Drive Shafts - Roll or Scroll Pins?

[Dilkris]

I know the Lotus data states that, in effect, 2 roll pins are used for each drive shaft yoke - and equally so does the Renault manual - pls refer to photo's.

I ordered the roll pins (large and small) from a Lotus parts supplier here in the UK and received the below. Whilst OD's are comparable, one I would describe as a roll pin but the the other I would say is a scroll pin, the latter obviously does not require a secondary pin, you couldn't fit one obviously.

Whilst I have a selection of generic roll pins that would internally fit the large roll pin, I am wondering whether it best to use the scroll pins.

Anybody else faced with this dilemma? Any thoughts or reasons this is not recommended?

(Note, if it transpires that I should stick to the original design, my generic roll pins are not long, meaning I would have to use 2 - one being inserted at either end of the large roll pin - I don't see a problem with this - other than it may prove a pita when wanting to remove them in the future... )           

[jbcollier]

I do not think it's an issue either way.  The pins are not critical.  They simply provide a reference point so you can shim the yokes correctly, and, help reduce fretting of the shim pack.

[BDA]

r.d. enterprises sells both kinds. The roll pins (big outer pin and smaller inner pin) are for the 336 yokes and the spiral pins are for the 352 and 365 yokes. According to them, the different pin setup is for different size holes in the yokes and stub axles.
 You might want to take a look at what they say about them (rodent.com look at the Europa parts page and look at the parts for suspension and running gear).

I think JB is right, shimming correctly is the most important thing.

[EuropaTC]

My car originally had scroll pins fitted and I've good reason to think this was from new. It's currently got roll pins fitted because that's what I could get to fit the holes at the time. Like the other posters I'm not convinced it's critical (as long as if doesn't fall out    ) because the pins aren't taking massive loads if the yokes are shimmed correctly.

If it's tightly shimmed the compression during cornering should go straight to the gearbox via the shim pack. Tension loads, if any,  (maybe on droop ?) aren't going to be much and well within range of either pin type.

Brian 

[jbcollier]

Some people have run without the pins in place with no problems.  You do need them to set up the shim pack though.

[surfguitar58]

For whatever its worth, the combined shear strength of concentric 1/4" and 1/8" roll pins appears to be about 15% stronger than a single 1/4" spiral pin.
t

[Dilkris]

For whatever its worth, the combined shear strength of concentric 1/4" and 1/8" roll pins appears to be about 15% stronger than a single 1/4" spiral pin.
t

That's actually worth a lot  All that there is to do now is collectively agree on what they are actually doing..... just holding in the shim set, providing a lateral fixing for the transaxle end of the drive shaft (which works as an upper radius arm no?) or a combination of both - in which case they are quite significant no?   

[jbcollier]

The pins commonly shear in service to no ill effect as long as the shim pack is correct.

The suspension loads go:  half-shaft - shims - seal spacer - diff carrier (supported by large bearings)

Without the right amount of shims it goes:  half-shaft - output shaft - spider gears - diff carrier (supported by large bearings)

With the large suspension load, the spider gears don't last long and their remains do a number on the rest of the transaxle.

[Steve_Lindford]

Years ago on and S2 I recall that when replacing the pins - the inner roll pin would push out the outer one. Has anyone else had this problem??

Steve

[jbcollier]

Some people run safety wire through the pins to help hold them in place.