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> 3rd and 5th Gear Swap
Van914
post Feb 12 2006, 09:37 AM
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Does anyone have the instructions for this swap.
Do you change both the imput shaft and main shaft gears?

Trying to get ready for the April DE

Thanks
Van
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groot
post Feb 12 2006, 10:13 AM
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Yes, you must change both gears... all gears are matched and should always be run together.
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KenH
post Feb 12 2006, 10:29 AM
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The gears are swaped from one shaft to the other.

So yes, you have to remove both shafts and gear stacks and the rearrange the gears.

Should inspect the Synco's at the same time.

Ken
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Aaron Cox
post Feb 12 2006, 10:40 AM
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All there is to it. flip shafts and swap positions....

A 'Q' or 'S' gear will compliment your new box as a slightly shorter 4th gear....
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Van914
post Feb 12 2006, 02:46 PM
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Arron,
Yes I have a S Gear for 4th. some one had a picture on a thread one on hear but I can't find it.
Thanks
Van
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Aaron Cox
post Feb 12 2006, 02:52 PM
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thats precisely what i have....
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slivel
post Feb 12 2006, 03:00 PM
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On the topic of swapping gears, does anyone know if it causes any problems when you have the opposite thrust factor applied to the transmission internals. Since the gears are helical cut (not straight cut) they produce some thrust vector and this would be reversed when swapping shafts.

Steve
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KenH
post Feb 12 2006, 04:07 PM
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I checked with Jerry Woods about the thrust issue and he said had not seen any problems from the swap.

Arron - I am making the same change to my tranny and was going to put a Z in for 5th. Any comments??

Ken
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KenH
post Feb 12 2006, 04:10 PM
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Oh - also changing 2nd to GA. Our AX tracks usually red-line 2nd just before a turn, thought a GA would keep me pulling.

ken
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crresind
post Feb 12 2006, 04:16 PM
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As KenH said, there does not seem to be a problem with swapping gears. Keep in mind that the trans can be used to decelerate as well as accelerate. There has been some duscussion among trans 'experts' but there is no diffinitive answer against the practice. One common swap is to take a ZD from 5th and swap to 3rd, giving a KA. I have several race cars using this swap. Five years so far and no problems.
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crresind
post Feb 12 2006, 04:18 PM
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Steve are you still using the 901/911/914 behind that 3.2?
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slivel
post Feb 12 2006, 05:00 PM
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QUOTE (crresind @ Feb 12 2006, 02:18 PM)
Steve are you still using the 901/911/914 behind that 3.2?

Yes, and it's now a 3.4 twin plug. I'm running AFMSX gears.
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Aaron Cox
post Feb 12 2006, 08:49 PM
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ken - is this a 4 banger?

a GA is a bit taller than an F....

so youll have a taller second, a shorter third (S or Q for 4th) and a Z which is a slighty shorter 5th....

so youll have a bigger 1-2 gap, a WAYYYY shorter 2-3..... 3-4 is a tad shorter 4-5 is a bit longer, but still shorter than a ZD

so youll have a close ratio 3 speed and a slight overdrive for streetability
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brant
post Feb 12 2006, 09:05 PM
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I had no problem using a KA (or K/L as I've heard it called) flipped for about 5 years on a race car

brant
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ottox914
post Feb 12 2006, 11:07 PM
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In the classics section there is a great thread on auto-x transmissions that goes over alot of this stuff. I'm considering a 5th to 3rd swap for the next rebuild, and possibly swapping the 4th gears, one shaft to the other, to make a cheep close ratio 1-4 set up, keeping 5th tall for the highway to and from the events. Anyone done this one? Waddya think? Is the jump from 4th to 5th just way to much, or do-able?
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KenH
post Feb 13 2006, 12:18 AM
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Arron - 4 cyl 2.0 track car. GA is to try and stay in 2nd for AX.
On the big track never use 2nd (except out of the pits) racing only 3, 4, 5. Thunderhill has the longest single section of the tracks up here and now when I Tach out of 4th and drop to 5th the car "mushes down". So my plan is to try short 3-4-5 gears to see if I can just red-line in 5th at the end of the longest section.

Ken
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JWest
post Feb 13 2006, 08:48 AM
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QUOTE (ottox914 @ Feb 13 2006, 12:07 AM)
and possibly swapping the 4th gears, one shaft to the other,

You can't do that, unfortunately, because one gear is splined to the shaft and the other is on a bearing with a syncro, so they can't be swapped directly. The 3rd to 5th works becase they flip and invert, but you could not just flip 5th or 3rd in there own position either.
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Aaron Cox
post Feb 13 2006, 10:27 AM
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QUOTE (KenH @ Feb 12 2006, 11:18 PM)
Arron - 4 cyl 2.0 track car. GA is to try and stay in 2nd for AX.
On the big track never use 2nd (except out of the pits) racing only 3, 4, 5. Thunderhill has the longest single section of the tracks up here and now when I Tach out of 4th and drop to 5th the car "mushes down". So my plan is to try short 3-4-5 gears to see if I can just red-line in 5th at the end of the longest section.

Ken

your 3-4 will be nice... but you need a wayy shorter 5th to stay in the powerband and not mush down....

if you go KA S id say want an X for 5th....

linda limits your highway cruising.....


ask trekkor for a ride in his M S X box....
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KenH
post Feb 13 2006, 10:31 AM
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I made a mistake. I did mean X.

Thanks for the reply and sorry I confused the issue.

Ken
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