MCC Forum

Technical Topics => Car Help => Topic started by: Paul K on April 29, 2016, 03:27:25 pm

Title: Beetle Raised Rear Suspension
Post by: Paul K on April 29, 2016, 03:27:25 pm
Some advice needed on a swing axle rear suspension. The car was raised when I bought it so I've inherited a problem with the axle boots. The clearance between the lower side of each boot and the cradle of the chassis is so small that when the rear suspension fully extends, the boot is pinched between the cradle and the axle tube. Consequently, the boot splits and I start to lose gearbox oil. (I attempted to insert an example image of the area, but that option appears to be unavailable. I did attach an example image of the area, hopefully, that can be seen.)

The solution would seem to be the removal of a semi-circular section of the cradle immediately below the axle tube, then weld in a similarly shaped piece of steel.  This would give sufficient clearance between the axle and the now relieved cradle such that the boot cannot be pinched. Unfortunately, the effective depth of the cradle is reduced, reducing the structural integrity of the cradle. Therefore, I suspect a reinforcing length of steel would need welding to the underside of the cradle to restore that integrity .

Has anyone resolved this problem with pinched boots in a similar or different manner?
Title: Re: Beetle Raised Rear Suspension
Post by: Simon Woodall on May 01, 2016, 12:30:00 pm
The simple solution is to buy "Best Quality" boots, which should survive this treatment.
The only time I've applied s similar solution to the one you propose, rather than cutting and welding, just warm up the relevant area to cherry red, and then beat the living daylights out of it with a hammer.   There's no need to return the strength on the underside.   if you look at a Beetle with double joint suspension you will see that Mr VW did this trick themselves to provide clearance for the inner CV Joint.

If you feel that you must restore the strength, then take a leaf out of the high performance fraternity, and run a bar from the far end of the gearbox fork, next to the engine, up to the top shock absorber mount.   But remember to make this a bolt-in addition, or you'll never get the gearbox back in.
Title: Re: Beetle Raised Rear Suspension
Post by: Paul K on May 04, 2016, 09:50:05 am
The axle boots presently on the car are from, part number 261.100.20; no manufacturer is given. I've done a bit of research on the internet and see that have a more expensive axle boot from Germany manufactured by Febi Bilstein; I take it that's the best quality available.

As for the 'beat the living daylights' method, I don't have access to oxyacetylene equipment, though, I could do the beating cold. I'll try the Febi Bilstein boots first and see how that goes. If I put the boots on just prior to the MoT, at least they won't get a failure.
Title: Re: Beetle Raised Rear Suspension
Post by: Simon Woodall on May 04, 2016, 10:22:59 am
Those are the right ones, should cost you just under a tenner.
When you fit them, make sure the join is at about 10 O'Clock or 2 O'clock
If you fit them with the join at the top - the natural place to discourage leaks - they don't flex properly because the seam is too stiff.
When you jack the car up to do this, put a chain round the top shock mount and under the jack, then the jack will jack the suspension into compression and give you lots of space between the axle and the gearbox forks to get the boot on and positioned easily.
Title: Re: Beetle Raised Rear Suspension
Post by: Paul K on May 05, 2016, 06:38:47 pm
To avoid using chains with the jack, can you get away with placing a suitable size chunk of steel, e.g. a nut, as I've seen suggested, between the underside of the rear spring plate and the suspension stop? I think I'd clamp the nut, or whatever is used with a G-clamp or mole grips just in case the nut chose to dislodge. Chains or nuts, there's going to be a lot of tension in the suspension.  Should be fun  :D.  The photo is an example of the parts.