Winter updates

[RCJ]

Have been discussing updates for the car.Looking at going to the reverse strut rod style lower a arm.Since we are building new a arms anyway and we have ran a 1'' spacer one the r/f all year. What are the pros and cons of building the a-arm 1'' longer and doing away with the spacer?
I noticed that people only run the reverse strut rod on the r/f .Any reason to not run a reverse on the l/f?
I have 2 brand new tires, other than putting them in two huge trash bags, any ideals on storing them over the winter?

[MBR Performance]

Don't lengthen the lower. Move the mounting point instead. Grind your tires, wrap in stretch wrap and store in hearted area. As for the rear struts I'm definitely a fan.

[zeroracing]

Some cars run reverse strut on the LF also.

[Kromulous]

Bloomquist runs a RF reverse, LF FWD. I talked to an Engineer friend of mine and he said that it would promote the car to compress the RF spring, without pulling the nose down on the fwd pick up point. If that makes sense, he says its more accurate compression of the RF spring, and less mechanical.

Hopefully we can update our car this year with this set up.

[billetbirdcage]

Bloomquist runs a RF reverse, LF FWD. I talked to an Engineer friend of mine and he said that it would promote the car to compress the RF spring, without pulling the nose down on the fwd pick up point. If that makes sense, he says its more accurate compression of the RF spring, and less mechanical.

Hopefully we can update our car this year with this set up.

If properly done that corner of the car can't tell whether it runs forward or backwards, but they have to be the same as far as mounting point left to right and at the same angle when compared to the inner pivot of the lower control arm. If all that is the same, then they will react exactly the same handling wise.

The main reason it not done on the LF as much is literally because of space and secondary not really needed for ground clearance. With the engines to the left of the suspension center there is more room on the RF to put the strut behind as the LF strut mount and support tubing can get close to the engine and also has to clear the steering shaft.

Like I said many get the location wrong when going to reverse struts and if that is the case then you will introduce caster gain/loss and therefore effect handling but if the strut is moved to the back and still inline with the lower and at the same angle as it was on the front (not necessarily the hieght of the strut end itself but the same angle between the 2 pivot points of the lower and the strut) then the car won't know the difference, besides some strength issues that can come up generally do to the strut mount being closer to the lower arm pivot thus adding load/stress/leverage to the strut.

[Matt49]

Bloomquist runs a RF reverse, LF FWD. I talked to an Engineer friend of mine and he said that it would promote the car to compress the RF spring, without pulling the nose down on the fwd pick up point. If that makes sense, he says its more accurate compression of the RF spring, and less mechanical.

Hopefully we can update our car this year with this set up.

I think your engineering friend might be making the assumption that dirt late models have a lot of anti-dive designed into the front end like most street cars do. Most late models have very little, if any, anti-dive in the front end.

[Kromulous]

He didnt see if there was a big difference in mounting points.

Why couldnt you design it with anti dive in the LF and none or negative on the RF? Promote the RF to roll over. There is still a bit of anti dive in these cars, maybe not passenger car degree but nevertherless.

I know one thing Bloomquist's car is the best i have ever seen on a dirt track, period. He can flat smoke people when he is on his set up, even when the car is off a tick he is top 5 usually.

[fastford]

If properly done that corner of the car can't tell whether it runs forward or backwards, but they have to be the same as far as mounting point left to right and at the same angle when compared to the inner pivot of the lower control arm. If all that is the same, then they will react exactly the same handling wise.

The main reason it not done on the LF as much is literally because of space and secondary not really needed for ground clearance. With the engines to the left of the suspension center there is more room on the RF to put the strut behind as the LF strut mount and support tubing can get close to the engine and also has to clear the steering shaft.

Like I said many get the location wrong when going to reverse struts and if that is the case then you will introduce caster gain/loss and therefore effect handling but if the strut is moved to the back and still inline with the lower and at the same angle as it was on the front (not necessarily the hieght of the strut end itself but the same angle between the 2 pivot points of the lower and the strut) then the car won't know the difference, besides some strength issues that can come up generally do to the strut mount being closer to the lower arm pivot thus adding load/stress/leverage to the strut.

i pretty much agree with all you are saying, the only thing im concerned about is under breaking, with a forward mounted strut rod, you are pushing on the chassis in front of the center line of the front axle( spindle to spindle} and when mounted to the rear, you are pulling the chassis behind the center line. My question is, would this loosen the car getting in or could it gain rt rear side bite and possibly tighten getting in?

[TheJet-09]

^^^ I think you have your "push" and "pull" backwards. Even under acceleration, but most certainly during braking, there's resistance against the front tires (which is why they rotate), and because of that resistance it pulls back from the front, or pushes back to the rear. Think about it...if you disconnected the strut rod (regardless of what direction it goes), where would the tire go while moving? Straight back.

[fastford]

yea, little brain fart there, but it should still have an effect, even if small....

[TheJet-09]

Agreed. I look at it as pulling a wagon by the handle versus pushing one by the handle. Swartz makes a point on their website about reverse mount struts being beneficial should you wreck the front end...less chance of misalignment from tweaking the strut rods/mounting points.

[fastford]

i remember seeing billy moyer in a chassis several years back with the strut running back. Im changing my right to rear mount this winter .

[billetbirdcage]

i pretty much agree with all you are saying, the only thing im concerned about is under breaking, with a forward mounted strut rod, you are pushing on the chassis in front of the center line of the front axle( spindle to spindle} and when mounted to the rear, you are pulling the chassis behind the center line. My question is, would this loosen the car getting in or could it gain rt rear side bite and possibly tighten getting in?


Fastford: There may be some vary slight differences there, but it's not noticeable at all. Besides not sticking the front strut rod into the ground anymore which is the reason for the rear strut. However for much force to be put on the lower to raise or lower the car under braking it has to have a fair amount of angle in it. Typically the angle is in the upper arm, thus the anti-dive force should typically be on the upper arm, however with today's cars and how much the car tilts you might be surprised....

Typically the front strut is around 20" or more in front of the cross member, so when the car is at attitude (obviously this will vary with each car somewhat) so for each degree the car tilts front to back the center of the front strut rod end is .35" lower then the center of the lower control arm rod end. So if the car tilts down only 2 degrees (back to front) it's roughly .700" lower then the control arm/cross-member and can drag real easy. Again this is not accounting for the material below either the strut or the cross-member but is the change that will happen in hieght over 2 degrees with a distance of 20", so you can see how easy it is to drag the strut over the cross-member.

[billetbirdcage]

i remember seeing billy moyer in a chassis several years back with the strut running back. Im changing my right to rear mount this winter .

Are you are talking the California victory circle? if so that is the part I'm talking about getting them in the wrong spot and changing the handling of the cars. Many converted the V/C cars back to front strut because the way they were mounted caused caster and anti dive lose on RF dive.

[fastford]

Fastford: There may be some vary slight differences there, but it's not noticeable at all. Besides not sticking the front strut rod into the ground anymore which is the reason for the rear strut. However for much force to be put on the lower to raise or lower the car under braking it has to have a fair amount of angle in it. Typically the angle is in the upper arm, thus the anti-dive force should typically be on the upper arm, however with today's cars and how much the car tilts you might be surprised....

Typically the front strut is around 20" or more in front of the cross member, so when the car is at attitude (obviously this will vary with each car somewhat) so for each degree the car tilts front to back the center of the front strut rod end is .35" lower then the center of the lower control arm rod end. So if the car tilts down only 2 degrees (back to front) it's roughly .700" lower then the control arm/cross-member and can drag real easy. Again this is not accounting for the material below either the strut or the cross-member but is the change that will happen in hieght over 2 degrees with a distance of 20", so you can see how easy it is to drag the strut over the cross-member.

thats exactly whats happening , but were changing the cross member and the right rail also, my calculations show that even with the strut run backwards, the cross member and possibly the frame may hit, so im gone correct it all. my chassis is basically an 08 rocket clone that i jigged up on and have changed a lot of things toward the rear over the past few years and am very satisfied with that end, just got to catch the front end up to date for what im trying to run now.

[fastford]

Are you are talking the California victory circle? if so that is the part I'm talking about getting them in the wrong spot and changing the handling of the cars. Many converted the V/C cars back to front strut because the way they were mounted caused caster and anti dive lose on RF dive.

do you think they turned the strut back without correcting the cross member? i would think all that has to work together.

[billetbirdcage]

do you think they turned the strut back without correcting the cross member? i would think all that has to work together.

The strut location was in the wrong place on the V/C's, it was mounted to the main frame rail which is too far outboard compared to the lower control arm mount so it made the lower ball joint move backwards under compression and lost caster.

It's no different then mounting the upper arm not square with the frame, like many modified's are. Not being square makes the ball joint move front to back or vice versa on the car.

[racer2e]

The victory circle cars with the struts to the back were designed this way on purpose. The rear strut mount was outboard of the lower control arm mount. Think of a Chevelle clip, but not that much. He wanted the castor loss/ pro dive in roll. Lots of guys did not like it. The later front end was more popular, but it was more than the just the strut rods, it had taller spindles.