FWD gearing question

[goinbroke2]

Keep in mind that while I LOVE drag racing, I like and am very involved in off roading.

On fwd vehicles there is a drive chain between the engine and transmission. Has anyone tried to find or make gears that would lower the ratio??

Kind of unrelated but a buddy with an awd excape was wondering how to lower the ring and pinion to make up for the bigger tires. I'm thinking two options;

1) Search through junkyards or parts books to see the different gear diameters/chain length/tooth count/etc and match up a gear reduction,

or

2) Take a planetary out of an automatic and fab up a high/low range.

This of course got me thinking, all fwd racers complain they can't get low enough gearing...since everybody and their dog has a lathe and milling machine now, has anybody explored this avenue? Has anyone tried to mix and match or fabricated a custom set up?

[ss3011]

We used to make underdrive gear sets by designing a drive sprocket with the minimum number of teeth and match that with a driven sprocket . Typically you add the drive and driven tooth count and that number is a constant. On the earlier GM FWD transmissions, that number was about 70. The best under drive ratio we could make was a 32/38 sprocket set. Anything smaller then 32 could not be packaged on the Drive sprocket support. So the best final drive ratio was 3.33, which gave an overall ratio of 3.95. That is why most of these cars had to put such short tires on them. It was hard to keep the engine up in its powerband with the wide ratios for 1st and 2nd gear.

[Charles Stewart]

You will find here a chart for different ratio option.
http://www.gmtuners.com/images/FWD_trans_ratios.pdf

[SDT1DYI]

Larry Dowty and Dick St John built a FWD SS car several years back. They manufactured their own gear sets. Larry's retired from racing but I pretty sure would answer your questions. Text me at 360 979 3126 and I could send you his # after I talk with him.
Steve Teeter Stk/ SS 620

[goinbroke2]

Thanks for all the replies and info!!
I was thinking SOMEONE must of thought of this before me, lol!

Charles, excellent chart you posted!

SS3011, although the gear ratios change, the chain length is still the same correct?

This is still in the "what if" stage, so yes, it is possible and has been done. I'll throw the ball to him to run with it and if the want is bigger than the $$ required (and I have time) I might get deeper into it.

This also answers the question if I ever build a fwd Stocker.

Thanks

[Charles Stewart]

Mr. Miller are you able to obtain the part name or a part number for the automatic transmission of the 2010 Ford Escape of your friend?
I know that Ford and GM has developed a joint venture on some FWD automatic transmission.

[FED 387]

2010 Ford Escape either FWD or AWD with a MANUAL trans with the 2.5L engine has a 4:13 final gear ---not sure if that was standard or optional but that's a lot better than a 3:51 gear set up---you will have to look at a parts book to get the numbers ---is this what you were looking for??? Fed 287

[ss3011]

Originally Posted by goinbroke2

Thanks for all the replies and info!!
I was thinking SOMEONE must of thought of this before me, lol!

Charles, excellent chart you posted!

SS3011, although the gear ratios change, the chain length is still the same correct?

This is still in the "what if" stage, so yes, it is possible and has been done. I'll throw the ball to him to run with it and if the want is bigger than the $$ required (and I have time) I might get deeper into it.

This also answers the question if I ever build a fwd Stocker.

Thanks

Yes, the chain is the same.

[Cglrcng]

Interesting, on our Mopar FWD vehicles (A413, series transaxle, lots of other numbers involved), there is no chain, just a set of side case gears that mesh w/ one another, that help lower or raise the final ratio. See the pics attached, only so many ratios were factory produced that fit, but it is possible to mill, or mfg different tooth combos to fit. And yes those smaller wheel/tire additions lower the final gear ratio. (Pics to follow, need to resize them first). Then, of course 1st and second gearsets can also be changed, third is 1:1. Then add the smallest wheel tire combo to lower that finial ratio. It certainly helps.

[Cglrcng]

Here are a few shop manual diagrams and pics of my stock side case gearset that came out of my Chrysler A-413 3.21 or 3.22 Ratio back in 1993, replaced, then had a lower ratio gearset cut (once I pull the transaxle next up (soon), I will be counting teeth on those for Greg Hogue to get his 84 Daytona Turbo edition Stocker he is building some info on). Like I said ours are direct drive gear to gear (no chain), but there is always more than 1 way to skin a cat! You may want to talk to him as he is already researching the same thing you seem to be.













No offense to cats of course.