Are engine mount clamps a consumable now?

I race primarily at East Lansing, and so far I’ve gone through three sets of engine mount clamps this season. They and the bolt wear so rapidly that I have to use a mallet to drive a ball-end Allen key into the mount bolt to adjust the chain. I’m using the magnesium ones that go all the way around the tube.

Did my track just get much rougher, or do they burn up for everyone else?

For sure I’ve had to replace clamps and bolts on those that protruded from the chassis. Even titanium is going to wear over time.

Lowest part of your frame and it’s exposed to
kerbs esp on exit of left hand turns and apex of righties.

I would say track surface, tire height, tire pressure and sidewall strength all play a role.

I run them till they break, have not broken one yet.

Last set has like 3-4 seasons on them. I switched engine types

I go through at least 1 set a year per kart I’ve forgotten to tighten one set fully and it shredded itself to pieces and the Allen bolt basically welded itself to the clamp. But in general 1 pair per year per kart, (Provided I don’t forget to tighten the bolts fully).

Are you guys typically using aluminum clamps?

Have you tried the odenthal style that wedge between the frame rails and sit flush on the bottom? I was skeptical until I started using them. Now, I wouldn’t own anything else.

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I quit using allround type clamps as on hitting something they would twist and put a dent into the frame tube. Went to flush type or wedge type like Derek - great solution. Havent had any issues with clamps after that.

But continued to have issues with motor mount clamp bolts. The bolt head was flush - at same level with the aluminum clamp - tarmac kept hitting it. The allen key didnt go in as the burs were formed.

So as a solution machined 2-3 millimeters off the bolt head so the head sits a bit deeper. Now its impossible for bolt to touch tarmac. The clamp is always the lowest point

After this mod have never had any problems getting the key to fit or getting the bolt out

Yes. They slip, but I run an X30 and a 10t driver so it’s fairly rough on them.

What tooling do you use to remove 2-3 mm of a hard Allen bolt? Carbide insert cutter on a lathe?

Lathe and carbide tooling would do it easily, or if you don’t have access to a lathe, hold the bolt in the chuck of a cordless drill and spin the bolt head in the drill while holding it up to a bench grinder. That will keep it fairly consistent as you’re grinding it down.

Jim nailed it on the instructions :+1:

8.8 10.8 12.9 bolts are relatively soft materials to turn. Even hss stuff is up to it - Just lower rpms a lot compared to carbide bits, use a sharp tool. Adding constant coolant flow keeps the bolt from hardening/tip burning up if doing a lot of material removal - for example drilling a hole through the whole bolt