M20B29 w/ Triple Webers into my '71 2002

[The Dark Side of Will]

The importance is exacerbated by the fact our beloved M20 engines are non-interference.

I know this is "just" a terminology gaffe, but M20's are interference engines.

[Old city bimmer]

man this thread is all eye candy....

[The Dark Side of Will]

Also, I thought an 89.6mm crank would fit in the M20 block. Is this not the case? Or does it fit but require way more clearancing?

[digger]

Counterweights are bigger on the 84mm cranks than on the 89.6mm so it's minimal issues. Rods may tap the aux shaft or bottom of bore a little more though nothing that can't easily be overcome

[MR 325]

Good stuff Andrew! :D

[318aye]

Random question: How did you refinish your trumpets? Sorry if I missed it earlier in the thread.

[2mAn]

Andrew!! I need to head out there one of these Mondays! I owe you a nights worth of labor

[Chilezen]

Dear jesus, I want my own engine just like this. Can't wait to see it at the open house!

So on the last bit when you said you wouldn't be safe running oversized valves, is that specifically the case with the custom pistons you used?

[SkiFree]

I know this is "just" a terminology gaffe, but M20's are interference engines.

Oops, fixed. Thank you Will.

Good stuff Andrew! :D

Thank you Matt, really. You will have to take it for a spin when its FINALLY done.

Random question: How did you refinish your trumpets? Sorry if I missed it earlier in the thread.

They are powdercoated (the color was “mirror red”, cannot remember the brand though).... and no worries, this thread is a little convoluted.

Dear jesus, I want my own engine just like this. Can't wait to see it at the open house!
So on the last bit when you said you wouldn't be safe running oversized valves, is that specifically the case with the custom pistons you used?

I can't wait to have it together! As for the oversized valves. It would be in regards to these higher-comp. pistons.

The design follows the ethos of balancing street-able power and longevity. In short, the valve pockets will handle a much more aggressive cam than a stock piston, but not as much as a full race engine (with it's inherent sacrifices to longevity in the pursuit of max powa').

For comparison's sake, here's a layout of a couple pistons. Note the valve pockets (also note the top of an aggressive M20 race piston the top changes altogether).

Is there any difference in counterweight radius between those two cranks ?

No, there wasn't a difference. I compiled the following data between the cranks this morning. The 84mm stroke cranks only have the taller radius on a couple of the pairings (this is why there are two measurements). I know the #277 is certainly forged, however I don't know what the metallurgical make up for the #751 is.

[digger]

There are guys in the uk and oz with 84mm cranks that have smaller counterweights because the crank clears stock Pistons with 130mm rods I wonder what the p/n for those are....

[SkiFree]

That is interesting ..... will do some poking.

NOW, on the to TRANSMISSION

Handling the transmission part of this car evolved into a pretty neat experience. I was talking to Rob Inhout last year about the project and he offered to take a Saturday to teach me how to rebuild and do the necessary work on the trans. Needless to say I was stoked.

Rob is one of the most humble and experienced people I’ve met within the 2002 community. There’s a decent chance you haven’t heard his name (or maybe heard it in passing) as he does not seek to promote himself publicly. He doesn’t typically deal with the public at all, outside of a few ebay listings, rather he deals with the multitude of great shops catering to vintage bimmers down here in SoCal.

Rob’s backstory is unique. He worked for JPL/NASA on both the Mars Rover and Hubble projects as an engineer. When he retired early he started racing vintage bimmers and ended up buying/owning 2002ad (and it’s neighboring Alfa wrecking yard) for a time in the late eighties. Now days he does transmission/differential/etc work out of his shop when he’s not skiing, backpacking, or tinkering (there was a half disassembled Prius battery pack on a workbench when I was there).

So on the scheduled Saturday I loaded up the transmission and set out to his shop. The one thing I immediately noticed was the copious amount of 2002’s on the premise. And before anyone whines“look at all those cars just sitting there”, remember each of these cars were saved from the crusher. Just by sitting there these cars got an unintended lease on life.









Under all that stuff? A nice little 2002 vert.



A unique way to remember projects … just put them in the way.



As stated in previous posts, the work being done to this particular Getrag 245 transmission consisted of swapping the bell-housing sections from the M10-compatible piece to the M20 compatible piece (e21 323i), replacing all 5 syncros, and changing out whatever bearings needed changing!

M20 w/245
Positives
-no tunnel fabrication (just some hammer work)
-mechanical speedo (no aftermarket speedometer)
-10lbs lighter
Negatives
-Difficult to find
-can be spendy

M20 w/260
Positives
-cheaper
-more plentiful
Negatives
-fabricate tunnel
-electronic speedo
-bit heavier



….. and for giggles, close ratio NK tranny? This would have been in something like a TISA.



The first step was to remove the input shaft shroud and split open the case. You do need to have a special tool to do this (or make one as Rob has done here).





Here’s the split trans you can see a couple of the synchro/gear/dogring assemblies.



Since we were doing the whole nine on this trans the rear cover and midsection needed to be split as well with a separate tool.



From here on out, things won’t necessarily be in order BUT I wanted to cover some neat bits. First he’s a shot of the midsection backside. The spring is for the shifter detents and the gear on the right is the speedo gear!



It reads off of this this piece on the main shaft.



Here is an example of the synchro and it’s position on the gear. The synchro is coated with a wearable-material much the same as the coated disks inside your clutch-type E21 limited slip diff. As the synchro wears it rides further up this taper and butting up against the gear and not allowing for gear engagement by the dog-ring (the spacing between the synchro and gear should be around .010. This comes in handy when doing a quick visual check through the fill hole with a flashlight. If you see a bit of a gap, you’re pretty good)



We wanted to disassemble EVERYTHING so that meant using a press to remove the main shaft from the center housing.



everything wash thoroughly cleaned. and laid out for reassembly.



One of the changes made was incorporating the stronger front mainshaftbearing. This meant machining the housing a little along with machining the shaft itself.







Everything going back together.



Rob himself!




We had to attached and then remove the bellhousing section a couple times to make sure everything was kosher.

One interesting note was my particular M20 housing was not initially tapped for the back-up light switch.



With the trans double checked and largely back together it was brought back to the IE shop and gave the outside of the trans a good cleanup.



Shop cat keeping an eye on things.




Now with the trans done all the major mechanical components are rebuilt and ready!

[SkiFree]

Also, thanks to Mike for the great photography (snapped during the open house)

http://www.stanceworks.com/2015/09/bmws-burgers-the-ireland-engineering-open-house-2015/

Edit, looks like Larry got a snap too.

http://www.pikore.com/m/1062601362693123728_199827778

[Sh3rpak!ng]

That's beautiful.


Sent from my iPhone using Tapatalk

[stanhayward]

That is one good looking engine Andrew!

[TrentW]

Thanks for my new desktop background Andrew!