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**01SG** · 08-02-2023, 12:09 PM

Can't speak for the track parts, but for the cooling system I went for the genuine BMW hoses and water pump. These cooling systems don't have the e36/e39 weaknesses. I don't think there's a Stewart pump available either.

I believe the driveshaft flex disc is originally made by Febi-Bilstein, and that one can be had at a significant discount. I can't remember if it actually did, but the comments on FCP claim it's one of those parts with the BMW logo ground off.

**heinzboehmer** · 08-02-2023, 12:29 PM

Yeah stick to the genuine BMW water pump. Aftermarket meral impeller one failed after a couple years on my car

The rein CSB I recently installed said BMW on it, so I'd go for that one. Can't remember who makes the OE guibo, but pretty sure it's whatever FCP says it is.

**bmwfnatic** · 08-02-2023, 01:43 PM

Some comments from me:

Originally posted by Nate047 View Post

RACP: Car has existing plates from previous owner, I’m going to leave well enough alone and I have a Yurkan Cages rear 6-point brace to address top side reinforcement

While the YURKan brace is probably absolutely fine to address the topside reinforcement, I would still inspect the underside and inside for damage.
My car was plated prior to my ownership, but had severe damage in pretty much every area where failure is known, popped spot welds all over the place, from memory around 15 of them.

I would suggest reading up on this article made by CMP

Part 2 – It’s Not Just The Subframe Mounts?!

https://cmpautoengineering.com/pages/part-2-it-s-not-just-the-subframe-mounts

That is correct. As we mentioned in the previous article, fatigue related failure is not limited to just the rear subframe mounts. This issue is so much more complex that it expands not just beyond the subframe mounts but, into sections of the unibody structure beyond the Rear Axle Carrier Panel (RACP)! In our previous

and inspecting all area's mentioned, and performing a repair if necessary.

Originally posted by Nate047 View Post

Rear axle: CMP monoball RTAB
SPL race rear adjustable LCA
OEM outer control arm bearings, upper
OEM outer control arm bearings, lower

Anything missing on the front or rear axle? What about the rear upper control arms themselves, are these typically fine to replace bearings and reuse, or do we consider them a wear item?

Sounds good, but keep in mind that the SPL camber arms use an open spherical joint.
Even though these arms sit in a cavity in the subframe, which would most definitely help against foreign debris entering the joint, they aren't exactly funny to replace, so I would go with either a sealed ball joint, or for example the ones from CMP which come with an optional boot to project the joint.

The rear upper control arm can suffer from cracking (mostly due to running coil overs with high spring rates), and can also suffer from heavy aluminium corrosion around where the spring pad is supposed to sit.
Inspect and replace only if necessary.

Originally posted by Nate047 View Post

Subframe and Diff: CMP solid subframe bushings
CMP solid diff bushings
Going to leave the actual diff alone for now. Also leaving rear axles and wheel bearings alone for now.
The car currently has poly diff bushings in it, has high amounts of NVH but I am used to it and don’t mind it (call me crazy if you want)
I was planning on dropping the entire rear end as a whole and doing all the cleanup and basic reassembly on my workbench. OR, I might honestly bring the whole rear end to a shop and have them do the teardown and reassembly off the car for me. I do not have a tool or experience doing all these bushings/bearings. What do I need to rent or buy tool wise if I decide to DIY? And what so I need to know as far as pre-loading things and reinstalling everything? Can we talk about the correct method and amount of preload to use to avoid issues with bushings?

If you have poly diff bushings already, as you stated, I would honestly just save your money and not purchase the CMP solid diff bushings, they won't improve your lap times, they will just cause more noise.

With the setup you mentioned, preload isn't required on anything except for the inner bushing for the rear upper control arm.
It isn't really preload, but sort of the opposite, avoiding having any preload at normal ride height.
You can achieve this by torquing the bolt for the rear upper control arm inner bushing at ride height, either by measuring or by putting the spring in and jacking the control arm up.

The need for this could also be entirely avoided if you changed that rubber bushing for poly or a spherical joint, I normally don't recommend this but as this is a track car that seems to be a fine option.

Originally posted by Nate047 View Post

Drive shaft: may replace center bearing and guibo. How do we feel about Rein and Meyle HD vs original BMW?

Genuine BMW, Meyle sucks.

Originally posted by Nate047 View Post

Also I plan on doing a cooling system refresh, as I’m unsure of the age of everything. I want to go OEM/OE/whatever is the preference de jour as I know the suppliers change. Advice on what can be aftermarket to save on cost vs. what needs to be original BMW would be appreciated.

Genuine BMW for all hoses and water pump.
Thermostat is made by Borg Warner / Wahler, can buy that after market if it saves you money, exactly the same thing.
Radiator made by Modine (NRF now), same thing as from the dealer.

**tlow98** · 08-02-2023, 02:38 PM

Agree with all of the above except the water hoses. I used rein with the Viton O-rings.

The hoses seemed identical to OE, but did not say BMW anywhere in them.

**Tbonem3** · 08-02-2023, 02:49 PM

Regarding the giubo/flexdisk - FYI - buy the "Febi/bilstein" part, and in the red box will be a Genuine BMW (SKG) part. Rein (which, admitted, is not the highest quality) CSB seems to be fine for many of us who have replaced that part.

**tlow98** · 08-02-2023, 03:36 PM

Originally posted by Tbonem3 View Post

Regarding the giubo/flexdisk - FYI - buy the "Febi/bilstein" part, and in the red box will be a Genuine BMW (SKG) part. Rein (which, admitted, is not the highest quality) CSB seems to be fine for many of us who have replaced that part.

FYI, Rein CSB I bought had the BMW logo on it. I’ve heard sometimes it says BMW and sometimes it does not.

ordering from AutohausAZ had the BMW logo. Just purchased last week

**WestBankM4** · 08-02-2023, 05:36 PM

Originally posted by tlow98 View Post

Agree with all of the above except the water hoses. I used rein with the Viton O-rings.

The hoses seemed identical to OE, but did not say BMW anywhere in them.

+1 on the Viton O-rings ( I bought mine on eBay and they came with the snyth lube, https://www.ebay.com/itm/295468391970 ), regardless if you go with OEM or aftermarket water hoses.

**Estoril** · 08-02-2023, 06:28 PM

One you install a roll bar - the car shouldn't be driven on the street. More so for a bolt-in.

**heinzboehmer** · 08-02-2023, 10:43 PM

Originally posted by tlow98 View Post

Agree with all of the above except the water hoses. I used rein with the Viton O-rings.

The hoses seemed identical to OE, but did not say BMW anywhere in them.

I did the same thing with the hoses. Threeish years + good amount of track time and they're still fine.

**OldRanger** · 08-03-2023, 03:53 AM

On the rear subframe: it’s going to be the little things that give you grief:

1) Wiring: the ABS wheel speed sensor and brake pad wear sensor. The plastic connector on the car side will crumble in your hands. Plan on replacing all three connectors with BMW ABS Wheel Speed Sensor Connector (2 Pin) - Genuine BMW 61131392246, they are $8.09 each. You will need small picks to remove the terminals. On the passenger side, paint or mark one so you can remember which is which.
2) Wiring: the cable clips that hold those wires to the rear trailing arm will break or have already. Get 10 or so because zip ties won’t be on par with everything else you’re doing. BMW Cable Clip - Genuine BMW 34521164653. They are $1.09 each.

Good Luck!

PS: new OEM bushings on the diff are my vote. Solid on the subframe is fine.

**Nate047** · 08-03-2023, 06:50 AM

Awesome, thank you guys! I'm going to piece together my own cooling system and cross shop. I think I have the info I need re the center bearing and guibo as well.

Originally posted by bmwfnatic View Post

Some comments from me: While the YURKan brace is probably absolutely fine to address the topside reinforcement, I would still inspect the underside and inside for damage.
My car was plated prior to my ownership, but had severe damage in pretty much every area where failure is known, popped spot welds all over the place, from memory around 15 of them.

I would suggest reading up on this article made by CMP
https://cmpautoengineering.com/pages...ubframe-mounts
and inspecting all area's mentioned, and performing a repair if necessary.

Thank you, the plan is to basically stop and reevaluate if I find anything wrong under there. I have the trunk gutted and I do not see any popped welds on the top area, I'm going to do as thorough an inspection as I can short of removing the sealant and plates that are already on the car.

Sounds good, but keep in mind that the SPL camber arms use an open spherical joint.
Even though these arms sit in a cavity in the subframe, which would most definitely help against foreign debris entering the joint, they aren't exactly funny to replace, so I would go with either a sealed ball joint, or for example the ones from CMP which come with an optional boot to project the joint.

good point on the bearings, I didn't think about that. I will probably still run these SPL arms though, everything I've listed I have already bought. I might reconsider the diff mounts.

With the setup you mentioned, preload isn't required on anything except for the inner bushing for the rear upper control arm.
It isn't really preload, but sort of the opposite, avoiding having any preload at normal ride height.
You can achieve this by torquing the bolt for the rear upper control arm inner bushing at ride height, either by measuring or by putting the spring in and jacking the control arm up.

The need for this could also be entirely avoided if you changed that rubber bushing for poly or a spherical joint, I normally don't recommend this but as this is a track car that seems to be a fine option.

For the rear upper arm inner bushing, I was under the impression that it isn't advisable to do a spherical joint because tha tcan limit movement which can in turn negatively impact how the rear sway bar moves since it's attached to the arm. Is that incorrect?

**Nate047** · 08-03-2023, 07:01 AM

Originally posted by Estoril View Post

One you install a roll bar - the car shouldn't be driven on the street. More so for a bolt-in.

I knew this would come up, maybe you can elaborate on your stance for posterity's sake.

I realize the flaw in the argument of "I know lots of people who have roll bars and have never had a problem in an accident" so I won't go there. Nor would I bring up factory crash tested cars with factory roll bars. I would just say my best data point is the legality of cars like ours with roll bars like these in Europe, namely Germany, where TÜV is satisfied. TÜV is not without its flaws, like any government agency, but they don't typically allow things that are flagrantly dangerous to the occupants.

**Nate047** · 08-03-2023, 07:11 AM

Originally posted by OldRanger View Post

On the rear subframe: it’s going to be the little things that give you grief:

1) Wiring: the ABS wheel speed sensor and brake pad wear sensor. The plastic connector on the car side will crumble in your hands. Plan on replacing all three connectors with BMW ABS Wheel Speed Sensor Connector (2 Pin) - Genuine BMW 61131392246, they are $8.09 each. You will need small picks to remove the terminals. On the passenger side, paint or mark one so you can remember which is which.
2) Wiring: the cable clips that hold those wires to the rear trailing arm will break or have already. Get 10 or so because zip ties won’t be on par with everything else you’re doing. BMW Cable Clip - Genuine BMW 34521164653. They are $1.09 each.

Good Luck!

PS: new OEM bushings on the diff are my vote. Solid on the subframe is fine.

Good call on the clips!

**simonnim** · 08-03-2023, 08:52 AM

Originally posted by bmwfnatic View Post

Some comments from me:

I would suggest reading up on this article made by CMP

Part 2 – It’s Not Just The Subframe Mounts?!

https://cmpautoengineering.com/pages/part-2-it-s-not-just-the-subframe-mounts

That is correct. As we mentioned in the previous article, fatigue related failure is not limited to just the rear subframe mounts. This issue is so much more complex that it expands not just beyond the subframe mounts but, into sections of the unibody structure beyond the Rear Axle Carrier Panel (RACP)! In our previous

and inspecting all area's mentioned, and performing a repair if necessary.

I know that the RACP is an issue, especially for tracked cars. But reading through these just remind me of why this chasis scares me. I'm just going to keep enjoying the car though haha.

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