Cheap compression rod bushing mod

[gearchruncher]

You like speed? You rather spend money on entry fees than parts? I got the mod for you.

Like many of us know, the front compression rod bushing takes a lot of abuse when driving the car hard. Many people have seen this tear after hard track use. It's also something that the aftermarket has created great products for, as making this bushing stiffer increases handling performance.

The compression rod only has force on it in one axis- directly in line with the ball joint. The stock bushing is meant to be most compliant in this direction, with two voids in the bushing creating a "beam" in this direction.

Rotate the bushing 90 degrees, and volia, no beam, just a solid bushing in the axis you care about. This should highly reduce the chance of tearing, while also making it a bit stiffer to boot with reduced deflection.

Top arm rotated, bottom stock

When I did this, I also did the old school trick of injecting urethane into the voids to make the whole bushing more solid, but this was just belt and suspenders. Not even sure this will do anything given there is no side load on this bushing once rotated.

As a hint for anyone needing to push this bushing out for any reason, you can borrow Powerbuilt 648617 from Advance Auto Parts. It has a great 2 9/64" socket that fits perfectly and makes pressing it out easy. Also has a 3" tube that works to go below the bushing as you press it out.

 

[Sam1]

That's a lot of hassle to put a broken part back into the car, when the arms are only $140 iirc.

 

[dsgerbc]

That's a lot of hassle to put a broken part back into the car, when the arms are only $140 iirc.

$280 buys plenty of seat time

You like speed? You rather spend money on entry fees than parts? I got the mod for you.

I'd be curious to know how this affects the bushing wear. The bushing will now resist lateral forces better, but the rubber stress from the suspension arm deflecting as the suspension goes through bump/droop will be considerably higher.

 

[gearchruncher]

@Sam1 - This mod is to prevent it breaking, and improve performance, not to try and fix a broken part.
Even if it was broken, if you bought the same part from Tesla, it would just break again if you track the car heavily.

 

[gearchruncher]

The bushing will now resist lateral forces better, but the rubber stress from the suspension arm deflecting as the suspension goes through bump/droop will be considerably higher.

That's a good point I hadn't considered. I guess only time will tell. I'd think this would be pretty similar to the inserts that MPP sells which also stiffen the system in the "tilt" axis.

 

[Sam1]

$280 buys plenty of seat time

It also buys better bushings to keep worn out bushings from creating stress on a different part of the suspension.

 

[dsgerbc]

It also buys better bushings to keep worn out bushings from creating stress on a different part of the suspension.

I would love to buy stiffer compression arm bushings that don't go full metal like those MPPs. Paying $$ for OEM arms to get new bushings seems like a waste tho.

 

[gearchruncher]

It also buys better bushings to keep worn out bushings from creating stress on a different part of the suspension.

What better bushings are on the market?
The only ones I know of are the full solid ones from MPP for $450, so $280 does not buy you better bushings. A solid bearing is not a bushing. MPP calls theirs MPP.R because of the NVH tradeoffs. It's a great product, but not right for everyone. You also need to press out your stock bushings and press the MPP ones in, so you still have to do all the same labor as rotating a bushing. And if you think a full solid bearing doesn't create new stresses on other parts of the suspension also.....

I know of no other aftermarket bushings, and you can't buy just the bushing from Tesla. What am I missing?

 

[Sam1]

Better bushings = new bushings. Easy peasy.

 

[gearchruncher]

Better bushings = new bushings. Easy peasy.

Cool, so how often would you put "better bushings" on your car, given new is relative? Every 20 track days? 10 days? 5 days?

I mean, everything wears out. Why not put "better" shocks, springs, tires, seats, batteries, etc in your car while you're at it? (better=new, of course)

I get this is all academic to you given you supposedly need to get a new car every 2 years for tax purposes. Some of us keep cars much longer than that, and actually enjoy doing a bit of work on our own cars and thinking about how they can be made better for our purposes in ways that doesn't just involve writing a check to someone.

 

[Motion122]

You like speed? You rather spend money on entry fees than parts? I got the mod for you.

Like many of us know, the front compression rod bushing takes a lot of abuse when driving the car hard. Many people have seen this tear after hard track use. It's also something that the aftermarket has created great products for, as making this bushing stiffer increases handling performance.

The compression rod only has force on it in one axis- directly in line with the ball joint. The stock bushing is meant to be most compliant in this direction, with two voids in the bushing creating a "beam" in this direction.

Rotate the bushing 90 degrees, and volia, no beam, just a solid bushing in the axis you care about. This should highly reduce the chance of tearing, while also making it a bit stiffer to boot with reduced deflection.

Top arm rotated, bottom stock

View attachment 846545

When I did this, I also did the old school trick of injecting urethane into the voids to make the whole bushing more solid, but this was just belt and suspenders. Not even sure this will do anything given there is no side load on this bushing once rotated.

As a hint for anyone needing to push this bushing out for any reason, you can borrow Powerbuilt 648617 from Advance Auto Parts. It has a great 2 9/64" socket that fits perfectly and makes pressing it out easy. Also has a 3" tube that works to go below the bushing as you press it out.

Fill it with urethane. Did that back in the days when rules didn't allow bushings changes in SCCA, but no mention of adding material to the existing.

Someone will likely come out of a HD replacement bushings soon. Meyle did years ago with BMW E46 lollipop bushings, they just called it their HD replacement. E9x BMW none M can press in E9x M3 solid rubber bushings to reduce the deflection. It takes aftermarket many years to catch up.

 

[gearchruncher]

Fill it with urethane. Did that back in the days when rules didn't allow bushings changes in SCCA, but no mention of adding material to the existing.

Already did:

When I did this, I also did the old school trick of injecting urethane into the voids to make the whole bushing more solid, but this was just belt and suspenders. Not even sure this will do anything given there is no side load on this bushing once rotated.

The SCCA rules don't mention rotating a bushing either

 

[Motion122]

Already did:

The SCCA rules don't mention rotating a bushing either

There you go!

 

[Moto Miwa]

Or better yet, fill it with hard plastic inserts like most JDM tuners have on older 90’s cars.
We used to call them rigid collars and it was alloy or plastic shaped to fit into the gaps in the bushing and also sandwich it between two plates to solidify the bushing but leaving the rubber parts to still function as a bushing.

 

[gearchruncher]

Or better yet, fill it with hard plastic inserts like most JDM tuners have on older 90’s cars.
We used to call them rigid collars and it was alloy or plastic shaped to fit into the gaps in the bushing and also sandwich it between two plates to solidify the bushing but leaving the rubber parts to still function as a bushing.

Mountain pass performance literally already sells this. I wanted to try something different. It's also why I filled it with urethane.

 

[Motion122]

Or better yet, fill it with hard plastic inserts like most JDM tuners have on older 90’s cars.
We used to call them rigid collars and it was alloy or plastic shaped to fit into the gaps in the bushing and also sandwich it between two plates to solidify the bushing but leaving the rubber parts to still function as a bushing.

Used Delrin or even a preformed urethane insert would work fine.

 

[Yperformance]

Has anybody had. Problem undoing the compliance arm to fit inserts. I am using a over 2 ft breaker bar and it's bending the nuts won't budge. Any thoughts or hints? Thanks

 

[gearchruncher]

Which bolts/nuts are you having an issue with?

Have you tried going the other way?

 

[dsgerbc]

Penetrating oil on the nut at the top? It's not welded in. Try to work the top nut instead of the bottom bolt?
Impact wrench should help as well, cause it's probably binding to that metal bushing core.

 

[Yperformance]

Hi, it's the inboard and outboard bolts that secure the rear front lower control arm that stops the suspension from moving forwards under acceleration an backwards under breaking. I know it's torqued really high about 139 ft lbs. Not left handed threads or anything like that. I do know the car was built after Tesla had a run if poorly torques front suspension and sub frame bolts that were coming loose but both sides are impossible to move . Even tried my air gun , it's not overly powerful but shifts most things , worried about breaking the ball joint on the outer end.