How to put telescopics on with lowering blocks

[learyd]

I've got the lowering blocks and the telescopic damper kit from bham centre. The only problem is with the lowering blocks on i now have to jack the axle up a tad from full droop to fit the dampers on which I know is not wise. Any suggestions to rectify this problem? I suppose I could skim the blocks but then I would lose my lowered height, how much damage would it do to the dampers in this state?

[learyd]

One more thing would fitting an anit tramp kit help reduce violent movements and protect dampers?

[dunketh]

Depends if the dampers are bottoming out. As long as theres enough travel in them before the axle hits the (presumably cut-down) bump stop I cant see it doing any damage.
Remember, running them at a tight angle wont give you their full performance but they'll still work.
Anti-tramp - I'd say go for it. No idea if it'll help your particular situation but it should tighten up the rear end a treat, mine was always 'tramping' but then that was more likely due to worn, almost flat, springs.

[bmcecosse]

Radius bars are a good enough idea if you have a LOT of power - but fitting 7 leaf Trav springs eliminates tramp and stiffens up the rear end nicely. Tele dampers are only any use IF they are mounted vertically - are yours?? And if the suspension has been lowered (why??) then you MUST make sure there is sufficient overtravel in the dampers to allow full suspension travel - including heavy deformation of the bump stops - which MUST stay in place........ Otherwise the dampers will be destroyed on the first speed bump - and the top mounts will smash their way through the floor of the car.... the ride and handling will of course also be terrible........ It doesn't sound like you have thought the whole thing out very carefully before buying.......

[Stig]

I wouldn't worry about them not being vertical, basic maths tells me that a 30 deg angle gives 87% of the full damping etc.

[dunketh]

Tele dampers are only any use IF they are mounted vertically

I've seen them mounted at a funny angle on minors before using the original lever arm pickup point and a set of van spring plates! Proper funny angles going on there but anecdotal evidence from the owners suggest they work just fine. Hasten to add I've not tried myself.

[bmcecosse]

Basic maths tells me that a 30 degree angle off vertical means only 66 % of the damping......

[Stig]

Basic maths tells me that a 30 degree angle off vertical means only 66 % of the damping......

Really? I get cos(30)=0.866

[Alec]

Hello Stig,

what you are saying is that the axle on full droop has the damper fully extended, i.e the damper is supporting the axle?
I don't think that will be any problem in practice, except when jacking the car up or going over a hump too fast will the damper be fully extended. The Triumph 2000's rear supension has exactly the same situation.

Alec

[bmcecosse]

I don't see 'cos' has anything to do with it. When vertical you get full damping. When horizontal you get zero. I don't see any reason to not simply apportion the damping rate to the mounting degree, So 'simple' maths says 45 degrees will give half damping , and 30 degrees will give 66.6667% damping - so yes, 67% really.....

[chrisryder]

For the benefit of the jury:

[frame][/frame]

Lowering blocks won't change the overall positioning, as the blocks just mean the axle is higher up, but the spring, where it mounts to, is in the same place.

the best i can think off is that the rear shackle plates are too long. if it had long plates, raising the ride height, it could explain the desire to lower it.

standard shackle plates are roughly 60mm between hole centres. any increase in hole centre spacing will equate to half that distance at the axle. ie: a 70mm shackle (10mm increase) will change the axle height by 5mm.

[Alex'n'Ane]

well for a start the angle changes as the damper compresses, from my rough calcs based on damper length of around 35cm and a droop between 30cm and 10cm the angle almost doubles! And I get the efficiency to be 73.5% as I said these lengths were just a rough guess. And my maths may be wrong?

[bmcecosse]

I think the original problem was one of 'length' - I muddied the water by commenting on angle..... Yes the angle will change slightly - but not significantly - as the spring compresses. I'm not sure if the problem is that the damper is too long - or not long enough?

[chrisryder]

the problem seems to be that there isn't enough extension on the shock.

i can only imagine it would be a wrongly supplied unit destined for another application, but odd that both are too short. could well be a batch problem, but not heard anything like it from anyone else!

also, the maths is largely irrelevant. if it works it works, if it doesn't it doesn't.

[Alex'n'Ane]

also, the maths is largely irrelevant. if it works it works, if it doesn't it doesn't.

I won't disagree with that one chris, but as an engineering student I felt the need to have a little brain workout and look through the numbers. I was quite surprised too, but my guess lengths now seem abit out..

[chrisryder]

i'm an engineering student too. ok the numbers are relevant, but if the damper is selected with a knowledge of what 'efficiency' or motion-ratio it will be working in, and factoring that in, then angled, or inward mounted dampers aren't necessarily all bad, especially when the packaging limits the ideal solution.

ok it's possible to re-engineer the whole lot, and put turrets into the boot to mount perfectly vertical dampers, but your average diy amateur mechanic won't want to, and may not even be able to, do the work involved.

how did we get onto the 'angled damper' discussion again?

[bmcecosse]

Just put decent oil in the lever arm dampers - they work fine ! The real problem with Minor rear suspension is that it's too soft - even with the 7 leaf Trav springs........ Dampers are only intended to 'damp' they don't change the spring rate, and the rear of a Minor is very softly sprung - so much so that it's on the bump stops as soon as there is the slightest undulation..... Does anyone sell/know of an Aeon bump stop kit for the rear ?? There are kits for the Mini - but i think probably too small to be any benefit on a Minor.
And -in the picture of the mocked up assembly - the spring is wrong way round.......

[Stig]

I don't see 'cos' has anything to do with it. When vertical you get full damping. When horizontal you get zero. I don't see any reason to not simply apportion the damping rate to the mounting degree, So 'simple' maths says 45 degrees will give half damping , and 30 degrees will give 66.6667% damping - so yes, 67% really.....

Sigh.

cos(0) = 1 (vertical)
cos(90) = 0 (horizontal)
cos(45) = 0.71

so at 45 degrees to the vertical a 1cm vertical deflection would give 0.71cm damper deflection etc.
As Alex says, that's ignoring the resulting change of angle as the damper compresses but I did say it was simple maths.

I seem to remember you were a chemist rather than an engineer Roy?

[Alec]

Hello all,

just to go on a slight sidetrack.
When I worked in Saudi Arabia we ran Chevrolet Suburban Estate cars and the very basic leaf spring and live axle had one interesting feature, one damper in front of the axle tube and the other side was behind. My guess that they were fitted that way was to limit spring wind up and so lessen axle tramp? I've never seen that on any other vehicle?

Alec

[minor_hickup]

Is the kit pictured the one actually fitted? I can't see a problem really as the dampers should never see full droop. Is the damper bracket mounted in the correct position? Perhaps it nees to go above the bracket for the radius arms if it is not already fitted like this? Unfortunately the Spax rear kit is not a very good kit at all.