Lowering Gurus wanted - The Gaz shock thread

[shawn82]

just ordered some of these today.
They dont have any 16" shocks in stock will be about 4 weeks so went with the 15" ones as they have some of them in at the moment. they said they should also work as good. i guess we will see.

Great! Let us all know how you get on.. :shadey: arty0021:


opcorn:

hoping to get them on and sorted next week in time for bug jam. if all goes well can maybe meet you in downham market if your about that way to have a look. or pop a bit further to my house near swaffham and you can compair how you want yours to look as camper running air and pickup will be on these etc. thats if you still at wisbech. lol.

 

[cunning plan]

That's nice of you chap, thanks, I do go to that part of the country sometimes

Jealous of the Bus AND the Scab. Do you have a build thread for either?

 

[shawn82]

No afraid not, I get to impatient and just do stuff rather than take photos and talk about it ha ha. Maybe on the next project altho I have enough to do for now with these two, ha ha.

 

[cunning plan]

That's terribly selfish of you ol' boy. You know how us VW geeks like to chat bus arty0021:

 

[cunning plan]

After initially reading this thread and understanding the information, I then found my brand-new Empi Coil-overs on the shelf:

I played with them for a couple of minutes out of interest, then remembered Geeze's reply:

My understanding (so possibly wrong :lol: ) but shock length is a matter of travel. If you measure the length between the shock mount at full height, then at full compression (and add a bit) then that's the length and travel of the shock that you need. For a given amount of movement (travel) in the suspension, the shock length remains the same and higher / lower or softer / stiffer is then all about the spring rate and length (that's the tricky bit and where I ran into indecision before :roll: ).

So.... If 16" bodies are working for people then that's probably worth sticking with 8)

The springs are then a bit harder. Imagine if you fitted the shocks with no coils then dropped it back on the ground (ride height at rest) and wound the adjuster ring to half way before measuring the distance between the adjuster ring and the tophat at the, erm, top. Let's call it 8 inches (I've no idea if that's the right number, don't copy it!).
You could fit 8" 80lb springs or 8" 500lb springs and your bus would sit the same height at rest on both (because neither are compressed). But the 80lb ones would ride soft and the 500lb ones, well, wouldn't.
If you fitted longer springs at the same rates or wound the adjuster up, then you would raise your bus a bit as you are now preloading the springs. For the same increase in spring length / movement of the adjuster, the increase in ride height will be less on the 80lb springs because the spring compresses more easily than 500lb ones.
But even with the longer springs, the ride will stay the same as on the 8" springs - preload doesn't alter spring rate.
So here's the trick. The spring rate determines ride quality. If you find the right (comfy) rate, it's the same regardless of spring length or adjuster position. If your bus sits too low on your favoured rate, then you either need longer springs or to adjust the spring seat. Too high and it's shorter ones (or adjust the seat the other way). If you run out of spring seat adjuster movement (all the way to the top / bottom) then you've definitely hit the point of needing different length springs.

So... if 125lb is comfy and it doesn't rub on full bump, then it's the right rate. If it's mushy and hitting the arches on bump then fitting longer 125s won't do anything and you need stiffer (higher rate) springs. For the length, if there's still adjustment left on the lower seat and you're happy with the ride height then it's good.

All of that's the simple version (big note - my understanding of it, anyway :lol: ). There is one more bit about preload, which is that if you got the spring length / adjuster position right, you could dial out that initial sag you get when you climb aboard which would be cool but that's where things get tricky and I manage to get myself confused...

This is probably the best post in the entire thread to help you understand all of the different elements within the Coilover shock absorber and what impact each of them has on the ride height and quality.

However, as highlighted in bold:

preload doesn't alter spring rate

The Empi Coil-Over is already at the top of its travel and cannot be lowered any further.

If the preload / making the spring 'tighter' does not alter the spring rate, meaning, it does not alter the ride quality and the Empi spring can only be compressed further, not 'lowered', what exactly does the Empi spring adjuster do? :? :?:

(Gaz coil-overs are the ones to have, no change there, just a question for my own interest).

 

[Moseley]

In the case of the Gaz coilovers in this thread and the Empi ones pictured, they differ from the ones normally seen on cars in that the adjusters are only fitted at the bottom of the spring. This means that rather than being able to alter the position of the spring on the shock but keep it under the same preload compression, the only means of adjusting the ride height is to compress the spring.

So effectively, the higher you wind the adjuster on the shocks (and the shorter you make the spring), the higher the van will sit. This is because the more the spring is compressed, the more it is trying to extend the shock absorber.

Does that make sense?!

 

[cunning plan]

In the case of the Gaz coilovers in this thread and the Empi ones pictured, they differ from the ones normally seen on cars in that the adjusters are only fitted at the bottom of the spring. This means that rather than being able to alter the position of the spring on the shock but keep it under the same preload compression, the only means of adjusting the ride height is to compress the spring.

So effectively, the higher you wind the adjuster on the shocks (and the shorter you make the spring), the higher the van will sit. This is because the more the spring is compressed, the more it is trying to extend the shock absorber.

Does that make sense?!

It makes sense for the Gaz ones, but the Empi ones cannot extend any further, they are at the end of the travel. So, if I use the C-Spanner to compress the spring, the shock does not get any longer, the spring just gets tighter. What is the purpose of that if it doesn't change the ride height and compression of the spring does not change the ride quality? :? :? :msn4:

 

[Moseley]

In the case of the Gaz coilovers in this thread and the Empi ones pictured, they differ from the ones normally seen on cars in that the adjusters are only fitted at the bottom of the spring. This means that rather than being able to alter the position of the spring on the shock but keep it under the same preload compression, the only means of adjusting the ride height is to compress the spring.

So effectively, the higher you wind the adjuster on the shocks (and the shorter you make the spring), the higher the van will sit. This is because the more the spring is compressed, the more it is trying to extend the shock absorber.

Does that make sense?!

It makes sense for the Gaz ones, but the Empi ones cannot extend any further, they are at the end of the travel. So, if I use the C-Spanner to compress the spring, the shock does not get any longer, the spring just gets tighter. What is the purpose of that if it doesn't change the ride height and compression of the spring does not change the ride quality? :? :? :msn4:

The Gaz and the Empi coilovers behave in the same way - the reason why you're not seeing any difference in shock length is because they're off the van; I.e. Not under compression. With the spring cup wound to it's lowest position (as per your picture) on either set of coilovers, the van will be at its lowest ride height. As you compress the spring more and more, the ride height will raise, as the spring compression will be trying to open the shock to its fully extended length.

 

[cunning plan]

The Gaz and the Empi coilovers behave in the same way - the reason why you're not seeing any difference in shock length is because they're off the van; I.e. Not under compression. With the spring cup wound to it's lowest position (as per your picture) on either set of coilovers, the van will be at its lowest ride height. As you compress the spring more and more, the ride height will raise, as the spring compression will be trying to open the shock to its fully extended length.

Okay, thanks for explaining, I understand what you are saying now.

As the Empi coilovers have a longer 'unloaded' length than the Gaz coilovers (the ones I will order), that means that with the spring cup / adjuster at its lowest position, the bus would be higher than the unloaded length of the Gaz ones - right? :|

Then as you explained, on both the Empi and Gaz coilovers, as the adjuster is wound up to compress the spring, this raises the ride height - right?

(Although, the Empi coilovers would have little or no height adjustment left in them as they are too tall for my application, meaning, you have to preload the spring just to get them on, which in effect, is raising the Bus to the next setting on the adjuster. The next two settings probably would not do anything as you are already at the top of the shock tube travel. However, that is a application / design issue rather than a engineering principal issue, as we are discussing here, which, is what my original question was asking). I now know, the Empi ones should be doing the same thing as the Gaz ones, but don't as they do not seem well matched to my application / bus / setup. However, However, However, I then start to think about if the Empi ones were compressed further, would the adjuster raise the ride heigh as it should, but then I think logically, it couldn't as the springs would already be too close together, similar to this:

 

[paulrobinson2010]

Ok after reading and re reading this thread. Have decided to go for the gas shocks to replace a pair of dud spax adjustables and some ok'ish replacements from the guys at T2D.

Question is looking at the machine 7 post on shocks they say it's better have more free play in compression than expansion which kind of makes sense.

So for my westy:

300 mm eye to eye at rest on lowered t2d beam adjusters - beam adjusters at highest they'll go for the nut to clear the bar - so minimal drop

I've worked out I need these to give me more compression.

140 / 095 / B12
1.9" / 140 / 9"

The ones most people have specced (but for dropped spindles) seem to be:

160 / 105 / B12
1.9" / 150 / 10"

So which should I go for and will it make much difference?

Is anyone running beam adjusters with gas shocks on the 160's without any issues...

Cheers

 

[Andy_sheff]

just ordered some of these today.
They dont have any 16" shocks in stock will be about 4 weeks so went with the 15" ones as they have some of them in at the moment. they said they should also work as good. i guess we will see.

Great! Let us all know how you get on.. :shadey: arty0021:


opcorn:

hoping to get them on and sorted next week in time for bug jam. if all goes well can maybe meet you in downham market if your about that way to have a look. or pop a bit further to my house near swaffham and you can compair how you want yours to look as camper running air and pickup will be on these etc. thats if you still at wisbech. lol.

 

[Daggman]

Does anyone run them on a 4" narrowed beam? , do they require mods to fit ?


cheers
Mike

 

[*Sam*]

Clem

 

[Lambretta-tom]

Read this thread a few times, Looking to order some up in the near future.
If fitting TH Spindles, what difference if any will fitting the 10" or 9" ?
Thanks

 

[Clem]

Does anyone run them on a 4" narrowed beam? , do they require mods to fit ?


cheers
Mike

Yes, you'll need new lower damper mounts as they can't be run out of line. I got mine from T2D, simple enough to fit but they do require welding into position.

 

[kiwisteve]

Thread from the dead..... :lol:

Do the coil overs work with the original torsion springs or do you replace them?

Also what shocks are people running on the rear to compliment the Gaz shocks up front?

 

[67westy]

Thread from the dead..... :lol:

Do the coil overs work with the original torsion springs or do you replace them?

Also what shocks are people running on the rear to compliment the Gaz shocks up front?

The torsion bars are left in place, can't help with the rears as I'm not sure what I have on mine. I think it might be some KYB's but not 100% on that

 

[kiwisteve]

The torsion bars are left in place, can't help with the rears as I'm not sure what I have on mine. I think it might be some KYB's but not 100% on that

Thought as much, thanks for the reply

 

[marmite monster]

ok so called rally design

they need to know a few things

what is the size of the bushings in the top and bottom of the shocks ?

what is the closed length ?

if anyone has some part numbers from rally design or an old invoice number they can pm me that would be a big help.

im also assuming these will fit the same as the original shocks I have on now regardless of having a narrowed beam ?

thanks

si

 

[Graham L]

With regards to the GAZ Dampers that Adam mentions above I'm happy to share the information with people as the intention was to offer them at a good deal by buying in bulk but couldn't get enough interest to buy them in the right quantity.

I've checked the records this morning and the dampers that have been fitted to Monty (my old 69 Panel Van, Adams (67 Westy) and are currently fitted to my latest bus 'Billy' are GAZ Units 160/105B12, they are fitted from memory with 9" Springs but can double check that, I'm currently running 150lb springs but when Adam had them they where fitted with 125lb springs.