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General Forum : BavAutoSport short shift kit

- BMW E21 Community
   - General Forum
      - BavAutoSport short shift kit
wharthog   Posted Friday, Sep 1st 6:33pm [Edit] [Quote] [IMS] [View car]
Member
Post nr. 45
   
SF Bay,California, USA
1982 323i, , R1150RT
I just put the BAS short shift kit in a couple of weeks ago. It's expensive but it REALLY cleaned up slop and shortened the throws. It feels great!Effort is up a bit but it's a good system. My wife hates it (that's probably a good thing) A little on the pricey side but I had a gift cert to help out. Anybody have any thoughts about accelerated syncro wear or orther long term effects of short shift kits?

BruceH   Posted Friday, Sep 1st 8:54pm [Edit] [Quote] [IMS] [View car]
Member
Post nr. 998
   
Atlanta, GA USA
81 323 Baur, 85 745
Not trying to be a smart ass but why would a short shift kit affect synchro wear?

I tried Fred's short shift from e21parts.net and it was very nice.

wharthog   Posted Saturday, Sep 2nd 12:13am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 48
   
SF Bay,California, USA
1982 323i, , R1150RT
I've got a neighbor who's theory is the shorter thow means faster engagement and the higher effort means you're slamming the synchros together faster and exerting more pressure on them to get them engaged...

He's kind of the anti-tuner. he doesn't understand that factory cars are set up as compromises.

melloh   Posted Saturday, Sep 2nd 1:43am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 410
   
California, USA (San Jose)
1980 320is, 1991 318is
well, my semi-educated guess is that he could be right, but for the wrong reason. This is what i'm thinking (though i'm ready to be proven wrong, as always)

Where he's wrong- the short shift does indeed mean you exert more force to move it into gear. this is because you have less leverage (closer to the fulcrum/ball joint). Whats the physics formula again? I can't remember the formula... But basically in the end, you are exerting more energy to get the exact same end result (think of a breaker bar). I don't think it's possible to get a short shift that doesn't have you use more energy unless its hydraulic or electrically assisted or something crazy like that.

Where he's right- so if you can accept that theoretically the same force is placed on the other side of the shifter (transmission), then how can he be right? Well, i think is more on the psychology part of it.

Theory 1) we are probably still used to moving the shifter a certain distance to get it in gear (muscle memory theory). Since we are used to pushing it further, we will probably inadvertantly keep pushing the shifter even though its already in gear until we retrain our muscle memory - hence pressure on synchros

Theory 2) Dude.. why get a short shift unless you're driving aggressively? what happens (to many/most, not necessarily all) when we drive more aggressively? We shift faster! F=ma=mv/d... so v is higher making F higher, and more (potential) pressure on synchros. Add this to theory one and well.. you get the idea.

Theory 3) Well, this is a wierd one, so bear with me here . Try moving something really heavy (a cement block). How hard is it to control the DISTANCE you move it (especially if you are using Velocity to produce more force)? Very. Now, push a carboard box. MUCH easier to control the distance. The heavier throw of the short shit is slightly harder to control the exact distance you move it, so again, more potential to push a little too much and hence put pressure on the synchros.

Well, thats my $.04. I know, I went $.02 over... so where's my change, eh?!?! I'm curious what the REAL scientists in the forum have to say on my hack-theories.

jbob   Posted Saturday, Sep 2nd 8:26am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 374
   
AZ, USA
81 320i
Nice choice! I have the same kit, and love it! Altho, it is a bit notchy...relatively speaking. But after installing it, I instantly got spoiled & hate shifting in an E21 w/ the stock shifter.
I think the E21parts.net one is a little better since it uses close-tolerance bushings to connect the lever & linkage (the bavauto kit still uses OEM hardware).

I think you're more likely to wear out the synchros from bad shifting/driving habbits than simply adding a short-shifter. So, I wouldn't worry about it.


If you want to further improve the shifter feel by having more consistant shifter gate locations (especially during hard engine acceleration/decceleration), the E21parts.net engine dampener and urethane tranny mount (i bought one from ireland engineering) are awesome.
But those parts also introduce more engine vibration throughout the car.

JJG323   Posted Saturday, Sep 2nd 12:18pm [Edit] [Quote] [IMS] [View car]
Member
Post nr. 1262
   
Reading MA USA
1979 BMW 323i
jbob wrote:
Nice choice! I have the same kit, and love it! Altho, it is a bit notchy...relatively speaking. But after installing it, I instantly got spoiled & hate shifting in an E21 w/ the stock shifter.
I think the E21parts.net one is a little better since it uses close-tolerance bushings to connect the lever & linkage (the bavauto kit still uses OEM hardware).

I think you're more likely to wear out the synchros from bad shifting/driving habbits than simply adding a short-shifter. So, I wouldn't worry about it.


If you want to further improve the shifter feel by having more consistant shifter gate locations (especially during hard engine acceleration/decceleration), the E21parts.net engine dampener and urethane tranny mount (i bought one from ireland engineering) are awesome.
But those parts also introduce more engine vibration throughout the car.


I asked about the short shift kit for our cars,
the last time I was up at the bav auto showwroom.
Its a close ride for me.

Aparently, a lawyer makes all their short shift kits for them on his downtime - in his garage.

I am not sure about Fred at e21 parts kit, but i know he sells good parts, i need one for a 5 speed dogleg tranny.

BruceH   Posted Saturday, Sep 2nd 3:11pm [Edit] [Quote] [IMS] [View car]
Member
Post nr. 1001
   
Atlanta, GA USA
81 323 Baur, 85 745
Fred's kit action was superb. I tried it at the V@V event a few years back. Any of Fred's products are first rate.

One comment directed at Melloh's neighbor, he (the neighbor)doesn't know beans and I would ignore him. The actual engagement rod going into the tranny stays the same length, nothing is going "faster".

I agree with JBob on the tranny mount. Order of of the UUC red urethane e30 tranny mounts and you will see a marked improvement. Another factor on m20s is to check your motor mounts. A torn mount will allow the engine/tranny to move slightly and mess up the shifter alignment.

Waferman   Posted Sunday, Sep 3rd 1:12am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 12

Oregon
78 320i, 83 320iS
jbob wrote:


But those parts also introduce more engine vibration throughout the car.


Hi Jbob! I second the the above statement. A good buddy o mine who totaled his 320i GAVE me his E21parts.com engine dampener, and even with a stock tranny mount there is a lot of buzzing going on in the dash due to vibration. I am going insane in the membrane trying to find them all and isolate squeaks with bits of foam. Jbob, are you letting it go or what are you doing with new interior squeaks?

John

jbob   Posted Sunday, Sep 3rd 3:01am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 375
   
AZ, USA
81 320i
I just let all the interior squeeks go wild...but i can't really hear them anyways since the turbo & exhaust are much louder.

you might also want to check misc bolts & screws in & around the engine bay on a somewhat regular interval...sometime after I installed mine I noticed a couple of missing screws that are supposed to hold the top of the heater-blower cover (@ the back top of the engine bay, just behind the weather strip)

wharthog   Posted Sunday, Sep 3rd 6:49am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 52
   
SF Bay,California, USA
1982 323i, , R1150RT
I'd consider the new bushings if I were racing but this is my daily driver for the forseeable future. I'll keep it smoother thanks. If I want a vehicle that constantly shakes itself apart I'll find the guy that I sold my '92 Harley to and get it back.


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