auszookers.com :: View topic - Random suspension and drive tech questions.......

3. I have 33" tyres ( which I have assumed measure 32" for the purposes of this question) and will have a ground to chassis clearance of about 600mm. Does this sound excessive? Its hard to visualise the stance of the vehicle when looking at a bare chassis :cry:

( if you have a similar setup, please share your figures)

That'll do for now donkey :wink:

Pete

Not to sure about most of the questions, but I do know my HQ Statesman was a pretty big car, quite long, and it had a single tail shaft, long time ago, but around the 6' mark, and look at the early american cruisers, they were near as long as a cricket pitch, and all single or one piece tail shafts.

Id be more inclined to be thinking along the lines that the longer the heavier it needs be to protect from distortion when being hit. That said, a two piece would be the go, but of course it will somewhat create its own problems with regard flex.

What help do you need with the geometry calculators? What type of links are you running? The 4 link calculator is pretty good, so is the 3 link one. If you plug your values in and see how it looks - post it up here and we can give you suggestions. For the CoG you can take a theoretical height of the top bolt of your bellhousing. The CoG is part of the you anti-squat calculations, but shouldnt alter your roll centre height, roll axis calculations. I still havent had a chance to have a look over your coil calculations yet sorry, just started back at work and been flat out.

Layto....

Any reason for the short links?
Layto....

just out of interest layto, what is a good anti squat to shoot for?

Round 70% AS should be okay.

My uppers have 3 adjustment holes. So range is from 70 to 100%. I dont know how its going to feel, So at least i can play abit.

Yeah your link lengths are playing a part of the pinion angle change. On the calculator it shows that your uppers are acutally 1" longer than you lowers, is that correct?

Layto....

LAY80N wrote:

Yeah your link lengths are playing a part of the pinion angle change. On the calculator it shows that your uppers are acutally 1" longer than you lowers, is that correct?

Layto....

No. That was a typo. I have changed it now :oops:

Author:	Fatzook [ Fri Jan 07, 2011 7:59 am ]
Post subject:	Random suspension and drive tech questions.......
Ok. I have a few Q's for the suspension and driveline gurus....... 1. How long can a driveshaft be before you should consider adding a centre bearing? 2. What is an acceptable distance between the bump stop and its landing on a coil sprung vehicle? (i know what I have planned is fine, this is just for reference. A measurement off a standard 4x4 would be great!) 3. I have 33" tyres ( which I have assumed measure 32" for the purposes of this question) and will have a ground to chassis clearance of about 600mm. EDIT: 535. Does this sound excessive? Its hard to visualise the stance of the vehicle when looking at a bare chassis ( if you have a similar setup, please share your figures) 4. Who knows what they are doing with those suspension geometry calculators? I have slapped my rear diff in 'by eye' and cycled it, and throughout its range of movement both driveshaft angles and clearances look fine. But I do plan to run a bit more power up this things ass eventually so I would like to confirm that my squat/ ant squat is not going to give me grief. That'll do for now donkey Pete

Author:	Red89 [ Fri Jan 07, 2011 8:17 am ]
Post subject:	Re: Randon suspension and drive tech questions.......
Fatzook wrote: 3. I have 33" tyres ( which I have assumed measure 32" for the purposes of this question) and will have a ground to chassis clearance of about 600mm. Does this sound excessive? Its hard to visualise the stance of the vehicle when looking at a bare chassis ( if you have a similar setup, please share your figures) That'll do for now donkey Pete 32 inch Simexs, leaf sprung, around 2 inch virtual lift in the front, 490mm chassis hieght on mine.

Author:	SuziBlu [ Fri Jan 07, 2011 8:18 am ]
Post subject:	Re: Randon suspension and drive tech questions.......
Not to sure about most of the questions, but I do know my HQ Statesman was a pretty big car, quite long, and it had a single tail shaft, long time ago, but around the 6' mark, and look at the early american cruisers, they were near as long as a cricket pitch, and all single or one piece tail shafts. Id be more inclined to be thinking along the lines that the longer the heavier it needs be to protect from distortion when being hit. That said, a two piece would be the go, but of course it will somewhat create its own problems with regard flex.

Author:	Red89 [ Fri Jan 07, 2011 8:28 am ]
Post subject:	Re: Randon suspension and drive tech questions.......
SuziBlu wrote: Not to sure about most of the questions, but I do know my HQ Statesman was a pretty big car, quite long, and it had a single tail shaft, long time ago, but around the 6' mark, and look at the early american cruisers, they were near as long as a cricket pitch, and all single or one piece tail shafts. Id be more inclined to be thinking along the lines that the longer the heavier it needs be to protect from distortion when being hit. That said, a two piece would be the go, but of course it will somewhat create its own problems with regard flex. x2 alot of the Hilux guys swap the 2 piece one out for a single piece one, as the bearing chews out pretty quickly.

Author:	Fatzook [ Fri Jan 07, 2011 9:57 am ]
Post subject:	Re: Randon suspension and drive tech questions.......
Ok, so It sounds like the driveshaft will be fine (895mm) without a centre bearing. Any opinions on the other matters?

auszookers.com https://auszookers.com/forum/

Random suspension and drive tech questions....... https://auszookers.com/forum/viewtopic.php?f=5&t=18061	Page 1 of 1

Author:	LAY80N [ Fri Jan 07, 2011 11:47 am ]
Post subject:	Re: Random suspension and drive tech questions.......
What help do you need with the geometry calculators? What type of links are you running? The 4 link calculator is pretty good, so is the 3 link one. If you plug your values in and see how it looks - post it up here and we can give you suggestions. For the CoG you can take a theoretical height of the top bolt of your bellhousing. The CoG is part of the you anti-squat calculations, but shouldnt alter your roll centre height, roll axis calculations. I still havent had a chance to have a look over your coil calculations yet sorry, just started back at work and been flat out. Layto....

Author:	Fatzook [ Fri Jan 07, 2011 11:51 am ]
Post subject:	Re: Random suspension and drive tech questions.......
opinions please The pinion angle changes less than 1 degree throughout the cycle. I'm pretty happy with that. Just for reference, thelinks are very short. Upper= 400mm, lower=465

Author:	Fatzook [ Fri Jan 07, 2011 12:00 pm ]
Post subject:	Re: Random suspension and drive tech questions.......
LAY80N wrote: What help do you need with the geometry calculators? What type of links are you running? The 4 link calculator is pretty good, so is the 3 link one. If you plug your values in and see how it looks - post it up here and we can give you suggestions. For the CoG you can take a theoretical height of the top bolt of your bellhousing. The CoG is part of the you anti-squat calculations, but shouldnt alter your roll centre height, roll axis calculations. I still havent had a chance to have a look over your coil calculations yet sorry, just started back at work and been flat out. Layto.... I'm running 4 link rear (triangulated uppers, parallel lowers) And 3 link front with panhard (single triangulated upper, parralel lowers) COG was assumed as you suggested. And don't stress about the coil calcs. Cheers Peter

Author:	LAY80N [ Fri Jan 07, 2011 12:07 pm ]
Post subject:	Re: Random suspension and drive tech questions.......
I prefer to have the seperation at the chassis about half to three quarters of that on the diff. This along with the difference in length (~75%) from uppers to lowers helps determine the AS value as well as the change to match the suspension position (increase and decrease of AS from full droop to full bump. Also having the lowers inline with the axle centreline will give your upper link bush's a fair workout. If you look at factory suspension designs that are designed for long term road use they will have the lowers a few inches below the centreline, as well as a difference in vert. seperation front to back. The lack of clearance can be a pain though so its up to you how you go. Pn the axle line will still work fine. I will throw your numbers in and see what other tings may come out tomorrow evening, gotta go to a wedding tomorrow afternoon. Dont be too concerned with a bit of pinion angle change. A few degrees isnt the end of the world. Your anti-squat is pretty low (though it is just an estimate due to CoG approximation) but often its a personal preference. Roll centre height is okay, depending on the application the height of the tyres is an okay rough rule of thumb. For street driving slight roll understeer is prefered to help the vehicle stability and mid corner behaviour. This is sometimes hard to achive in full body rigs, so as neutral as possible is good. The closer you can get your roll centre to the CoG, the more stable the rig will be on side slopes and cornering, but as a trade off the higher the roll centre the more the body has to shift "sideways" when one rear wheel hits a bump. This can make the rear of the car feel a bit like its swaying at speed, as well as make the rear suspesnion less compliant over general potholes and simillar things. Any reason for the short links? Like everything, no matter how good it looks on paper it will be a compromise as to what fits on the car, and your personal preferences. Layto....

Author:	LAY80N [ Fri Jan 07, 2011 12:11 pm ]
Post subject:	Re: Random suspension and drive tech questions.......
If you have some (Shitloads acutally) spare time, this thread is pretty good reading. http://www.pirate4x4.com/forum/showthread.php?t=168577 Layto....

Author:	Fatzook [ Fri Jan 07, 2011 12:33 pm ]
Post subject:	Re: Random suspension and drive tech questions.......
LAY80N wrote: Any reason for the short links? Layto.... Yep. Its a DD and a work ute, so I don't need massive travel. (10" would be heaps!) Also I am using OEM arms to cut down on the engineering issues. Lowers are surf lowers, uppers are GQ uppers. I couldn't find any GQ lowers cos they always snap like twigs while still fitted to the GQ's I'll try and drop my axle end lowers and drop my frame end uppers.

Author:	LAY80N [ Fri Jan 07, 2011 12:38 pm ]
Post subject:	Re: Random suspension and drive tech questions.......
Sweet. If its a DD then the slight loss of ground clearance will not really matter, and the life expectancy of the bush's will improve. With low travel the shorter links should be fine too. In all honesty it will probably work fine as it is in the end. The link differences and AS variations usually come into play on the noise up climbs and stuff, which im guessing is note the intended use of your work car haha. Look at the chassis end upper mounts and see if you can drop them a bit, getting rid of the almost infinate instant centre. But dont stress about it too much. Link geometry is usually a huge compromise between what the computer says and what actually fits, unless you are building a ground up buggy. Looking at something for DD perspective is strange, everything i look at has to either get abused offroad, or go round corners on a circuit hard. Layto....

Author:	Fatzook [ Fri Jan 07, 2011 12:56 pm ]
Post subject:	Re: Random suspension and drive tech questions.......
Ok. I dropped the lower axle mount 1" and droped the upper frame mount about 5mm bringing the instant centre close to the front of the car.

Author:	LAY80N [ Fri Jan 07, 2011 1:09 pm ]
Post subject:	Re: Random suspension and drive tech questions.......
Can you drop the upper chassis any more? Round 70% AS should be okay. Is there any way to inboard the lower chassis mount, this will help the roll axis flatten out a bit more? Either way it looks okay. You could build some adjustability into the mounts if you wanted, the last one i did has 3 different mounting points for the upper chassis mount. I will find the calc for that rear end, but we have had no trouble with axle hop on TT style cources at full noise from a tuned 1UZ. Looking at your link lengths in the above diagram, your uppers are acutally longer by about an inch to your lowers too. Is that correct? Layto....

Page 1 of 1	All times are UTC + 9:30 hours
Powered by phpBB® Forum Software © phpBB Group https://www.phpbb.com/

Author:	Fatzook [ Fri Jan 07, 2011 1:31 pm ]
Post subject:	Re: Random suspension and drive tech questions.......
If I bring my frame end upperd down at all, the pinion angle skyrocket during compression cycle..... 8 degrees or more at 5" Sees similar at 10" dropp too. I think my short arms are causing most of this, but thats just one of the compromises. Just playing with the calc I have managed to achieve +1 degree roll axis at static height, with roll understeer achieved at any stage of compression. Given that its a trayback ute I think this is acceptable.

Author:	93zook [ Fri Jan 07, 2011 1:41 pm ]
Post subject:	Re: Random suspension and drive tech questions.......
just out of interest layto, what is a good anti squat to shoot for?

Author:	Fatzook [ Fri Jan 07, 2011 1:53 pm ]
Post subject:	Re: Random suspension and drive tech questions.......
93zook wrote: just out of interest layto, what is a good anti squat to shoot for? LAY80N wrote: Round 70% AS should be okay. My calcs have me at 75%. close enough.

Author:	BlueSuzy [ Fri Jan 07, 2011 1:57 pm ]
Post subject:	Re: Random suspension and drive tech questions.......
My uppers have 3 adjustment holes. So range is from 70 to 100%. I dont know how its going to feel, So at least i can play abit.

Author:	Fatzook [ Fri Jan 07, 2011 2:07 pm ]
Post subject:	Re: Random suspension and drive tech questions.......
BlueSuzy wrote: My uppers have 3 adjustment holes. So range is from 70 to 100%. I dont know how its going to feel, So at least i can play abit. Yeah I might do the same.

Author:	LAY80N [ Fri Jan 07, 2011 10:32 pm ]
Post subject:	Re: Random suspension and drive tech questions.......
There is no perfect AS number. But basically the lower the number the less chance of hopping you will have under throttle. The lower the better for a rough rule. Keep it under 100% or you will start to have toruble when getting on the gas under climbing. Getting it below 80% would be a good goal, but id really depends on what locations options you have if you are keeping a full body. Build some adjustment in and have a try how it feels. Remember that unless you have an accurate CoG calculated, the AS value that spits out will only be an approximation. Yeah your link lengths are playing a part of the pinion angle change. On the calculator it shows that your uppers are acutally 1" longer than you lowers, is that correct? Layto....

Author:	Fatzook [ Fri Jan 07, 2011 10:46 pm ]
Post subject:	Re: Random suspension and drive tech questions.......
LAY80N wrote: Yeah your link lengths are playing a part of the pinion angle change. On the calculator it shows that your uppers are acutally 1" longer than you lowers, is that correct? Layto.... No. That was a typo. I have changed it now

Author:	Fatzook [ Sat Jan 08, 2011 9:45 am ]
Post subject:	Re: Random suspension and drive tech questions.......
Fatzook wrote: LAY80N wrote: Yeah your link lengths are playing a part of the pinion angle change. On the calculator it shows that your uppers are acutally 1" longer than you lowers, is that correct? Layto.... No. That was a typo. I have changed it now Where I am at.... I can't really lower the tops too much as the x-member that they hang from may interfere with the rear driveshaft. I'll get a pic to better demonstrate the clearance issues tomorrow.