Lower control arms

[95rayburn]

which is better a one piece control arm or a strut style or it dosent matter

[merc123]

What I've been told is one is cheaper if you break it. Put the one piece on the side that doesn't get hit as much (LF?) and two piece on the other. If you bend a one piece you need a new one. You bend a strut style you can replace pieces, not the entire part.

[Matt49]

The reason the one piece setup has become more popular is because you can have a complete spare with rod ends on it and ready to go.
If you bend a piece of a two piece, you have to replace it and recheck all your alignment at the track which is a pain in the arse and time consuming. If you bend a one piece, you just bolt on your preset spare and go back on the track.

[merc123]

The reason the one piece setup has become more popular is because you can have a complete spare with rod ends on it and ready to go.
If you bend a piece of a two piece, you have to replace it and recheck all your alignment at the track which is a pain in the arse and time consuming. If you bend a one piece, you just bolt on your preset spare and go back on the track.

You could pre-make tie rods, strut tubes and lowers also for the 2 piece configuration.

[zeroracing]

Disclaimer, I am using 2 piece right now, have not fabricated my one pieces yet.

Yes you can pre-set each individual piece then replace each one that may be bent... the issue that I have is how do you tell what is bent, is it just the strut rod or strut rod and ball joint, or is the strut rod bent and ball joint rign cracked but dirty... If I were to pre-set the 2 piece, I would go ahead and replace both at the same time, then inspect at shop and replace only what is broken. Often time things we dont catch are bent or broken at the track and stay on the car all night, this is a nice aspect of the one piece in that you know all the parts of the lower are good, also the lower in my opinion is one of the most vital components of the entire car. Of all the parts that can fail the lower seems to have one of the worst outcomes. Break an upper, shock, tie rod, even rotor and often you spin or tear up some things, break a lower and some of those cars look like an IED took them out. The first late model I ever drove, true fab stub, broke one on lap 3... nice welcome mat. Did not flip but did get some crazy air and considered myself extremely lucky so really inspect them hard now.

[Matt49]

Disclaimer, I am using 2 piece right now, have not fabricated my one pieces yet.

Yes you can pre-set each individual piece then replace each one that may be bent... the issue that I have is how do you tell what is bent, is it just the strut rod or strut rod and ball joint, or is the strut rod bent and ball joint rign cracked but dirty... If I were to pre-set the 2 piece, I would go ahead and replace both at the same time, then inspect at shop and replace only what is broken. Often time things we dont catch are bent or broken at the track and stay on the car all night, this is a nice aspect of the one piece in that you know all the parts of the lower are good, also the lower in my opinion is one of the most vital components of the entire car. Of all the parts that can fail the lower seems to have one of the worst outcomes. Break an upper, shock, tie rod, even rotor and often you spin or tear up some things, break a lower and some of those cars look like an IED took them out. The first late model I ever drove, true fab stub, broke one on lap 3... nice welcome mat. Did not flip but did get some crazy air and considered myself extremely lucky so really inspect them hard now.

Exactly what I mean (better explained) about the benefit of the one-piece.
And exactly my experience with breaking a lower. First time on the track last season we had the front rod end of a lower control arm come apart because somebody decided it would be a good idea to use a three piece rod end instead of a two piece rod end so the race pulled out of it.
When it let go setting the car into the corner it broke the lower in two (piece of it was wedged in the race track), bent the spindle, bent both ball joints, bent the shock shaft and body, bent the tie rod and both ends, and twisted the upper control arm all to hell. The only thing salvageable on that corner was the spring.
$800 of damage because we used the wrong $20 part on the lower control arm.
I knew better than to use a three-piece heim on anything that takes an axial load but it somehow got overlooked during assembly. Lasted about 2 and a half laps.

[merc123]

I guess my biggest take away was cost. You could pre-make a 2-piece ready to bolt on completely just as the one piece. The big thing is once I get the "bent" one back to the shop like you say then I can figure out exactly which part is messed up. Then I can replace that part. If it's just a lower it's a $30 part as opposed to $100. Strut tubes, used, can be had for about $10.

This stuff is all new to me so I was just throwing out ideas of what I'd heard. Nothing from experience.

[Matt49]

I guess my biggest take away was cost. You could pre-make a 2-piece ready to bolt on completely just as the one piece. The big thing is once I get the "bent" one back to the shop like you say then I can figure out exactly which part is messed up. Then I can replace that part. If it's just a lower it's a $30 part as opposed to $100. Strut tubes, used, can be had for about $10.

This stuff is all new to me so I was just throwing out ideas of what I'd heard. Nothing from experience.

It really comes down to personal preference and what works best for your program.
I will say this about a major CON to the one-piece versus that two-piece lower:
You can't really adjust caster on the once piece like you can on the two piece by shortening and lengthening the strut. That angle made by the control arm is fixed so wherever you have to get the heims to get it to bolt on is pretty much all you have to work with. I know most cars now have the turn buckle deal on the right lower but all that does it put everything in a bind when you crank on it. To avoid putting stuff in a bind, you should adjust caster using a slotted upper control arm if you are using a one-piece lower. This is my opinion and is NOT shared by many including some car builders that I've discussed it with.
A one piece lower is a rigid triangle once the heims are set for the holes to line up. If you start cranking the turn-buckle after that, you ARE putting unnecessary pre-load on the heims and pre-stress on the control arm and the chassis.
And if you think about it, because of the spindle snout's relatively low position on the spindle vertically, you are changing wheel base less by moving the upper ball joint to change caster than you are by moving the lower ball joint.

[jason29a]

It really comes down to personal preference and what works best for your program.
I will say this about a major CON to the one-piece versus that two-piece lower:
You can't really adjust caster on the once piece like you can on the two piece by shortening and lengthening the strut. That angle made by the control arm is fixed so wherever you have to get the heims to get it to bolt on is pretty much all you have to work with. I know most cars now have the turn buckle deal on the right lower but all that does it put everything in a bind when you crank on it. To avoid putting stuff in a bind, you should adjust caster using a slotted upper control arm if you are using a one-piece lower. This is my opinion and is NOT shared by many including some car builders that I've discussed it with.
A one piece lower is a rigid triangle once the heims are set for the holes to line up. If you start cranking the turn-buckle after that, you ARE putting unnecessary pre-load on the heims and pre-stress on the control arm and the chassis.
And if you think about it, because of the spindle snout's relatively low position on the spindle vertically, you are changing wheel base less by moving the upper ball joint to change caster than you are by moving the lower ball joint.


This is exactly right.... And if you want to put lead in the front end you will have some issues using one piece lowers. And if you have never measured your front end lead you maybe surpised at what you actually have in it.

[toloud]

Depending on your car there may be good reasons a one piece is better. On our blue front rockets the lower spring mount hole is an inch lower to keep the shock from bottoming out. On these cars when using rocket parts once the measurement is set on the short arm and the end on the strut almost totally threaded in caster will be close and the bolts will slide right in .They will also do so after 1 or 2 turns to set caster. Check with some one who runs your type of car to see if there is a performance advantage to one piece. With some info on your car someone on here can might answer you better.

[Matt49]

Depending on your car there may be good reasons a one piece is better. On our blue front rockets the lower spring mount hole is an inch lower to keep the shock from bottoming out. On these cars when using rocket parts once the measurement is set on the short arm and the end on the strut almost totally threaded in caster will be close and the bolts will slide right in .They will also do so after 1 or 2 turns to set caster. Check with some one who runs your type of car to see if there is a performance advantage to one piece. With some info on your car someone on here can might answer you better.

Good point. MasterSbilt does their one-piece like this also allowing for additional shock travel. Makes a big difference.