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So who's a tranny expert?

1.1K views 13 replies 9 participants last post by  TuscaniTibby04  
#1 · (Edited)
My buddy Chris and I were discussing rev's at highway speeds. For us the maximum speed limit on a 100 series highway is 100-110km/h. Now my car rev's about 25-2700 RPM's, it's a 6 speed. Chris's mutlible VW's usually pull about the same but their 4 cylinder and 5 speeds.

So Chris mentioned he wanted to put a TDI 5th gear in his Corrado, apparently it'll drop the RPM's to abou 18-2000. So I mentioned I wouldn't mind replacing my 6th to get the RPM's down to 1800, we both do A LOT of highway. And sense I can drive around town in 6th pullin 1500 I figgure there's no reason it couldn't be swaped out.

BUT, then I thought shifting from 5th to 6th at 100km/h (60 mp/h) would mean a 700-1000 RPM drop. Seems excessive, so I thought maybe insted of swaping the 6th gear, why not swap out the final drives in the differential (crown/ pinion). I'm not sure what the current ratio is, but it seems to me that if I swap those gears, I could lenghen out ALL the gears and gradually build up to that 1000RPM drop.

If I could gain 1-200 RPM per gear, then by the time I hit 6th wouldn't I be down to the 1800RPM mark?

I'm no expert on gearing, I've swaped a few pinions over the years, but I never had to sit down and come up with a ratio. I imagine the ole man could answer this one but he'd need to know the final drive ratio.

So any thoughts from the experts would be great, probly poke a hole or two into what I said. Basicly I'm askin if I'd be better off to swap the finals (what's the ratio?) or take it to a tranny shop and have 6th swaped from whatever stock is to something more highway friendly?:einstein:



EDIT: Sence I have you attention; Would anyone reccommend the XTD clutch kits? (stage 2 or 3) I tried Fidanza but they said they don't make a clutch kit for the 2.7L Tiburon.....
 
#3 · (Edited)
You're pretty much totally correct. Do some digging up around the boards with this topic to start:

http://www.newtiburon.com/forums/showthread.php?t=113870

Might see a few names in there too, whom you can email/PM or whatever.

EDIT: Sence I have you attention; Would anyone reccommend the XTD clutch kits? (stage 2 or 3) I tried Fidanza but they said they don't make a clutch kit for the 2.7L Tiburon.....
Oh, I have first hand experience with XTD. Don't buy their Ebay crap. Mine lasted a little over a week before it flew into pieces, and their customer service/ "warranty" is crap. I tried for 10 straight months to get my money back, but nothing. Brickwalled, got the runaround, blocked my area code (which is yours too) if they can even do that.....

-BRR
 
#4 ·
You're pretty much totally correct. Do some digging up around the boards with this topic to start:

http://www.newtiburon.com/forums/showthread.php?t=113870

Might see a few names in there too, whom you can email/PM or whatever.

Oh, I have first hand experience with XTD. Don't buy their Ebay crap. Mine lasted a little over a week before it flew into pieces, and their customer service/ "warranty" is crap. I tried for 10 straight months to get my money back, but nothing. Brickwalled, got the runaround, blocked my area code (which is yours too) if they can even do that.....

-BRR
lol nice, I figgured as much but I hadn't noticed it on ebay, I saw it in the clutch/ flywheel sticky, then took notice on ebay. I was hopin to go with Fidanza but no clutch kit yet. It's good to know that I'm not totally ignorant of all aspects of the Tib, I did look through this section a bit to find anything on the 6th gear swap but either I missed it or didn't come across anything. Typed in "6th gear" & "Gear swap" but not much seemed to come up.
 
#5 ·
well i dated a tranny back in my 20's but thats before i found out he was a pre-op. Giggidy giggidy...
 
#7 ·
Would a stockish tiburon be able to pull up a hill at only 1800 rpm? that is nearly half the rpm as usual, so approximately twice as much torque would be needed, and it (at least mine) isn't making much torque at 1800 rpm.
 
#10 ·
Well, from what I've seen with mine, I can curse throu town at 50km/h in 6th gear at 10-1300 RPM up and down hill no problem. It will accelerate like a 96 year old man, but it will accelerate. So I'm 50% sure it would be fine with the gear swap I want, 1800 is a little lower then I was thinking, played around a bit with the stock gearing with a Maxima FD (3.812:1) which if installed will drop the RPM to 1800ish in 6th @ 60mph.

Now if you split the difference between stock (4.428:1) and the Maxima (3.812:1) and take roughly 4.000:1 it puts the RPM to 21-2300 RPM, the flip side is you also achieve ROUGHLY the same RPM drop with just the Maxima 6th gear swapped (0.630:1). It's been my experience that removing and swapping a FD is a little more straight forward then changing gears in a 6spd tranny, but I've never opened a tranny (shut up Staw512 lol).

It's all theory for the time being, I'm not going to waste time and money with this util I know where I can get parts and how much, then find a weekend that dad's around to give me a hand with it, probly need his advice on setting the lash. So it's pretty much my little pipe dream for the time being.
 
#8 ·
V6 Six Speed final drive ratio is an ungodly 4.43:1
5 speed tranny has a final drive ratio of 4.06:1 which IMO is still pretty insane. But we're dealing with tiny little engines, so it's basically the 1930's again.

Given that the 6 spd has a granny 1st gear and you can basically start the car off in 2nd if you have even the slightest roll (or a windy day) so the car could definitely benefit from a numerically lower gear ratio.

The unfortunate part in all this is that the 5 speed and 6 speed are entirely different. No parts interchange between the two and I highly doubt that the internals can be swapped around either.
I've yet to see an aftermarket gearset for the Tibs either - so no matter what you try, you're hooped.
 
#9 ·
Since you have a 6-speed your best bet is to attempt the Maxima gear swap... or you could just put on some 22" wheels. That'll put your FD to around where you want it.
 
#11 ·
I wish I was... in case there are any tranny experts, someone please tell me why my auto transmission is "stuck" in 3rd gear. P-R-N-D works fine, but shiftronic doesn't do anything, I'm throwing a TCM and Transaxle range circuit error CEL. When I put it in drive it just stays in 3rd gear. Indicator doesn't display in instrument cluster, and cruise control does not work. Anyone? I'm hoping my TCM isn't shot but that's the only thing I can think of...
 
#12 · (Edited)
Sounds like an electrical problem. Have you checked all your fuses? I believe the transmission is manually shifted, and electronically controlled; so it would leave me to believe it was a TCM problem or a sensor problem. Transaxle range circuit Error makes me think that the TCM can't figure out what gear is active.

When you put it in D, is it stuck in 3rd?

edit: What code did you throw? P0707/P0708? I'm thinking you need a new Range switch if its either of those two.
 
#14 ·
The problem that I could see popping up with a numerically lower final drive would be that putting the engine into the lower RPM's like that you may sacrifice a lot of fuel economy.

I've noticed with the Tib, is that it seems to be most efficient cruising around 3,000 rpm. This took me a LOT of getting used to as I've always driven old car with high (2.81, 3.08, 3.15) final drives.

Putting the engine into a lower rpm in 6th with a higher final drive will definitely take you out of the efficiency range. Not to mention, you'll have to drop out of 6th to accellerate, pass, etc.
(again, that's how it used to be - way back when)

It would be something to try, though if you're so inclined.