1976 BMW Motor Replacement - BoJo

[BeMyWay]

I have started a motor replacement for my 1976 '02 called BoJo (because he can dance...use to).  Well anyway, I was told by the PO that I have a rebuilt engine with a 10.5 to 1 compression, 292 cam, and thats about all I know.  

 

So, I am planning on doing the following:

• Using a 38/38 Weber Downdraft
• I plan on using a honed-out intake manifold...not sure about leaving indiidual ports or making a peanut shaped opening in the manifold
• I wanted to use a 228 flywheel-clutch assembly
• I 'm using a 5-speed getrag 245 (the 5-speed was installed when I purchased the car years ago)
• I will be keeping the stock rear differential
• Install a stock exhaust manifold from an earlier Tii

 

My problem at the moment has been the sourcing of a 228mm flywheel...on my, this has been the most unexpected time sucking experience I have run up against...if you dont want to spend loads of cash...and I didn't want to.

 

I did find a flywheel, but it is worn a bit to say the least. 

The clutch plate contact raised area...1)  is not so raised; 2) there is a ring dividing the raised area (plate contact) and the outer lip.  3)  the raise area (clutch plate contact area) is lower than the lip in some areas and almost equal in height in others.  4)  using a straight edge, I do not see any warpage....and 5)  insult to injury, so far, I have not been able to locate a machine shop in the area who can or is will to smooth the surface for me!    I did read in one faq article, the raised area was a way to insure tighter contact and provide for longer life on the clutch plate. 

 

There is a lip from the outside to the inside...however, it is not 5mm difference in the height difference.

 

 

 

 

So, my questions are:

• Is this flywheel worth dealing with, or should I scrap it and bite the bullet and try to find a newer one?
• Should I just go with a 215mm and call it good...I am not racing or hard on the car, I'm an old fart just looking for a little trouble every now and then?
• If I keep it, can I smooth-shave-sand the plate contact area and call it good? 

 

This will be just a weekend fun to drive car.

 

Thanks in advance for any advice you may have for me.

a

[Son of Marty]

If you have a good 215mm flywheel use it you'll save some weight and you'll see no difference in holding power or longevity IMO. 

[Dudeland]

I debated the same thing when I replaced the clutch in my car with a 5-speed.  Your 75' with a fresh engine is 80-90 at the wheels.  A 215mm is more than enough.   

 

I fully accept the backlash from the community from the following statement. 

 

A lightened flywheel will make it a bit more peppy.  The physics of this is debated (sometimes hotly), and I don't pretend to know the details.   I lightened my flywheel and it seemed to accelerate faster (better) after I had it done.  It is a stock-lightened flywheel, maybe 1.5-3 lbs off it.  

 

When I eventually put my turbo on, I may consider the 225, but I will cross that bridge when I get there.  That bridge may consist of the RX8 transmission I have in my garage. 

 

Regards

 

 

[Dudeland]

6 hours ago, BeMyWay said:

So, my questions are:

• Is this flywheel worth dealing with, or should I scrap it and bite the bullet and try to find a newer one?
• Should I just go with a 215mm and call it good...I am not racing or hard on the car, I'm an old fart just looking for a little trouble every now and then?
• If I keep it, can I smooth-shave-sand the plate contact area and call it good? 

 

This will be just a weekend fun to drive car.

 

Thanks in advance for any advice you may have for me.

a

• Is this flywheel worth dealing with, or should I scrap it and bite the bullet and try to find a newer one?

Have a shop check it out.  I have seen worse. A machine shop will charge you about 80 to resurface it. 

• Should I just go with a 215mm and call it good...I am not racing or hard on the car, I'm an old fart just looking for a little trouble every now and then?

215 would be fine. 

• If I keep it, can I smooth-shave-sand the plate contact area and call it good? 

I would not try it yourself.  It will be warped and could cause the clutch to chatter.   It isn't much to get it resurfaced. And if you are just ripping it around now and then it will last you for decades. 

[BeMyWay]

Thank you Dudeland and Son of Morty.

 

I am hoping to get 130-140hp out of this engine according to the PO.  He has the same setup, with sidedrafts and get 150hp...I'm thinking at the crank (I said in a whispering voice)  

 

The real concern ios to get it back on the road.  I will continue to search out a machinist to turn it.  I think if it is turned flat it will be okay.

 

Unless I can find a good 215mm flywheel I will continue to try to use this 228 flywheel. 

 

My 228 flywheel actually looks good, except for where it doesn't!  

 

[TobyB]

Almost anything that's not cracked can be resurfaced.  

I've had 0.020" and .5mm steps put on, and even a parts 

car that came apart with a mm (!) step.  Flat doesn't seem to last long.

 

As to which one to use- which one can you put together with the least

hassle for the least bux?  Anything used ought to be resurfaced, so

factor that in.  Anyone with a horizontal grinder can surface one-

I suspect a lathe would also work, but every machine shop I know grinds them.

Probably to keep the lathe clean...

 

So if a 228 pressure plate and disc are cheap, go that way.

If the 215 parts are cheap enough to offset the cost of the flywheel, go THAT way.

 

The difference in weight is negligible- both flywheels are the same diameter-

(you can even drill one to use the other pressure plate)

but the rotating inertia of the 228 is a bit higher.  Which is un- noticeable in 

even spirited driving. 

 

t

 

[BeMyWay]

All right, I'm back in the saddle again and I have started to put the engine parts back together.

 

However, I openend my Ireland Engineering intake manifold bolts package and noticed:

1.  The bolts are not the same size (old = 13mm vs new =11mm) and nut body is longer.  Following is the IE link:

Stud & 11mm Nut for Intake Manifolds – M10/M20/M30 – Ireland Engineering | Racing & Performance Parts for BMW & MINI

WWW.IEMOTORSPORT.COM

---

Each

2.  If these are the right ones to use, should I use washer (lock or not?) ?

 

I am sure I will coming back to the faq trough a lot in the next few weeks.

 

Thanks for any knowledge any of you can provide on this point.

 

Happy Holidays everyone!!!

[Son of Marty]

Yup, the 11mm nuts provide more clearance for your wrench/socket use a wave washer under the nut.

[BeMyWay]

Thank you for the quick reply.

 

I dont have any wave washer handy at the moment, therefore do you see any issues with using a lock washer?

[jimk]

2 hours ago, BeMyWay said:

lock washer

A lock washer gouges the aluminum.

[Son of Marty]

Do your self a favor and order a bag of 6mm and 8mm wave washers from Belmetric they are cheap enough and BMW's use them everywhere.

[BeMyWay]

I took your advice and bought the wave washers.

 

Thanks for your time.

 

I'll be back...

[Son of Marty]

I think what you were trying to say is.

 

[BeMyWay]

I'm back....

 

I have a question about my water divider.  Is there any problem with using either?

I am planning to use a single 38/38 carb and run water through the intake manifold.

[Mark92131]

3 hours ago, BeMyWay said:

Is there any problem with using either?

 

Either one will work, but I would use the top one which has the water fitting to the intake manifold integrated into the water neck.  Save the bottom one if you decide to go dual carbs, it seems to have a plug and will allow you to bypass the water connections to the 2 barrel intake manifold.

 

Mark92131