ring and pinion setting issues

[johnwalklett]

Hi All

I’ve got a ring and pinion setting up issue. It’s a Scat 3.44 ring and pinion. The first picture was with .6mm pinion shim. The pattern is the opposite on the other side of the gear tooth.. same pattern but on the toe. So this would tell me I need the pinion deeper. As I increase the pinion depth the pattern doesnt move I just get less contact.. with 0.3 shim I get the pattern in the second picture. Any advice would be appreciated .. many thanks John





This is with no shim at all

[Bruce2]

Is this a US Gear R&P or a China one?

What's your backlash?

[Casting Timmy]

Bruce has set a lot of these, he can probably help you more than me.

I do find for me in these situations looking at the pinion as well helps as I get a better feeling for the depth.

[johnwalklett]

Im guessing its a Chinese one, I've used loads of there 3.88's and they set up just fine.

Bruce The back lash varied a little between the different pics but was always between 6 and 10 thou.

I've had to walk away from it I spent 4 hours on it on monday. Going to try again tomorrow.

[Bruce2]

I've only installed the US Gear R&Ps.
To identify the one made by US Gear, look between 3rd and 4th on the pinion.
It will be stamped "T1-3.44P 31-9 U.S.A." then their logo and "L5".
They will also have numbers written on the end of the pinion head in white paint. One 3 digit number to match to the ring gear, then another that must be some kind of pinion depth measurement. It is in the range of 2.103 - 2.110 as far as I've seen.
The US Gear pinion has a splined 4th, threaded end, and no groove for 3rd gear clip.
What configuration is your pinion?

Try to keep your backlash in the 0.2 - 0.25mm range. I've seen pretty poor contact patterns at 0.15mm even though that's at the spec limit.

From your first pic, I would put in a thicker pinion shim to pull the pinion away from the diff. Then set your lash in the .2-.25 range. My suggestion is a 0.8mm shim.

Never look at the contact pattern before your lash is correct.

Here's a tip that I find helpful. Paint your bluing/grease in two locations, 180º apart, and label them A and B. Then when you make a shim change or lash change, it's very easy to compare what you have now to the previous pattern. Recording the patterns is also easy with your pocket phone.

[johnwalklett]

Thanks Bruce.

I was wondering If maybe increasing the back lash to the top limit may help. I'l give it a go on monday.

Also I like your idea of marking the crown in two places to compare. Although I do use my phone a lot to take pics. I find the markings actually easier to read and clearer on a phone picture sometime.

Also I use to some yellow marking paste i used to buy from here in the UK but it was quite thick and i didnt feel it was giving me an accurate reading so switched to the engineers blue which is much more sensitive and shows up discrepancies much better.

[johnwalklett]

I'm not in work today so can check the making but its a splined pinion with threaded end and no 3rd gear clip groove. the thread is the standard size VW used not the smaller size you find on the Weddle ring and pinion