Checking the mesh of a R&P...

[streaky]

Here's one that's crossed my mind before I whip the rear diff lock out (again).

When fitting a ring and pinion set is it really nessesary to use engineers blue to look for high spots and whitness marks prior to fitting the diff back in?

Many installers will say that they've done loads of rear ends and not had a problem with them...but what about 100,000km down the road when the incorrect settings between the R&P have caused premature failure? Will they warrant their workman ship then???

My workshop have said that they will check the pre-load & back lash, but when I asked them about checking the meshing between the R&P they didn't have a clue what I was talking about. Am I being too critical?

Thx.

S.

[rtbarton]

I would say yes, if it's adjustable it needs adjusting correctly.

[Turbocharger]

Depends how acceptable a failure would be to you. For the challenge boys who will probably blow it up rather than wear it out anyway, and who expect to be swapping diffs on a semi-regular basis, doing it 'by feel' will be fine. If you're going to drive into the middle of the Australian outback then a failure could kill you, and I can see that you'd have a different attitude.

Be aware that blueing it will only show you the 'no load' mesh - the pattern changes as the teeth deflect under load. It's a good starting point though, but I suspect you'll need to find someone 'old school' who has the skills.

[Jon White]

Yes! Its impossible to correctly set the pinion height without using blue.

Once the pinion height is set, the precise mesh is set by feel.

Frankly if you dont know what you're doing get an adult to set it up properly for you, as they wear VERY quickly if not correctly set up. You need to set the pinion height first, and then the input preload by mesing with the shims, and then finally adjust the meshing.

Jon

[steve_d]

What would you find if you 'blued' the assembly and what would you be able to do about it?

I'm guessing you would only be seeing machining imperfections of the gears which you can do nothing about unless you had them re-worked.

Steve

ETA Should have typed quicker, looks like my answer is above.

[Off Road Toad]

To set the pinion height you do not use engineers blue!

setting pinion height involves using a height block to accurately set it.

with regards the initial question,

we always use blue as a final check, not for setting up. thats why it's called a blue check.

to set up properly you need the proper blocks and gauges.

i would suggest any fitter that knows what they're doing will use blue.

it is possible to set up a diff by feel to get you out of trouble but for a long term build up it should be done properly.

there are full instructions/ information on our web site on how to do this. www.kamdiffs.com

Cheers, Steve

[HoggyN]

Frankly if you dont know what you're doing get an adult to set it up properly for you, as they wear VERY quickly if not correctly set up. You need to set the pinion height first, and then the input preload by mesing with the shims, and then finally adjust the meshing.

x2

I changed the ratio in my Triumph rear axle and set it up myself using the workshop manual. I used all the correct tools, even going so far as to blue the assembly and adjust according to a chart showing contact patterns.

It lasted 15 miles. The axle got so hot it melted the plastic breathers and when I drained the oil it looked like metallic silver paint!

[streaky]

it is possible to set up a diff by feel to get you out of trouble but for a long term build up it should be done properly.

there are full instructions/ information on our web site on how to do this. www.kamdiffs.com

Cheers, Steve

Thanks Steve.

I've scoured your website but can't find any specific insructions regarding setting up of the R&P. Do you have a link to the page please?

Thanks very much.

Regards.

S.

[Jon White]

I've always set pinion height by blueing it per the instructions here.

I was shown how to do it by the guy that does Jez's Volvo diffs.

Jon

[streaky]

Thanks Jon. I wish I had a Rover specific article though....fussy git arn't I.

The job I have to do involves removing the rear ARB diff locker and fitting new bearings. Whilst the diff is out I want the workshop to check all of the settings, back lash, pre-load, meshing of the R&P etc.

When the Ring gear was fitted to the new Locker it wasn't checked for mesh with the pinion gear...this is what my original post was all about really.

I'm not the person doing the work. This will be done by a Filapino at the ARB workshop in Abu Dhabi on Saturday. Having spoke to him on the phone yesterday...he had never heard of checking the mesh of the R&P using Engineers blue hence my post.

I'm not the expert in these matters but I am probably a dammed sight better at reading instructions that he is. My experaince when working with these people is that they usually have the basics of a job down to a fine art...but when it comes to getting technical they suffer from brain freeze and just start to waffle.

I beleive that anyone with basic skills can install a diff fitted with a new ring gear...but the expert will know how to set it up and get maximum life out of it. Do you get my drift?

Thanks.

S.

[Off Road Toad]

Here you go, the website is intermittently being an a**e at the moment as it's undergoing complete re-design so please bear with it.

These instructions are for early vehicles but essentially the same for all rover diffs.

hope it helps, Steve

http://www.kamdiffs.com/land_rover/fitting_instructions.pdf

[jwriyadh]

Streaky, read, learn and understand that write-up from Steve's site. However the only way you will get the job done to your satsfaction is to be stood next to the fitter as he does the job. Then you can verify that all the setup is correct. If you're not present you know as well as I do that all checks will be a figment of imagination.

jw

[streaky]

Thanks Steve. I've printed them out and will take them with me on Saturday. I also found a really good write up on the d90 site which shows more details when using the marking Blue compound.

Hi John...about time you stuck yer nose in here mate!

I hear exactly what you are saying and it's for this reason that I'm going to the workshop to over see the work myself. I simply don't trust anyone to do the job properly and even more important to carry out the checks like those shown on Steves site.

Before I had the lockers fitted the first time I asked a number of garages how they measure the back lash in the R&P's.....one of them said "we do it by eye".... understandably I walked out quick sharp.