clearym

This has probably been beaten up but, can anybody comment on an upgrade to 3.73 vs. 4.10 from a stock, manual GT. I realize that upgrading from the stock 3.55 to a 3.73 is a very small margin (and some would think its a waste of money) but, it is an improvement in launch right? Somebody recently told me that due to the gear ratios in the tranny, etc., etc. the 3.73 makes no difference and to get a better launch you must go to a 4.10. I'm not a rocket scientist but, I think this opinion defies the laws of physics.

I'd like an increase in launch without spinning the engine RPM too high at 80 mph, engine wear, gas milelage, etc. So, I thought I'd go with the 3.73. Please let me know if this makes sense (regardless of the return on the invesment in having the work done) or if my source was correct for some reason that I don't understand yet.

thanks

cool06

I have the 4:10 rear and was surprised at the difference - no where close to the radical change I expected. With the 5speed, there is no difference in gas mileage if you drive it judiciously. i have not been anywhere close to the top end!

mustangman02232

manual, 4.30s, and no im NOT kidding, the t-3650 has a .68 OD ratio and with a 26" tall tire will turn 2800 rpms in 5th gear @80, you will still get atleast 30 mpg (if your foot stays off the floor board)

and top end is the power in the upper RPM range, top speed is how fast a car will travel

cool06

Gotcha - that's waht I get for reading the forums while on a conference call! Haven't been at the top end very much either!

blackv6

i won some 4.10's off ebay a few days ago and they came in today!!!

I won them used... i have a few q's...
1) how can i make sure they're 7.5 not for an 8"?
2) on fordracing.com the nstruction manual states i should not mix and match rings/pinions and to make sure the #'s match
(ring states 6 140 247 ? BA 10 41? BB3) (PINION STATES 410 FO7DA H T)
the question marks represent an item i cannot make out... ring has 41teeth, pinion has 10. so its a 4.10 but is it for a 7.5"? i measures the outer diameter and it is 7 3/4since it is shaped as the top portion of a "V"the shorter distance is 7" my fear is that i will take it to get installed and i will hear "its for an 8" "
3) how can I remove the pinion bearing? should i even try?

GT John

Man, I sure would be careful with those used gears. Kinda like buying used pistons.

RICVA05

I would definitely stay away from used gears as stated before me not a good idea they could end up being a set somebody was having problems with. Some shops won't even install a used gear.

blackv6

seriously? i thought that there was no prob with used gears as ling as there were no cracks/pits/dings etc. then why are so many buying them used?

MikeHawke

Used gears are not a big deal because you can usually see burning or chips/cracks or unever wear patterns. If it looks good, it usually is.

7.5" and 8.8" refer to the diameter of the ring gear (obviously in inches).