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MG Midget and Sprite Technical - Telescopic rear conversion and rebound strap

When you have a telescopic conversion on the rear do you still need the rebound strap?


Rob
Rob aka MG Moneypit

Isn't the top rebound strap mount used as top mount for damper? In which case you couldn't have the strap as well.
Bernie Higginson

Rob,

You shouldn't need it as the damper should have an internal buffer and the rubber bushes to provide some compliance when it goes solid. I fitted telescopics to the back of my frogeye and ditched the straps as I increased the suspension travel in droop and I didn't use the strap top mounts either and haven't had any problems.
David Billington

Hi Rob on the spax kit I had the top of the shock was attached to the spax plate that came with the kit so yes you could still use rebound straps in the original mounting . I cut them in half overlapped them about an inch and clamped with a nut bolt and some penny washers . I didn't like idea of the full weight of the rear axle bearing on the extended telescopic damper
Mike Fairclough

Mike,

Is your car 1/4 or 1/2 elliptic?
David Billington

1/2 , it may be different for Frogs !
Mike Fairclough

Mike,

A mate had the Spax kit on his Austin Sprite (1/2 elliptic) and liked it. I fitted the Spax kit to my frogeye (1/4 elliptic) and ditched it a couple of days later as I found it reduced the droop travel to about 1" and you could pick-up the inside wheel and lose traction around the most minor slow speed bend so not good, they acted as the straps. I engineered my own after that and ended up using the Spax dampers on the front instead.
David Billington

Its a SPAX setup with Gas SPAX Shock absorbers om a 1973 midget. There is a thick metal plate (8mm at a guess) mounted where the lever arms were, along with inverted and swapped L to R plates on the bottom, where the lever arm drop link used to attach.

The rebound straps had seen better days so I was wondering whether to replace or omit.

Rob
Rob aka MG Moneypit

Same set up as mine then Rob and similar age car . I chose to keep the straps as I said but it seems they may not always be necessary I was just concerned with axle drop . Try jacking the car up by the body and see whether the shocks are on full extension .
Mike Fairclough

OK Mike, I'll give that a try.

Rob
Rob aka MG Moneypit

I wouldnt recommend using the strap bolt as an anchor for the telescope shock

there have been a number of horor stories of the bolt ripping out esp if there is any rust bunnies in the area

prop
Prop and the Blackhole Midget

I run the angled Spax kit and rebound straps. Turns out my axle hits the exhaust anyway while stretching the strap....
Rob Armstrong

I run avo shocks through the strap hanger top mount with a secondary bracket to give additional strength. I've seen it done before and it works well. Also the shocks are more vertical with this set up.


Dave Pratt

Dave

I LIKE THAT....That little bracket was smart idea and certianly provide the added strenght needed

well done !

Prop
Prop and the Blackhole Midget

Mike, I managed to get time to fit the telescopics back on the car. As you suggested I propped the car up under the body and measured the length of the shocks at full axle droop. There was about 1/4 of an inch of extension left so the rebound strap is probably redundant. I'll leave them off for now and see how it performs on the road.

Rob
Rob aka MG Moneypit

You'll not be able to tell the difference unless it's off the floor! Going to be a serious test. ;)
Rob Armstrong

More critical is the length of the shock under full compression. If its too long and reaches the end of its compressed travel before the axle hits the rubber bump stops, then you will get one hell of a bang every time you bottom out the rear suspension. And this will have the weight of the car behind it so is considerably more forceful than the slight clunk you might get on full axle drop over yumps.
GuyW

I expect SPAX thought of that when they designed it and I've been running it this way for 3 or so years and no sign of any thump on full compression.

There are some nice undulating minor roads on the nearby moors that can induce moments of minimal road contact if your brave enough (which I'm not). The only time I have experienced full compression is in the Frogeye when we first bought it. Travelling quite fast we decended a dip with a parabolic shape with a hump at the bottom. One hell of a bump that caused!!!

Rob
Rob aka MG Moneypit

Yes Rob, I wasn't necessarily meaning with the Frontline / SPAX kits which I suppose should have been sorted in that respect. I use the DIY version; mini front shocks fitted to a (reinforced) upper check strap mounting. They work fine but needed a bit of initial sorting to stop the crash from the rear suspension on full compression. I discovered that not all the mini front shocks compress down to the same extent.
GuyW

Some (many?) tele shocks are *not* designed to withstand sudden full compression loads. When I first fitted a set of Gaz Gold to my ZS180 we destroyed the fronts at the first race meeting; on investigation Gaz admitted they'd been built with too short a stroke length, and rebuilt them FOC. Been fine since...
David Smith

Glad you got them fitted , be interesting to know how you get on with them , I always ran with them quite soft .
Mike Fairclough

This thread was discussed between 05/09/2016 and 09/09/2016

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