Silver Surfer

Does anyone have experience with this product? I have a 1997 C4S and I am contemplating a re-gear. I have heard that Guard offers a replacement main shaft with a slide-on 2nd gear to replace the stock main shaft with machined-in 1/2. I can't find any information about this product. Is it compatible with the C4S AWD? And what are the 1 and 2 gear ratios? I was contemplating going with the Guard 1-2 and the RS 3-6 gears, but I'm not savvy enough to know whether this would make a good close ratio gear box.

Bill Verburg

I don't know the GT ratios either but there are 2 different RS transmissions, 3 if you count the Swiss version, Here's a summary of most w/ the Singer version thrown in for kicks, th RS versions have that nice taller 1st, I have a /30 in mine and find it perfect for track but could use a tad taller 6 for the street, The Row /21 is pretty much the same as the /31 in gearing except for fpr the /21 having the shorter street orient 1 & 2, The /32 is probably the better compromise dual purpose trans, The other thing to keep in min is that gearing isn't the only difference between the /2x and /3x trans, There are lots of very expensive track oriented parts in the /3x more in the /32 than the /31 and even more in the /30

mgerber

Mark - I have the Guard mainshaft with the 3.50 1st gear in my car. Give a call when you can...

Silver Surfer

Matt - I thought about your car, but since it was a 1995 I assumed that you had the changeable second gear. Now that I think about it, Bill showed somewhere that the changeover was during the 1995 model year.

GTgears

http://www.guardtransmissionllc.com/...ets/993-gears/
https://rennlist.com/forums/993-foru...mainsheet.html

A little extra info for you guys.

Silver Surfer

I was contemplating Guard 1st, stock 2nd, RS 3-5, moving stock 5 to 6. Based on Bill's good work, the ratios would look like this:

First: Guard 3.5
Second: Stock 2.048 (21:43)
Third: RS 1.522 (23:35)
Fourth: RS 1.242 (33:41)
Fifth: RS 1.024 (41:42)
Sixth: Stock 5th 0.921 (35:38)

Do any of y'all have an opinion on these ratios for a close ratio gear box?

tsloeza

My gearbox was done over 15 years ago, looking at the sheet I have from when it was done those ratios look close to what was done to my trans. All I can say is that I love the way it drives, I also have a 98 C2S and I prefer driving my NB when going out for a spirited drive.

mgerber

Almost identical to what is in my car. I think the spacing is perfect for what I (we) do with the cars.

Bill Verburg

worst thing is 5 is too low
you want a wider spread
W/ a stockish motor and tires look for drops of ~ 37% 24% 18% 17% 20%, your money gears are 3 - 5 speeds of ~ 95 120 140 +/- work well for these, w/ a bit taller 6 for the interstates

Silver Surfer

Bill, would 5 work better with the RS 6th gear: 0.821 32:39

That would give me Guard 1st, Stock 2, RS 3-6

Bill Verburg

That helps a lot gearing 3.500,2.048, 1.522, 1.242, 1.024, 0.821

spread is 4.26 good
drops 41%26%18%18%20% good

GTgears

Why keep the stock ratio 2.05 instead of using a 2.00? You’re buying a new second gear either way.

Silver Surfer

Good point. Looks like Guard in second for me. And you think 2.00 is a better choice?

Silver Surfer

Looks like the Guard options are 2.000 16:32 or 2.056 18:37 from the link you sent me.

GTgears

I do consider the 2.00 a better choice. We don't use the same toothcounts that they do, which is why I almost always talk in decimal ratios for clarity. In general, we reduce the toothcount for added strength and durability. The trade off is that's part of where the added noise comes from. For example, on the 2.00 ratio we do it as 16:32 versus 20:40. They do 1.521 35:23 whereas we do 1.526 19:29, etc.