Hay I got a 99 GS 420a with an Automatic tranny and I need to know how many ribs are on my belt so I can order an underdrive crank pulley and maybe a few more goodies from Summit Racing.

The guy at Summit shot me a fastball and asked me if I got 4 ribs or 6.

What size or part number belt should I order too?

I'm out of town so I cannot pop my hood to get a look see.


Please let me know ASAP Thx!!!

Originally posted by fullmoon
Hay I got a 99 GS 420a with an Automatic tranny and I need to know how many ribs are on my belt so I can order an underdrive crank pulley and maybe a few more goodies from Summit Racing. The guy at Summit shot me a fastball and asked me if I got 4 ribs or 6. What size or part number belt should I order too? I'm out of town so I cannot pop my hood to get a look see. Please let me know ASAP Thx!!!

"Using the AFX sizes causes for the tensioner to max out (turned all the way to tighten). When they max out they usually don’t have enough tension, the tensioner bolt usually snaps, and no more tension can be applied when the belt stretches a little after initial break-in. K0 = Vribbed 50 = 5 ribs 490 = length in inches. The best belt on the market is BY FAR the Gatorback brand belts. They are very tough, don’t stretch, and if they do slip where as a normal cheap belt would squeal these belts just tend to hiss (barely can be heard)."

Power steering with AC K050490 (one inch shorter)
Alt. K040310 (1/2 inch shorter)

Originally posted by eclipsed08

Originally posted by fullmoon Hay I got a 99 GS 420a with an Automatic tranny and I need to know how many ribs are on my belt so I can order an underdrive crank pulley and maybe a few more goodies from Summit Racing. The guy at Summit shot me a fastball and asked me if I got 4 ribs or 6. What size or part number belt should I order too? I'm out of town so I cannot pop my hood to get a look see. Please let me know ASAP Thx!!!

"Using the AFX sizes causes for the tensioner to max out (turned all the way to tighten). When they max out they usually don’t have enough tension, the tensioner bolt usually snaps, and no more tension can be applied when the belt stretches a little after initial break-in. K0 = Vribbed 50 = 5 ribs 490 = length in inches. The best belt on the market is BY FAR the Gatorback brand belts. They are very tough, don’t stretch, and if they do slip where as a normal cheap belt would squeal these belts just tend to hiss (barely can be heard)." Power steering with AC K050490 (one inch shorter) Alt. K040310 (1/2 inch shorter)

What about Unorthodox? Which one should I get?

Well on this forum the search button is your friend... :-) I would love to help you out but I'm having my own demons now.

AFX or unorthodox there both great items, either will be fine.. but yes use the search button its a way to find the info. this site has everything u need to know about our cars. good luck:thumbsup

dosent matter which just make sure its for the 420A

AF/X 30% underdrive #AFXDSP95S
Unorthodox Ultra S #020100202