Dry or Wet Arms?

[Gary Schulz]

Are these dry or wet? Just trying to collect all my hydro parts for the next build and I can't quite make out the part numbers. Just has a different number on the back along with EN16T

20201113_153539.jpg

[Spider]

Those are for Dry Suspension

[360gts]

Gary, those look like 'dry'.....they do have the shock absorber stub shafts....the wet item has a smaller diameter hole where the shock stubs go....
Here is a picture of a dry arm...maybe this will help.
Cheers
D

[Gary Schulz]

OK. I didn't remember if I fitted shock pins to a set of wet arms or not. I think my rear arms are from the original hydrolastic setup but converted to be used on a dry suspension.

I also thought there was a way to tell based on the location of the suspension ball knuckle. Are they slightly different between dry and wet?

[Spider]

I also thought there was a way to tell based on the location of the suspension ball knuckle. Are they slightly different between dry and wet?

The Shock Pin is not always a good indicator as the Arms may have been drilled.

It was the location of the Socket for the Knuckle Joint that I worked from. On Wet Arms, it's 0.150" closer to the Ball Joint Hole.

[Gary Schulz]

It was the location of the Socket for the Knuckle Joint that I worked from. On Wet Arms, it's 0.150" closer to the Ball Joint Hole.

You have a very good eye if you can see 150 thou in my lousy picture! I guess I'll keep looking for my wet arms then. One point of confusion remains though- I can just barely make out the part number prefix on one of the arms and it indicates 21Axxx. I thought the 21A prefix arms were wet arms?

EDIT- Just found my wet arms and you really can see the difference in locations for the knuckle socket. The dry arms then are 21A611/613 I would guess...

20201114_074846.jpg

[Gary Schulz]

OK this one is a lot more obvious (I think!) I am pretty sure this is a wet arm that has been modified to take a shock absorber?

20201114_104050.jpg

[jay weinstein]

Wet arms have the brake line on the bottom of the arm so that arm
is a wet one.

[Gary Schulz]

Yes brake line on the bottom is the most obvious indicator. Must be the original arm for my current hydrolastic project then. Thanks for the reply.

Now, I wonder how hard it is to press-in new stub axles with the correct pins for the helper springs...

[LuisM]

a question on rear trailing wet vs dry arms, do they have the same leverage ratio ? meaning if wet arms are converted to dry, we get same "spring rate" ?
I know front wet ones lead to stiffer "spring rate" & ride with rubber cones.

Cheers
Luis

[mab01uk]

Quote:
"Now, to avoid all sorts of hassle, it really is strongly advisable to use dry-type radius arms. The hydro design will see your Min fall flat on it’s arse unless you get some severely lengthened rear trumpets. Then there’s nowhere to bolt the dampers to. The dry type have a pin sticking out to take them, the hydro doesn’t. This damper mounting pin is part of the rear stub axle, swopping these can be an absolute nightmare and they’re not cheap either. It’s cheaper in the long run to buy a pair of completely refurbished dry arms. Honestly."

Extract taken from Keith Calver - Suspension - Converting from wet to dry:-
https://www.calverst.com/technical-info ... et-to-dry/

[Gary Schulz]

Well I turned this wet arm into a "dry" arm when I was in high school and there was no internet to set me straight on what a bad idea it was!