Maybe a dumb 8.50 to 7.50 chassis ?

[mikeT]

I have a M/S round tube chassis car that is NHRA cert to 8.50, The guy I bought the car from said with a few more bars it will cert to 7.50?
what areas are they usually referring too to adding bars? or is it something that is unique to each chassis ??

[bracketracer]

I don't think a MS chassis can cert to 7.50 anymore...

[John_Heard]

25.5 can be MS I believe. Mike that's more or less the addition of a funny car cage, probably more door bars, etc. You'll need to get the specification or have a chassis guy look at what you have to see if you can upgrade easily.

[DOTracer]

To go from 8.50 to 25.5 is more than a few bars. The addition includes full funny car cage, kidney bar, door x-brace, roof diagonal, roof gussets, inner frame rails, front & rear crossmembers, and depending on the floor configuration, possibly outer floor diagonals and center floor X.

Yes, 25.5 can be done in mild steel, but I wouldn't, unless you want a tank.

[tigwelder]

difference in m/s to 4130 moly in a full tube chassis 25.4 cert is about 70 lbs, just did the 98 mustang 7.5 cert and it weighs 2360 lbs, less driver,mild steel, with steel headed 388 ford, jerico. ran to fast for the 10.00 class in k.c., went 9.66, 147 mph with 1.29 60 foot.

[mikeT]

Thanks for the info DOTracer!
I checked the car today and it has most of the bars you listed.
Just not sure about the kidney bar and the F&R crossmembers?
can you give me a better idea on them???
THANKS!!

[DOTracer]

Thanks for the info DOTracer!
I checked the car today and it has most of the bars you listed.
Just not sure about the kidney bar and the F&R crossmembers?
can you give me a better idea on them???
THANKS!!

Rear crossmember (#1 bar) must be either 1 5/8" or 2 x 3". The crossmember needs to intersect/connect to the main hoop. The forward crossmember (bar 6 A, B, & C) needs to be 1 5/8" and needs to intersect the roof line bars where they intersect the rocker/floor pan/etc. This bar ban be three pieces, but there are definitions in the spec showing allowances for offsets, etc.

I suggest you purchase the 25.4 spec from SFI Foundation for $35 to familiarize yourself with what is required to certify your chassis.

Most of the cars we do are either 25.5 or 25.2, so I'm not up on the 25.4, but it should be very similar to 25.5 only some specifics which are for the full chassis type car compared to the stock body/frame cars in which 25.5 and 25.2/25.3 are used.