FWD gearing question
 

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?

Re: FWD gearing question
 

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.

Re: FWD gearing question
 

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

Re: FWD gearing question
 

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

Re: FWD gearing question
 

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

Re: FWD gearing question
 

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.

Re: FWD gearing question
 

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

Re: FWD gearing question
 

Yes, the chain is the same.

Re: FWD gearing question
 

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.

Re: FWD gearing question
 

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.Attachment 69912

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No offense to cats of course.

Re: FWD gearing question
 

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I personally got a hold of and purchased finally a full set of the dealer's original Mopar shop/service manuals for my specific 84' Model year Daytona 2.2L TBI (3 Book Shop Repair Manual Set, Body, Mechanical, Electrical), for under $40.00 that the dealer's service units are liquidating and selling off as they no longer have need for them, and in the manual set (though my books are not here at the moment, up w/ the car in storage in Vegas), on gearing in the transaxle section, there is a list of every vehicle gearset combo that was manufactured, sold, and released in the stock car, truck, and van, for the model years1980-1995 that also fit in the 1984 year series transaxles, and a really nice chart & writeup on how and what you can mix and match (with stock sold parts at least), to get many different final gear ratios, and it also lists out some weak part #'s to stay away from as they were not ideal, and it appeared there was input from many sources including the Dodge/Chrysler/Plymouth division engineers along w/ Shelby, and Dick Landy, and others who were refining and racing these specific cars back in the 80's 90's, and beyond (so I know I received an updated manual set that was printed in the early 2000's).

It was interesting to see all the different parts, and that it is possible to hunt down some more ratios (Direct Connection only sold so many side case and planetary gearsets back then in 1993-94, listed as performance parts), so I purchased the lowest ratio sets avail., then visited a great master machinist friend who had the knowledge, and better math skills than I possessed, (a mechanical engineering degree, expertise, and machine shop equip.), and he asked me what final gear ratio I really wanted and I said somewhere around 4.56 (he wanted the transaxle on his disassembly cart as it was already out of the car, and I was doing the valve body work at the time, and ordering the Turbo Action Converter), he slightly disassembled the transaxle down to the planetary gearsets with me there, and he did the math, and went to work. (I was not there again until he had it ready to drop the valve body back in!) And I have not had the transaxle apart beyond pan off filter/ fluid changes, and I did take off in car the Diff. Cover to look at the spider gears, retention pin and inspect the big Ring Gear, carrier, etc. in car, and replace the silicone sealant/ paint the diff cover/ pan and replace the axle seals at Diff.

When it was all done he took the tires/wheels measurements 20" tall MT/ET FWD Slicks (or the much taller 28.5" Steel Belted Radial Street Tires), on the 14" X 6.5" 4 Lug 100mm Bolt Circle Stock Rims that came with the car added those to the mix and told me after all the math was done that he got it close to AVG 4.56:1, as close as he could get and that it was a lowered low gear and 2nd gear & final drive ratio of between 4.64:1 and 4.88:1 on slicks or street tires. (He said it was the easiest lower ratio set to do, anymore, and I could expect to pay through the nose), and charged me $100 for materials and $200 Labor. He was a friend. I moved away, and lost track of him not racing for 2.5 decades later (after 1997).

The difference between running the slicks and street tires has always been really evident (slicks are 2 tenths exactly quicker ET -same track at 1/4 mile, but the Street tires are almost always 1-2 MPH faster than the slicks 1/4 mile). The combo is low HP 99 Factory /NHRA Factored @ 105 HP, only actually have broken 1 axle cv joint due to racing so far in 1994, and had 1 replaced due to a damaged boot in 1997 (Axles are about $100 bucks w/ ret. core), but I have learned how to disassemble, inspect, repair and reboot them (purchased the simple tools & parts I needed), as I have 2 spares that I have recently serviced, so I have them at the ready if needed. Mine is the non-equal length half shft setup, though I have a damaged equal length half shaft setup someone gave me, it needs fixed (a damaged carrier bearing and cv joint).

I recently attempted to contact the machinist in San Clemente, CA, and was told the shop was sold during Covid, and they do not know how to locate the now retired owner, they gave me his phone # and it is no good. (Greg is awaiting me pulling the transaxle out soon, so I can rebuild it & have the Converter loosened up, and count teeth on side gears and planetary gearsets for him as a starting point (though his is a Slightly Boosted much higher HP application, and mine is Naturally Aspirated application), it should get him close to a good starting position based on my not much breakage history so far.

It was nowhere near the Make / Model you were asking about, just thought I would add other FWD info I know about. You surprised me mentioning chains...involved at all. I guess Mopar decided "Chains, what chains...We Don't Need No Stinking Chains!" Belts Yes, Gears Yes...Not a chain in the whole 2.2L drive train that I have seen. Even the 2.5L, get rid of the balance shafts (recommended), w/ the balance shaft delete kit, bye, bye chain.