Bimmerforums - The Ultimate BMW Forum
Go Back   Bimmerforums - The Ultimate BMW Forum > Bimmerforums BMW Cars > M3 Series (E36)
     10/17/2005, 12:06 AM
Join Date: Mar 2001
Location: SF Bay Area
Cars: 1995 M3/2
Posts: 909
Why the B&M might not be a good shifter... (pics)

Hey Guys, checking in after a couple hours of being under my M3...Below you'll see a pic of a de-installed B&M Short Shifter from my 1995 BMW M3. A little background...I bought my 1995 used from the original owner, the car came with a 45126 Model B&M Short Shifter. The shifter was installed brand new and has less than 10k on it.

The Issue
On warm days (70+ degrees) and/or under hard driving, the heat from the Catalytic converters heat up the transmission tunnel...thus causing the shifter linkage to have a binding feeling. I've had the tranny fluid changed to Royal Purple Syncromax about 2 weeks ago. Good stuff, that helped BUT as soon as the next warm day came, the shifter would bind.

The Symptoms
When cool, the shift is smooth and feel great! Fast fast fast. BUT On a warm day, the shifter would almost fight against feels like you are forcing it to get it into gear. You can feel/hear a CREAKing in the linkage. It's definitely noticeable. It's not shifter slop or bad synchros (as you would notice those issues even when cold).

The Design and Thermodynamics Issue
I've driven one other BMW with a similar B&M short shifter (it had a similar issue) and asked around online...this binding issue isn't new and a couple of calls to various BMW vendors tell of customers with similar experiences. The B&M at sub $200 might be a great price and offer great shifting, but once that heat issue kicks in, it makes the shifter useless.

Ok here's the skinny, you'll notice from the pic that the shifter shaft is similar to every one else's, stainless steel and an aluminum top portion. The B&M has a nice feature in that you can pretty much just drop in the shifter (as it comes almost pre-assembled and it sits at the right height and utilizes the stock shift linkage. Shifts are fast and smooth.

BUT, here's where the fairy tale ends...once your car is pretty warm (i.e. the cats are flaming red)...the transmission tunnel begins to get some heat. You'll notice this especially driving in stop/go traffic, city traffic, etc. on a warm day. This heat collects in the tranny tunnel where the shifter is at the highest point (think heat rises)...The aluminum carrier of the shifter soaks up this heat (aluminum loves to soak up heat) AND this heat is transferred to the aluminum bearing collar of the shifter... from this point ignore the blue carrier and concentrate on the bearing collar and bronze bearing of the shifter.

According to B&M, this collar and bearing are "self lubricating". But if you have a look at this unit, there is no lubrication other than a thin oily film.

Once the shifter collar is heated up, it begins to resist the movement of the bronze bearing. I tried looking up the expansions properties of the bearing and collar and came up with 2 theories:

1. The brass bearing gets hotter and expands. Not a lot, but enough to take up the gap between itself and the collar, thus offering resistance.

2. The heat buildup increases friction - it breaks down whatever little lube there is in there
If you had this unit to try right now off my car, it actually fights you as you try to rotate the bearing collar around the bearing. Not to noticeable when the unit is on the car and leverage helps you move it around.

All in all, I'd advise strongly against any of you guys buying this thing.
I've got an MRoadster lever in my M3 for now, but am looking at the UUC as an option.
Hope you guys found this helpful.
ex-1996 Luxo M3

1995 BMW M3 - Prod 11/95 - Yep like the last one!. Almost all stock, but not for long. Team John 3:16.