engine and drivetrain 2002 Turbo Gearbox ? 4 Tom Jones+ Byron

[tisalover]

Gents- I have a 1982 320is overdrive 5 speed (245) and have researched the 90mm shift rod/platform/driveshaft shortening, longer (automatic) speedo cable issues but am wondering if the 4 bolt output flange from a 242 gearbox that came with the car (NOT a real 2002 turbo 4 speed as was represented) will fit/bolt up to the currently 3 bolt  output flange 245 gearbox ? I realize that with the 0.81 OD 5th and Turbo 3.36 diff that the car would have very long legs but I have a Radar detector and am not going to hurt originality as the correct gearbox is missing. 5 speed CR would be ideal but they are becoming unobtanium. Would you go with the "leave it alone 4 speed" or upgrade to the OD 5 speed- Byron  are you running a 4 or 5 speed?  Sometimes, to paraphrase Voltaire- " the enemy of good is better."    sincerely, Peter

 

P.S. I added some irrelevant photos to help ease boredom- Mille Miglia breadvan etc.

[Preyupy]

If you are going to stick with the 3.36 final drive I would not go to the effort to put in the 245/5 OD box. You would have to be doing at least 75-80 mph before you could put it in 5th gear because unless you have some boost available you won't have enough power to push the car through the air much less up any hill (4000 rpm in 5th would be 97 mph just as it starts to make any boost) .   You will have to shorten the driveline, modify the shift tower and move the rear transmission mounts on the chassis.  If it is an original 4 speed car then just use the standard 242 4 speed box (you won't hurt it, I have no idea why BMW thought they needed to beef up the turbo 4 speed but not the 5 speed) 

 

To answer your other question Yes the 4 bolt flange will fit on the 245/5 OD box as long as it is the fine spline flange (the early 4 speeds had a course spline shaft and flange but not many of them are still alive) 

 

I am running the correct turbo 4 speed in my car with the 3.36 final drive.  I wanted a CR 5 speed so bad but mine was a 4 speed car and I did not want to modify it.  I might consider a 245/5 with a 3.90 final drive but nothing taller, it would help you get on boost faster at the bottom end and still give you a comfortable cruising gear, but I still would not modify the car.   That would give you an effective 3.31 final drive in top gear, a 3.64 final with the 245/5 would be a 3.09:1 in top gear  

[conkitchen]

Gents;

 

If I may; I am running a 245 with a 3:90 diff on my "turbo" car and I yearn for more off the line bottom end. The motor is built over stock and has 8:5:1 custom pistons with stock tii cam. Which is higher than the low comp spec in a factory turbo motor.

That being said, any boost that comes on really happens in third gear as I am out of gears/RPMs in first and second with the typical sundial pace turbo lag. 

 

On the highway...look out comin through!

 

Edited June 13, 2013 by conkitchen

[tisalover]

Byron-thanks for your expertise and thanks to you and conkitchen for confirming my suspicions about gearing. Best just to go with a 4 speed gearbox. sincerely, Peter

[tjones02]

Well, 4spd for the time being. But, bear in mind that with the 2002Haus 5spd trans crossmember a 5spd becomes a true bolt in. Well, I always do have to add some washers on top of the mount to shim the trans up 10mm. You'd only have to massage the tunnel to clear the later clutch slave for an OD box... No clearance necessisary for a '02 CR 5spd. I installed an '02 CR box in a customer's Turbo with a 2002Haus bracket last year. All I had to was slot the trans mount hole to reposition the mount or the slightly shorter CR box vs the 245/5 OD box the brack was designed for.... The customer kept the original 4spd and all shift linkage and driveshaft. If I were in your position I'd keep looking for a reasonably priced CR box but go ahead and plan on and use the 4spd for now. You never know what'll turn up.

Cheers,

[allbim]

Gents;

 

If I may; I am running a 245 with a 3:90 diff on my "turbo" car and I yearn for more off the line bottom end. The motor is built over stock and has 8:5:1 custom pistons with stock tii cam. Which is higher than the low comp spec in a factory turbo motor.

That being said, any boost that comes on really happens in third gear as I am out of gears/RPMs in first and second with the typical sundial pace turbo lag. 

 

On the highway...look out comin through!

 

Love that gif.