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rebuilt diff howling


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After rebuilding my tr6 diff with new bearings and seals and hoping that I had got the various preloads and contact pattern right,it seems that I hadn't as the diff is now howling at speeds above 30mph,and does it when both accelerating and decelerating.

When my depression eases I intend removing the b*****d again and give it one final chance to behave, otherwise I`ll have to exchange it for a recon one.

What does anyone think of the contact pattern images, I thought that they were ok but now I`m not sure and I think that this could be the source of the noise.

Dave 

contact pattern 5.JPG

as fitted.JPG

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I'm no expert Dave but they don't look too bad to me.  If it's any help, here are the contact patterns that I got when I rebuilt mine last year and so far (2K miles on) it seems ok.

FWIW, I have in the past had success with some stuff called Faher Anti Friction HD (http://www.faher.co.uk/anti-friction-hd/)  It really does work but don't use it on an LSD or in an overdrive because it reduces friction so much that they stop working.  If you are at the point of going for a recon unit, you have nothing to lose for a tenner for a small bottle.

Rgds Ian

Final Setting #1.jpg

Final Setting #2.jpg

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Hi Ian, doesn't seem to be a lot of difference between your contact pattern and mine, possibly your pinion is maybe a bit deeper in the crownwheel,  towards the heel, which means I think that I need a thicker pinion shim.

I may try that if I decide to strip it again.                                                                                                                                                                                                                                    

Dave

 

 

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Hi Tom

            Crownwheel backlash was approx  4/5 thou, but one thing I`ve just discovered after removing the diff today and measuring the pinion preload of 

the complete unit, without yet stripping it, is that it is only around 18lb/inch.

The preload of the pinion alone should be 15-18lb/inch according to the bible , without including the preload of the carrier and bearings and the drag of the pinion seal and crownwheel,so this preload is probably too low.I originally set it using a lb weight and a measured length of iron bar,this doesn't seem an accurate method, but I`ve now got hold of a lb/inch torque wrench so I may have another go.

Dave

 

 

 

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Dave,

I've found that the preload drops off pretty rapidly with use.  When I set my diff up the first time, (with a 3.7:1 CW&P) I set the preload up correctly but when I subsequently stripped it after not many miles to install a 3.45:1 CW&P set, the preload had virtually disappeared.  For the 3.45 unit and based on some advice from GT6M (Marcus) I set the preload at the very top end of the range.  As he pointed out, there is some hefty torque going through the unit and trying to force the CW&P apart.  The preload is there to try and ensure that the gears stay fully engaged.

Rgds Ian

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Ello Dave, welcom t,the  tired best I can, in spec, good pattern, but noisey Club.,

them patterns look ok t,me,  if with oot load on em,

wid load on em, then the pattern should go up the tooth a wee bit

{bigg pry bar wacked into housing an CW, turn wid a breaker bar , BUTT, cant doo this ona collapse spacer type, as it may crush it up, orrid thingys }

 

ev a good look at the teeth face, see if there an indented area where  the 2 wer running t,gither originally,

yours looks ok, but  best t,check.

If there is, then im afraid it,ll ev t,go back to that OE  took apart., as if  moved CW, or pin, it,ll be running on either side of a ..trough,or hollow, an it,ll wine,  some times they rattle, on v v slow speed in a electric drill,

thats a good indicator ive fun oot, that it,ll be noisey

 

putt,n it so its quiet, may mean yer running 10-35 thou, or even moer  backlash.

as a worn diff CANT be put back t,factory set,ns

 

BUTT, a 2 thou shim, either on CW, in or oot of mesh can ev a biggggg effect

or a 2 thou pin shim, although the backlash hardly alters, the noise levels go up alot.

 

So, thats gonna be a shim in ya side, leave pin, test

noisey, as below., till its quieter.

shim in other side, leave pin, test

then sim in  ya side, an pin, test,

other side, an pin, test,

nee shim on CW, one int pin, test

its a long hard drawn oot effort, an still it,ll no be spot on.,grrrrrrrr.

 

Its a real pain ev,n t tek every thing apart, this why solid spacers are a boon,

hoo many collapsable type would ye go thru if its in /oot a dozen or moer times,!!!

 

All I can say is try the slightest of shims t,see what it does,

ALSO, mek sure that the nut tourque is the same for all tests,

as just tightening the nut up lightly,  then pin height will alter whenst its really tight, by at least 2 thou.

if it runs quiet wid yer MK1 Lug Ole listening intently  on diff whilst its running,

running slow,an fast, offload an on loadings, as it meks a difference load does,

and cant here owt, its fine,

hear owt other wise,  like it rattlin at v v low speed wid yer electric , or batt  drill in top gear an going slow,      then it wont be, !!!

 

{ I got a diff at Stonehenge show on Sunday, paid 140£ for it,

seemed ok, bit of play, but ev spent 3 nights at it, an binned the CW/P last night.

73 thou backlash befoer I got it t,bits,  an pattern on it wer ok,

butt trying t,set it  tighter, it rattles , and pattern aint there, it just disapears, faint specs on ya side,

as its riding on the edge oft trought / hollow.

runs quiet at 73 thou, but farr too much clonk on tek up, it,ll brek teeth off .}

 

Any one want a good looking ,worn 3.45 CW/P for free,!!!

 

some consolation for ye,

I spent a looooooong time on me own, just forit, t,whine owa 50-55 , its coming oot too.

 

M

 

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Ian/Marcus

Stripped diff again today,nothing untoward found apart from the pinion preload setting being too low.

removed 5thou shim and set pinion preload at a strong 18 inch/lb.Pinion turns smoothly with no tight spots. Measured with dial type torque wrench

Checked crownwheel teeth which were all ok in good order and measured backlash with bearing caps tightened to 38 ft/lb

At 4 equidistant points around crownwheel backlash  was  1-3.5 thou,

                                                                                                          2-6 thou

                                                                                                          3-6 thou

                                                                                                          4-4.5 thou 

Point 1 a bit tight but others within spec.

Carrier bearing preload seems a bit tight as I had to stretch the case a bit to get the carrier, in but not excessive, I may check the shims on the non crownwheel side tomorrow and reduce this preload a tad.

Then its on to the contact pattern again.If this again looks ok then but it still howls when fitted, then I give in !.

Dave

torqing pinion nut.JPG

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Just a note on power consumption:

If the “torque loss” during normal driving would be 18 lbs.in (which equals 3 Nm), this would result in a loss in power of 840W (a bit more than 1hp). Not only “power” is lost, but also the diff is heated up with the same power. This is why differentials in our cars can get very hot. Not much we can do about that.

And the 18 lbs.in is measured without full torque an energy consumption by hydraulic friction etc. Makes you think if a fully syntetic oil is better?

The above may not help making your diff quieter but I was wondering if there is something we need to consider here when rebuilding a diff? And can a high oil temperature result in damage?

It is certainly not good for roller bearings!

Waldi

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Dont use a diff spreader, nee need at all,

a good copper hammer t,wack the bearings in, evenly.

really can be that tight,

too slack, and the CW moves side ways on load.

 

If ye need 2 big screwdriver / pry bars, on the CW bolts, and casing t,pull / lever it oot, its fine.

if it comes oot easily,its not.

 

Ye too have found that most teeth give diff readings, some of the new CW/Ps are alott wuss than that, 10 thou on some, an 2 thou on other teeth,

 

Looking v closely at yer picks, is the side of the teeth shiney cost the blue es been worn off by the pin, or is it cos yer hands ev caught the edges,

If its worn off, then its no sitting right,

this seems t,be a condition wid worn teeth

Blue em all up, going sideways across teeth, so the lines int blue ar at right angles t,teeth

this,l show up pattern better, as ther wont be a ..missed streak.. doon the tooth, follow,!!

run wid oot load, check, then run wid a load, or turn wid a load on CW and casing

see what the pattern shows after booth tests,

if ye can, bung pics up of both tests.

good luk.

 

regarding Oil, I use 85/140 Penrite stuff,

on the trip  to an frae Scotchlandshire every weekend, Im regularly dooing warp 1+ for 40-50 miles at a time on the empty B  road,next to M way, { olde Main road }, can go 40+ miles at times,  wid nee cars at all , great

{ some of the Local TR Mobsters know of this road, think its great too, never a cam van,cop car or bikelist,,!!! }

 

the Castrol , comma oils wer Black, like really black an  very dirty when handling it whens draining, also it wer  like thin pish after one run,  { 270Miles }

the Shel Helix was nee better, it got 2 runs

as temps wer 200 degs  going by me infra red thingy

the heat was killing the oils

went to Penrite fully synth 85/140, an could get a dozen runs, an oil still  same,ish colour

still thick,ish too, no like the thin pish other stuff.

 

try it, give  Dave Parker a ring

http://www.classicgroup.net.nz/product_pcid_344.html

got 5 litres at Stonehenge show, 30£

works oot alot lot cheeper than the cheeper oils.

 

M

 

 

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Marcus

       If its  the face of the teeth being shiny you are referring too, that's how the pinion has marked it, you think then that the contact pattern is wrong and some adjustment may be needed somewhere.

Hopefully tomorrow I`ll paste them up again in the way you suggest and see if the contact markings have changed.I`ll put the results on here so you can have a look at them.

I think I`ll leave the carrier bearing preload as it is for the time being as well.

I`ll get some of that Penrite oil as well, I have been using Comma when I`ve changed the oil for the past 20 years.

regards Dave

 

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ello Dave,  the shiney bits im on aboot are right on the edge oft teeth,

they look like the blues  been rubbed off

yer hands or pin  the culprit !!

 

compare yer edges wid Ians edges, see the dif, no shiney edge to Ians

 

its no so much the contact pattern, {its an olde diff } its hoo it runs,

 

M

Edited by GT6M
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Hi Marcus,

I`ve done the contact pattern again,what do you think.

1st pic--drive no load,  2nd pic --coast no load  3rd pic-- drive load. Applied load as you say with pry bar against casing

can only send 3 pics at a time if you need any more I`ll have to send them on another post

Dave

CIMG6747.JPG

CIMG6749.JPG

CIMG6754.JPG

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Ello Dave, is the coast pattern wid the diff going backwards,under load,

as its gotta be same as the drive

 

Looking at yer teeth pattern, they all different, { thats nowt fresh, even new,ns are like that or wuss } but look at the pic on drive, wid ne load, top pic

see hoo some teeth are showing a pattern at bottom, an nowt after ,

an also going into the teeth base, also a wee bit on the coast too.

 

this t,me says ye need moer backlash on CW

the pin height seems OK,

 

BUTT, gotta no if going backwards was under load,

gotta bung a prybar int bottom,an rotate

 

as it meks a difference, as can be seen on the loaded an unloaded pics

aim for gett,n the drive an coast heights the same,

whenst that done, then its a matter of shift,n the CW side t,side.

2 / 3 thickness  thou at a time, if ye got plenty , if ye aint, its harder work

 

as it is noo, CW needs t,go away frae pin,{ bigger gap } reduce CW side, an bung shim int t,other side,

 

{wee tip, mark roller cap on CW side wid a notch int grinder,  ont bottom fat side, then ye no thats for that side. as its easy t,get em mixed up,}

 

will be back in in a few hours, will see whats wot then,

cant doo much moer as aint got a phone wid tinternet onit,nor does it show pics

gotta come on comp. an Her Nibbs is want ,t,go oot soon.

rgds M

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  • 1 month later...

Hi Ian, 

Only had the diff re-fitted a week ago but it still has a whine above 40mph, same noise whether accelerating, decelerating, or coasting in neutral, and increases in  noise level when speed is increased ,good news is the clunking on take off has been sorted.

Tried your suggestion of Fahers additive but didn't seem to make any difference.

Drained oil off and refilled with Dynalite 85/140 for noisy gears from Moss, but that didn't seem to make much difference either.

Its even got me wondering if its one of the rear hub bearings,even though they feel ok with no play at all and the hubs were renewed about 5000 miles ago.

Might live with it for a while and see if it improves or gets worse with use.

Dave

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Sorry t,hear this Dave,

now ye no just how hard it is t,get an olde diff t,run quiet.

As found oot, the pattern was as good as could be gotm both sides oft teeth

and still it whined.

I fear a so called speacialist will doo no better, if they doo, it,ll be a fluke,

1 thou here,or there and thats it. even if pin height is as factory

but whos t,say it were right int fust spot !!!

Ive spent days try,n t,git some quiet, gev up int end,

even me own, gawd did I spend some time onit, it whines after 2500 rpms in top on part throttle

it,ll be oot in next few weeks as a clucth  required,  so doo the lot, t,gither.

 

 M

 

 

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Hi Marcus,

                   Yeah I thought I`d cracked it but not to be , although on the positive side the clunking on take offs been sorted, and the bearings and seals have all been renewed,  the whine I`ll live with  for the time being.Diffs are certainly a patience tester, I didn't realise I had so much, I prefer problems that are black or white, a part fails you replace /repair it and job done, still its been a learning curve and I have learned a lot about diffs along the way.

Best of luck with yours and thanks for all your advice and suggestions.

regards Dave

 

 

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