Shock absorbers for parabolic springs

[dave88sw]

Hi,

I'm sure this has been done to death in the past but there's lots of differing opinion out there.  I rebuilt my series 3 many years ago onto a galvanised chassis, at the time i fitted britpart parabolics and pro comp shocks.  The britpart springs were awful, the bush eyes weren't parallel so they ate bushes and they sagged, swapped them side to side and they sagged the other way.  I've sinced replaced them with a nice set from GB springs but the old pro comp shocks are still on there and looking decidedly tired.

Tbh, any conclusions about ride quality are pretty pointless, it will never be smooth riding, and really, i don't want it to be, it's a series Land Rover.  So, is it ok to use standard shocks?  I've read suggestions that they're not well matched to parabolics but is there any reason not to?  Or is there anything better available that isn't horrendously expensive, it doesn't get used enough to justify huge expense.

Thanks

Dave

[Snagger]

Conventional wisdom is that parabolics, lacking internal frictional damping, need gas dampers.  But coil and air springs don’t have internal frictional damping either, and are fine on standard oil dampers.  I really don’t see a problem with oil dampers on parabolics as long as the dimensions are correct.

The original spec Series dampers would have a damping rate matched to a certain amount of spring damping, so might not be quite strong enough for parabolics, but something with the rate that Defenders and Rr/Discovery had would work.  The problem with dampers for those vehicles is the fixings.  I just fit MoD 109/1-ton dampers on my 109, which are made for the taller suspension of 1-ton  chassis and shackles, so the length matched, nd hoped that the damping rate would be suitable given the increased payload they were made for, and they worked very well, much better than the god-awful ProComps they replaced.

109 rear dampers have a stud on the axle end, rather than an eye, but the front dampers are the same as 88’s.  It may be possible to fit the front dampers on the back of an 88 too, if they are long enough when extended, but you must check that length.  Certainly, they’ll fit the front end with parabolics nicely, but it may be worth fitting a small spacer under the bump stops as they are longer than standard dampers and if the suspension compresses against the stops, it’s possible the longer dampers will bottom out and be damaged.  Mod and 1-ton 109s have a steel spacer between the chassis and the standard bump stop block to achieve this.

If the rear dampers on the 88 are a different length or stroke to the front, then you can fit 1-ton rear dampers if you weld the axle brackets on.  YRM will stock them and they should be cheap.

[Arjan]

Koni

Worked for our TIC parabolics for many years

 

[Bowie69]

1 hour ago, Snagger said:

Conventional wisdom is that parabolics, lacking internal frictional damping, need gas dampers.  But coil and air springs don’t have internal frictional damping either, and are fine on standard oil dampers.  I really don’t see a problem with oil dampers on parabolics as long as the dimensions are correct.

I would say that's not the case, gas dampers just help to keep the damper working, longer, as the best builds up. Gas dampers don't inherently have a stronger damping rate, but they will last longer on higher speeds roads between comparable models, for example.

A damper that is better than damping is needed for parabolic springs, vs normal leaf springs.

 

 

[dave88sw]

Thanks for the replies, lots to think about.

There doesn't appear to be a huge amount of choice.  Most of them appear to be britpart 🤢, whether that be standard shocks or gas ones.  I've read that the cellular dynamic shocks they make are apparently half decent but i hate poly bushes, which they appear to come with (bad experiences of them wearing the parts they're fitted to, the bush should be the sacrificial part).  Paddocks stock Monroe gas shocks which look interesting, bonus being they come with rubber bushes and they're black, which is a massive plus.  I'm thinking i might give them a go.

Cheers

Dave

[Bowie69]

3 hours ago, Bowie69 said:

as the best builds up

This is supposed to say 'heat', stupid fingers.

[Bowie69]

Monroe are a decent make, but all manufacturers make stuff at high and low end.

[Jon W]

The length is probably the most important part hence why people have recommneded the 1Ton shocks as they are longer. I have the standard cheap britpart shocks with parabolics and the ride is awful the shocks constantly top out as only have about an inch of droop, hence why i think a lot of kits come with procomp +2inch shocks with them 

 

[markyboy]

I fitted GB Parabolics to my Series 3, I asked them for their recommendation with regards to dampers. Their advice was that standard dampers were good enough if you use the vehicle mainly on road and would suffice for leisurely off roading, say green laning. My car is currently not in use, but the little bit of driving I've done so far suggests the ride is going to be quite 'bouncy'. I honestly can't say whether it is any worse than it would be with standard springs, the last time I had a series in regular use was about 19 years ago. I think I may end up investing in some better dampers but I need to use the vehicle properly before I can make that decision.

 

Regards,

Mark

[Snagger]

On 10/1/2020 at 11:32 AM, Bowie69 said:

I would say that's not the case, gas dampers just help to keep the damper working, longer, as the best builds up. Gas dampers don't inherently have a stronger damping rate, but they will last longer on higher speeds roads between comparable models, for example.

A damper that is better than damping is needed for parabolic springs, vs normal leaf springs.

 

 

That is the point I’m making.  The coilers don’t need gas dampers for normal use, though for arduous off road or competition they may.  Parabolics are no different. 

[Gazzar]

Monroe gas magnums, good enough for most use. Long enough for Parabolics, and last well enough. Good price.

[dave88sw]

I like the look of the monroe shocks, i think i'll probably go with them but i can't see any information about length.  Considering mine sits at normal ride height i can't see it being too much of an issue?

[Snagger]

It shouldn’t be a problem to use normal length dampers if yours sits at normal height.

[Bowie69]

5 hours ago, Snagger said:

That is the point I’m making.  The coilers don’t need gas dampers for normal use, though for arduous off road or competition they may.  Parabolics are no different. 

Yeah, I was agreeing with you, badly!

[Bigj66]

I posted the same question a few months ago and ended up going with the Monroe shocks.

[Cory]

I installed the Britpart Cellular Dynamic on my Series 2 109 SW with rear GB Springs 4 leaf.  They seem to have lots of travel.  The polybushings look to be the same size as stock rubber bushings.  You could order stock rubber bushings to replace the polybushes. 

I hope to have a drive on the new GB springs in 2021 when it's done getting repairs.

The stock shocks were too short.  They were Bearmach Stock 109 shocks.