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Thread: Dlux BMW E21 build

  1. #101
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    Quote Originally Posted by Erik Dlux View Post
    Yep, that would be ideal to me too.

    Heck if youre up for running one of those crazy batteries that weigh 2lbs, its really silly to even consider moving it to the back. Obviously youre gaining almost as much weight as youre moving.
    I run a ltw odyssey battery pc680, and they are excellent durable batteries. It's all about the weight. True the battery may only weigh say 20-50 lbs itself, but its the placement that is everything when you put on corner balance scales. The further from an axle line the weight is, the more exaggerated it is. So that 50 lbs can actually be an extra 100 on that corner if near the end of the car. Hence the popular spot to relocate on E21's is center the rear axle. BMW started shoving batteries in much better locations on next gen cars like the e30. By having it in the back trunk corner it actually offsets majority of the driver weight more than you think unless see it on scales. Also weight that is further away from axle lines gives more pendulum effect on handling. Food for thought.
    88 M3
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    91 318i
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    08 X3 3.0si

    "If it flys, floats, or f*cks, rent it!"

  2. #102
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    Imagine a really fat guy or girl riding a road bike. They still have their valve stem caps on their bikes.

    Is the valve cap really hurting their performance? Shoot, I guess thats the science. Is taking off their valve cap really something you want to suggest to them? I dont think it would make even a slight difference.

    Edit: changed the analogy
    Last edited by Erik Dlux; 01-24-2019 at 06:23 PM.

  3. #103
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    Fyi, I weighed my battery and its 30lbs.

  4. #104
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    Quote Originally Posted by Erik Dlux View Post
    Fyi, I weighed my battery and its 30lbs.
    Depends on the purpose of the car I guess and how much it matters to the owner. For us it was just one track minded build so everything mattered. Weight and weight placement was the main focus of the build.

    Following with interest to see it go, keep tackling the fitment challenges man. It's part of the fun isn't it; making things fit together and work.
    88 M3
    91 318is
    91 318i
    83 320is
    08 X3 3.0si

    "If it flys, floats, or f*cks, rent it!"

  5. #105
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    Yep, I can totally see that. If I were to want this car to perform as a top priority, I would take a look at it for sure. Its just not what this cars main function is though.

    Figuring everything out is where its at for sure. This car has been super fun to build and I am glad there are no major issues that could not be addressed so far. Pretty lucky.

  6. #106
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    I worked on getting the gas tanks, fuel lines, vent lines, pump, filters all sorted out along with fresh undercoat above the tanks.


    I went with all stainless braided lines for durability. I did do 5/16 hardline from just after the filter to the engine bay. I ran the hardline in the trans tunnel so it never has a chance of being smashed.


    I am liking this much more than the factory BMW setup. I feel like its placed much better and much easier to service each individual part.










  7. #107
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    Now that I have the tanks installed, I showed some pictures of the interference that I worked with from the tank to subframe.




  8. #108
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    I added some trailing arm mount bracing and also got the diff mount on the chassis done. Getting closer to having that rear end in!





















  9. #109
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    I hit the weekend with the goal of getting the rear end in. I need to learn to not have goals as sometimes they can just leave you disappointed.


    I knew that there was a chance that my brackets on my subframe would not allow for the adjustment that I needed. I totally forgot as I was half way done welding them! Whoops!


    My adjustment on the side for toe is good, the camber adjustment was not.


    The camber adjustment needed to be moved up a ton. I need to check but I think close to 2" over stock.


    As I cut off the inner brackets to make them correct for camber, I was also bothered by the binding that comes from twisting the toe side bushing to make it have the same angle as the camber side. After resisting all the work I would have to put in to cut off everything I had made and also make new brackets, I did it, I cut it all off and not only put on proper brackets but now, since I had a great idea of where my arms need to be, I put them in that spot and then made all the brackets at an angle so the bushings would see close to no binding.


    So, in the end, even though it was a ton more work to redo it all, I am glad I did it and I am really glad that everything is as proper as can be.








  10. #110
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    I've been contemplating doing new rear trailing arm mounts on my spare subframe to get the exact alignment numbers as well. If I had a lift it certainly would make that a quicker option to explore, but for now I'll just try to make the stock ones work.

    I really like all of the bracket cutouts, that type of work takes a ton of time to do as well as patience.
    Last edited by captain awesome; 02-04-2019 at 10:37 AM.
    91 318is
    83 320is

  11. #111
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    It does suck to redo things, but thats why tack things together first. Have you mocked up on the car and assembled with wheels to see ride height? Just asking cause how it sits you can move the subframe with spacers (roll center) and it will change your available camber also. Lowering the subframe on the pins will lower the roll center and gain more camber. This promotes traction but may not have enough adjust ability to remove excessive camber. Doing the opposite raising the subframe takes away camber but raises the roll center and available traction. If mock up on the car I'd also tape bubble levels on the halfshafts and see the limits. Basically try to keep them parallel at minimal or slight angled up to the diff for best traction/power to the pavement.

    If axle angle is a problem you can space the diff upwards on it's mount. Difficult to do using the later subframes where the hat has to be cut and placed higher. Would cause you to drill another diff mount hole since made that already. Moving the subframe itself is much easier if gets where need it.

    I'd do a full mock up on the car and set on the ground before completely welding out the mounts. Just saying. So much fab goes into this, but it's the patience and multiple circles of mocking up that makes it worth the end game. Looking good!
    Last edited by autox320; 02-05-2019 at 07:00 AM.
    88 M3
    91 318is
    91 318i
    83 320is
    08 X3 3.0si

    "If it flys, floats, or f*cks, rent it!"

  12. #112
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    Quote Originally Posted by captain awesome View Post
    I've been contemplating doing new rear trailing arm mounts on my spare subframe to get the exact alignment numbers as well. If I had a lift it certainly would make that a quicker option to explore, but for now I'll just try to make the stock ones work.

    I really like all of the bracket cutouts, that type of work takes a ton of time to do as well as patience.
    Thanks, I appreciate it.

    Quote Originally Posted by autox320 View Post
    It does suck to redo things, but thats why tack things together first. Have you mocked up on the car and assembled with wheels to see ride height? Just asking cause how it sits you can move the subframe with spacers (roll center) and it will change your available camber also. Lowering the subframe on the pins will lower the roll center and gain more camber. This promotes traction but may not have enough adjust ability to remove excessive camber. Doing the opposite raising the subframe takes away camber but raises the roll center and available traction. If mock up on the car I'd also tape bubble levels on the halfshafts and see the limits. Basically try to keep them parallel at minimal or slight angled up to the diff for best traction/power to the pavement.

    If axle angle is a problem you can space the diff upwards on it's mount. Difficult to do using the later subframes where the hat has to be cut and placed higher. Would cause you to drill another diff mount hole since made that already. Moving the subframe itself is much easier if gets where need it.

    I'd do a full mock up on the car and set on the ground before completely welding out the mounts. Just saying. So much fab goes into this, but it's the patience and multiple circles of mocking up that makes it worth the end game. Looking good!
    Oh, its been mocked up on the car for sure. Probably 10 times now? LOL

    I thought moving the trailing arms up on the subframe increased anti squat, not decreased it. Youre saying its the opposite?

    Why does having the half shafts at an angle increase or decrease traction?

  13. #113
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    Quote Originally Posted by Erik Dlux View Post
    Thanks, I appreciate it.



    Oh, its been mocked up on the car for sure. Probably 10 times now? LOL

    I thought moving the trailing arms up on the subframe increased anti squat, not decreased it. Youre saying its the opposite?

    Why does having the half shafts at an angle increase or decrease traction?
    Yes moving them (control arms or subframe) up does increase anti squat (high roll center) which also decreases traction. Depending on how setting up the car this allows to rotate faster ie like having stiffer spring rates. Rolling allows more traction for the rear. Roll center and anti-squat/anti-dive can be thought of as the same. The height of the car ie spring height/ride height will determine how much roll center you'll want at each end of the car. In a nut shell I just go off the front control arm angles and rear axle angles. Moving the diff up allows best of both for the rear but more difficult to do on later subframes.

    Axle angle is usually overlooked. Having the diff forward of the axle center line and upward angle to the diff promotes the most traction. If the diff angle is below the hub or the diff is behind it angle wise; the hub has more leverage. Power transfer is worse than optimal and could notice wheel hopping etc maybe even snapping halfshafts quicker. Optimal is have enough angle on the halfshaft upwards to maintain level during suspension travel. The CV joint limit is another factor to do this so it doesn't limit and just break.
    Last edited by autox320; 02-05-2019 at 11:37 AM.
    88 M3
    91 318is
    91 318i
    83 320is
    08 X3 3.0si

    "If it flys, floats, or f*cks, rent it!"

  14. #114
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    I’m glad to see your subframe swap! Makes me feel more comfortable doing mines for my e21! Awesome build!

  15. #115
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    Quote Originally Posted by autox320 View Post
    Yes moving them (control arms or subframe) up does increase anti squat (high roll center) which also decreases traction. Depending on how setting up the car this allows to rotate faster ie like having stiffer spring rates. Rolling allows more traction for the rear. Roll center and anti-squat/anti-dive can be thought of as the same. The height of the car ie spring height/ride height will determine how much roll center you'll want at each end of the car. In a nut shell I just go off the front control arm angles and rear axle angles. Moving the diff up allows best of both for the rear but more difficult to do on later subframes.

    Axle angle is usually overlooked. Having the diff forward of the axle center line and upward angle to the diff promotes the most traction. If the diff angle is below the hub or the diff is behind it angle wise; the hub has more leverage. Power transfer is worse than optimal and could notice wheel hopping etc maybe even snapping halfshafts quicker. Optimal is have enough angle on the halfshaft upwards to maintain level during suspension travel. The CV joint limit is another factor to do this so it doesn't limit and just break.
    Strange. In 4x4 stuff like a tri 4 link or 3 link or whatever the more anti squat you have the more traction you put to the ground. I wonder why its different?

    I am confused on how a half shaft has anything to do with traction. I will have to find some time for research. While it make for a good conversation, parts are pretty much going where they have to within reason. Not much choice I can see in where I put most things.

    Quote Originally Posted by AndronPrime View Post
    I’m glad to see your subframe swap! Makes me feel more comfortable doing mines for my e21! Awesome build!
    Man, glad its helping you. I feel like I am making it look 2x as hard as I need to be. I think if I would have left the stock brackets on the subframe it would have been a super simple swap. I dont think they would have done the job for me at the same time though.....

  16. #116
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    Wow, loving the dedication to getting it perfect, meanwhile I'm over here contemplating using a 2-5mm spacer to square things up. Choose a springrate for the rear yet? Or a swaybar? You're making me think about rewelding mine

    Unrelated, but what size tire? I have 235/45/r17s on it and it's about as big as the tires can go
    -John

  17. #117
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    I wont have my spring rate for the rear until I am complete and can get corner weights. I wouldnt be surprised if I kept what I have now though. They seem to do the job well. Time will tell on those.

    For the sway bar, I think I have the stock E28 one figured out. I will post details when I figure more out.

    Man, youre able to fit that big of a tire on there? Maybe I am being too conservative but I dont want any rubbing issues. I was thinking 215/40r17?

  18. #118
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    More work on the rear subframe. I tore off all the mounts and started again.




    I put the subframe back in, camber and toe are now good to go, zero binding. Should be good, right? No. I dont like where my wheels sit. They are just a bit too far out.




    Ideally I think a et47 wheel would have fit best, problem is that if youre looking for an et47 wheel,they are not in abundance and harder to find for sure. Its a pretty deep offset wheel. I am not getting new wheels.




    So, knowing that I wanted to make my et41 wheels work and looking at my subframe, I thought "I want this setup to be as ideal as possible, no compromises" That conflicted with me knowing this could screw up other fitments such as my half shafts.




    Screw it! YOLO! I want this to be as good as I can get it, even if it means a lot more work.




    So, I took it back out from underneath the car (AGAIN!) and I cut off all the mounts, made new ones and this time, I moved all the mounts as far inward as I could on the subframe. The inner mounts are almost touching the diff mount.




    I put the subframe back in (AGAIN!), measured camber, perfect, toe, perfect, wheel fitment in the wheel well, PERFECT!










    Perfect, right? Well, no, now my half shafts wont fit as expected. LOL. My minimum length is right around 16.937" and minimum the shaft would compress was right around 17.063". About .125" I need to take off...








    I actually might have been able to get away with it. They only bound up at full extension of the shock but I dont want to run that way. Time to figure out how to modify the half shaft.




    I took the shafts apart and to my surprise, and I saw a couple of openings to shorten the shafts. Here is a shot of what youre looking at stock...














    Notice, the raised lip on the back side that provides the stop. Also notice the front side and how the splines are proud and do not engage fully. This is where the beauty will happen.




    Now look at the back side again. If you look in at the splines, there are raised splines that do not even engage. This measures .150"














    Now, the catch here is that the measurement above of .150" is more than it should have been. It should have been close to .080". If you look at the shaft, there is a void on the shaft where the stop is of .080". So, the gear that slips over has an unnecessary .070" that does not engage. This again is where the beauty will happen.









    I thought for sure these parts would be hardened so much that I could not machine them. Nope, they are actually super soft and really easy to machine.




    I took off .200" on the inside of the gear. If youre following along, thats only .050" of spline engagement since .150" above was not used stock.


    Stock left, machined right.








    The gears can now slide further on the shafts by .200". I did this on both sides so now we are taking about the gears sliding .200" per side or the total shaft should be .400" shorter than before over all.


    Stock



    After machining.












    Since the gears and splines will now go all the way to the bottom, I had to clear out the .080" space right above the stop so the splines would slide over. I took .040" or 1mm off this space.









    .900" worth of gears spline engagement after machining









    .866" of shaft spline engagement












    After all installed, the gear slides past the top of the splines approx .100". So, doing the math, I should have .766" of spline engagement after the mods. Stock would have had .794". So, all this modding, I lost approx .028" of spline engagement. Pretty much nothing.

    Math:
    Bottom of splines .080" not used
    Bottom of gear splines not used .150"
    .070" (from above) of available .866" splines, .794" used, stock
    Modded, all bottom splines used, top .100" splines not used from .866" available, .766" used.







    It really seems like BMW planned for this to happen. Too perfect.





    If you needed to go shorter, I think you would be fine. I might dare to take it another .125" per side? I dont think that would hurt strength too bad but I am not sure. Thats another .250" or .650" shorter from stock.




    In the end, I got a half shaft that is .400" or just under 1/2" shorter than stock. Since I only needed .125" or 1/8", I am good to go. I put it in the car and it seems perfect.


    Final length compressed



    So, unless somebody can see something I missed, I will hopefully be welding up the subframe this afternoon.
    Last edited by Erik Dlux; 02-07-2019 at 11:09 AM.

  19. #119
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    worth the squeeze

    I'll admit the machining off is a much cleaner solution. If the distance was more I'd just cut and weld axles back together :o). Sometimes we learn when in circles and repeat things to perfect them. Some see insanity, but to us it's not when you can measure improvements. Sometimes we have to full assemble and stick a tool to measure actual real world position and travel. Nice to see I'm not the only one that goes through this lol Part of the fun isn't it. When it's done some never understand what it takes to get it right.

    Without springs installed can raise and lower the arm. Assume you did this but what matters most is static measurements at the ride height your springs have you at. Trail arms swing through an arc depending on sweep(less sweep less change). So measuring at parallel to the ground won't be the same as what angle it is at ride height. If your adjustable ears allow a good "window" of adjustment at your expected height....golden.
    Last edited by autox320; 02-08-2019 at 08:49 AM.
    88 M3
    91 318is
    91 318i
    83 320is
    08 X3 3.0si

    "If it flys, floats, or f*cks, rent it!"

  20. #120
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    I spent the weekend installing the fuel lines/pump/filters, brake lines and sub frame.




    Subframe all welded up.












    You can see the subframe and how I pushed the mounts in. If you remember, most will cut the stock E28 subframe right at the mounts, flush with the mount. So, all that gap you see there is how much I moved it in.














    I figured out a simple way to install the stock E28 sway bar. I simply put it on the bottom of the arms instead of top like stock and then put the torsion bar along the subframe after making some simple mounts. Its almost like it was supposed to mount like this. Pretty perfect fit and good geometry for the end links and torsion bar.

















    Subframe with poly bushings, painted and ready for install. Last picture of the subframe on the floor. LOL. I promise.












    I decided to do the bearings on the trailing arms. I read online that people said it was a horrible job. I just thought they did not have the proper tools or know how. No. Its a horrible job. LOL. I took me about 8 hours and thats with everything already apart! I am glad I did it though. After taking the old bearings apart, they were due for sure.










    I ran poly bushings throughout the subframe and trailing arms. I really like the idea of a firm feel on all these parts but one thing I dont like is the idea of the squeaking coming from them. I put in some zerk fittings to I can grease them if they do start to squeak.









    Another thing I noticed when putting the poly trailing arm bushings in is that they are offset, just like the stock bushings. If you needed the wheel to come in a hair more, you should be able to install them back wards and it could bring the whole assembly in? Looks good for almost .200". This might be a good idea for me depending on how the tire clearance looks.

















    Whole under carriage is not undercoated. I really like the black undercoat vs the stock blue.




    Rear end is in and painted. I just need to finish up with half shafts when the rebuild parts get in, brake lines to the trailing arms and e brake lines.





























  21. #121
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    Quote Originally Posted by autox320 View Post
    worth the squeeze

    I'll admit the machining off is a much cleaner solution. If the distance was more I'd just cut and weld axles back together :o). Sometimes we learn when in circles and repeat things to perfect them. Some see insanity, but to us it's not when you can measure improvements. Sometimes we have to full assemble and stick a tool to measure actual real world position and travel. Nice to see I'm not the only one that goes through this lol Part of the fun isn't it. When it's done some never understand what it takes to get it right.

    Without springs installed can raise and lower the arm. Assume you did this but what matters most is static measurements at the ride height your springs have you at. Trail arms swing through an arc depending on sweep(less sweep less change). So measuring at parallel to the ground won't be the same as what angle it is at ride height. If your adjustable ears allow a good "window" of adjustment at your expected height....golden.
    Yeah, cutting and welding was something I was looking at but avoiding at the same time. LOL

    Yep, setting everything at ride height is the way to go!

  22. #122
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    Quote Originally Posted by Erik Dlux View Post
    Yeah, cutting and welding was something I was looking at but avoiding at the same time. LOL

    Yep, setting everything at ride height is the way to go!

    great job man looks awesome


    are those rear e30 calipers steel?
    88 M3
    91 318is
    91 318i
    83 320is
    08 X3 3.0si

    "If it flys, floats, or f*cks, rent it!"

  23. #123
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    Thanks

    I am not 100% but I think they are aluminum? They are really light, I would have a hard time thinking they were steel. They are E28 calipers though.

  24. #124
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    You can go bigger on the rear discs. I have 300mm vented rears from an e32 740i. Roller bearings fit in the trailing arms of the e32 instead as well, if those poly ones ever fail. That sway bar solution is so simple and clean, I love it
    -John

  25. #125
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    Good info. Thanks!

    Did you ever drive on the smaller rotors? As good as the E21 drums treated me, I dont know that I will have an issue but vented and bigger? I am in. Do you have to swap out to different calipers too?

    I read about those roller bearings but couldnt ever figure out if they were direct drop in. People sound like they love them and they are the way to go. They are expensive though, no?

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