Hello. I heard that 348 was available with 2 different gear ratios: -speed (long) -acceleration (short) You suppose to take off the clutch and change 2 gears behind the clutch (20-30min work). These kits were available from ferrari and they were used for Challenge cup or anybody who likes to do a track day. Anyone knows something more about this (is it true)? I would love to buy a shorter ratio for mine. Cheers,
The 1994 348 Spiders have a 4.34 to 1 final drive ratio. The 1993 348 TS's have a final drive ratio of 3.53 to 1 (click here: http://maximum-cars.com/Cars/Car.php?carnumber=337 ). The 1992 & 1993 Ferrari 348 tb and ts Serie Speciale had their rear track widened by 50mm from 1578mm to 1628mm by adding 25mm of offset to each wheel, and their final drive was shortened from 26/27 on the earlier cars to 25/29 on the SS. A taller fifth gear was fitted (early cars having p/n 70000592), to maintain top speed with the new lower main gear installed (click here: http://www.ferrariclub.com/faq/348versions.html ). The 1990 348 TB's have a final drive ratio of 3.56 to 1 (click here: http://www.*super*cars.net*/cars/564.html - remove the *'s for link to work).
In fact, the acceleration gearing uses the Mondial t final ratio which is 25/29... I have a 348 gearbox and a Mondial t gearbox... That is the difference. I have fitted the longer ratios 26/27 to my Mondial t, as this reduces the engine RPM to wheel movement for normal daily use resulting in about 10% RPM lowering, fuel saving and reduced wear and tear... The above ratios refer to the teeth on the cogs that go from the clutch shaft to the pinion. The final drives referred to below on the various cars mentioned refer to different gears on the actual 5th gear cog on the mainshaft (I believe the 4/5th are on the mainshaft, and reverse, 1,2,3rd are on the layshaft, but may be reversed I don't have the manual to hand...) When I am in tracking season, I swap back... Marco
Just one note to this: the Serie speciale and Spider gearboxes are Identical. Bacically, the Speciale`s were fitted with the Spider gearbox. Regards, Jim
Indeed. I have a Spider gearbox on my 'ts' after my standard gearbox blew up. I'd wager that 99.999% of the people who drive these cars (myself included) cannot sense one iota of performance difference. I'd go a bit further -- if you're bashing on a 348 box hard enough to know the difference, you're in for a nasty surprise at ca. 50k miles anyway.
I am interested in doing this converion. My 348 has the 3.5 final drive ratio and would like the 4.3 used on the Challenge cars and convertables. I found the gear set 7000800. I think you would need the Ring Nut Tool to get at the pinion shaft to replace one gear and a puller for the clutch shaft gear. I have the clutch basket out but no tools. So i thought I'd have someone do it for me and called Ferrari Ontario... they expressed no interest in doing the job ( i think because i had already removed the gearbox from the car and was only going to take the gearbox to them... i felt they want to do the complete job or nothing) After he said "that if i came in and sat down with them they can discuss the job" ??? I never get any usefull info from them over the phone, and its a waste of time to drive 1 hour to nowhere with them. I felt like i had to convince them to do the work. ??? So step 2... I called an independent who worked on ferraris who said it is a 20 hour job and the gearbox has to come completely apart to get at the gears. ??? I am a little confused... I'm not sure what to do next... Can anyone shed some light on this. Is it posible to change these gears in an hour or does the gearbox have to come apart? If it is possible i should just buy the tools and do it myself... Any input would be fantastic. -daniel
Daniel, You do have to take the whole box apart. You can change one cog on the clutch shaft, but to the to the other one on the pinion, you need to remove the lay and main shaft. So 20 hours is about right, if you can do it blindfolded. For a mere mortal it will take about 40-50 hours as you will most probably have to prussian blue the alignment of the pinion, change various bearings while you're there and then re-ship the bevel, lay and main shafts... So unless you REALLY want the mod permanently don't bother. I do it because I have 2 boxes I can swap between, and it gives me the winter to tinker... M
thanks for the confirmation. I did get the gear set and ordered the ringnut tool. I am going to do it myself over the winter. I was looking at the shop manual and it does not go into great detail. I will get my tool in a week and start then. Dismantal procedure: I'm thinking the transmision shaft will come out via the intermediate housing way one you take the three seals off, then you pop the clutch shaft out with a slide hammer puller. Unbolt the intermediate housing and pull it off. (do you have to do anything with the shifter shaft before?) Remove the shifter shaft and selector rods, forks, rollers, springs, balls. (how do you align the forks again when you reinstal? Should i make a template before i take it apart?) take side covers off thats as far as i got looking at the manual so far. Does anyone have a write up on this, if not i can try and document it hear with pictures as i do it. -daniel
Took the gearbox out and started taking it apart... Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
Nice. While you are at it, I HIGHLY advise you to to changed the outer bearings on both sides of the gear box. Especially the bearing on the oil pump side of the gear box. That particular bearing has a history of the cage breaking. So while you are in there may as well do some preventive maintenance.
Cut the 3 seals off to slide the transmission shaft out. I then made a puller attachment to pull the clutchshaft out using a slide-hammer and a little heat with a propain torch. It came out easy with about 3 or 4 slides of the hammer. You can pull the clutchshaft out complete with the transmission shaft in place if you dont want to take the 3 seals off. The clutchshaft holds the one of the two gears i will be replacing. This is the easy one to get at. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
great i will look into new outer bearings, thanks pulled the diff flanges and spacers off both sides... now the diff is loosely in there. I then removed the shifter shafts out the side of the tranny watching not to loose the small spring and ball in each shaft. Tried to slide the diff out but seems like i have to either remove the main and layshaft first or take the diff apart while still in the housing. -daniel Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
No. All you have to do is rotate the diff inside the housing. If you look at the last pic you put up in post #17, what you need to do is rotate the diff so that the left side goes back into the box (the part with the clutch/cross plates, and sun/spider gears inside of it. In short all the limited slip guts). The big ring gear comes out the front first. It's a REALLY tight fit, but it will come out, and you don't need to remove the bearings, at least I didn't have to. What made it easier for me was to lay the box on it's back on the floor, so that the opening was facing up. Then get ahold of the big ring gear and slightly pull up towards the open face of the box. This will allow some room for you to drop the limited slip housing back inside the box. Then lift the ring gear out more, and continue to rotate it to the left. By rotate I don't mean "spin it", I mean move the big gear so that the edge goes left. You want to rotate it so that you look at the face of the gear. Or "rotate it so that you are looking at the face of the coin, and not the edge" (if that helps describe it better???) So the edge facing out goes to the left, and the part of the gear inside the box comes up and out to the right. It may take a few times trying but it will come out. You have to position the gearing just so, as there really isn't any wiggle room. Hope that helps?
i used the ring-nut tool to remove all four ringnuts on the ends of the mainshaft and layshaft. I used rope to jam the gears so i could loosen the nuts without the shafts turning. next, the driver side bearings and intermediate housing which hold the bearings was not wanting to slide off so i made up a plate, bolted it to the intermediate housing then used 2 pullers and the assembly came right off with no problems. ( i did use a heat gun to heat up the bearing area.) Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
worked on the passanger side today... pulled the 2 outter bearings off and took all the gears out. so i have removed all the gears and bearings off both sides of the gearbox. Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
held the gears in place with some steel beam and mounted my custom plate on the driver side to help pull the shaft while i was hammering it out from the passenger side. The shaft came out fairly easy with not too much hammer banging. after the shaft came out i plucked the rest of the middle gears out which made room for me to take the diff out complete with bearing assembly still on. (ernie... i now understand why i couldn't get it out before i took the layshaft out... i didn't remove the one side bearing off the diff.) -daniel Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
more pics Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login Image Unavailable, Please Login
That looks like fun! Check for pitting & deterioration of both shafts carefully.Looks like this. Image Unavailable, Please Login
