Track car build questions

[APR-M4!]

I would like to make some reliabilty and handling improvements to my 15 bmw m4 and a couple questions about two parts.

1) catless downpipes; do they improve cooling and/or underhood temps?

2) aftermarket rear tow links; currently, the stock tow adjustment is maxed out at 2.25 degrees negative camber. I would like to increase the negative camber to 2.5 degrees and maintain some tow-in in the rear. However, I am concerned about the reliabilty of the aftermarket tow arms. Is there a known most reliable option?

Thanks for any advice.

Anthony

[SYT_Shadow]

Catless downpipes indeed reduce temps. The car has secondary cats, so if someone were to remove the catted downpipes, it doesn't smell much. Or so I've been told.
I would definitely not track a car with aftermarket cats. Been there, done that, and it cost me an engine.

I'm sure bimmerworld has a nice rear tow link, that's what I'd buy

[jfritz27]

I've never heard of reliability issues with either SPL or Fall Line, I've had both (on different cars). The only issue with most of them is they use exposed Heim joints, so if you drive in rainy/salty conditions they're prone to corroding and can get squeaky/creaky. I try to remember to periodically douse them in Teflon-based lube to try to stay ahead of it.

[M3SQRD]

Removing cats will reduce under hood temperatures.

SPL, Fall Line, Ground Control, Carbahn and Dinan offer rear toe links (some offer all lower and upper rear arms, some offer covered/sealed versions). Most recommend getting rear eccentric lockouts along with the rear toe arms. They’re all quality parts with similar useable life.

[APR-M4!]

My concern for the rear toe arms is based on one comment on this forum about a wreck at the track. The comment said the toe arm snapped on an m2 at a track in CA. The snapped toe arm could have been a result of the wreck and not a cause.

I have spun off the track due to an aftermarket rear toe link mount breaking. The mounting was different than stock, requiring this peace. Snapped at the welds. The tire turned in and locked against the inner fender well. I was just along for the ride after that. Not much damage due to the track layout.

[SYT_Shadow]

I'd trust oem parts to not break way more than aftermarket ones!

[M3SQRD]

I agree with SYT_Shadow that stock arms are stronger than aftermarket arms. However, with frequent inspection (which should be done on stock arms, too!) and preventative maintenance (e.g., replace suspension arm bolts once per season/after X number of days or as required due to off track excursions, etc.), aftermarket suspension arms can be used safely. Suspension arms are one of the last things that I do (except for front thrust arm monoballs and rear toe arms) when modifying a street car to a dual-use car.

[sly1types]

Originally Posted by SYT_Shadow

Catless downpipes indeed reduce temps. The car has secondary cats, so if someone were to remove the catted downpipes, it doesn't smell much. Or so I've been told.
I would definitely not track a car with aftermarket cats. Been there, done that, and it cost me an engine.

I'm sure bimmerworld has a nice rear tow link, that's what I'd buy

How did aftermarket cats ruin an engine?

[SYT_Shadow]

Originally Posted by sly1types

How did aftermarket cats ruin an engine?

They melted. Then were ingested into the engine during overrun and, collapsing, they blocked half of the cylinders exhaust. Took the engine out after 5k miles of mechanics chasing their tails

[Track/S]

Originally Posted by APR-M4!

My concern for the rear toe arms is based on one comment on this forum about a wreck at the track. The comment said the toe arm snapped on an m2 at a track in CA. The snapped toe arm could have been a result of the wreck and not a cause.

I have spun off the track due to an aftermarket rear toe link mount breaking. The mounting was different than stock, requiring this peace. Snapped at the welds. The tire turned in and locked against the inner fender well. I was just along for the ride after that. Not much damage due to the track layout.

Only GT4 arms, the rest is garbage.
I have already said it a thousand times, and I will repeat it as many times as necessary.

Mine customized slightly modified ready to install:

[M3SQRD]

Originally Posted by Track/S

Only GT4 arms, the rest is garbage.
I have already said it a thousand times, and I will repeat it as many times as necessary.

Mine customized slightly modified ready to install:

Did you modify the length of the arms?

[GuyLedouche]

Originally Posted by Track/S

Only GT4 arms, the rest is garbage.
I have already said it a thousand times, and I will repeat it as many times as necessary.

Mine customized slightly modified ready to install:


[img]https://i.ibb.co/sHwWvLz/20240216-215509.jpg[/img]

I think I asked you before but why are SPL arms garbage?

[Track/S]

Originally Posted by M3SQRD

Did you modify the length of the arms?

Length, exterior/interior design, and anodizing color.

[GreenGoblin]

Originally Posted by SYT_Shadow

They melted. Then were ingested into the engine during overrun and, collapsing, they blocked half of the cylinders exhaust. Took the engine out after 5k miles of mechanics chasing their tails

Do you mean aftermarket high flow cats? What brand were you running?

I have Turner High flow dps and this makes me slightly nervous

[SYT_Shadow]

Originally Posted by GreenGoblin

Do you mean aftermarket high flow cats? What brand were you running?

I have Turner High flow dps and this makes me slightly nervous

Yup, aftermarket high flows. I'll never do aftermarket cats on a tracked car (again). Either oem or catless.

[GreenGoblin]

Originally Posted by SYT_Shadow

Yup, aftermarket high flows. I'll never do aftermarket cats on a tracked car. Either oem or catless.

I might switch to catless then. I see Turner doesn't even sell their branded dps anymore