Shocks & Struts

[JohnB_SPY8808053]

Does anybody have the measurements (minimum and maximum length, etc.) for the shocks and struts used on the Hawk? Yes, I know I could take mine off of the car and measure them, I was just hoping to avoid that if possible.

Thanks,

John B.

[chris.richard]

Beta or Leda?

My beta ones are dismantled, so I can measure easily, my Leda ones are made up so I can't compress and extend them - but they're off the car, so if you tell me which measurements you want, I'll see what I can do

[JohnB_SPY8808053]

That's interesting - I thought the two were the same. Do you know what the differences are? Now I'm interested in both but the measurements from the Beta struts would be great. Maybe one of the other guys can measure their Leda units.

As for the measurements, the most important are extended length, compressed length, body length. I'd also like to know the body diameter and rod diameter if it's not to much trouble.

I have also been wondering about the adjustment on the Leda units. I think it's 24 way but I am not sure if bump & rebound are set seperately or if there are preset combinations. While we're on the subject - does anybody want to tell us about their preferred shock/strut settings?

Thanks again for all the help,


John B.

[Matt No VAT]

I agree with John, it would be extreemly useful if someone with Leda struts, who is up and running could share thier settings with us newbies.

It'd at least enable us to get somewhere close to good handling before venturing out at speed:D.

[Stratos]

I was very scientific about setting up my Leda Struts.

I first tried on the softest setting - the car bounced around all over the road.

I then set them to the middle position - the car seemed OK with that, so I haven't changed it since!!!!

[Matt No VAT]

And there was me thinking that everyone with Leda struts would be making minor adjustments to thier platform heights/pre-load for the springs and then adjusting the damper in the search for the optimum suspension settings!! LOLOL

:D

[mogul_x]

John,

If no one else posts the Leda Strut Dimensions, I'll take care of it sometime this week. Mine aren't on the car yet, and I have to take them apart anyway to machine the shoulder out of the upper spring pans.

As for adjustment, they only have one knob to adjust them, so I'd guess that all of the jounce / rebound settings are fixed relative to one another.

[Stratos]

Originally posted by Matt No VAT
And there was me thinking that everyone with Leda struts would be making minor adjustments to thier platform heights/pre-load for the springs and then adjusting the damper in the search for the optimum suspension settings!! LOLOL

:D

Ha, optimum suspension settings, my car!!!!!!
:rolleyes:

You obviously haven't read CCC this month, pages 70-75!!!

[chris.richard]

Leda on the left, Beta on the right. Leda hasn the beta topmount mounted. Beta top spring pan separate, bottom spring pan is integral part of strut. Leda has separate spring pans.

[chris.richard]

Beta upper spring pan from above, showing bearing surface for needle bearing of topmount, and large hole whoch allows pan to slide down over the rod. ( see thread about drilling out Leda alloy spring pans)

[mogul_x]

Originally posted by JohnB_SPY8808053
Does anybody have the measurements (minimum and maximum length, etc.) for the shocks and struts used on the Hawk?

Leda Strut dimensions are as follows:

Overall Diameter : 2.38"
Piston Rod Diameter: 22mm

Length of strut body: 13"
Overall length*, fully extended: 19.5"
Overall length*, compressed: 13.38"

* distance measured from bottom of strut to top of shoulder on piston rod. Does not include reduced diameter or threaded length of piston rod.

Also, the lower mounting hole on the tabs at the lower end is located just about 1" from the bottom of the assembly.

I'll get the dimesions for the front shocks if anybody needs them.

[JohnB_SPY8808053]

Thanks for the dimensions! If it's not an inconvenience, I'd appreciate the measurements for the fronts also.

Thanks again,

John B.

[JohnB_SPY8808053]

Just did a bit of quick conversions. If the Leda strut has a 2-3/8" or 60mm body, am I correct in thinking that the piston must be something like 55mm in diameter?

John B.


PS - Anybody know where to get a set of those swanky dual spring perches?

[Andrew Way]

All,

I've just received my front and rear Leda’s with 325lb/in springs for my HF3000. I've already got lots of questions....

For the rear, as there is no longer any steering requirement for the strut do I ditch the needle beading assembly and cut the nylon collar back flush with the beta top mount?

Has anyone got any experience with using the front Leda’s? I’m panicking! The HF3000 kit contains a few spacers to use on the top and bottom mount of the shock. The bottom mount of the shock is a perfect fit into the Hawk suspension arm so no worries; I’ll ditch the spacers from the kit. The top however is my area of concern. If you look at the attached photo (with Hawk spacers fitted) the bush on the shock is too wide. Can anyone see any reason why I shouldn’t cut the red tube of the chassis back (up to the weld) and reduce the length of the left hand spacer?

How much effect does the front tie rod length (as governed by the position of the rose joints thread) have on the position of the struts top mount. That is, if I adjust the top to suit the current position will it change if the tie rod is adjusted?

The Hawk has two sets of mounting holes on the chassis (front and rear) for most suspension components. Am I correct in using the upper position for road use?

Regarding the rose joints, for a starting point for suspension set-up is it best to wind them all fully in or half way in?

Sorry for all these questions, I hope someone can help. The manual doesn’t quite cover these issues…

Many thanks.

Andrew Way.

[chris.richard]

Yes, ditch the needle bearings and cut off the plastic bit back flush. You will also have to ream out the new upper spring pan a bit - see thread "telepathy"
I haven't got to the front yet, but I'm sure there was discussion about the spacers etc. on another thread

[Andrew Way]

Thanks Chris.

[rutthenut]

Originally posted by Andrew Way
The top however is my area of concern. If you look at the attached photo (with Hawk spacers fitted) the bush on the shock is too wide. Can anyone see any reason why I shouldn’t cut the red tube of the chassis back (up to the weld) and reduce the length of the left hand spacer?

How much effect does the front tie rod length (as governed by the position of the rose joints thread) have on the position of the struts top mount. That is, if I adjust the top to suit the current position will it change if the tie rod is adjusted?

Agree with Chris's comment on the rear shocks, lose the bearing and trim the plastic part to suit.

For the front, I'd suggest shortening, or replacing, the spacer rather than cutting back the tube from the chassis. Note that you don't want a solid flat surface against the side of the 'eye' on the shock, it should only contact the spherical bearing.

Adjusting the tie rod to change castor won't make much difference to the position of the upper mount for the front shock, but it can change the angle of the shock itself when viewed from the side - it will appear to tilt back if you put on plenty of castor. No problem with a slight angle when using rose-joint mountings at each end of the damper, but it can cause rubber bush types to shift out of alignment (did for me, anyway).

As for rose-joint adjustment, I'd suggest going for a half-way or two-thirds engaged position to start with. You are going to want to play around with these to get the geometry settings you want anyway.

For safety, I think the recommendation is to have at least one-and-a-half x D of thread engagement, so if a joint has a threaded section of 20mm diameter, aim for a minimum of 30mm inside the wishbone/arm. If someone knows of a different figure, then by all means post it here. I believe similar rules apply to the amount of engagement of wheel nuts onto exposed studs (but the hub does only accept about 10 or 12mm at the other end, which isn't so great).

I've not used the Leda front shocks (got AVOs on mine) but if you want to use the lower shock mounting point on the bottom arm, you may need to file out a bit of the lower arm 'cutout' for clearance with the 'back' of the shock, in the area of the threaded section for the spring seat. This would only show up with the suspension on full droop though. I think later suspension arms have more clearance than those on the earlier kits.

[Andrew Way]

John,

Many thanks for the reply. Following a read through the appropriately titled ‘telepathy’ thread I’ve removed the plastic part of the beta top mount and I’ve almost got enough thread to engage in the nylon part of the lock nut (which according to a lot of the comment in the thread means I’m doing well)!

Unfortunately my Leda front shocks came with rubber bushes not rose joints. This does however mean I can (almost) fit them up against a flat face. I’m not keen on cutting the tube on the chassis back but I can’t see any alternative short of some serious modifications to the shock. If I don’t make a modification the result is the shock is angled which will result in damage to the bush.

I agree with your comments regarding 1.5D of thread being the norm (above 2D gives negligible benefit) and 1D being the minimum. To start with I’ll set the rose joints 1/2 to 2/3 in, as you suggest (a good starting point anyway).

I did offer the shock up to the lower hole in the suspension arm but I’d have to make a similar modification to the one you mention to clear the back of the shock. Which set of holes is recommended for road use (front and back)? Presumable both holes still offer enough range for most suspension setting but just have a high / lower range.

Cheers,

Andrew.

[rutthenut]

Originally posted by Andrew Way
If I don’t make a modification the result is the shock is angled which will result in damage to the bush.
...
Which set of holes is recommended for road use (front and back)? Presumable both holes still offer enough range for most suspension setting but just have a high / lower range.

Note that a small angle in the position of the shock may not matter too much, so you might want to see how it comes out once you have set up the castor angle you desire. There might be a possibility to change the spacers at the bottom end of the shock to straighten it up a bit. But I guess there's not much room down there, so that may be a non-starter.

As for the choice of upper or lower mounting holes for road use, I'm not sure it makes so much difference really, as it can still depend upon the fitted spring length (and rating) and the position of the lower spring collar.

I think that there is a very minor advantage to be had in terms of suspension leverage by using the lower mount, as the shock will work in fractionally better angle (when viewed from the front). But when you work through the maths, it's probably not ever going to be noticeable. And I doubt that the spring rates are worked out to that sort of accuracy anyway.

The choice will depend upon the ride height that you want to run with at the front, against the spring length and platform height. You could get the same results using either set of mounting holes.

If you try to drop the front of the car too much, then you will find that the suspension arms start to travel in the wrong arcs and will have bump steer that is almost impossible to adjust out. With (much) stiffer springs, travel is reduced enough to avoid this problem. For road use, don't aim for too low a setting.

As for a simple recommendation, I think you'll be fine with the upper mounting holes - to start with at least. Then you can lower the spring pan to get the ride height you want (once the car has its loaded weight). If the car is too high at that stage, look to using the lower mounting points (or a shorter road spring).

Following that, you should then make finer adjustments to the spring platform to get the correct weight balance, although that would require access to corner-weight gauges or scales.

Not aiming to confuse, but there are so many options available, many desired outcomes, and multiple means to achieve them.

(edited to add)
Forgot to answer question about rear mounting points. These are less critical in terms of ride height, as that is mostly affected by spring length and platform position (again). If you use the upper position for the inner wishbone rose-joint, then it could lower the car a small amount, which I guess you might want. The theoretical 'roll centre' will also change, but I have no idea which setting would be 'best' for road use - I suspect it won't make any real difference in terms of geometry except under smooth circuit conditions.

[Andrew Way]

John,

Thanks again. I won’t dive in with the hacksaw just yet! For the time being (whilst I shunt the car around in the garage) I’ll fit the shock as is. Unfortunately there is no room to move the bottom mount backward/forwards as the rubber bush is the same width as the fabricated arm.

As far as setting the suspension up for road use I bet I’ll be posting hundreds of questions. The problem with everything being adjustable is its hard to know where to start……

Cheers,

Andrew.:confused:

[roger001]

Andrew, my chassis is an early spyder chassis, supplied with the old Koni dampers, which have the same rubber bush, and comparing your picture to my chassis the length of the "tube" attached to the chassis side appears the same, I would simply cut the spacer to allow enough room, if I can I'll post a pic of the offending area, if I remember to take the camera next time I'm heading up to the "barn"

[Andrew Way]

Roger,

If you do get a chance to take a picture it would be useful. It sounds like I may be making a mountain out of a molehill and simply modifying the spacer is the best answer.

Thanks.

Andrew.

[mogul_x]

Andrew,

I agree that modifying the spacers is the way to go. My HF3000 had a similar problem to what you are describing. Ended up having to make the following modifications:

1) Machine rear spacer at shock upper mount to make room for rose joint. When all of the suspension washers and spacers were installed, there was about 7mm in between the front and rear spacers. I needed 12mm to accomidate the rose joint.

Originally, I took 2.5mm off of both the front and the rear spacer tubes, but after assembling it, decided that the angle of the shock was too far forward. I ended up replacing the front spacer and taking more material off of the rear. I think the front spacer ended up being 7mm, and the rear 27mm, but I'm not sure. I could measure the final thickness of the spacers for you, but since your shocks have nylon bushes, your dimensions would probably be different anyway. Also, I haven't aligned my suspension yet, so it's possible that I'll need to change the dimensions again.

2) Machine new spacer for use between front upper suspension bushing and suspension bracket on frame. On my car, after installation, there was a 3mm gap between the control arm and the frame. Ineeded to make a thin spacer to fill the gap.

3) Grind "pocket" on lower control arm to fit shock body. On one side only, at full droop, the lower control arm was making hard contact against the side of the shock. I had to modify the mount as John R. described to ensure that that both sides of the car had equal travel, and that the shock was floating freely on the rose joints thoughout the suspension travel.

Also, I ended up mounting the front shocks in the lower hole, and the rear lower control arms in the upper hole. This was based on some feedback that I got on the forum some months ago, but I can't seem to find the thread now. I think this is how John told me his car was set up, but I might be mistaken.

[Andrew Way]

Scott,

Thanks for the info. I Think I’ll build the front up without any spacers in for now and wait until I get to set the suspension up before making any modifications. I don’t really want to grind / machine the pocket on the lower suspension arm (no that it’s been painted on top of the powder coat) but it’s looking like I’ll have to.....:(

Andrew.

[chris.richard]

My front suspension has been built without any spacers - what material should I make them of?

[mogul_x]

Chris,

The spacers supplied with my kit appear to be either white zinc or satin chrome plated steel. I don't imagine that it's very high strength - they machined very easily.

You could probably use any grade of mild steel, possibly even 6061-T6 Aluminum. Given that all of the parts that contact the spacers are steel, it might be best to stick with steel for the spacer material as well. A higher strength grade wouldn't hurt, but it may be harder to find.

I'd imagine that it would be less work to just ring Gerry and see if he can supply an assortment of spacers for you. He probably has a supply of them on hand. My car came with a few more spacers than were needed to mount the suspension, but they were all either 7.5mm, 10mm, or 34mm, if I recall correctly. If you want, I'll go out to the garage sometime and make a list of what sizes are used in which locations.

[Andrew Way]

My spacers are mild steel with zinc & colour passivate. From memory the shaft is 1/2" as a 1/2" UNF nut is used on the ends. So bore a 1/2" hole in 5/8" bar. If you can find any you may as well use some stainless so you don't have to worry about rust!

Andrew.

[roger001]

Piccie of the upper front mountings on an early transformer chassis, ussing bushed rather than spherical joints.

As promised

[Andrew Way]

Thanks Roger. This has confirmed what I expect to achieve.

Andrew.

[chris.richard]

What happens without them.

[roger001]

In the words of J McEnroe - "You can not be serious"