Aftermarket shocks (Boge) vs OEM (Girling)

[jagwit]

During a 3000+ km triop in February last year, one of the Boge aftermarket shocks broke. Replaced it with an OEM.

This is how the OEM shocks clear the IRS cage at the top :

tn_20170108_114255_Richtone(HDR).jpg (135.37 KiB) Viewed 7340 times

This is how the Boge shocks interfere with the IRS cage (pic upside down, sorry, nothing I do can fix it)

tn_20170108_114946_Richtone(HDR).jpg (158.05 KiB) Viewed 7340 times

Clearly the interference between the spring top flange and the IRS cage is what caused the Boge shock to break.

Shocks made and fitted locally in South Africa resulted in THIS:

tn_20170601_114724.jpg (145.77 KiB) Viewed 7340 times

Sometimes it IS better to get OEM parts....

[mgcjag]

How did the top flange hit the cage...can only see this happening if the top bush had failed (sleeve missing)..never seen this befor and there are hundreds of Es useing Boge

[andrewh]

likewise not seen this , but its very easy for someone to love out the steel centre tube. What I have noticed with Boge on the front, is that the upper dust shield is wider diameter than the originals, or even my Konis. This could present a problem in setting the castor angle. If you look at the proximity to the upper wishbone, they are very close. . I don't think you would be able to adjust the upper castor fully to the front of the car, i.e most vertical without fouling the wishbones.

[mgcjag]

Hi Andrew....once you put a guage on it and adjust you wont have a problem.....done it on a few cars with boge on the front

[andrewh]

thanks Steve. Hopefully not. I need to think about setting up the front. I have one of the dual use , that is castor and camber, gauges from Gunson. Rather than hijack this thread if you have experience of these sort of gauges, perhaps you can pm me Steve? thx A

[jagwit]

How did the top flange hit the cage...can only see this happening if the top bush had failed (sleeve missing)..never seen this befor and there are hundreds of Es useing Boge

The top surface of the Boge shocks are 20mm away from the nearst edge of the mounting hole. The OEM is 23mm away from that same point.

That 3mm is enough to bring the spring mount into contact with the IRS cage as can be seen in the pictures. Under dynamic conditions there is some compaction of the bush combined with the rotation of the shock when the wheel moves upwards which brings the flange even closer to the IRS cage. These two factors together may result in the spring mount being subjected to regular bending moments which could lead to metal fatigue and eventual failure.

What is interesting is that despite the broken shock, the car did not lean. There was only a cloncking noise coming from the rear, but everything else seemed fine.

[jagwit]

More evidence of how the Boge shocks were interfering with the chassis: