Would 3.73:1 be too much gear for an HO-swapped panther?

[turbo2256b]

yOU can figure RPM and speed based on gears and tire dia

http://users.erols.com/srweiss/index.html#jcalc look at bottom right

Many trany sites have info to figure driven gear tooth counts

[JeffBoudah]

ran 4.10's w/ lsd on my 90mgm (had alum. shaft), p-heads, HO cam, HO upper, systemax1 lower. got 18-20mpg on the highway doing 70+. Boumann shift kit too. car ran like an ape, sounded mean with dumped 2.5" dronemasters.

[gadget73]

Difference between a 3.73 and a 3.55 on the highway is not significant. Assuming stock size 215/70-R15 tires and AOD, you're talking 2376 rpm vs 2497 at 80 mph. 121 rpm is fuck-all and the difference reduces as you slow down.

Don't go buying a 3.55 set if you have a perfectly good 3.73 set.

[SirFoxx]

Difference between a 3.73 and a 3.55 on the highway is not significant. Assuming stock size 215/70-R15 tires and AOD, you're talking 2376 rpm vs 2497 at 80 mph. 121 rpm is fuck-all and the difference reduces as you slow down.

Don't go buying a 3.55 set if you have a perfectly good 3.73 set.

So if I have 2.73's and want better acceleration, would you recommend the 3.73's? I know that is a bit of a broad question, but I am mainly concerned about the rear end at the moment.

[gadget73]

With an HO? 3.55 or 3.73 would be a big improvement over the stock gearing. The HO cam makes lousy torque under ~2500 rpm and with a 2.73 that takes forever to get to. Acceleration with an HO and stock gears is going to be considerably worse than the lopo because of that.

[His Royal Ghostliness]

Difference between a 3.73 and a 3.55 on the highway is not significant. Assuming stock size 215/70-R15 tires and AOD, you're talking 2376 rpm vs 2497 at 80 mph. 121 rpm is fuck-all and the difference reduces as you slow down.

Don't go buying a 3.55 set if you have a perfectly good 3.73 set.

^^^ This! Basically if you don't drive like most of the rest of the state population and keep it under 80mph you'll be alright. Also 2500 RPMs ain't nothing for an HO engine, so don't worry about it, just get some quieter mufflers if it starts to bother you. If you're not in a hurry do your Mustang gear swap and then move its gears into the GMQ, no money out and you know for a fact the gears are good.

So if I have 2.73's and want better acceleration, would you recommend the 3.73's? I know that is a bit of a broad question, but I am mainly concerned about the rear end at the moment.

Anything will give you better acceleration there, lol. The 3.73s is IMHO more of a busy traffic type of gearset cause it's very easy on accel and decel but can hurt you a bit on long high-speed interstate trips, but if that's what you can get the best deal on go for it. The 3.55s you mentioned earlier would be the other set that's good for off the line and really all-around performance.

[Giraffe]

^^^ This! Basically if you don't drive like most of the rest of the state population and keep it under 80mph you'll be alright. Also 2500 RPMs ain't nothing for an HO engine, so don't worry about it, just get some quieter mufflers if it starts to bother you. If you're not in a hurry do your Mustang gear swap and then move its gears into the GMQ, no money out and you know for a fact the gears are good.

That makes sense. The Mustang swap is likely to have to wait until early-spring. This winter will be spent collecting parts for a big brake and an HO or GT40 engine swap.

Thank for y'all's input. I'm looking forward to having some more get up and go with the Mercury.

[Lincolnmania]

i can run at 100 mph all day long if i want to.

[sly]

My 93 DID run for about 3 hours at near 100 (following a Charger) down to Houston on Christmas last year. No issues. 3.55 gears. PI swap. But I also have an F150 dual core rad and trans cooler in that one.

[His Royal Ghostliness]

Sly, apples to oranges friend, 100mph sustained is no big deal for a mod motor, not so much for a 302W. Scott wins the coolness award there

[gadget73]

A 302 in good shape will stand it a whole lot better than a slapped out one will. A typical lopo in a box is probably not going to survive a few hours at that rpm and still have any oil in the pan, assuming it doesn't just overheat horribly before it gets that far along.

[SirFoxx]

With an HO? 3.55 or 3.73 would be a big improvement over the stock gearing. The HO cam makes lousy torque under ~2500 rpm and with a 2.73 that takes forever to get to. Acceleration with an HO and stock gears is going to be considerably worse than the lopo because of that.

I can say first hand that this is the exact problem I have right now lol. It cant even spin one tire on loose material. Probably going to pick up a set of 3.73's from ebay. A seller supposedly has a ring and pinion for $50 with ~$14 shipping.

[His Royal Ghostliness]

That sounds about right for used Ford 8.8 gears, they're all over the place by ways of Ranger trucks so they're not worth a whole lot - good for you when you need them

[knucklehead0202]

Hell in southern california if you're on the freeway going 75 they try to run you off the road for going too slow. With the stock cluster i was out of speedo most of my road trip last weekend. With 3.55s and a pretty-stock lopo i averaged 21mpg mixed. Can't wait to have 347 power though. Mileage may suffer but the fun factor will make it worthwhile.

My wrecked '90 had 3.08s and i was going to trade my brother for the 3.73s in his mustang since he was going turbo and wanted the longer gears to load and spool the turbo. Never worked out because his project stalled and my car got fucked. I scarcely drive the car so freeway economy isn't a huge deal but i like to stay reasonable.

[His Royal Ghostliness]

Hell in southern california if you're on the freeway going 75 they try to run you off the road for going too slow.

Tends to be the case in TX as well. The solution we have found works best is simply growing up, in vehicle size that is. Few people are stupid enough to fuck with a 4-door longbed truck built on a medium-duty chassis and rolling on 10-lug dump truck (literally!) wheels with axles to match. When your fuel tanks alone are larger in diameter than some people's tires and longer than other people's truck beds, both groups generally tend to leave you to your own devices if you're going close to the speed limit and instead simply wait more or less patiently for an opportunity to pass you. In other words fuck the right of way, right of weight tends to be what most iphone-totting fuckheads out there seem to respect more So just make sure you got more weight than them, simple enough.