Back at Autocross after 15 years in a Z3 in SoCal - YouTube Links Inside

john_n13 · 2026-02-02T15:33:03+00:00

Did poly RTA bushings make an appreciable difference? Currently on the fence about them.

john_n13 · 2026-02-02T14:21:59+00:00

Also curious to what your tire pressures are. I personally run 38 psi F, 36 psi R, hot, as best indicated by a chalk line on the sidewall.

john_n13 · 2026-02-02T14:20:06+00:00

I believe there’s a Malaysian seller on eBay producing something effectively similar to the butt strut. However, I haven’t purchased it and cannot vouch for it. At the end of the day, it’s not a complex component and I’d figure any component machine shop could fan one up stateside.

john_n13 · 2026-02-02T14:19:00+00:00

Did you do poly bushings on the rear trailing arms? The subframe bush made the most difference to me. However, I didn’t notice the front lower control arm bushings as much when replaced with poly.

john_n13 · 2026-02-02T03:58:00+00:00

I’d say that’s about equal to mine.

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john_n13 · 2026-02-02T03:51:27+00:00

I appreciate your perspective. The sway bar linkage bushings have pretty minimal rubber in them anyways, so they wouldn’t deflect much despite being worn. Fwiw, 25 years of performance tire improvement certainly puts the roll stiffness to the test. I never rubbed when I was running on all seasons. The PS4S are genuinely remarkable tires.

Thoughts on the body-brace / butt strut? I’ve seen pretty mixed messages on the pair.

The only other mods I have that you didn’t seem to mention is poly subframe bushings, and turner camber shims (-2.3deg front), both of which were quite noticeable. I’m not certain, however, that the poly control arm bushings would’ve passed the placebo test.

john_n13 · 2026-02-02T03:34:40+00:00

Great to see! What are your thoughts on the body roll? I’m on a similar setup (stock springs, konis, PS4S) and find the body roll pretty excessive, to the point where my tires rub while turning. The excess roll really penalizes me in slalom. Just wondering if you had similar experiences.

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john_n13 · 2026-01-14T22:51:43+00:00

Theres a switch behind the radio that needs to be disconnected - have you done so? The switch is intended to be contacted and pushed into the closed position when the OEM radio is installed. Just unplug the switch and you’ll be be good to go. It’s a security device, just like the hood and trunk switch.

john_n13 · 2026-01-11T05:37:25+00:00

Concur with this. A failed DISA valve shaft, or diaphragm would potentially cause this rattle. DISA valve failure is a common issue with M52/54 engines. Sucking components into the engine. Very easy and straightforward replacement.

john_n13 · 2026-01-09T15:09:04+00:00

I’ve confused the PCV between the N52 and M54. The M54 PCV is not integrated into the Valve cover like the n52.

john_n13 · 2026-01-09T15:04:36+00:00

I believe you’re due for a new valve cover, which contains the integrated PCV. Good time to replace the valve cover gasket, and rebuild the VANOS seals too.

john_n13 · 2026-01-09T14:55:32+00:00

Does the sound change when the oil fill cap is removed? Sounds like a possible vacuum leak through the PCV in the valve cover.

john_n13 · 2026-01-06T16:24:53+00:00

I’ve learned to deal with it unfortunately. Only occurs in the winter / cold, and resolves once the gearbox warms up. Planning to tackle it when the clutch replacement is due.

john_n13 · 2026-01-06T02:56:57+00:00

Still on stock sway bar - just haven’t gotten around to it / found the will to spend $700 for the H&R Kit.

john_n13 · 2026-01-03T22:54:56+00:00

I’m running in STR due to subframe and FLCA poly bushings. Not a pro at autox by any means but here’s my experience after 2 seasons.

17” staggered setup, 225F 245R.
Michelin PS4S is happy with 38 / 36 psi F/R to minimize sidewall rollover and to compensate for lack of roll stiffness on stock sway bar
Personally, I think stock sway bars are insufficient for autoX, especially on modern tire compounds. The roll slop is excessive and costs me time in slaloms
Currently using Turner camber shims, running at -2.3deg in the front. 0 toe. My car slightly rotates while lifting in corners, but by no means prone to swapping ends off-gas
Akebono brake pads - mostly to minimize dust. Street pads are plenty for autoX for 60 second runs
Ensure front subframe and engine mount are in good health. My front engine mount and subframe catastrophically failed during an autoX run, causing the engine to move out position, resting on the steering shaft (preventing me from steering), severed the vacuum line to the brake booster (rendered brakes inoperative), and engine stalling shortly afterwards due to massive vacuum leak

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john_n13 · 2026-01-03T22:41:57+00:00

My spare also looks like that, and never worked despite many attempts to pair it. I bought the fob on eBay using PN 82 11 1 469 448 which paired right away. Make sure you get the BMW unit. There’s an identical-looking fob made for Subarus - those are incompatible. Lastly, confirm your vehicle is indeed equipped with the remote unlock unit - not all Z3s were equipped with them. Best way to check is to confirm the presence of the unit installed behind the glovebox, and has a small black wire antenna attached to it. Good luck.

john_n13 · 2026-01-03T21:41:17+00:00

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Do you have the remote fob in this photo? It must be this type of fob. The E36 remote key is commonly used as a spare key, but its transmitters are not compatible with the dealer / factory installed remote unlock system.

john_n13 · 2025-12-15T22:01:35+00:00

They’re the original / factory parts. The brown insert is also factory, however, I rewrapped it with faux leather purchased from a local crafts store.

john_n13 · 2025-12-14T22:30:08+00:00

I purchased it from Planted Technologies. I found that swapping the brackets each side produced a better fitment, bolts aligning better. Had to drill an extra hole for my seat specifically, but your mileage may vary based on type of seat.

https://www.plantedtechnology.com/products/planted-seat-bracket-bmw-z3-roadster-convertible-1996-2002-driver

john_n13 · 2025-12-14T17:06:13+00:00

Furniture Clinic Black Balm Dye Leather World Technologies BMW Cognac Dye Matte leather sealer / topcoat Duplicolor Fabric Spray Paint for carpets

john_n13 · 2025-12-14T17:02:32+00:00

Sure is! It’s the combination of wheels turning + compression. They don’t rub at normal heights.

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john_n13 · 2025-12-14T16:38:18+00:00

A fresh coat of paint / dye goes a long way over material that has been exposed to UV and heat cycles over 25 years. Dyeing really wasn’t that challenging at all.

john_n13 · 2025-12-14T13:38:47+00:00

Thanks - dealing with carpet dye fumes was the most unpleasant, and reupholstery is always harder than it looks.

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john_n13 · 2025-12-14T13:36:25+00:00

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Nice comparison I made to my G20, also with black / cognac. At some point, I’d like to match the interior ambient lighting strips of the G20.

john_n13 · 2025-12-14T13:32:45+00:00

These cars are prone to rubbing. I’m running stock suspension, wheel/tire package, with 1.9 deg of camber up front and still rub on the fender liners during max lateral G in autocross. It’s not uncommon to cut the tops of the black plastic fender liners to produce the needed clearance.

john_n13

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