MX32 Chassis Question

[PatrickT]

My son participated in the 2008 Rotax Nationals in Wisconsin this year.

During the Rotax Senior LCQ race on Friday afternoon the driver's right side seat mount snapped. With no support on the right side of the seat he had to pull off the track. We had a Rotax Masters driver in our pit area who also had an MX32 chassis. During the Saturday morning warm-up or pre-final his chassis broke in the same place.

My question is... How do you know when seat struts are needed to help support the load on the chassis or should the chassis been able to withstand the load without seat struts?

The kart is a 2006 model. We purchased it from the original owner in July 2008. Since we don't know the race history of the kart it is possible that the seat mount was already weakened.

[Garry Lobaugh]

This is an excellent question. There is only one way to prevent something like this. First, careful examination of the chassis after each race day can help discover cracks and signs of stress. What we do is completely take the race team chassis down to bare metal and wipe with WD 40 to examine for stress cracks. Hands on love if you will.

Birel has a very good history of their metal and welding. However, improper weight placement, improper seat installation techniques may create stress fractures on the seat mounting points. Almost always, it is the right hand attachment areas, lower leg and right rib, that create the problems. We have few like this compared to other companies.

One possible solution is to install seat struts to the seat for back up. If they are not needed for handling purposes, loosen the bolts just to add the extra protection to finish the race.

Our family has experienced this situation some 18 years ago on a domestic chassis when we were in contention for a national title and during a critical race the seat strut broke and nearly caved in to the right side rib cage of my oldest son. I certainly am concerned about your situation.
There are many issues to digest in this presentation. We could be more flexible in our discussion by a phone call to the office. Please ask for Steve to help walk you through options and solutions. 269 756 9133.

Thanks very much for an excellent question.

[PatrickT]

Garry, Thanks for the quick response. This information helps.

I'll contact Steve this week to discuss options.