Installing Ohlins RT. Rear shock mounting minor issues.

[bavarian3]

Noticed a couple fitment issues installing Ohlins shocks.

1. The lower mounting bolt doesn't have enough length to completely go through the knuckle. Anyone else notice this with Ohlins? Looks like new longer bolts are required.

Other option is to not use a bolt washer, but then the bolt would dig into the shock's spacer/sleeve. The bolt is about 2mm short of the making it out of the threaded hole on the other end.






2. Not ohlins related issue, but rear shock mounts with an x-brace. The studs on the RSM(I used Rogue Eng) don't extend far enough for the nuts.

Because the X-brace acts as a reinforcement plate I can ditch the the Rogue stud plate, and use bolts and nuts. This would require a helper to hold one end, otherwise does anyone see any issue with this?

[fattycharged]

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[Deen HK]

On my last m3 the bolt didn’t go all the way through either for my ohlins

[maupineda]

Ideally you want 3 threads passed the nut. You can get a bolt from McMaster to the length you need.

[Maxhouse97]

I have this setup and used all the standard HW, has been tracked, no issues

[bavarian3]

I ended up ordering new bolts. For those curious I found this site called belmetric.com. Fantastic selection, interface, and shipping.

[T-Rex]

I ended up ordering new bolts. For those curious I found this site called belmetric.com. Fantastic selection, interface, and shipping.

Could you please share details on what you ordered? I am about to do an Ohlins upgrade on my car and would appreciate it!

[oceansize]

I've used Belmetric, legit, bought some Norma clamps for my ESS intake from them as well as other odds and ends.

[bavarian3]

Could you please share details on what you ordered? I am about to do an Ohlins upgrade on my car and would appreciate it!

So for the lower mounting bolt you need a 10.9 grade m12x1.5 bolt. I used 65mm length. Stock bolt is 60mm. Yellow zinc is nice too. Get the corresponding 10.9 flat washer.

https://belmetric.com/hex-bolts-10-9-m12x1-5-fine-din-960-961/?sku=BH12X1.5X65YLW

If there's other specific fasteners you need I can help advise on sizing.

BTW I got my Ohlins kit second hand, so it may already come with what you need but I'm not sure.

[T-Rex]

So for the lower mounting bolt you need a 10.9 grade m12x1.5 bolt. I used 65mm length. Stock bolt is 60mm. Yellow zinc is nice too. Get the corresponding 10.9 flat washer.

https://belmetric.com/hex-bolts-10-9-m12x1-5-fine-din-960-961/?sku=BH12X1.5X65YLW

If there's other specific fasteners you need I can help advise on sizing.

BTW I got my Ohlins kit second hand, so it may already come with what you need but I'm not sure.

Thank you, this is very helpful!

[bavarian3]

Thank you, this is very helpful!

You're welcome.

FWIW here are my results with the new fasteners. Much better.

[Tbonem3]

The thickness of the mounting point is much greater than the bolt's diameter. You don't NEED it sticking through, flush is fine (there's no collar to capture extra threads like in a "lock nut" type of situation).

Looks like OP has 2 washers or an unneccesarily thick washer. I would have removed one washer (or use some other hardened washer that's not so thick, and re-use stock hardware)

[Tbonem3]

Ideally you want 3 threads passed the nut. You can get a bolt from McMaster to the length you need.

This isn't a lock nut (collar, castle, nyloc, pinch). Rule of thumb is engagement depth be equal to shaft diameter.

[bavarian3]

The thickness of the mounting point is much greater than the bolt's diameter. You don't NEED it sticking through, flush is fine (there's no collar to capture extra threads like in a "lock nut" type of situation).

Looks like OP has 2 washers or an unneccesarily thick washer. I would have removed one washer (or use some other hardened washer that's not so thick, and re-use stock hardware)

Thanks for the input. There's something that irked me about having a bolt responsible for that much tensile strength not fully threading through the hole.

To clarify, in the first pic you're seeing the stock bolt with washer, then the spacers for the shock itself.

[maupineda]

This isn't a lock nut (collar, castle, nyloc, pinch). Rule of thumb is engagement depth be equal to shaft diameter.

Agreed, but the knuckle is threaded, you still want the bolt to pass through to ensure you spread load on all threads on the knuckle.