Hey OLD MAN, I'm shopping around for tubing for my roll cage and was just wondering what kind of tubing did you use ? I was reading some 2015 rule books and the minimum sizes needed for formula D is DOM 1.5" x .095, for FIA it is DOM 1.75" x .095 main hoop and 1.5" x .095 for bracing .... I was thinking of going with DOM 1.5" x .120 ... what are your thoughts ?
1.5" x .120 ? which rules have you seen those from ? I've only really read the 2015 formula D rules (1.5" x .095), the 2015 FIA rules (1.75" x .095 main and 1.5" x .095 braces), and the 2015 CARS (canadian association of rallysport) rules (1.5" x 2.5mm which is equal to .098 so I am assuming that it is the same as a 1.5" x .095 ) ...
I was thinking about getting 1.5" x .120 because of an old rule book of 2010 for the ASN Canada FIA, National solosport regulations stating that for a car under 2500lbs you can use 1.5 x .095 or 1.375 x .120 and for over 2500lbs you can use 1.5 x .120 or 1.75 x .095 ... I am estimating the car to be right around 2500lbs or more so I'd go with 1.5" x .120 to be safe.
Stiffness goes up by the square of diameter, so there isn't really a good reason (other than weight increase, which is minimal) to go with the 1.5" over the 1.75" when you're talking about critical components of the roll cage. I do like to use the smaller diameter sometimes for non-critical/non-mandated stuff (like subframe bracing or whatever) where a minor weight savings will suffice, but I'm selective. Just some food for though.
We could discuss about this all day but I love mathematics so I found a few numbers and made some comparison. it also depends on the wall thickness .
DOM Tensile Stength = 70,000 psi
Dia, Thickness, ID, Cross Sect. Area, Tensile Strength, Weight (lb/ft)
1.75" x 0.125 1.50 0.64 44,668 2.169 lb
1.75" x 0.095 1.56 0.49 34,575 1.596 lb
1.50" x 0.120 1.26 0.52 36,416 1.769 lb
1.50" x 0.095 1.31 0.42 29,352 1.426 lb
so:
100 feet of 1.5x.120 = 176.9lbs (smaller, stronger)
100 feet of 1.75x.095=159.6lbs (-17.3lbs)
100 feet of 1.5x.095 = 142.6lbs (-34.3lbs, weakest pipe)
100 feet of 1.75x.125=216.9lbs (+40lbs, strongest, heaviest)
I think I will try to build the cage with 1.5x.120, it's smaller diameter, stronger, and not much heavier...
NASA and SCCA have the same tubing requirements for main structural tubing for cars between 1501 and 2500 pounds.
https://nasa-assets.s3.amazonaws.com...282/2015.3.pdf
For what it's worth I went with 1.75 x .120, just because.
I missed all this - sorry. I used 1.5" .095 wall chrome molly, DOM is used more often then chrome molly because of cost I believe. I have a friend who builds Midgets and Sprint Cars so I had a good source for the tubing and bending of it.
Always FUN TO DRIVE - Build Thread & Tech info - 79 320/6 track car build thread -- Videos of track car -Adam in car Auto-x video - Start-up video - 4/2011 Adam's TOP BMW time San Diego BMWCCA - 4-5-15 Dyno break-in run new M20B25 - Exhaust Thread - Link
I would use 4130 too.
You're probably going to be safe with whatever you choose, but more food for thought...
I did a quick google search and found a calculator for you that will give you the idea of what I'm saying about tube OD.
https://www.easycalculation.com/mech...tube-beams.php
I think you'll find that the 1.75" X .095" tube is a good bit stronger in bending, which is what I was trying to convey above, though possibly not clearly enough.
There are lots of websites with the calculations if you want to do more engineering on the subject, you might be able to come up with a better solution still.
I'm not trying to argue your choices, just suggesting you consider all the variables.
interesting ... no offence taken, I love a good debate / discussion , cause I might be totally off track and missing something that someone else already knows.
you are right that that website and those calculations shows the 1.75 x 0.095 deflects less than the 1.5 x .120 ...
but one more reason I am thinking about going with 1.5 is because I do not have the 1.75 die for my bender, I have a cheap 16 tons Pipe bender that needs a few modifications in order to be able to do a perfect bend. I took a 1.75 tube and tried it in my dies and none of what I have fits snug. I haven't tried a 1.5" diameter one yet but I am hoping it will fit snug in the 1.25 Pipe die.
sorry for Hijacking the thread OLD MAN,
here's the modifications I need to do to my bender:
something among those lines.
It has been a long while since I have up dated this thread - and we have not done much to the car up until this past week or so, except run it and try the new engine, rebuild LSD, Brake pedal set-up, new tires and wheels.
New Tires we got at Christmas 225/45-15 Maxxis Victra RC-1 slicks New wheels we got three years ago 15"x9" with zero off-set.
End of last year Adam and I took the LSD apart and did some wire EDM work, precision grinding and fitting of new parts - so now instead of a two clutch LSD it is a four Clutch LSD. It is way more looked up under power now!
Two months ago we ran an SCCA auto-x where they had scales set up so I got a quick corner weight done still need to balance it - total weight with 4 gals gas 2147lbs
Ordered some new Bilstein rear racing shocks - custom valved and they are single adjustable doing both compression and dampening at the same time
Sent the doors and hood out to get painted - Chevy hugger orange to match the body of the car
OH and the Steering quickener is really sweet on course but a lot of work in the pits going slow!
So I will be doing some work in the next week and a half as there is an SCCA auto-x event at El Toro on July 9th we are signed up for - lots of testing!
Last edited by OLD MAN; 07-08-2016 at 09:34 AM.
Always FUN TO DRIVE - Build Thread & Tech info - 79 320/6 track car build thread -- Videos of track car -Adam in car Auto-x video - Start-up video - 4/2011 Adam's TOP BMW time San Diego BMWCCA - 4-5-15 Dyno break-in run new M20B25 - Exhaust Thread - Link
I got home from a business trip last night to my new rear shocks that arrived Tuesday - Bilstein AS2 double adjustable. I ordered the 5" stroke ones that have an extended length of 16" and compressed length of 11". So now to build upper mounts for them as tops are mono ball unlike the shaft top stock shocks. If I can get the top mounts correctly measured and made I will get to try these out tomorrow at an SCCA auto-x event. Need to work fast!
Last edited by OLD MAN; 01-24-2018 at 09:17 AM.
Always FUN TO DRIVE - Build Thread & Tech info - 79 320/6 track car build thread -- Videos of track car -Adam in car Auto-x video - Start-up video - 4/2011 Adam's TOP BMW time San Diego BMWCCA - 4-5-15 Dyno break-in run new M20B25 - Exhaust Thread - Link
Made some quick upper mounts yesterday 7-8-16, ran the car today and it was fun! Still have more tuning to do but now I can do it!
Always FUN TO DRIVE - Build Thread & Tech info - 79 320/6 track car build thread -- Videos of track car -Adam in car Auto-x video - Start-up video - 4/2011 Adam's TOP BMW time San Diego BMWCCA - 4-5-15 Dyno break-in run new M20B25 - Exhaust Thread - Link
Awesome work!! Looks great
1996 328i (m52B28US) OBD1 euro ZF 5spd. 3.23LSD conversion / Chem. PnP Head/ DINAN stg.2 CHIP/ VAC race valves/ S52 cams/ A/C delete/ fan delete/ Washer Fluid resv delete/ ARP head studs/ Cometic 140MLS / VAC Solid Engine/trans Mounts/ CAI / 2.5"Borla race exahaust/ NGK R spark plugs, M50 Mani, S50 Oil Res, Riot Racing HFTB, SAMCO Hoses, JBR FW, X-Brace, Mtech Front Bumper, RE RSMs, stoptech SS lines, Bilstein sports, H&R Race Springs, S52 Reinforcement plates, Kosei K1 w/ bridgestone RE960as, Brembo/stoptech slotted rotors, M3 Trailing arms, M3 Calipers, M3 Axles, ACS strut brace, weight reduction.
http://mbuild.blogspot.com/
Thanks - turns out I made the extensions too long. The shocks are compressing to within 1/4" off full compression in the turns, so I will drill new holes further up and cut off the extra material.
Some slow motion videos of the car. one where the car is gray, blue and white is from 2010 with not so much suspension work to it and on Hankook 225-45/15 RS2s on 7" wide KO1s.
Current videos from this past Sunday we were running the Maxxas 225/45/15 RC-1s on 9" wide rims.
http://public.fotki.com/makofoto/201...-cs/c0088.html
http://public.fotki.com/makofoto/201...-cs/c0108.html
Last edited by OLD MAN; 09-03-2016 at 09:10 PM.
Always FUN TO DRIVE - Build Thread & Tech info - 79 320/6 track car build thread -- Videos of track car -Adam in car Auto-x video - Start-up video - 4/2011 Adam's TOP BMW time San Diego BMWCCA - 4-5-15 Dyno break-in run new M20B25 - Exhaust Thread - Link
Hello OLDMAN!
I'm about to put a B25 in my E21 using my M20B20 carb intake and distributor.
What advance did you use? I've read 15 degrees in your thread but at what rpm?
Do you have the vacuum advance connected?
Thank you in advance
Best regards
Bumping an old, nut recourcefull thread. I'm about to start my e21 build. Mostly track car that will fit into DP if I do autocross. I've been interested in hillclimbs/Time Trials for a while.
Fabrication is what really excites me. It does suck that most of the pictures from when you lost oil pressure to having an orange car with a full cage did not show up on my phone.
I love what you did with your dash though.
Hi Gustav129 - sorry for the lack of up dates. Adam went to school out of town and I got busy working around the house and camping with the wife the last 16 months or so.
I was thinking of doing some You tube videos of the car and maybe some Q and As - but I am not really good with video editing so still just thinking about it.
Also I had a company I sold 1.5 years ago with a web site that all the jpegs are posted on, the new owner has been nice to leave the old pictures on the site, but if he every changes the host I may lose them all.
Anyway I am happy to add forum attached pictures and answer any questions you have. Always glad to help people out.
Some pictures of the car with cage finished and painted and body work started for new paint "Orange".
AB5.jpg AB6.jpg AB8.jpg doorbar.jpg doorbar2.jpg
Always FUN TO DRIVE - Build Thread & Tech info - 79 320/6 track car build thread -- Videos of track car -Adam in car Auto-x video - Start-up video - 4/2011 Adam's TOP BMW time San Diego BMWCCA - 4-5-15 Dyno break-in run new M20B25 - Exhaust Thread - Link
One of the up-grades we did earlier this year was to build an adjustable suspension rear subframe with E21 323i trailing arms which came with disk brakes on them.
I did some mod work to a pair of E30 rear calipers to fit and added breaded stainless steel flex brake lines to the assembly. My biggest reason for going to disk brakes in the rear was not for better braking over all as the stock rear drums with good shoes stop great. The issue with the stock rear drum brakes is that for them to work really great you have to readjust them after every outing and E21 rear drum brakes are a PAIN to adjust correctly! But with the rear disks all I have to do is put in new pads and bleed the system once a year or so.
Had the whole assembly sandblasted and powder coated and installed a set of Euro/Metric polyurethane bushings.
I cut the stock pivot mounting points for the trailing arms off the subframe made a new set with slots that were also taller/higher off the subframe cross tube. The reason for this is to get closer back the the stock rear suspension geometry when the car is lowered. Plus with the adjustable toe-in and caster a can get things adjusted for the track.
All I have to do now is get a good four wheel alignment.
323 RE 6.jpg 323 RE 4.jpg 323 RE 3.jpg 323 RE 2.jpg
Last edited by OLD MAN; 10-01-2018 at 11:03 AM.
Always FUN TO DRIVE - Build Thread & Tech info - 79 320/6 track car build thread -- Videos of track car -Adam in car Auto-x video - Start-up video - 4/2011 Adam's TOP BMW time San Diego BMWCCA - 4-5-15 Dyno break-in run new M20B25 - Exhaust Thread - Link
Binding rear suspension.
In the above post are pictures of the new 323 rear suspension with adjustable camber caster mods. Since I have put this in the car the rear is much stiffer and car seems to want to drift a lot more. This is with even much softer rear springs and shock setting. Basically the same shock and spring set up that use to be the "Dialed In" setting before the rear end redo.
I am thinking the Poly bushings are locked into the adjustable camber caster slots in the sub-frame and not letting the arms move freely.
Have two choices I can think of:
#1 remove the adjustable rear sub-frame and put a stock one back in. I am wondering how much the adjustable rear suspension is needed in an E21? Car was really fast Handled great" with stock rear suspension with rubber trailing arm bushings. Biggest reason for the E21 323 rear suspension is to get the disc brakes in the back - having to re-adjust the stock rear drums after every event is a lot of work, and a real pain.
#2 pull the poly bushing out - mill them down on the outer flat "spacer" out side edges and make some steel and delron washers to keep the poly bushings from locking into the adjusting slots.
Always FUN TO DRIVE - Build Thread & Tech info - 79 320/6 track car build thread -- Videos of track car -Adam in car Auto-x video - Start-up video - 4/2011 Adam's TOP BMW time San Diego BMWCCA - 4-5-15 Dyno break-in run new M20B25 - Exhaust Thread - Link
I still get emailed updates on this thread . As discussed in my build thread the adjustable trails get the arm holes out of plane. If enough causes binding.
Another cause can be the bushes themselves vs the sleeves. The arms are meant to pivot on the sleeves. Most kits put the bushes too wide when installed which causes unwanted binding/drag on trail arm travel. Some are so bad rubbing with bushes that it can break the ears off the subframe with a race setup. The inside trail arm bush on each sleeve should be shaved down to allow the sleeve to protrude a few thousandths ie about .010 or more. This way when tighten the bolts all the way down your clamping the sleeve itself with the bolt. The trail arm should then be able to move up and down by hand. Most of the time this is the issue with ALL aftermarket RTAB kits.
The out of plane can cause binding if one leg is too far out from the other. The arc of the arm changes and at some point in travel can bind or wedge. A swing up by hand without brakes or axles or shocks attached should revel this.
I use AKG motorsport sleeves. They fit the e21 trails. Usually are better fit, and sometimes even have the sleeve slightly protruded when assembled so barely have to shave the edge of the bushing. Also since the trail rides on the sleeves when pivoting AKG bushes have grease grooves inside for much needed lube where it counts. I've them in my daily driver e30's without issues.
88 M3
91 318is
91 318i
83 320is
08 X3 3.0si
"If it flys, floats, or f*cks, rent it!"
Always FUN TO DRIVE - Build Thread & Tech info - 79 320/6 track car build thread -- Videos of track car -Adam in car Auto-x video - Start-up video - 4/2011 Adam's TOP BMW time San Diego BMWCCA - 4-5-15 Dyno break-in run new M20B25 - Exhaust Thread - Link
Hi Daryl,
this is Andre off Facebook who is building the e21 lemons car. (possibly two of them, a e21 and a 2002 or two e21s). The idea is something to continue racing with the team if 1 car goes down. I've read this thread eons ago and am back at it now. Thanks for shooting me your email address and now I see clarification on these.
I'm searching now why you didn't run 245 tires, my guess is to preserve wheel bearings? My guess is they don't hold up with 8 or 9" wheels under long duress? We did one 24 hour race and blew a front left bearing mid race on a miata. Luckily had a spare. But it dropped us to 10th place /5th overall. I'd like to build a reliable competitive car with luck. Just ugly as sin...
thx, A
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