radius arm botl

[jackb_ms]

hello

 

Could some one let me know if the radius arm bolt going into the chassis is a fine or coarse thread?

 

Cheers

 

Jack

[Richard Price]

What year chassis?

If pre 2007 then it will be a UNF thread

[Paul Deslandes]

The upper 'comfort' holes are tapped, the lower 'performance' holes are not and need to be longer and have a washer and nut on the inside of the car. 2 3/4" X 3/8" UNF from build guide.

[Jonathan Kay]

Looks as if it varies. 2010 Assembly Guide:

RADIUS ARMS

 

14 If Watts link has been specified refer to Para 17.

 

15 Fit the radius arms to the upper chassis bush with the waisted section facing outboard, to provide maximum clearance to the brake calliper. The arms are fitted using M10 x 65 mm cap head bolts (fastener pack 30R011A Item 2) passed from the inside of the cockpit through the radius arm and secured with nyloc nut (8) and plain washer (14). The bolts should be tightened to 34 Nm with the arms parallel to the ground. This preloads the bushes in the correct position for when the suspension is properly loaded.

 

NOTE

On some series 3 chassis a lower fixing boss is supplied to give optimum suspension geometry when used only for race and track purposes. This setting is not recommended for road usage.

 

16 Fit the rear end of the radius arm between the brackets on the top of the De Dion tube using bolt (3) passed inboard and secure using a nyloc nut (6). Do not fully tighten.

Jonathan

[Richard Price]

Quoting Paul Deslandes: 

The upper 'comfort' holes are tapped, the lower 'performance' holes are not and need to be longer and have a washer and nut on the inside of the car. 2 3/4" X 3/8" UNF from build guide.

 

On my 2002 chassis, both the upper and lower are not tapped.

[jackb_ms]

thank you gentleman

 

it is for a 1996 21.

 

I have the size however when I wanted to buy a couple I was asked if the thread was fine or coarse.

 

Which one is it more likely to be?

 

Jack

[Stationary M25 Traveller]

From the above posts ..... UNF is a fine thread F= fine

 

UNC .... C= coarse.

[Jonathan Kay]

I don't have any specific manuals or similar for the 21: do they exist?

 

For 1996 de Dion 7s the manual says:

14 Fit the radius arms to the upper chassis bush with the waisted section facing outboard, to provide maximum clearance to the brake caliper. The arms are fitted using cap head bolt (fastener pack ZRS21, Item (2)) passed from the inside of the cockpit through the radius arm and secured with nyloc nut (9) and plain washer (16). The bolts should be tightened to 25 lbft (34 Nm) with the arms parallel to the ground. This preloads the bushes in the correct position for when the suspension is properly loaded.

In order to find out what the bolt is you then need to go to Charles' wonderful fastener pack site. This tells you that ZRS 21 item 2 is:

Bolt 3/8" x 2 3/4". Caphead bolt with provision for Allen key (fine thread)"

and shows you a picture.

 

What Paul said.

 

Jonathan