JT's M20 Build Thread

[digger]

did you just holesaw to fit that on the driver side (passenger side has the hole for the A/C iirc) ? you dont have ABS? i was thinking of running an air feed/duct up through there was wondering how easy access was with a large holesaw

i ran my catch can near your coolant one but vented down under near the front spoiler

[JehTehsus]

Catch cans are mounted. Only thing left at this point is the fan brackets and fan mounting, then a little bit of painting and touch ups and I can get the radiator, power steering cooler and oil cooler all mounted. After that I just need to go through the joys of running hose!

Drivers side CC: Will be connected to the valve cover breather.



View from the bottom:



Passenger side CC: For coolant

[JehTehsus]

Managed to get a bit done this weekend - mostly tedious bits. Fuel filter is mounted, flex fuel sensor is mounted, vac station and power steering reservoir are also mounted. About halfway through getting custom fan brackets together. Ran the brake lines, wish I had one with double ended L fitting; I will probably just get a couple of the short problem ones remade by a local shop.

Also replaced clutch master and slave cylinder, most of the plumbing is done and in place. In terms of mounting, the only thing outstanding at this point is the two catch cans and the remaining fan brackets, then I am running fuel and vac lines.

Here is where the bay is at: still a big mess but getting closer, bit by bit.

[vWBIRDWv]

subbed

[JehTehsus]

Nothing too revolutionary yesterday evening, except getting my driveshaft in. I have also included a few pictures of the tranny mounts. Note that they are torqued to the lower spec that IE lists for them - the one with the broken tab and bracket broke when it was torqued, and I noticed it had broken again when I went to loosen it to fix power steering rack. I am not sure if switching back to regular mounts will make a difference or not, however.

[JehTehsus]

Got a little bit done last night, basically just pulled the degree wheel installed the shifter linkage. Somehow mixed up the bushings, so I had to pull it back out and redo it... popping the clip took about 40x longer than everything else combined. Such is life. Also, added a couple furry family members, feel like this place is starting to turn into a bloody farm house, between the chickens, dog and now two kittens.

First time trying out the IE DSSR. Maybe not the most beautiful but seems solid enough. The short shifter is the UUC kit. A discerning eye may also not that the tranny is a little low, this was taken before I tightened up the mounting bracket. You can also just see where the mount is, the one I got welded. Broke again, naturally. I may grab a pic of the poly mounts later tonight and put it up, I followed the IE lower torque spec for them but tbh they look pretty sketchy, I am not so sure it is a good idea. Motor mounts seem totally fine, however.





Coffee for scale. Second night they learned how to climb the tower; buggers are like velcro. Only time they fall off is when they battle for the upper platform, so I have strategically placed pillows around the base until they are a bit bigger.

[JehTehsus]

Final bit of work on the throttle body tonight, aside from some painting touch ups. Not incredibly happy with it, clearances are tight and I had to grind down a fitting. Biggest concern is vacuum and boost leaks... O ring is probably not perfectly seated (I don't exactly have a setup to machine a solid receptacle for it) but I did dump a bunch of thread sealer in there too, so fingers crossed.

[JehTehsus]

Hoses are in (strictly speaking need to replace clutch master and plumb line to it, but brake hoses are in). Overall I am fairly happy with it, will probably try pushing the hoses onto the master cylinder connections a little bit more (they are a nightmare... 30 minutes to get them that far with a heat gun) but they are definitely solidly connected, no air will be coming in there.

Due to height limits the reservoir is right up against where the hood is when closed. I don't think I am going to flip the MC bracket after all, there is no way for any of those hoses to end up caught in the balance bar assembly, which is what I was concerned about.

[JehTehsus]

Car is back in the shop! Will be wrapping up all the last little bits these next couple weeks (although I am still waiting on a few adapters and things that are likely a month out, but nothing major. Just more delays before first run).


Installed the massive brake kit. Currently the 0.75 I had will be running the rears, and the 0.625 for the fronts. This is strictly temporary, moving around the property setup while I wait to get my hands on another 0.625. Kit went together very smoothly, biggest issue I had is my poor cutting skills for the master rods, but really no problems at all.



Installation also went well. Going to mount the reservoir today then see how far I get mounting other goodies and preparing to run fuel lines.

I may have a bit of a bend in the hose for the brake lines (not too tight, but a bit) if I mount it like this. Debating flipping the bracket upside down so the MCs are lower.

[JehTehsus]

Sounds great guys, thanks for the input. I am going to get that on order with a few other bits here, things are starting to come together and it feels good.

Had some 'fun' messing around with fuel rail a bit more. I ended up getting some socket head bolts so I could lower rail a bit (it was sticking out just a bit too far, I thought). Turns out it isn't enough, you can see in some of the attached pictures that when I got the boroscope in behind the injectors they are clearly not seated. In my best estimation the angle of the injectors is correct, or at least very close, but any simple bracket I build for the nuke rail is going to either push the rail too close to the head and totally ruin the angle, or else like what I currently have, will not let the injectors sit deep enough. For that reason I am leaning towards some spacers, I think another 10mm or so will be perfect.


(yes, I know there is some crap there... paint/powdercoat that was around the rim of that injector hole I believe. I cleaned the friggen IM 30 times before I put it in but there is always something...)






I also discovered my right-angle-swivel-female 8-AN + union fitting is too large/long. Wooohoooo. Going to use one of the right angle swivel fittings like I used on the front of the rail going to the FPR, it is just a bit shorter but that should be all I need, hopefully enough clearance that a tiny bit of engine movement doesn't bump the rail and start a big ol M20 bonfire.... If not, I will have to further modify that blower fan shroud plate.

[whodwho]

...
- 0.75/0.700 has the best bias % when weight transfer is considered assuming the pad compund front and rear are the same (probably arent)

Good to hear, I have the original .70 I used for the front that I have wanted to try for the rear in place of the current .625 once it is back on the street

I need to make up my mind on whether to go with 0.7/0.625 F/R masters or 0.625 for both, with the stock brakes. I am leaning to 0.625 for both and making a significant adjustment with balance bar. This is just for street use while I get everything working with the motor build.

Do you think I will be irrecoverably ruining the brake balance if I run twin 0.625s and bias a fair bit using the balance bar? Even if it isn't great balance wise fronts should still lock first, and I can likely use a 6.1 pedal ratio as well so hopefully travel isn't abysmal. Really at this point I just need something drivable until I can figure out suspension, wheels and brakes.

In other news, hopefully getting the car back on the lift this weekend, things should then be moving pretty quick.

I started with the .70/.625 with stock brakes and I think you will be better off with the .625 x 2 and like you said between the bar and the ratio adjustments you should be able to get it dialed in

[digger]

i'd go with same size if the delay valve is deleted that way on limit the fronts should still lock first (accounting for weight transfer) assuming the front pads a slighty higher friction compound.

[JehTehsus]

yeah the force in the MC should be split equally if the balance bar is adjusted 50/50. ive corrected a few logic errors and added some vehicle weight distrubution and weight transfer

here are my revised calcs

what it says is assuming i didnt balls it up
- from a force and bias point of view that stock brakes without the rear delay valve has to much rear braking for the tyres
- 735i mkaes the pedal very hard
- 735i 25mm MC swap has the same bias and braking forces as the Massive booster delete setup with his 280mm street kit with 0.700/0.625 MC. the pedal travel will differ though.
- 0.75/0.700 has the best bias % when weight transfer is considered assuming the pad compund front and rear are the same (probably arent)

I need to make up my mind on whether to go with 0.7/0.625 F/R masters or 0.625 for both, with the stock brakes. I am leaning to 0.625 for both and making a significant adjustment with balance bar. This is just for street use while I get everything working with the motor build.

Do you think I will be irrecoverably ruining the brake balance if I run twin 0.625s and bias a fair bit using the balance bar? Even if it isn't great balance wise fronts should still lock first, and I can likely use a 6.1 pedal ratio as well so hopefully travel isn't abysmal. Really at this point I just need something drivable until I can figure out suspension, wheels and brakes.

In other news, hopefully getting the car back on the lift this weekend, things should then be moving pretty quick.

[digger]

MC piston size will definitely affect bias. Even if you kept a 50/50 setting on the balance bar, at 100lbf on the pedal and say a 6x ratio you would have 300lb on each master. Different sizes will then give you different pressures for each circuit. I think that normally with smaller rear piston areas you would likely want a smaller rear MC by a bit to even out the braking force you would be getting from the rear wheels (higher system pressure from a smaller MC will translate into higher braking force). All that said, I am not sure exactly how pedal travel comes into play. I guess ideally one would match front and rear MCs to produce equal braking force then tune bias with balance bar.

yeah the force in the MC should be split equally if the balance bar is adjusted 50/50. ive corrected a few logic errors and added some vehicle weight distrubution and weight transfer

here are my revised calcs

what it says is assuming i didnt balls it up
- from a force and bias point of view that stock brakes without the rear delay valve has to much rear braking for the tyres
- 735i mkaes the pedal very hard
- 735i 25mm MC swap has the same bias and braking forces as the Massive booster delete setup with his 280mm street kit with 0.700/0.625 MC. the pedal travel will differ though.
- 0.75/0.700 has the best bias % when weight transfer is considered assuming the pad compund front and rear are the same (probably arent)

[JehTehsus]

you sure at 100lb you are over 1100psi?

i couldnt upoad the XLS file but here is the next best thing. i need to check the FR vs RR circuit pressures

unsure if the pressures are just force / total FR + RR MC areas meaning the pressure will be the same in both circuits and hence the bias is only adjusted with the adjustable bias lever not MC piston size but i do not believe this is the case. My calulations use the ratio of areas to work out the pressure in each FR and RR line

MC piston size will definitely affect bias. Even if you kept a 50/50 setting on the balance bar, at 100lbf on the pedal and say a 6x ratio you would have 300lb on each master. Different sizes will then give you different pressures for each circuit. I think that normally with smaller rear piston areas you would likely want a smaller rear MC by a bit to even out the braking force you would be getting from the rear wheels (higher system pressure from a smaller MC will translate into higher braking force). All that said, I am not sure exactly how pedal travel comes into play. I guess ideally one would match front and rear MCs to produce equal braking force then tune bias with balance bar.