grimmspeed strut tower bar
 

so i just got my grimmspeed bar yesterday

was surprised to find that the bolt holes for it are basically slotted.

all the strut bars i've ran on any other platform have either fit exactly, or had threaded ends to put tension on the bar. i was surprised to see that with this bar and its slotted holes, you can slide the bar back and forth damn near a 1/4 of an inch before you bolt it down... and given that we are talking about trying to prevent very small fractions of an inch of deflection.. it seems wrong to me that the bar has so much "slack" in it. the only thing preventing movement is 4 bolts torqued to 12 ft-lbs?

maybe this will work fine.. but it just doesnt seem right to me. i have a hard time trusting that small amount of clamping force is really going to keep this thing in place under hard transitions through a slalom or around a hard corner at the track.

has anyone had issues with this? or can anyone comment on other strut tower bars for this platform? is this common now a days? i havent bought a strut tower bar in a number of years.. but i went through a lot "back in the day" on AE86s, supras, civics, etc . and i dont remember any bar being like this. generally the issue was more towards being a pain in the ass to install them because they fit so precisely.

The holes either need to be slotted or grossly over-sized to slip onto the studs because they point in to the center of the car at an angle. If they fit "exactly" it would be impossible to get the bar on. Also the slots are designed with the tolerance of different vehicles in mind, as well as what we can predict to be strut tower fatigue in aging vehicles.

With that said, the clamp load for a single stud/nut of that size at around 12ftlbs of torque is in excess of 2000lbs. So you're looking at over 8000lbs total. That bar isn't going anywhere. Just like the stock strut tower to firewall brace doesn't move or you'd be able to see rub marks under it.

It might be even easier to visualize if you think of a camber plate where the entire strut assembly is held by 4 small allen bolts.

http://raceseng.com/wp/wp-content/up...amber_dev4.jpg

I picked the Raceseng Camber plate because I think it's beautiful ;)

You have the weight of a corner, and a lot of force going through it to the strut tower, and they don't slip despite the fact that they are small in size and low torque in a long slot.

Nothing to worry about as far as slippage, the clamping force is HUGE. You can always put it on, then drive the car as aggressively as you can, and then check for signs of slippage (it would be obvious rubbing of the powdercoat) under the head of the nut.

Chase
Engineering

I installed a similar bar (same design, long tube that bolts into those 4 bolts) and while it did had some minor play on it, it wasnt 1/4 of an inch, you might be exagerating, I dont know. What I do know is that it does not move once installed. I have been to the track since and I race on r compounds, the thing didnt move at all.

Now, did it make me a whole new driver and shaved a second of my lap times? No, but it did felt different, in a small but good way different. I assume the grimspeed one would work just the same.

That's how bolts work. Google bolt clamp force. Same way your wheels are held on.

This guy is right, you know :p

A single 6mm nut torqued to 12.5 ft-lbs has ~3000 pounds of clamping force. That thing is going nowhere.

I recall that the brackets for my TRD strut bar had a little bit of wiggle room as well before being tightened down. 2 years later and no signs of slippage.

It sounds like there was plenty of R&D and the play/slotting wasn't just by accident. Good explanation by the GS team.

And that Raceseng camber plate does look pretty great too

That defeats the purpose of the car.

It's grounded to the ground, man!

http://uploads.tapatalk-cdn.com/2016...d48ec1378c.jpg



-Josh