question for Jonathon

[Willie]

JONATHON....could you advise me please? I am trying to work
out the maximum deflection of the rear axle in order to accurately
position the pivot points for tele dampers. At 'rest' there is a gap
of 1 1/2" between the top of the rubber buffer and its stop plate.
What I do not know is how much further movement there is likely
to, be on a bad bump,after the buffer has hit the plate? I am thinking
of allowing an extra 1/2", i.e. 2" maximum upwards movement from
rest. Does this tie in with your experience please?

[jonathon]

Normally a road driven car will seldom exceed 1"-1"1/2 . If you have 11/2" before contacting the bump stop, then this in theory is all you need.
Now what are the open and closed lengths of your dampers,measured between the mounting eyes or eye and pin depending on your design. What angle are you intending on setting your dampers. I would mount them vertically as near to the ends of the axle as is possible. If you lean them either backwards or inwards then you will loose about 60% of the damping. Do your dampers have an integral bump stop.

[Willie]

The closed distance pivot centre to pivot centre is 8+5/8", the wide
open distance is 12+7/8". since I am utilising the original top
damper link pivot,with a 5/8" spacer the dampers will be at an
angle front to rear but will be parallel vertically. Appreciate that
vertical is best but also know that this set-up will be a great improvement
on the lever arms as I have been running the 'Not ideal' O B set up
until recently. the one advantage of an angled damper is that the
vertical movement of the axle translates to less movement on the
damper so I reckon my amount of total movement will suffice,
especially since you reckon I don't have to allow my intended extra
1/2" over the initial buffer to plate contact. There is no integral
bump stop and they are 30% uprated Mini fronts.

[jonathon]

Do you know the given length between your intended bottom mounting point and the top one

[bmcecosse]

But if the bump stop breaks off - as they often do - then your damper will become the stop and will transfer metal breaking forces into the mountings. You would be better to have either metal bump stops with short rubber bumpers on top - or use dampers with long enough stroke to allow the full axle movement, even if the bump stops disappear.

[Willie]

JONATHON.. no, that is why I asked for advice. I know the top
position but have not decided the bottom position until I am
confident that I have built in enough movement to avoid damaging
the dampers. At the moment I am thinking of placing the pivots
10+3/8" apart in the 'rest' position which should be sufficient in view
of your remarks on maximum upward deflection??

[jonathon]

Sorry, brain fade I think. Lets round up your figures. to 13" open length and 9" closed. thus giving you 4" 0f free movement. You will safely require 11/2 ins for normal road condition deflection .and the ammount of travel taken up by the cars laden weight ,however pot holes or kerbs will increase this requirement. If you mount the eyes at a 10" gap then you will have no margin for travel over the 11/2-2" you require.
You need to contact the maker of the dampers, give them the model number ,and corner weight of your car, this is around 220lbs , then the angle you wish to mount them assuming a 10" center.. they will know the given damping rate and therefore answer the question for you. Ideally you should fit a damper with a bump stop, and the ones we sell in our turreted kit have a minimum of 9" worth of travel, equating to around 6" at laden weight.
As BM correctly states if you loose the bump stop then you will encounter serious problems as your choen damper is really too short , even if the mountings are spaced at the maximum allowable.

[plastic_orange]

Just a piece of advice - if you use Spax shocks, they don't like being used at an angle. I went through 2 pairs on the front of my Rover p6B in 3 weeks before substituting for Konis (got a refund though). They also failed on the rear of my minor mounted in a similar manner to what you describe.

[Willie]

JONATHON....ok thanks for the advice. I am puzzled that there
has been no mention of allowing for the axle to DROP? on my
car the axle drops 2+1/2" from the 'rest' position when jacked
up. Is this not fed into the equation?

PLASTIC ORANGE.....no they are not spax (Boge) and are still
ok after some considerable time on the car in a decidedly angled
position.

[jonathon]

Have PM'd you willie with a response and info

[bmcecosse]

You should restrain excessive axle drop with straps - as fitted to MGBs and so on. Don't allow the damper to carry the load - it's only designed to DAMP !

[Willie]

BMC...fair point but I think my 2 1/2" drop is perfectly normal?
Must admit that I don't go over many hump backed bridges at
60mph these days so hope it will not be a problem.

[Matt]

I now know what you look like johnaton... I read Retro Cars this month...

[jonathon]

I know, its so embarassing, just don't print it off and use as a target, there's too much to aim at

[TerryG]

There were some pictures in practical performance car a couple of months ago too

[jonathon]

Shh!! stop it your making me blush!!!

[Matt]

Well it told me you did original restos when I thought you only did mods..... (oh and don't give me ideas about targets! as some people on here know one of my over activites involves projectile weaponary!)

[jonathon]

Yea!, but is that only after a coupe too many pints ??
Its strange, but we are actually a bodyshop and cover the full range of work needed by the minor enthusiast. The modification side of the business is my own passion, and has been promoted quite hard in the past, probably too much, as like you have pointed out , this is not a well known fact. Still ,you know now!!

[Matt]

Yea!, but is that only after a coupe too many pints ??

Err no, that would just be plain dangerous....

Did i hear a little while ago you had branched out in to putting K series in midgets because you wern't doing enough minors? or was I just imagining it?

[jonathon]

We are still fitting the K series into Minors, but thought we could utilise the existing kit parts to fit the MGB and Midget, or any other rear wheel classic.
The number of requests for the K series transplant is not great, due to the high cost of the components. Mind you we have done eight now, and we would be pushed to do another this year due to existing workshop commitments. Next year we will be opening part of the workshop, so as owners can have the oportunity to work on their own projects but use the full facilities of our workshop and help from staff. A reasonable charge will be made, but we think its a great opportunity for novice,even experienced DIY'rs to glean inside experiences and practices from a professional bodyshop.
We currently have two such projects on the go ,one a Lada with a Fiat TC conversion and the other, which will form the basis of a new product range, A Rover V8 and space frame chassis,independant suspension and discs all around. The engine has 300bhp plus 150bhp nitros oxide, should be fun!!!.