MTF.

Check out this thread for extensive information on this topic:

http://forums.bimmerforums.com/forum/showthread.php?t=1076268

 

[d00df00d]

That's definitely thicker than ATF.

 

[ticktockdock]

the reason I want thicker is that it shifts better when cold now, which leads me to believe it wants a thicker fluid

 

[d00df00d]

Possibly.

If you really want something slightly thicker, try to track down some Motul Multi-ATF. It's a very new product that is slightly thicker than most ATFs, but it's still an ATF. That might be all you need.

I love Amsoil's gear oils. Ι'm just wary of using a product meant for a different kind of transmission.

Since the problem only happens in a high gear, I really think it's just a slightly worn synchro. It's okay to go a little thicker to compensate, but you don't want to play dice with the rest of your transmission just to Βand-Αid a problem.

 

[hooperswish1]

I too run the synchromax but in a different application- jeep nsg370 6 speed. As you have stated, mine does run better when cooler, and gets a tad notchy when it gets hot. However, imho I feel that it still runs better with the rp than the factory stuff.It has been in for two years and about 16,000 miles, and I have decided to stick with the rp and change every two years. Good stuff, but it may shear...
As stated earlier, it could be a synchro issue with that particular gear.With only 1000 miles, I doubt it has anything to do with the fluid.
Good luck.

 

[harbor]

I've had great results with Amsoil 0W-20 in my Crossfire 6 speed transmission with regard to cold weather shifts.

Also, eliminated a 1st to 2nd gear cold weather grind in my 5 speed Jeep Patriot by switching to Redline C+ ATF. Spec for this vehicle is Mopar ATF+4.

 

[PT1]

If you want thicker try Redline MT90