E30 Zone

I've been tinkering at work and have knocked up some offset rear top mounts
the original Leda units are modified BMW jobbies with a solid centre welded into the original steel housing. the spherical (rose) bearing is central in the mount and doesn't allow enough clearance between the spring and inner wing. a lot of folks attack the mounting on the chassis to move them outwards but i don't like the idea of slotted holes, especially on a lardy touring. Also, being a touring it's a real pain having to remove half of the interior every time i need to access the mounts, so i produced these little babies. the shock can be removed by removing the bearing retaining screws from under the arch, saving loads of time and making spring rate swaps a 15 minute job

made from stainless steel 431 (all we really use at work) with a 5mm offset within the mount. the linisher i used to deburr has left a few lights marks that have caught on the flash but they look spot under normal light

Top work Gareth. If you are thinking of machining a few up for resale I'd imagine a ready market for them.

good thinking mate! If I would run them I would add another retaining screw (are they M6 or M8?).
But this largely depends on how stiff your shocks are. Don't underestimate the rebound forces!

Cheers of the positive comments

Brian, it took me over a year to finish these off so i would't want to take too many orders!
my bit took very little time but i had to ask one of the lads to produce the profile on the outside for me and we've been busy, and he's unreliable, and i kept forgetting!
They would be a useful thing for someone to make though

Uwe,
there's no space for a 3rd retaining screw without breaking out the side of the 'top hat' section. and yes they are M6 but will be fitted with grade 12.9 fixings.

my rear shocks are coilovers so don't actually 'pull' on the shell in the same way - the spring rebound/damping forces act between the ends of the shock, not between the shock and the chassis.

when you think about it, a coilover setup reduces the load cycling on the rear mounting points considerably over a conventional setup. obviously compression damping loads and spring reactions will be higher but the rebound forces will be lower.

the original leda unit just uses a single circlip to retain the bearing. the specs for this show a pullout load rating of 3.6kN (about 350kg). each M6 screw will safely hold several times that.

gareth wrote:
the original leda unit just uses a single circlip to retain the bearing. the specs for this show a pullout load rating of 3.6kN (about 350kg). each M6 screw will safely hold several times that.

I know, I know. I am just a little scared and like to over engineer things. Braces and belt syndrome

I like the offset position!

i like to over-engineer too however space wouldn't allow three M6's or two M8's

the stainless steel is 431 and in the right heat treatment state has about the same tensile strength as a grade 12.9 (such as ARP) bolt. not lightweight though but on a 1400kg touring, who cares!

Hi Gareth, great work.

Sorry, but I must be missing something. Can you please explain to me how it is that you can disconnect the damper by removing the bearing retaining screws. I have sperical bearings on my front turrets and the nut on the top of the damper shaft would prevent the shaft from being withdrawn through the hole in the mount even if the bearing were withdrawn. But then I guess that could just be because of the shape and size of my nuts . If your nuts are small enough to pass through the hole previously occupied by the bearing then it's an entirely different story. Sorry, I guess I just answered my own question . This must be how your idea works?

Great idea BTW.

Regards
Geoff

i do indeed have significantly smaller nuts. at least i think i do! The measurements were done from memory of the spanner size when i drew them up... over a year ago now though so i can;t rmemember what it is!

i'll have to measure them up (ballache to get to them) and if space is tight, i could 'clip' the corners on a lathe if needed

GeoffBob wrote:Hi Gareth, great work.

But then I guess that could just be because of the shape and size of my nuts . If your nuts are small enough ......
Geoff

Oii! too much information here, too much!

Ooooh spangly!

Are they offset to help the coilovers clear the wheels or something like that?

cheers!
They're, offset to help the coilovers clear the inner wings as BMW never left space for springs there. how inconsiderate!

i have them fitted
and i do indeed have adequate nut clearance

gareth wrote:i have them fitted
and i do indeed have adequate nut clearance

Well done,

If your nuts were a bit tight I was going to suggest smearing on a little lubricant .

plenty of lube used, one hard shove and it was up to the nuts in the hole. two quick screws later and it was all tightly fitted up the rear end...

gareth wrote:plenty of lube used, one hard shove and it was up to the nuts in the hole. two quick screws later and it was all tightly fitted up the rear end...

Dare I even say it,



or possibly better left without

err, best without i reckon!

so gaz coilovers contact the inner wing when fitted normally?

I'm not sure on the gaz units specifically but if they don't have eccentric top mounts and do have 2.25" springs, they'll rub.

gareth wrote:I'm not sure on the gaz units specifically but if they don't have eccentric top mounts and do have 2.25" springs, they'll rub.

ok thanks

really nice mounts btw.

if u did make a few sets id have one

garath can i have some please

Just clocked this thread, Impressed to say the least that the "Ginger" does have a Brain.
Good work there Gareth

Rav, i'm not sure if that's a compliment or not!

I'm not really able to produce more as it literally took ver a year to get space on the CNC machine and a bloke to do the profile milling for me. plus they'll only fit the wierdo imperial size rose joint used by Leda, not a BMW shock.

RPM do a similar top mount but not eccentric... i reckon they should do an eccentric version really...

Ground control sell something very similar to these - http://www.ground-control-store.com/pro ... I=656/CA=8

well spotted that man!

Just thought i'd follow this up a year on...

They've not broken and proved themselves very useful on the zone roam 2011 when i lost all of the fluid from a leaking shock seal so i needed to pull one off for a get-me-home top-up.

It took about 20 minutes to get the shock off, refilled and refitted before a day's hooning I didn't even have to unpack all our gear from the boot

gareth wrote:Just thought i'd follow this up a year on...

..... so i needed to pull one off for a get-me-home top-up......

That's just wrong.

Whats all this about the rear topmounts not being able to take a true coilover setup? Or is it not a true coilover setup?

randomspeedfreak wrote:so gaz coilovers contact the inner wing when fitted normally?

Bit late now, but for future referance Gaz Golds come with offset spacers for the bottom mount to allow clearance.

Jozi wrote:Whats all this about the rear topmounts not being able to take a true coilover setup? Or is it not a true coilover setup?

With a coilover setup the rear shock tower takes the hit when the spring compresses and when it goes into rebound.
On tourings there is additional bracing on the shock tower, but the area around the 2 bolt holes suffer from stress fractures over time,hence the addition of Z3 reinforcement plates.
You could still use E46 cab rear topmounts but you'd be replacing them more frequently that you normally would with a standard setup

R/J topmounts are the way to go IMO

The fully thing is, on rebound with a coilover setup, the load on the top mount / shell is a load less than a conventional spring setup as the wishbone is not pulling the shock down (loaded by the spring). It's still being pushed down by the spring. This means it's cot a varying compressive load on the top mount, not a cyclic load

A hard concept to grasp without sketching it all out and working out the forces involved.

What do you mean by R/J? Rose jointed?

So I did well getting a touring Would this setup be recommended over adjustable spring perches in the conventional location on the trailing arms?

Sorry for straying a little of topic. I was always under the impression coilovers didnt fit because of space in the housing and lack of strength in the towers and so a little interested as coilovers are my next mod on te list.

Gareth: Your right, I don't quite get it Get sketching so I can learn :p

Jozi wrote:What do you mean by R/J? Rose jointed?

Yes

So I did well getting a touring

Yes

Sorry for straying a little of topic. I was always under the impression coilovers didnt fit because of space in the housing and lack of strength in the towers and so a little interested as coilovers are my next mod on the list.

I have Gaz golds on the rear of my touring with R/J topmounts,Z3 reinforcing plates and offset spacers supplied direct from Gaz.
Had them fitted for 2yrs+.

All brands of coilovers will foul the fuel breather system on the OSR

As BadDave says the GAZ ones come with an offset spacer on the bottom, and we can also supply offset rear topmounts for the top to clear the breather pipes: http://www.raceperformancemodified.com/ ... -Topmounts

Thanks to Gareth giving us a nudge and some help

No worries