Anti-vibration upgrades with some graphs

JamesLaugesen

Hi everyone!

Here's some rough vibration graphs, which I'm hoping will make for an interesting comparison after some upgrades.

These were recorded with an iPhone 4 (3-axis accelerometer), laying on the gearbox-tunnel cover, held with a velcro strap.

The Niva is a 1992 1600 in good condition, with everything correctly aligned, balanced, tightened & greased, no cracks near gearbox & TC mounts, all new bushes and rubber mounts, etc.
The body has ~20mm of new insulation + 15mm extra under the plastic gearbox tunnel cover, plus some foam on top of the plastic. So the high-frequency vibration/sound through the body & plastic is minimal.

All samples are 5.12 seconds at 50Hz with compensation for gravity.
Car is raised on stands and suspension hanging at full extension, so wheels are free to spin.

I repeated each sample 4 times over a couple of days just to minimize anomalies.
The results were very consistent so I didn't bother averaging them.

First some baselines with the gearbox output disengaged:

~600rpm (slowest smooth idle I could get), gearbox neutral;

3000rpm, gearbox neutral;

With the gearbox in gear and the transfer-case in neutral, so the doughnut is spinning:

3000rpm, gearbox 1st, transfer-case neutral;

I can't explain the changing pattern, it happened every time I did this sample. I guess there might be a pattern if I took a longer sample.

3000rpm, gearbox 4th, transfer-case neutral;

3000rpm, gearbox 5th, transfer-case neutral;

Now the dangerous ones ( Laughing

), in gear, transfer-case in high range, with diff locked (so all 4 wheels are spinning equally):

3000rpm, 1st gear, high-range, all wheels spinning;

3000rpm, 4th gear, high-range, all wheels spinning;

3000rpm, 5th gear, high-range, all wheels spinning;

0rpm to 3000rpm to 0rpm, 5th gear, high-range, all wheels spinning;

I think the Z-axis (yellow) is stronger due to the phone being held down by a strap.
These clearly show the increase in vibration due to the gearbox/transfer-case connection, and again with the wheels spinning.
I thought of doing another test with the wheels removed, but they've just been balanced with new tyres so I don't think they're significant.

Next I'm installing these new gadgets one-by-one, and will re-do the same tests each time;

That's a rear drive shaft with CVs, intermediate joint with CV (just the standard one from late model nivas), and front axle disconnect unit.

These are from LadaWorld.com. Stig is a good guy, have no fear about shopping from the other side of the world.
He's better to deal with than most of the russian sellers, and I guess he doesn't have the same export concerns too, because my stuff arrived within a couple of weeks (including a stop in our customs.).

I was also thinking of recording some other cars for comparison, if I have time.
So lemmie know if you're particularly interested in seeing them.
I could do my Jackaroo (Isuzu Trooper), holdem commodore VL, bently turbo R and a few jags.
I think It'd be cool to see the Bently comparison haha.

Cheers

JamesLaugesen · Posted: Sun Mar 27, 2011 10:17 am Post subject:

Ps, here's Stig's comment regarding the products he sells that could potentially reduce vibration/noise.

baxter · Posted: Mon Mar 28, 2011 5:27 am Post subject:

Yep, I'm totally betting on the CV between the 'box and TC making the biggest difference. Smile

JamesLaugesen · Posted: Mon Mar 28, 2011 5:46 am Post subject:

Neil Chowney · Posted: Mon Mar 28, 2011 5:26 pm Post subject:

Why doe sthe rear prop have a saving of 40% yet the front, which is basically the same, only has 5%?

Is this specifically for your car and is therefore an indication of the overall condition of the joints you already have fitted?

This is very interesting though, I have often wondered where the vibes came from.

The transfer case UJ/CV replacement will also get my vote as well.

Incidentally, how much are the parts?

CV, Doughnut, rear prop?

JamesLaugesen · Posted: Mon Mar 28, 2011 9:56 pm Post subject:

JamesLaugesen · Posted: Tue Mar 29, 2011 9:40 am Post subject:

CV prop shaft is on the rear.

3000rpm, 4th gear, high-range, all wheels spinning;

BEFORE:

AFTER:

3000rpm, 5th gear, high-range, all wheels spinning;

BEFORE:

AFTER:

I re-did "before" tests 3 times each and got close to exactly the same results as in the original post.
Then I re-did the "after" tests 3 times each and got the same (in terms of RMS) results each time.

There's a clear reduction (significantly lower RMS Mag.), which is kinda cool.

It's interesting that the X axis (red) has increased. I suspect that it's something to do with how I placed the phone this time, but I re-did it a few times after repositioning and got the same result, so I dunno.

BUT there's a problem!
After the tests I checked the new CV prop and found the TC-side flanges (on the CV & TC output shaft) were very hot.
So I'm concerned that the CV might not be greased (unlikely, it felt pretty smooth), otherwise the almost new TC output shaft bearing is probably dead, which means all these tests are stuffed!

I'll remove the prop and do some tests without it to try to gauge how much the TC output contributes to the vibrations recorded so far.

Bugga! Laughing

simonallen · Posted: Tue Mar 29, 2011 5:57 pm Post subject:

Thos cv's do get hot. My v6 niva, the gearbox mount collapsed and cause the back end of it to drop down. I bodged it to get me going again but the transfer box was out of alignment. By the time I had done the 50 miles to get home, the cv joint had boiled it's grease out and was making a horrible noise. They just aren't made for running at an angle and I fear that if you're running a lift as well their lifespan will not be very long at all. Over here I think they are £80 a joint as well, so not cheap by any means!

JamesLaugesen · Posted: Wed Mar 30, 2011 9:59 am Post subject:

JamesLaugesen · Posted: Mon Apr 04, 2011 10:50 pm Post subject:

Just a quick update, I've driven a couple of KM of windy hilly roads with the CV-prop (still haven't installed the other stuff) and there is a definite improvement.

Noticeably less vibration during acceleration and engine-breaking.

Unfortunately I don't have any smooth roads nearby to get any meaningful on-road measurements, so I can't prove it.

I've got a few urgent things to sort out for renewing rego, then I'll get back into this stuff.

nivapulledout · Posted: Fri Apr 08, 2011 5:19 pm Post subject:

Cool work James.

I was keen on getting these cardin/CV shafts as well but forgot all about them. I have done a lift as well so the angle will be increased on the rear. Sad

However I never knew the newer Nivas had a CV donut, and did not really want to go to the hassel of making one out of a SPAM CV.
How much was the shipping to Aussie?

will keep an eye on your results, I think you will get the biggest difference from the TC-GB CV joint.

JamesLaugesen · Posted: Sun Apr 10, 2011 10:37 pm Post subject:

nivapulledout · Posted: Fri Apr 15, 2011 8:06 pm Post subject:

I can feel another purchase coming up (if I can sneak it past the wifey) Very Happy

JamesLaugesen · Posted: Sun Apr 17, 2011 11:29 pm Post subject:

CV-donut joint is back together and installed with the TC.
I didn't align the TC "properly" because I want to compare rough alignment vs careful alignment.
So I just found the combinations of spacers which I have available which gave the most freely-spinning CV-donut joint, then ran it for a while to let the TC find it's place.

3000rpm, gearbox 5th, transfer-case neutral;

BEFORE (TC carefully aligned with unbalanced UJ-donut in good condition);

AFTER (TC roughly aligned with new ex-balanced CV-donut);

Clearly a big improvement ay, RMS Magnitude down from 0.299g to 0.137g Very Happy

I've written the new CV-donut as "ex-balanced" because my destruction & reconstruction has probably upset it's balance.

Now comparing the 'after', with the original "3000rpm, gearbox neutral;"

RMS Mag down from 0.168g to 0.137g... that's interesting, but not statistically significant because these measurements should have a margin of error around 0.05g.
It has got me thinking though, so I'll do another 'after' test, 3000rpm GB neutral vs GB 5th TC neutral. Maybe the TC is dampening vibrations from the engine, clutch & GB input.

I did an experiment to see how much difference the balance of the CV-donut makes.
I added an thin 1/2" washer to a bolt on the donut to unbalance it (maybe ~15 grams?).
But I wasn't brave enough to accelerate to 3000rpm 5th gear and do a measurement Laughing

!
Vibration was worse than with the original UJ-donut - And very consistent, directly proportional to RPM.
So from that I (think?) we can conclude that my original unbalance UJ-donut was still less than ~15grams(?) out of balance.
And, (I think?) the unbalance I created made more difference than the improvement offered by the CV (not including real-world driving.).

So to anyone with consistent vibration issues (getting progressively worse through all RPM), I would suggest (aside from the usual alignment, fix cracked floor, etc) that you try to balance the donut joint (everything that spins).

I'm going to test the balance of mine (after possibly upsetting it) by adding some very thin shim washers (like ~2g?) to different bolts on the donut, and see if I can reduce vibration further.

I had another interesting problem, after my first attempting reassembling the CV-donut I had EXTREME vibrations happening suddenly, around ~2000rpm 5th gear.
So from 0-2000rpm everything is very very smooth, then immediately after ~2000rpm, BOOM!! If I didn't drop the RPM immediately, I'm sure something would break.
The problem was the CV sliding on it's spline, moving away from the donut, and I assume (happened too fast for my iPhone camera to pick up haha) being able to wobble around on the end of the spline.
The CV is held onto the spline by a snap-ring (or maybe it's just a "ring"... there's not much snap to it), and in my case it had un-snapped from it's groove, allowing the CV to slide back.

What I couldn't figure out (woulda been cool to have a high-speed video camera haha) is if the CV was simpling moving away from the doughnut, place the TC & CV joint on a greater angle, and creating the vibration. Or if the CV was actually getting after enough off the shaft to wobble.
So I'd suggest anyone with a CV-donut & unpredictable vibration to check that the CV can not move along it's splined shaft (ie, move away/towards the donut).

Also the front axle disconnect seems to work great, it looks & functions absolutely 100% OEM.
ie, the diff-lock lever now moves through 3 settings, with approximately the same amount of movement as stock, so the lever & rubber boot move together fine.
The positions are;
* Foward - RWD (Front output disconnected).
* Middle - "4WD" (Center diff locked + warning lamp on).
* Rear - "AWD" (Center diff unlocked).
The engagements are less smooth than my original unit, but it probably just needs grinding in Laughing

; I can change between all 3 settings while driving straight ahead with a quick blip of the throttle while applying light pressure to the lever (like a couple of fingers, not a whole hand).
At first I thought it would be annoying with the center diff locked in the middle position, but it actually works out great; since the lever has less travel between settings, it's easy to change between RWD & "AWD" (ie foward & back, just like standard), but a little bit fiddly to stop in the middle & lock the diff - Which I think is a good thing.

My niva hasn't got any brakes at the moment, so I haven't done a road test.
But driving around the property (up to about ~60km/hr on rough dirt) everything feels much smoother, especially under acceleration.
RWD is damn fun(!!!) and lightens the steering, but I haven't noticed any noise/vibration reduction yet (pretty hard on my tracks & driveway.).

Next up I need to fix a few unrelated things (brakes Laughing

), then I'll do some road tests and a ~1500km trip over easter, and I'll compare 2WD vs AWD fuel consumption if we do enough highway driving.

nivaman · Posted: Mon Apr 18, 2011 4:45 am Post subject:

Would be good to hear how you got on.
When i made the front diff mount for my Fiva, i made it too weak and it bent.
What this did was pulled the back of the diff up and rocked the t/c forward and that pulled the CV off its spline.
I fixed that by mounting the t/c with four mounts and welding the spline to the CV, fixing it in place as once it was loose it always popped out when the t/c moved on its two mounts.
This resulted in a smoothest Niva i have had, not to mention i had also fitted a Fiat 131 gearbox in place of the Lada original.

JamesLaugesen · Posted: Mon Apr 18, 2011 5:26 am Post subject:

JamesLaugesen · Posted: Sun May 01, 2011 11:27 pm Post subject:

An update

So far I've driven about ~500km on sealed roads and ~200km on dirt with these mods, and it's driving soo soo smooth!

Previously during a typical trip (going to the shops or something), there would be a few very obvious "phases" of vibration.
I'm sure everyone who drives a Niva has the same thing haha.
Like, "Yeep, there's that 'accelerating hard from a traffic-light' vibration", etc.

That's all gone now (or at-least isn't any worse or more noticeable than my other cars.).

It is still pretty noisy (higher freq. than vibration).
I'm putting that down to an old after-market stainless exhaust system with dying muffler, and low-pitch rumble from the rear end (I think is the brake drums.).

JamesLaugesen · Posted: Wed Feb 01, 2012 1:45 am Post subject:

Hi everyone, sorry for reviving this thread, but it seems the most appropriate place to let you all know that my Lada (the anti-vibration/noise project) is up for sale.

I'm NOT trying to advertise, so please don't kill this post haha.

Due to changed circumstances (far less time & a bit more money Laughing

) I've turned to the dark side and bought something big and fancy.
So now I'm genuinely looking for someone who wants to take the Lada and keep running with the project.

I'm not out to recoup any costs (that'll never happen!), it'd just be a shame if it lived the rest of it's life being driven up my driveway to check the letterbox Laughing

.

PM me if interested.

Cheers!