Rear upper damper bracket to chassis torque setting

[CubanGav]

I'm replacing the rear damper bracket - the one that bolts to the chassis on the top end - I can't find a torque figure for it.

The front damper bracket to chassis says 25NM. Do I assume the rear is the same?

Thanks in advance.

[robin]

no. rear is m10 i think? if so and assuming that bolt is 8.8 grade then assume 65nm. if m8 then 45nm unless you can find other figures.

[CubanGav]

The bolts are M10 so should be 65 then. I've only done them to 45 looks like I'll be poping them off again. Ah well.

Thanks though.

[robin]

Did you change it yet? I'm thinking that 45Nm might actually have been closer to correct than 65 ... 50Nm seems to be what various people recognize as the appropriate torque for an M10x1.50 bolt. The 65Nm that I listed (from memory) is the torque for the tensioner bolt which is also M10 but is a cap head bolt and no doubt a higher grade. Hope you haven't done them up to the higher torque setting yet ...

Cheers,
Robin

[CubanGav]

No it's fine - I had a lazy day yesterday so never got out to do anything. A lazy day means plenty time to look up things.
Going by what you said earlier and this table below 50nm looks like the right amount.

http://www.finaldrives.eu/PartsBoltTorque.htm

I'm not 100% on the bolt spec and wouldn’t be able to tell by looking. The saaaarff is on a bank holiday so can’t check with Elise Parts till tomorrow.

Thanks again though.

[roadboy]

They should definitely be 8.8s as the bolt into Ali.

They'll be fine as they are. Did you use Duralac on the threads though?

Dan

[robin]

Agreed, they should be 8.8 but over time people have messed about with higher spec bolts for various parts of the suspension (which is a dangerous game unless you know what you're doing).

8.8 bolts have 8.8 written on the flat of the bolt head and should be easily visible if you wipe the head of the bolt clean, even if the bolt is already installed.

Agree with Dan that if you want to be able to remove the bracket and bolts later Duralac is in order.

If the bolts have 10.9 or 12.9 written on them, chuck them away and get the proper bolts from Lotus or your favourite bolt supplier.

Cheers,
Robin

[CubanGav]

Roger.

I'll have a look shortly.

The brackets and all the bolts have copper(slip?) all over them. Went into a few places to get odd looks when I asked for Duralac. Was told this will do the same job.

Gav.

[robin]

Well, it won't do the "same" job, but it might work OK. Duralac prevents electrolytic corrosion caused by two dissimilar metals touching; various aluminium alloys+steel is a common problem on Elises and Duralac is always called for, both on thread and mating faces. I have some here, and you can order from EP, etc. It's yucky stuff and can be a PITA to dismantle as it makes the bolts "tight" all the way out, but it does stop them rusting in which is a good thing! Lots of places won't have heard of it because most cars use steel fasteners into steel chassis and mating faces are steel to steel.

Chances are that copperslip will also aid disassembly by keeping moisture out of the joint, but copperslip is probably not a good enough insulator to totally inhibit electrolytic corrosion (copper by itself is a good conductor, for example).

Personally if it was a choice of copperslip or nothing, I wouldn't be unhappy with using copperslip, but if you can get some duralac at some point you can always dismantle, clean off the copperslip and put on the duralac for total piece of mind. Only a proper material science sort of person could tell you whether there is a significant long term risk in using copperslip instead of duralac ... I doubt it though.

BTW, the copperslip will lubricate the thread and so increase the required tightening torque a tad - maybe make it 55Nm.

Cheers,
Robin

[tut]

"Duralac prevents electrolytic corrosion caused by two dissimilar metals touching; various aluminium alloys+steel is a common problem on Elises and Duralac is always called for, both on thread and mating faces."

Which is exactly what caused the front wishbone brackets on N1 to fall apart.

tut

[robin]

That and a total lack of maintenance

[CubanGav]

For the time it'll take to do it's not a big deal. Duralac duly ordered.

"Duralac prevents electrolytic corrosion caused by two dissimilar metals touching; various aluminium alloys+steel is a common problem on Elises and Duralac is always called for, both on thread and mating faces."

Which is exactly what caused the front wishbone brackets on N1 to fall apart.

tut

Interested to see what the fix was and if anything can be done to prevent it.

[robin]

The fix required cleaning away the debris and welding some new metal in to strengthen what was left; I don't know whether the original inserts were reused or new ones sourced/made. I also don't know what finishing is required to prevent the welded material from corroding again. It looked like a work of art though! Probably would be quite pricey in any case ...

In terms of preventing it, that's a tough one to sort out I believe, though you can obviously apply duralac to the bolt, tubular mounting on the chassis, castor washers and the bush.

I think the real issue is that there are steel inserts bonded into the alloy chassis and it's actually the interface between these inserts and the chassis that allows the corrosion to take place and there is nothing you can do to prevent that without some major surgery. Simplistically you could cut out the inserts and then design some new ones that could be fitted with Duralac and still support all the cornering and braking loads, etc., but I know that's more than I could do so would be relying on Elise Parts or someone like that to come up with a kit and then wait for the first 50 or so to be fitted and tested under load before ordering the second or more likely third generation kits

Cheers,
Robin

[CubanGav]

And there was me hoping for a 'unbolt X and smear product Y on it' type solution.