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jmz jmz is online now
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Join Date: Feb 2003
Location: Texas Gulf Coast
Posts: 3,202
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Quote:
Originally Posted by Matt Monson View Post
Hello,
Based on what I see in the initial post, I have a sneaking suspicion that confusion around how 915 gears are traditionally listed versus how G50 gears get listed have led to a misunderstanding with respect to exactly what gears the shop is offering.

When I chart it, there just doesn't seem much point in installing the 4th gear they seem to be suggesting ( QP 26:25 0.96). This is the gear that Bill has charted.

A far more likely option is that they have a PQ 25:26 1.04 4th that they are trying to plug in there. That's a bit tighter on the 3-4 shift as well as offering a reasonable RPM drop on 5th that makes their suggested 5th quite useful in pulling hard up from roughly 110-130mph.

I suggest you go back to your builder and ask him specifically the letter designation of the gear to clarify what you are getting. If it's a QP, I wouldn't bother. If it's a PQ, they are steering you in the right direction and it's a good option for 4th regardless of whether you go with their suggested 5th or something a bit taller to preserve some highway cruising ability.

---Understood more-or-less. This is all new to me as is the nomenclature and/or numbering.

I'm not sure which number should be the numerator and which the denominator.

That said, Assume I have an 11/35 first then the shop is recommending the 25/26 4th not the other way around.


Bill, Does this look "less ugly"?

Thanks again
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-Jay '74 Mexico Blue 911 3.0 EFI (Fast and Loud)
'70 914/6 Race Car (Faster and Louder)
'71 73RSR tribute vintage race car 3.0
'68 SWB 911T "RENNRAT" 2.8 twin plug/915 gearbox
'81 Magenta IROC clone in progress 3.6 varioram/G50
Old 02-07-2008, 11:54 AM
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