Gaz Shocks

[Guest hypermick]

Guys,. thanks for all the info.

 

This Hoodie here has had all its work done on it off the ground rather than being moved in and out of the garage, but its been (and still is) a slow build due to lack of time, and probably more because of over judicious cleaning and restoring. That aside, Im glad I raised the point about the shockers since lots of things didnt seem right, as you can tell by my questions. (Putting aside they (the Zimmers) are not getting used anyway).

 

They have lay in the boxes since day 1, and through my questions I now discover that I should have received different pairs, well length differences anyway. OK so RH got mine wrong, but the consensus of opinion being 18" on the rear, is what I'll go with. Those of you who have mentioned it seem happy with the results,....good enough for me.

 

Whilst on the subject of suspension, (wishbone front ) the lower wishbones have quite an angle (about 25 deg) from horizontal on the lower balljoint holding eye. I take it that this is intentional, presumably to create the correct suspension geometry ? Its just that it looks a lot and somewhat rather odd.

 

Anyone offer anything on this point ?

 

comments very welcome !

 

 

Mick

[Graham B]

Mick

 

I have just had a similar thread running.

I have 12" Protechs on the front, but with the 8 valve DOHC lump squeezed in.

The 12 " are tto short !! I will try and get them re worked to 13".

12" with springs on , part compressed - takes the lower mount to the edge of the brace plate, not up close to the lower ball, as would be ideal.

My calc for new ones is - 10" vertical (from top mount to level of mounting on lower wishbone ), parallel to floor. 6" horizontal to mount. With a newly made lower mount I reckon I can get to 7" . This gives the damper an overall lenght of 12.6" on 6 and a bit more for 7".

 

The DOHC lump must be heavy --I saw an entry that suggested the RHE green springs are 380lbs - I have 7 1/2" 350's and they are wound up. The car just flattened my initial 300's. I will try some longer 375s. 9" maybe. The Zeemers mounted within 1/2 inch of the Protechs, they were screwed up about 1/2 way.

It was enough to keep the front level. BUt now Ive bent the wishbones .....

 

Graham

[Guest timswait]

Theoretically the shocker (whichever-whatever make) should in the sierra rear arm set up be positioned (as Ford did it) on the outer arc of the rear arm

No it shouldn't!

We have coil over dampers so the whole weight of the car goes through wherever the shock mounts, on the Sierra only the damping loads go through it, which are much lower. Far better to mount them where the springs go on the Sierra, which is where most people put them. Mounting them on the damper mounting lugs on the trailing arms applies much greater forces and moments than on the Sierra.

 

So what is best, Longer shocks or shorter?

My vote is for longer since all the anglular displacements are less, but I don't really think it makes much difference.

 

the lower wishbones have quite an angle (about 25 deg) from horizontal on the lower balljoint holding eye. I take it that this is intentional, presumably to create the correct suspension geometry

On the factory standard wishbone front suspension the wishbones are angled downwards. Like most things RH I doubt it was really designed that way, it just turned out like that. The geometry really isn't great, I assume it was probably done like that to make it easier to manufacture.

[Grim]

12" with springs on , part compressed - takes the lower mount to the edge of the brace plate, not up close to the lower ball, as would be ideal.

...

The DOHC lump must be heavy --I saw an entry that suggested the RHE green springs are 380lbs - I have 7 1/2" 350's and they are wound up. The car just flattened my initial 300's. I will try some longer 375s. 9" maybe. The Zeemers mounted within 1/2 inch of the Protechs, they were screwed up about 1/2 way.

It was enough to keep the front level. BUt now Ive bent the wishbones .....

 

If you have mounted the coilovers further from the lower balljoint, this reduces the effective spring rate, which is probably why you are having problems. Stick with the same rate springs, but move the bottom mount outwards with longer coilovers.

I ahve 350 rate springs on my sluiding pillar conversion to wishbones. I think they are mounted slightly further out than wishbone 2bs, so you shouldn't need to go above this spring rating.

 

The dohc is lighter than a pinto.

[Guest Andy Hamilton]

I would suggest that the old RH supplied green springs are more like 180lb rather than 380lb. I have put 13"x9" 1.9's with 350lb springs on mine at the front and it is absolutely fine. I wouldn't go any stiffer though, so somewhere around 325lbs and 350lbs should do nicely judging by all of the comments.

 

I still have the Sierra rear suspension on at the moment, and whilst it is doing the job quite nicely for now, I will change to coil overs during the winter. looks like 18"x12" with 300lbs springs. Just need to make up some brackets for both ends.

[Guest hypermick]

Sorry guys, seems like Ive opened up a real can of worms here.

Tim, Grim, Graham, Andy, thanks for all the mutterings on this one yesterday and today.

 

Clearly there are many issues with the 2B suspension but the one thing that does stand out in all of this from further research done is that different manufacturers with same rated springs do not necessarily use the same number of coil turns for the given length,. This to my mind is where some builders are experiencing coil binding and others are not.

 

I find it hard to otherwse understand how some guys need to use front springs up to 350 lbs + when others say their suspension is well sorted at 200 ish lbs, given the use of the Pinto in common.

 

I wrote in an earlier part of the thread that the Caterhams run 170lbs on the front coil overs, more or less as standard, but account is made for the lighter overall build and would seem fair to accept this is best for their needs. I personally on the next point cannot see any mileage whatsoever in using very short springs particularly on the fronts, what can it achieve considering that for given working length they would have to be almost rock solid in tension to assist with the absorption effect ?

 

Surely the balance is to achieve controlled damping. I'm inclined to believe that too much emphasis is currently being placed on spring rating and length and the poor old shocker is left straggling to cope with what the spring cannot do, rather than the other way around !

 

I can feel a large bout of experimantation and further study coming around the corner on this one !

 

Happy Days

 

 

Mick

[steve in stockport]

Mick

just to throw a spanner in the works, my car was supplied with 4 x 12.5" zimmers and was built with them as i didn't know there were any other lengths.

have since changed to 4 x 13" gaz shocks and have done nearly 5000 miles, so the 4 same length shocks will work.

 

the car does seem to sit better at the back with about 65mm between the tyre and the wheel arch

 

Steve

[Guest timswait]

IMHO A large part of the variation in spring rates comes from differences in mounting, so placing more or less leverage on the spring, the rest probably comes from differences in the weight of the car and differences in personal preference. Going from the Zimmers to 300lb Gaz has made the ride far more refined (fewer crashes and bumps) and also I feel slightly softer (although I've also increseased the leverage on the spring).

Damping should be set to match whatever spring rate you choose, which is fairly easy if you have adjustable shocks. It's characteristed by damping ratio, which depends on mass, spring rate, and damping coeffiecient. A damping ratio of less than 1 is under damped, so the car will bounce, a ratio of greater than 1 is overdamped so the car will not oscillate, but the suspension responds slowly. A ratio of 1 is critically damped, since it is the fastest the suspension can respond without oscillation.

Typically most saloon cars have a ratio in the range 0.8-1, most sports cars 1- 1.2 and most racing cars higher still.

[Guest hypermick]

Tim, thanks for that input.

 

Steve,. you have come up with exactly the same scenario as I've had here, ( 4 x Zimmers 12.5" supplied initially by RH) and Im very grateful to you for pointing out your experience of using 4 x GAZ at 13".

 

Youve obviously made up the 5" difference (18" shox as used by others in the thread) by extending the shocker tubes well down towards the radius arms and perhaps not cutting any off the roll bar tubes during the build.

 

I must admit I'm inclined to still do some experimentation with the rear end and post the outcome later on perhaps benefitting others.

 

Would be grateful Steve if you could confirm you left the tubes uncut.

 

Thanks again guys !

 

 

Mick.

[steve in stockport]

Mick

see this thread gaz shocks for how i fitted them.

 

cause the roll bar is cut uneven in the factory and i didn't trim it at all one of the shock mounting tubes is pushed fully in and the other protrudes by 1.5", so i didn't really do anything to make up the 5" difference

 

this is the car in France (thanks to adi1 for the piccy)

as you can see the rear height is fine

 

Steve

[Guest hypermick]

Steve,. thanks for all the further info.

Its very kind of you to help, especially with the piccy of the car in France. It seems to sit pretty well on the set up.

 

I'll turn some new inner steel bushes to sleeve out the GAZ shox eyes when they've arrived.

 

Cheers

 

Mick.

[Guest salty_monk]

I think Gaz will supply the sleeves if you ask for them....

 

Dan

[Guest timswait]

You might find it just as easy to open up the mounting holes to 1/2" and then use a 1/2" UNF bolt. I've always felt the 3/8" bolt was a little small for the job (although I've never heard of any problems with these), they were meant for mounting the dampers in the metro the zimmers originally came from, not taking the whole weight of the car in the coilover application.

[Guest SEgan]

I too have the Zimmers, covered 2 miles so far and suffering from deformed bushes.

 

Are these any good.

 

HERE

 

Is is a good price, I have no idea!

 

Sean

[Guest hypermick]

Sean,.

Theyll be slightly too short. That seller has a good range periodically of GAZ.

 

Go for `13" open 9" closed when he offers them,. he'll do 4 for the price of about £199, inc P&P but youll have to get your own springs.

See Steve in Stockports message regarding using 4 the same length, he's well happy with his but you'll need to keep the rear tubes full length since the longer ones are rormally 18" open.

 

 

Mick