Wishbone torque settings.....confused.com!

[John B]

Just upgrading wishbone bushes to Superflex ones and have checked all the various places for torque settings on the wishbone bolts and now I'm confused

Mike's site shows 40 Nm + 180 degrees for his front bones which are cast/forged...ok
.....and 70 Nm + 90 degrees for his rear bones, which are pressed. So far so good.

Paul's site shows 40 Nm + 180 degrees for his front bones which are cast/forged...ok

Then we go to the Bentley manual section 40.30 (for the CQ), which shows pressed steel front bones and gives 40 Nm + 90 degrees.

My 4 bones (1994 ABY Coupe) are pressed steel and take SPF1428, which is 8A0407181.
So my logic is that they should be the same as Mike's rear pressed bones, which also take 8A0407181 bushes and therefore should be 70 Nm + 90 degrees.

Can anyone confirm? BTW some of the bolts are real boogers to get (e.g. O/S front bone rear bolt) at whilst others are p*** easy (e.g. O/S front bone front bolt)

Cheers,

JB

[Lago Blue]

More Lower A-arm inner bushing torque and fastener questions...

Twisted about torques:

Are the variety of torque figures found, perhaps due to possibly different fasteners used at these various locations, and not A-arm material specific? I suggest that the reason for the various numbers seen, may be that they are both model and location specific.

My B3 Bentley lists 40Nm plus 1/4 turn for front and rear bushings whether cast or forged; &

My B4 factory books list 40Nm plus 1/2 turn for front bushings whether cast or forged; and 70Nm plus 1/4 turn for the rear.

IIRC, the nut is a different size between My B3 and B4, for the front A-arm inner bushes. At the same time, the sub-frame ears being clamped are the same size. Perhaps the steel bushing cores are the same OD, for both pressed and forged front A-arm bushings as well?

You may know that the front A-arm bushings are different diameters usually depending on A-arm material, but not always (see elsewhere on this forum).

You may know that a B3 could have the same A-arm bushings at the front and rear axels, but doesn't have to; and that the B4 couldn't have the same lower A-arm bushes on the front and rear axels.

The B4 rear lower inner bushings are not the same as either of the pressed or forged front A-arm bushings, and again IIRC, are different even front to rear on each arm, the forward one is 2-piece, while the rear is one piece. So different fasteners may be in use here also.

As to your logic, I'm afraid I know nothing about your car, but I have found no reference that calls for 70 Nm on the front A-arm bushing fasteners for B3s or 4s. You say your car can use the equivilent of an 8A0407181 OEM bush (see picture) on the rear A-arms, that is the (smaller of the two typical sizes) 37.3mm diameter bush used on the early cars up tp 1991 over here. Your car being a 1994, what does the Bentley say to use on the OEM's for your car? Does your car not have double A-arm rear suspension, or are you on struts all the way round?

Finally, as you are going to poly bushes, that the steel centre core is not bonded to the bush, it should not see any torque compared to the OEM's, but by following the factory location specific instructions for your car, you can't be wrong!

Wrenching Interference: I loosen the rear-most sub-frame bolts for example, when trying to remove the rear bushing bolt, on the front A-arm.

[John B]

Wishbone bush torque

Thanks for the reply. I have a coupé, which is effectively a B4 front end with a B3 rear end in broad terms, so your B4 factory books showing 40Nm plus 1/2 turn for would appear to be appropriate for the front. I don't have any factory books other than U.S. Bentley manual.

I appreciate that i have put on urethane bushes, which effectively rotate on the steel cores and torquing on the ground is not therefore damaging to the bush unlike the factory bushes. What I don't understand is why the front torque settings should be any different to the rear, when the wishbone is the same, the bush is the same, the bolt and nut are the same and the subframe on the coupé rear is effectively a front subframe turned round 180 degrees.

Paul / Mike / anyone - can you shed any light on the correct settings?

In my desperation to get the beast back on the road, I have gone for 70Nm with 90 degrees but may have to get new bolts at a later stage and re-torque if i am wrong.

Thanks,

JB

[Mikes2]

Thing to remember is that the Bentley manual doesn't cover the S2, only the cq and 90q 20v

The values quoted on my site are for the S2. The cast / pressed material is irrelevant as the values never changed

[John B]

Wishbone bush torque

Thanks, Mike for the reply

Yeah I was aware that Bentley only covered the CQ and 90 q 20V. The query arose because of the different values on your site front to rear, when on my S2 coupé the materials were all the same.

So just to clarify the values are: -

Front - 40 Nm + 180 degrees
Rear - 70 Nm + 90 degrees

Irrespective of whether the wishbones are cast/forged or pressed

Out of interest, can you tell me which source these values come from?

Thanks,

JB