Thread: Arthur gets new (parabolic) spring in his step

Originally Posted by Johnno1969

Hey, does anybody know much about mixing parabolics with normal semi elliptic springs? I have a good set of elliptics on the rear of my 88 that have not done much work, and I want to change the front springs now. I have considered parabolics, but am unsure about the ride characteristics I would get from mixing spring types. The vehicle is a 2.25 diesel.

Cheers,

John

Not recommended really, as parabolics raise the ride height, so would change the dynamics from front to rear. Manufacturers usually recommend changing all springs too.

Originally Posted by Johnno1969

Hey, does anybody know much about mixing parabolics with normal semi elliptic springs? I have a good set of elliptics on the rear of my 88 that have not done much work, and I want to change the front springs now. I have considered parabolics, but am unsure about the ride characteristics I would get from mixing spring types. The vehicle is a 2.25 diesel.

Cheers,

John

As I was upgrading Arthur's springs, I did the back ones first and drove around on them for a day before finishing the job and doing the front ones. Whilst it was only for a short time, I noticed the imprvement with only the rear springs being parabolic. I'm not sure how it would go with a permanent set up of mismatched types.

RM Paras are not handed - not sure about the others. The spring rates are actually stiffer than (most) standard springs (the softer ride is given by less interleaf friction), so the fact that thay are not handed makes negligible difference.

Originally Posted by Johnno1969

Hey, does anybody know much about mixing parabolics with normal semi elliptic springs? I have a good set of elliptics on the rear of my 88 that have not done much work, and I want to change the front springs now. I have considered parabolics, but am unsure about the ride characteristics I would get from mixing spring types. The vehicle is a 2.25 diesel.

No problem at all - despite what anyone else says. However as mentioned above there may be a noticeable difference in ride height between front-rear. You could get the rears reset to match. However - the rear springs usually have more influence on ride than the front.

Just out of interest, I took a photo of the chassis with the engine mounted. It's pretty clear the engine and gearbox are sitting significantly over towards the passenger side, with the transfer box and diffs (and eventually the tank and driver) on the driver's side.

It might turn out to be reasonably balanced with the parabolics installed.

If I get the chance, I'll put it on a weighbridge one wheel at a time to see what the weight distribution is like.

Peter

Hi Peter,

It was pointed out to me the other day when I was talking to someone about the parabolics on mine (more of that story in series three section shortly) that the diffs are actually unsprung weight so they don't affect the lean from the springs at all. Maybe some of the problem is that fuel tank and driver are outside the line of the chassis so influence things a bit more than things inside the chassis? In mine the battery is also on the right hand side in the engine bay so would also be a factor.

TimJ.

Doh . . . unspring weight of course.

It's still interesting to speculate on the various weights, though. The engine is about 200 kg, the gearbox about 50 and the transfer box about 20. I weight 72kg (OK, 74 after Xmas) and a full tank would be 40+kg. The battery would only be about 15kg.

It's still a significant weight on the passenger side, although as you point out, the tank is further over and exerting more leverage about the centre of gravity.
Peter

I have the sprung weights on each corner somewhere...