Hello all, while working on the car I get these random ideas. This one is driven by one of the many article that Paulchua is nice enough to provide for all of us. It stated that the Mondial is almost ridiculously high rev, "4th is higher rev than 5th in most cars", and I can certainly attest to that after the long drive through Nova Scotia, New Brunswick and Quebec. I used to tinker a lot with 60s and 70s Mercedes...it was one of the most common things to swap rear axles with a lower gearing, mostly those would be found on the US models (as the engines were usually larger displacement). What about the Mondial, is there an easy swap (e.g. bevel gear @ differential) to lower the RPM? What would be alternatives, e.g. in the gearbox itself, or is there even a living example around ;-? cheers braq PS: I know the drawbacks regarding acceleration, let's just assume for the moment that I enjoy long drives on lonely roads at the border of Quebec and Maine, staying mostly in the same gear and admiring the GTs waftability.
You are correct our cars do not exactly have 'overdrive'. I offer this consolation. In the old days a sports car was intended to achieve top speed in top gear and this provides close ratio transmissions. My 3.2 car has peak hp at 7,000 rpm and peak torque at more then 5,000 rmps. This is RACY! Sort of the definition of Ferrari! But it hurts not a thing as far as I can tell. Two years and going on 11,000 miles [never once towed in] I have experimented with various cruising rpms in my mountains where fifth gear at 3,000 rpms can exceed many speed limits. Here are my observation running BELOW 3,000 and running above 3,000 rpms. And in this case I mean running 4,000 - 6,000 rpms in the boondocks. The car really likes higher rpms. First and foremost it gets up into serious throttle response and fun thrust! The car runs fine sub 3,000 but I think it does not like it. Every time I seriously use 4,000 -6,000 on a beer run it always seems more contented at idle and driving off from a stop light. On the down side my car has an oil radiator leak and the front engine main seal is a bit weak. Accordingly I get more oil use and a seriously messy rear undercarriage. I have this all scheduled for my local wrench in the next couple of months but the car could go on like this for years. I will probably bypass the oil cooler all together unless the wrench finds replacement of the cooler is easy to do. I have always revved the bejeseez out of my cars. For instance, my 1965 Corvair. It was worn out in 1979 when I found it, was worn out five years ago when I had it overhauled, and did not need to replace rod bearings. It has a 50 year old alternator. The Corvair water pump will never need replacement. My 1991 supercharged Mark VII never wore out an alternator, water pump, or power steering pump or automatic transmission in 190,000 miles. And never leaked, used, or dripped oil. I believe in using my machines throughout their design range. The Mondial is no exception. My practice braking, for instance, seems to have reduced the front rotors by thirty five thousandths. So, even though they work just fine I have decided to replace them. I will soon be on my third set of tires. This car sits in my carport every day. I just get in, turn the key and drive away. And I have read the shop manual that cautions the mechanic that the cylinder liners are unlikely to show much wear. This is a car designed to race around at 6-7k rpms all afternoon on track days. Even with the moderate hot rodding I do I do not plan to replace the cam belts as specified. Why? Every last cam belt failure I have ever read of took place after replacement! Take a look at these belts. They look MilSpec for an Abrams M-1 main battle tank. Me damage them? We will see in one more year.
@Jeka, sounds interesting, would you happen to have numbers on the ratio? Was there a particular reason like a sweet spot for swiss emission testing for it? I kind of wanted to respectfully avoid a discussion about sense in this thought but then I will politely counter the hi-rev argument: 95% of the time I have plenty of gear to choose from for a downshift ;-) and there is a reason for the dog-leg pattern, you hardly touch 1st... Going from the original TRX circumfence to the 360's wheels brought it up a tad, first time that spedometer and GPS read exactly the same. Cheers braq
Here you can see the differences. The over-all gear ratio is approximately 7% longer. Image Unavailable, Please Login Image Unavailable, Please Login
I hardly ever touch SECOND. But driving along at 3,500 rpm does not need a downshift. You CAN downshift and seriously get the max and I have done this in second in hard right hand turns but these are few and far between. Fun scampering and slithering about but gearing is very low. So I generally go into all my local sub 40 mph turns in third. But I simply delight in routine throttle response between 4,000 and 5,000 rpms. And thats one gear HIGHER then this car can do! Hey! No disrespect intended. But I DRIVE a FERRARI!
I have done something similar on two of my other cars and I love the results. You get lower cruising rpms and less wear and tear on the engine. If you can spin the wheels in first gear, you don't need any more gearing. On both of those cars, my goal was to get the gear below top gear after the change to equal top gear before the change. So in a 6 speed, new 5th equaled old 6th. In the 5 speed auto, old 5th was similar to new 4th. In each case, top gear was now a true overdrive being 12-15% taller. When going to taller (not lower, the number is actually higher) gearing, I offset the loss in total torque by adding power. Both times I added at a minimum headers and tune, which increased torque offset the gear multiplication torque loss. So more power, better mileage, relaxed engine speed cruising. No downside other than perhaps an infinitesimal loss of acceleration from 0-60. Your butt will never be able to tell. Taller wheels (larger diameter) help slightly, but the difference is not going to be that great. 3-5% typically. On our cars, there is a "reduction" gear (not sure if that is the correct name). If you can change that, you will affect all the ratios. Unless you are going to go about 12-15% increase, probably not worth the hassle. Regards, Jerry
I agree with Rapalyea, it's difficult to put all engines/cars into one category. Ferrari V8s like higher rpm's, due to the fact that their small displacement V8s tend to make power high up. When I had My Viper, I used to cruise along in 6th gear at 1500rpm, no problem at all. Do that in a Ferrari, and it will feel asthmatic at best.
I am in entire agreement. My positive displacement supercharged 5.0 Mark VII with 2.73 gears would hit the speed limiter at 130 mph at 3,000 rpm in tomb like silence. And I could still brake start a 1/4 mile drag strip and if not careful seriously smoke the rear tires. Torque Monsters are way way fun. But the little bitty screaming flat cranked Ferrari with its orchestrated symphonic assembly at my back is an entirely different animal. The Mk VII was a dead mans sleeper. I had it set up for simple full throttle acceleration from a stop light so there never was any engine noise, exhaust noise, or tire noise. Just GONE by 3,500 rpms! I am having my second one built as we speak, but it will have a bit of a show off exhaust note. And even though it will have all the regular suspension tricks that would make a C4 and the occasional C5 Vette weap for mercy I will probably drive the Mondial more.
Cant help myself. My supercharged engine has all the boost in at 6500 rpm so it really limits what I do on open roads. So mine is just a townie car
