I have New CNC parts Made !!!

[Tom D]

yeah, that would make sense, the largest mulitplier.

[Jester323]

Tom, you are spot on, the weakest link is the body mount, but what James has developed here is a very attractive housing for bushings that are far superior to either the worn out original equipment, or the Mexican-tar that they call rubber these days.

[TheNeek]

Tom, you are spot on, the weakest link is the body mount, but what James has developed here is a very attractive housing for bushings that are far superior to either the worn out original equipment, or the Mexican-tar that they call rubber these days.

Stock bushings are made of black crayon and earth worms.

[gsumzzz]

with the addition of new engine and tranny mounts and jr's engine strut delete upgrade?, along with the urethane diff bushings, my old e21 feels solid with less driveline slop. nothing scientific, but subjective. shifting feel is much improved and less "noise" from drivetrain while it is going about it's business. shifter/tranny do not shake and move as much as before work was completed. diff hanger alone is not an end all but a single piece of the puzzle. and dont ask for the gearing on my ass please.

[jrcook320]

jr, you sound so official. I got a question, what does the 3.628 in your formula represent?

also as we all know, a chain is only as strong as its weakest link. so unless you design and sell a complete package including a new body mount, bushings, bolts(?) and reinforced diff mounting, then a dogbone twice as strong as the factory is in reality not stronger at all.

however, I completely agree with you!

The analysis is a little more complex than what I stated and is an estimation at best (you have to account for tire coefficient of friction, tire od, counter torque at the diff pivot point, x1 distance to subframe mounts, x2 distance to rear diff mount and from there it's a statics problem), but it's a starting point.

The only reason I brought it up is to talk about actual engineering, not just designing for visual appearance. You'd be amazed how what you THOUGHT looked right early on in the design process ends up being way off the mark once you actual start simulating... and more importantly, road testing.

As far as the weekest link, sometimes you can't let best get in the way of better, meaning, just because there may be a weaker link somewhere else in the system doesn't mean I would want to purposely limit the strength of a new design for a single component. Design what you're designing for worst case scenario to ensure it will never be a failure point.

After that, if you expose the next weakest link then design a solution for that problem. You can't always determine all the weak links at once. Sometimes you have to expose them one at a time. Otherwise you may end up re-designing the entire chassis and upgrading far more components than is actually necessary. It's easy to fall in to the pointless upgrade trap...

Tom. That's first gear I think

[edit] pretty sure [/edit]

yup.

All that said, I'm certain James' part is better than stock. Perhaps it's over engineered. End of day, who cares? It's not a race car where you're designing every nut and bolt for maximum strength and maximum weight savings. I'm just happy people are interesting in designing parts for the e21.

Tom, you are spot on, the weakest link is the body mount, but what James has developed here is a very attractive housing for bushings that are far superior to either the worn out original equipment, or the Mexican-tar that they call rubber these days.

I'd have guessed the weakest link in terms of actual performance characteristics is the bushing itself, which you've addressed. The alpina diff cover with 2 bushings in parallel rather than 2 in series is 4x stiffer than stock, and of course twice as strong since there are 2 body mounts. If only there were a cheaper alternative to eliminate the dog bone altogether.

[jimjim69]

[Tom D]

jim, can't you reduce the thickness? I think that's the biggest distraction.

[jimjim69]

The new re done dog bones are done and ready to sell.

[Tom D]

I'm liking the new one better jim. I think I would also dish out some of the middle section.

[jimjim69]

With Ireland Engineering urthane bushing.

[jimjim69]

http://www.iemotorsport.com/bmw/E21-...E21dfhngr.html

Has them in stock now.

[gsumzzz]

i guess they make them in china now.

[jimjim69]

The Dog Bone is made here in the U.S.A.

I.E is a dealer as Im for them.

I dream them up for my e21 race car first. That has been my mule for 6 year now.

Im working my summer in chicago now a have NOT Had my hands on them.


50 have been made. A small # had been shiped to a few dealers @ this time.

[gsumzzz]

james, just kidding. i am the proud owner of a dogbone "classic" model. very happy with it. good luck with future sales.