Torsional Rigidity
Discussion
Adam, thats a great photo and clearly shows a lot about how the test is to be conducted. From that photo you can start to plan a strategy about how to pas it. Little things can be easily done to improve the performance in the test.
From the photo It looks like the chassis is suspended from the hubs, solid bars are then used to replace the springs and shock absorbers. It also appears that you are able to test with the engine in place.
Given the above, the following things should give you a benefit in the test.
-Install solid engine and gearbox mounts that have absolutely no play in them. This will allow the engine to function as a stressed member during the test. You may then be able to remove these at a later date to provide better noise and vibration control.
-install suspension wishbones with solid rose joints, uniballs or spherical bearings. Any compliance in the suspension bushings is going to show up as extra distortion in the chassis test. Make sure that the bolts in the suspension are all of the correct design and do not have any threads in the load bearing areas as these will quickly distort where the threads are under the loads. Again giving you a false reading.
-check and make sure that wheel bearings are torque correctly and have no play.
There are other things that could also improve the results, however I do not wish to discuss them on an open forum, i would after all like to place an order in the future.
From the photo It looks like the chassis is suspended from the hubs, solid bars are then used to replace the springs and shock absorbers. It also appears that you are able to test with the engine in place.
Given the above, the following things should give you a benefit in the test.
-Install solid engine and gearbox mounts that have absolutely no play in them. This will allow the engine to function as a stressed member during the test. You may then be able to remove these at a later date to provide better noise and vibration control.
-install suspension wishbones with solid rose joints, uniballs or spherical bearings. Any compliance in the suspension bushings is going to show up as extra distortion in the chassis test. Make sure that the bolts in the suspension are all of the correct design and do not have any threads in the load bearing areas as these will quickly distort where the threads are under the loads. Again giving you a false reading.
-check and make sure that wheel bearings are torque correctly and have no play.
There are other things that could also improve the results, however I do not wish to discuss them on an open forum, i would after all like to place an order in the future.
Edited by ezakimak on Friday 24th July 02:45
deadscoob said:
I meant his performance tests, not stiffness - braking, handling etc which were affected by altered compnonents which were quite different from stock. Special shocks, rejigged wishbones, extra caster, special brakes and wheels etc. Significant changes which appeared to make little difference.
Was there back to back tests done with another std Ultima then?G'day guys,
I've just stared an Ultima GTR build in Melbourne and would like to stay in the loop with the ICV registration process. If you haven't found this link on the testing procedure here it is. http://www.infrastructure.gov.au/roads/vehicle_reg...
I would expect that this is the national standard and that the individual states and territories would adhere to it.
Cheers
I've just stared an Ultima GTR build in Melbourne and would like to stay in the loop with the ICV registration process. If you haven't found this link on the testing procedure here it is. http://www.infrastructure.gov.au/roads/vehicle_reg...
I would expect that this is the national standard and that the individual states and territories would adhere to it.
Cheers
Hi all,
Coincidentally I have just finished having the test completed on my chassis.
On our test bed, the factory supplied chassis came in just under 4200Nm (4180 to be exact)
We fabricated a simple cross brace to the engine bay and this pushed it up to 5800nm.
I haven't any photos of the brace as it was very rudimentary and temporary.
I will fabricate the final brace once the engine is installed to make sure I have clearances correct.
In addition to the engine bay brace I have inserted bushes into the diaphragm second from the rear of the chassis. These will allow for removable braces to be bolted in and thus triangulate that section of the chassis. Even though we could pass the test easily, we noticed some distortion in this area.
In a nutshell, it is easy to get the torsional rigidity beyond 6000Nm
Although VSB14LT (the regulations that detail torsional rigidity in Australia) requires 4oooNm and doesn't mention engine capacity etc. WA, QLD and Vic have all agreed to 6000Nm for any vehicle fitted with an engine greater than 4 cyl. This supplement to regs is enforced in these 3 states, I believe NSW is the same, but I can't confirm.
There are moves underway to have this lifted to 8000Nm in future (when ? who knows...)
I will upload a photo of the bushes once I get back to the workshop.
Alan May (Ultima in NSW) and I have agreed to share costs involved in the testing procedures etc, if you are interested in joining our little co-op, just let me know
Cheer
Adam
Aluminium panels are bonded and riveted in place. Steering, suspension and brakes are on. Substituted a rigid brace for dampeners. The whole thing is held down by the hubs and pressure applied to one corner. We had 6 dial guages along the length of the chassis on each side and measured the "flex" as pressure was applied.
The tester felt the fitment of the cockpit will add a little once in place. Engine/trans will make no difference due to rubber mounts.
I'm toying with the idea of doing all of Jay's suggested mods, just for the exercise.
I figure the stiffer the chassis the better....
Cheers
Adam
The tester felt the fitment of the cockpit will add a little once in place. Engine/trans will make no difference due to rubber mounts.
I'm toying with the idea of doing all of Jay's suggested mods, just for the exercise.
I figure the stiffer the chassis the better....
Cheers
Adam
GTRCLIVE said:
Yes std chassis is not very high at all....
I was told the same at the Autosport show by engineers from Radical, they mentioned liquorice and Ultima Chassis in the same sentence but I had just put it down to rivally at the time.Perhaps not...
Anyhow, GTR's still go round the top gear track fastest.
Ok I have just read through the thread again, and feel I have to clear something up after re-reading my previous post.
I don’t have a problem with the Ultima Chassis. It’s a fine product and it’s designed around its builders and the cars performance.
I am however aware that should I be in a position to build an Ultima in the future it will probably have to go through that beaming and torsion testing that we have to do in Australia. So I am mindful that I will need to make it jump through hoops to get it on the road. This is all that I care about initially. Getting it on the road as quickly and easily as possible.
In response to the torsion rigidity issue, I have located a source for aluminium honeycomb panels. They are able to do them in a variety of thicknesses and can do them curved at additional cost.
You can also get them with a stainless steel skin as well. I was thinking that this might be a good idea as I could get one side alloy and one side stainless. You would have to mill the bits of stainless (or alloy) off on the edges where it needs to overlap the chassis and then fit the panel into the opening in the chassis. Glue and rivet as normal. The panel – by virtue of its honeycomb nature will be stiffer, and the stainless skin on the back side would reduce the heat transfer into the cockpit from the engine bay. Haven’t worked out how much extra it would weigh but it’s another possibility.
Ryan
I don’t have a problem with the Ultima Chassis. It’s a fine product and it’s designed around its builders and the cars performance.
I am however aware that should I be in a position to build an Ultima in the future it will probably have to go through that beaming and torsion testing that we have to do in Australia. So I am mindful that I will need to make it jump through hoops to get it on the road. This is all that I care about initially. Getting it on the road as quickly and easily as possible.
In response to the torsion rigidity issue, I have located a source for aluminium honeycomb panels. They are able to do them in a variety of thicknesses and can do them curved at additional cost.
You can also get them with a stainless steel skin as well. I was thinking that this might be a good idea as I could get one side alloy and one side stainless. You would have to mill the bits of stainless (or alloy) off on the edges where it needs to overlap the chassis and then fit the panel into the opening in the chassis. Glue and rivet as normal. The panel – by virtue of its honeycomb nature will be stiffer, and the stainless skin on the back side would reduce the heat transfer into the cockpit from the engine bay. Haven’t worked out how much extra it would weigh but it’s another possibility.
Ryan
HurryUp said:
G'day guys,
I've just stared an Ultima GTR build in Melbourne
http://www.infrastructure.gov.au/roads/vehicle_reg...
Thanks For that, Ryan In Melbourne.I've just stared an Ultima GTR build in Melbourne
http://www.infrastructure.gov.au/roads/vehicle_reg...
ezakimak said:
Proposed using honeycomb panels instead of skinning
I agree these panels will be very strong and stiff and add significant strength to the chassis.However, purely from an eyeball stress analysis I don't think many of the ali skins are having much effect on torsional stiffness. On that basis I would suggest doing a very simplistic FEA CAD model to find which panels are worth replacing with honeycomb and which can be left as ali. It may also show benefits in skinning areas that are currently not skinned.
Steve
Gassing Station | Ultima | Top of Page | What's New | My Stuff