62 replies to this topic

[ls2lxhatch]

Can you run the car on blocks without axles to see if you still have a vibration. (You will need to seal the diff tubes.)

The diff pinion will turn up somewhere between 1 to 3 degrees depending on the suspension bushes and load. If the gearbox is down 3 degrees then somewhere around 1 degrees up at the pinion should be right.

Are you measuring the angles at ride height?

[rexy]

bit of an update but took the diff in to aussies diff down at currumbin, worked out that both tubes where pulled in giving big toe in so guessing at higher speeds the tires where fighting one another, also said that the studs were not perfectly central giving the tyre a hop. hopefully this is it.

Crikey, which tard did that fine work for you?

[73TORANA!]

I had a similar problem on my LJ ( BANGO ) I changed tailshafts had it all balanced , even ran it on stands with no axles in it .
It turned out to be that the new uni's were a metric equivalent of the old original imperial and they were causing a slight runout of the tail shaft at the diff end .
Fixed by pin punching the inner face of the yoke where the uni cup sits just near where the circlip meets EVENLY ON BOTH SIDES OF THE YOKE to tighten up the uni end float . Result no vibes at all even at 200kph on the strip. before the rear vison mirror drooped from the vibe . Hope this helps .

[Growla]

I just solved my vibration as well, as there are so many variances in my car LX SL/R with LS1, T56 and Borg Warner diff. I just thought it was something wrong with the conversion. I changed Engine, Gearbox angle, Pinion angle, tail shaft and the company that did the diff replaced the centre and pinion twice. I thought it was never going to solve the issues to be smooth and noise free. This week I bit the bullet and took it to an engineering place to check the housing, axles etc (thanks Struggler for the advice) and yes bent housing and very ordinary bearings poor lashing of the diff. Just an absolutely crap job. So my now “gold plated" diff is how it should have been in the first place. One thing I have learnt doing up (restoring) a car, is there are many businesses who will take your money and not deliver.

Anyway, happy to hear your issues were solved as well..

Cheers

Mark

[73TORANA!]

Hi NYS71 have you read my post on march 23 , Have you checked for end play of the uni's , even new ones , any float or end play of the uni's will cause a rumble of the shaft at hi rpm . Mine would change with load on and load off ( power ) and foot on clutch and rolling at 140- 160 it would be realy violent and as soon as the clutch was slowly engaged it would come good until the clutch was totaly released . All this was caused by the end play in the uni's mind you it was only about 10 thou but you could feel it when moving the shaft by hand up and down . A bit harder to pick at the gear box end because of the output shaft bush but even that can cause it it to sloppy but as you said it was ok with the other set up . check that the dif yoke is true ,rotate the shaft and check the runout .

Hope this helps , my hair is only starting to come back but now it grey....

[73TORANA!]

I feel for you , there is nothing more frustrating than getting profesionals and pay top dollar to a job for you and its worse than when they started.
Over the year's I have learnt to do as much as i can myself and if I have to get someone else I'm very sceptical and do a lot of reasearch. I had an engine issue with cam bearings and twice the shop said it was all good and blamed me for lack of oil, the 3rd time i went to another shop and they checked the block and said the jurnals were out for the cam . They line honed the cam jurnals and all is now good ,the original shop dismissed the idea .
It sounds like you can get your hands on some tools to do the job .

Just a thought have you run it on stands without the wheels on , don't know how safe it would be though.

We had profesionals do our bathroom 6 moths later the shower leaked so i gutted it and did it myself , 2 year on still good.

good luck it sound like your on the home strech .

[biga064]

I had a similar problem on my LJ ( BANGO ) I changed tailshafts had it all balanced , even ran it on stands with no axles in it .
It turned out to be that the new uni's were a metric equivalent of the old original imperial and they were causing a slight runout of the tail shaft at the diff end .
Fixed by pin punching the inner face of the yoke where the uni cup sits just near where the circlip meets EVENLY ON BOTH SIDES OF THE YOKE to tighten up the uni end float . Result no vibes at all even at 200kph on the strip. before the rear vison mirror drooped from the vibe . Hope this helps .

Any more info on what you mean dont quite get what your saying ?? thanks

[73TORANA!]

Hi Adam , I give it a shot , on mine when the uni's were new and all the circlips fitted , the trunion ( the uni cross piece ) could move up and down inside the cups ( not in a twisting movement but vertically ). you could tap the cups in a but further to tighten it up ( this is on the diff yoke with the "U" bolts) but after couple of good flog the caps would move back out until stopped by the circlips and the vibe would return , I tried to get slightly thicker clips but could only get ones that made the uni too tight . So on the macined radius area where the uni sits i put 3 center punch dints equaly spaced arond the radius , about 1 mm away from the face where the circlip sits , the center punch marks made small raised section appear on the face of the yoke where the circlip sits , this effectively pulls the uni caps in a little . NOTE don't get too carried away with the punch as you only a couple of thou on each side of the yoke , Also try to make each punch hit as accurate as you can to keep it equal on both sides.The uni should have only slight resistance when sliding it onto the yoke , if too tight gently file the punched rased areas equaly on both side for a nice snug fit , not loose, tighten "U" bolts an check for end play What you want to accieve is to have each uni cap seating a little further in the yoke to keep the trunion from moving up and down inside te cups I.E keep it running true .

I have only ever needed to do this on the dif yoke and was told by a tailshaft dood that its because of manufacturing tollerances from to old imperial uni's to the average metric ones that you get now , he said the F100 utes are natorious for this.

let me know if its not all that clear and i'll dig out a yoke and take some pix

Geoff.