Suspension opportunity at hand.

[Goran Malmberg]

Originally Posted by DMSentra

Would you explain what you mean by packing?
Would it not benefit CofG for using low horizontal mounted dampers? Or would the added mass of the pullrod assy. discount that possible gain?

That is to locate things in a funktional way, or things placed in an area becouse of room, or location other than for egineering reason.

A shock absorber weight in at about 5 pound. The weight of the moved object times the moved distance devided by total mass of the car is the change of cg. But then the pull-puschrod and rocker arms of that system must enter the equation. The reason for using puschrod system is if long A-arm is used, so that a direct working coilover want be practical, or on an openwheeler where windage enter the picture. Also, on a formula car the A-arm could not take bending loads from a coilover. If nothing call for it, I should use direct working coilovers.
Goran Malmberg

[AU N EGL]

Originally Posted by DMSentra

Tom, please don't back out on me now? I can read that you have knowledge that I could really use. Please help me learn.

I've looked at every forum I can find so far and no one I can find has done anything terribly progressive with this B11. The B12-on cars have totally different suspension factory so it's tough for me to compare. And on B14 cars that have beam style rear I have read quite a bit of grumbling about it.

I am here. I may not be a hot shot engineer, or know Sentra's let alone front wheel drive cars very much. But on track experience, I tend to put the design engineers to shame for what works, doesnt work and reliablity.

I have had pleanty of HOT SHOT engineers in my right seat telling me the most exting details of some non-essential part, or worse someone whos says my car is for chit and he does not even know way he agreed to ride with me.... Lap or 5 latter if they arnt puking their guts out ( and I am really a smooth driver ) they are re-evaluating their carrear choice, or questioning all the BS that was feed to them in classes and by departmental bosses. Soo much fun.


Ok hmmmm. No or little money? Have time to work, hmmm?

Ahh I think the first thing I would do is go to some junk yards that have the B11 and B12 sentras. See what I could do to barter, trade or what ever for suppension parts.

Next look at the B11 shocks. what are they and what size are they? Can you find a same size shock that has more rebound and is stiffer? Another trip to the junk yard. Can you revalve those shocks?

Sway bars. what size are the B11s ? what else might work? Back to that junk yard.

Springs: same thing

Can you weld? if so put a in a roll cage, it will stiffen that car up like no suppension ever could.

The OTHER thing I would do is get lots of seat time doing autocross in that sentra. Getting that literally seat of the pants feeling of how the car works is more valuble then any suggestions on any forum.

OK next where do you live?? have you check out the autocorss action in your area??

[DMSentra]

Originally Posted by phoenix

Moving the engine back and lower is quite easy and effective in a front engined/rear wheel drive car. Next to impossible with your setup, I would have thought.

Oh, yeah. It'd be pretty tough to go far with the drive axles lined up with the wheels. But, I got a Infiniti G20(Primera in other lands) for engine donor and it's trans outputs are somewhat behind the wheel centerline so I could move it a bit evidently.
I was mostly wondering about putting as much of the coolant system and other bits in the rear as I can. Battery and fuel will be moved rearward, but so much mass is coming out of the rear half of the car it'll still be horribly front heavy. I'll replace the hood and trunk with a skin, but that won't do much for the matter.

[DMSentra]

Originally Posted by Goran Malmberg

That is to locate things in a funktional way, or things placed in an area becouse of room, or location other than for egineering reason.

A shock absorber weight in at about 5 pound. The weight of the moved object times the moved distance devided by total mass of the car is the change of cg. But then the pull-puschrod and rocker arms of that system must enter the equation. The reason for using puschrod system is if long A-arm is used, so that a direct working coilover want be practical, or on an openwheeler where windage enter the picture. Also, on a formula car the A-arm could not take bending loads from a coilover. If nothing call for it, I should use direct working coilovers.
Goran Malmberg

Ok, as I would say to pack it all in there.
Common mounted coilovers will stay towards the top in consideration then.

[DMSentra]

Originally Posted by AU N EGL

I am here. I may not be a hot shot engineer, or know Sentra's let alone front wheel drive cars very much. But on track experience, I tend to put the design engineers to shame for what works, doesnt work and reliablity.

**** Great, I'm glad to have you on board, so to speak. There is just a massive amount of information that you fellas have, that put time on the track, that I couldn't replicate in the rest of my life.

I have had pleanty of HOT SHOT engineers in my right seat telling me the most exting details of some non-essential part, or worse someone whos says my car is for chit and he does not even know way he agreed to ride with me.... Lap or 5 latter if they arnt puking their guts out ( and I am really a smooth driver ) they are re-evaluating their carrear choice, or questioning all the BS that was feed to them in classes and by departmental bosses. Soo much fun.


Ok hmmmm. No or little money? Have time to work, hmmm?

** My "no budget" reply meant I don't have a figure to work with. I do have some pockets here and there that I'm buying parts with, and I want to plan this out well enough that I can buy the good stuff first, instead of wasting time and money on junk. Koni's are a typical example. My favorite damper brand, period. If I buy anything else it'll be for something like the strut housings or other hardware to fit Koni's to. And, Most of what is going to be done to the money pit will be me making it, modifying it, and where I just can't, then buying it. All control arms, mounts, links or whatever else will be fab'ed right here, or using the equipment at my work.

Ahh I think the first thing I would do is go to some junk yards that have the B11 and B12 sentras. See what I could do to barter, trade or what ever for suppension parts.

** There again, there just isn't much of anything that has been used, at the least in this area and on these cars, that would benefit me with where this project is heading. If I can find coilovers springs with the correct rates, it may be the most likely items. I am collecting what I can that fits the list though. I've been buying parts from across the country for the engine swap and am just about done with that hunt.

Next look at the B11 shocks. what are they and what size are they? Can you find a same size shock that has more rebound and is stiffer? Another trip to the junk yard. Can you revalve those shocks?

** Again, holding out for design specs and the Koni's that fit them, or at least close enough the compromise isn't a problem.

Sway bars. what size are the B11s ? what else might work? Back to that junk yard.

** Yep, I bought a B13 bar a while back for a song and am waiting to find if it'll be the right stiffness. Changing the mounts and resulting leverages may make that work well. I can get various bars easily enough.


Springs: same thing
** see above.
Can you weld? if so put a in a roll cage, it will stiffen that car up like no suppension ever could.

** I can and do weld for a living. But, I'm leaning towards paying for this segment of the build. I don't have access to bending equipment and have already found a shop that does nice work there.

The OTHER thing I would do is get lots of seat time doing autocross in that sentra. Getting that literally seat of the pants feeling of how the car works is more valuble then any suggestions on any forum.

** This kind of homework we LOVE, right? I started driving autocrosses last fall and missed first in class by .5 seconds my Novice day. First race day was 1st. Second event was a national event and I finished 5 of 7. 3 more autocrosses placing first and a 3 lap exhilarating enduro handed me a class champion plaque. Believe me, I'm having a BLAST! First event of this year, another 1st. So far, all these events have taken place at 4 different clubs. The car driven was my daughter's Inf. G20, not the donor car, in H Stock class.

OK next where do you live?? have you check out the autocorss action in your area??

** Being involved in this discussion and learning more about suspension design has me pumped up. Almost couldn't stop smiling today for feeling like a kid again. Ha ha ha.

[DMSentra]

I feel like I'm getting away from the reason for starting this thread. Still trying to get the type of suspension pinned down.

With the adjustability and control of geometries a pull-rod system gives, is the complexity of build and design a big enough problem to warrant ditching the idea? Or why else shouldn't it be a consideration?

[Goran Malmberg]

Originally Posted by DMSentra

I feel like I'm getting away from the reason for starting this thread. Still trying to get the type of suspension pinned down.

With the adjustability and control of geometries a pull-rod system gives, is the complexity of build and design a big enough problem to warrant ditching the idea? Or why else shouldn't it be a consideration?

A commonly mounted schock with spring on it, coilover, is a very simple construction without to many parts creating play and other unwanted negative problems. I like simplicity. Adjustability is good, but very much of what is needed is within the shock itself. It is also that motion ratio (lever ratio) from the wheel to the valve system of the shock affect the valving needed since a change in mr will affect the shock piston speed. What I am saying here is that whatever we do with the "adjustability" we want get rid of drawbacks. A direct working shock manufactured for the mr ratio and the sprung and unsprunged weight in quesion will take care of most things one need. A push or a pullrod system will in no way make up for the the need of shock quality by poviding adjustability. The bad thing is that we are stuck
with the high cost of these good shock absorbers whatever the Mr ratio solutions. We may also use a number of shock mounting holes in the chassis
for different "tilt" of the shock to alter the Mr a bit.

I am in no way against using push-pullrods in an application like yours, it might also be interesting to fabricate and play around with. You might very well try it. I have been doing so myself and dosent regret it, it add to real life experience.
Regards
Goran Malmberg

[AU N EGL]

Originally Posted by DMSentra

** Being involved in this discussion and learning more about suspension design has me pumped up. Almost couldn't stop smiling today for feeling like a kid again. Ha ha ha.

It gets the jucies flowing, the brain working on new things. Racing or autocross gives us a reason to do the best that we can, and then strive to more. AND THAT MY FRIEND is why we race.

[DMSentra]

What advise on planning wheel travel amounts do you folks have. I think we'd want it stiff to help limit body movement, but not so stiff the tires end up airborne at times? My gut feeling there is it'll end up close to 3-4 inches total travel for the rougher courses, then spring and damp it stiffer when smoother asphalt comes around?