hi all I'm new here so i hope i act appropriately! i have a 246 that jumos out of first gear. we originally pulled the box down because it jumped out of reverse. after replacing all the bearings, some shafts including the selector rail it, doesn't jump out of reverse, but now it jumps out of first, we've had it down about 5 times so far but to no avail. we've replaced all the first gear parts including the gear and synchro parts, it still comes out. seems fine if you nail the throttle and even off and on rapidly. the problem occurs when just rolling along in first , like in a traffic situation. has any body struck this before? there are signs that the car has had a major accident in the pass, could the case be distorted? thanks Les
First check all engine mounts. Make sure the engine is not moving around. Next I would think this is an assembly error. Inside the gearbox you have three ball bearings and 2 small oval looking pins. These act as locks if you will to prevet the shiftrods inside the transmission from moving once a gear is selected. My guess would be that these have either not been installed correctly or they ar not there at all.
Things like this happen all the time with Alfas, and many times it's just the motor or gearbox mounts.
thanks for your views, but there isn't a detent ball and pin for first gear, only for reverse and neutral, we even fitted one in the hopes of persuading it to stay in gear. we also removed the sump, engaged first, loosened the selectors on the rail and disconnected the linkage to isolate adjustment and mount problems, still no joy. the only thing that seems to keep the thing in gear is the synchro itself, same for the rest of the gears (except reverse which doesn't have a synchro of course). this has obviously been a previous problem with this box as someone in the past had also tried to fit a detent to the first gear rail (badly). also first has no more and probably less end float than the rest of the gears. thanks again Les
This sounds more like a selector fork problem. Have you checked that the appropriate fork is in good condition? FYI 1st gear and reverse use the same fork... I rembember someone posting here for a company that has remade some Dino selectors not so long ago.
You nailed it, the only thing that keeps it in gear on a transmission with Porsche style syncros are the syncros. The outer diameter of the syncro ring is convex and the inner diameter of the slider is concave. When the gear is selected the syncro should pop into that cavity and keep it there under no load conditions. The oval balls at the shift rails are only provided to prevent more than 1 rail from moving out of neutral position at a time. It is a classic problem if either the syncro or slider is excessively worn. In addition to the motor mounts and shift forks mentioned previously make sure that the shifter is not bottoming out in the gate so that the gear is completely engaged.
all the parts for first gear are new genuine parts- gear, drum, split ring, spider, detents, bearings, inner sleeves and anything else i can't remember. and the fork measures the same as all the rest. on one of our dismantlings we even mixed and matched other parts from the other gears. which is why i'm left wondering if some how the case is distorted (hard to imagine given it's size and construction) thanks Les
OK I'm 99% sure of what's the problem. While rebuilding your box you have inversed the retaining springs for 1st and reverse. The retaining spring for 1st gear is too weak. It was previously used for reverse apparently and when rebuilding you have used it for 1st gear. These 2 springs look identical and have each a small bearing ball at their end. You need to replace this spring with a stronger one. The gear will be a little more difficult to engage but it will not jump any more. I hope this helps.
Thanks for your reply. I'm trying to work out which springs you mean. are they coil springs? the only coil springs in the box are the ones that have the balls that work on the selector rails. there is only one per shaft and and it doesn't operate in first, only for reverse and neutral. I'm told there are 2 types 246 gearboxes, maybe we have a different one?
Yes it's these springs. Check that the one for 1st gear (formelly used for reverse in your car) is strong enough. In fact just change both this one and the one for reverse for stronger ones. Like I said before your problem is either due to these springs or to the fork. If you checked the fork and it's OK then it's the springs.
in the box we have this detent doesn't operate in first. only reverse and neutral. there is no groove for the ball to engage in, although we have added one without success
It can't be 74 as production ceased sometime in 1973 I think. Anyway it's an E i.e. the latest type and my comments apply to this variant. Both 1st and reverse have retaining springs with bearing balls at their end. You must have inverted them but your problem is that the one now used in 1st (previously reverse) is weak. Better change them both but this means engine out again, gearbox out, etc.
Dino Production 1973 S/N 05468 January 1st RHD British version built 1973. S/N 07202 1st 308GT4 numbered in the 246 sequence. S/N 07486 December Last European version 246GT coupe. S/N 07520 December Last USA version 246GT coupe. Estimated 1973 production - 471 246GT, 681 246GTS Total 1152 cars 1974 S/N 07526 January 1st RHD British version built 1974. S/N 07650 February Last RHD British version 246GT coupe. S/N 07650 February Last 246GT coupe. S/N 07778 February Last RHD British version 246GTS. S/N 07784 February Last European version 246GTS. S/N 08518 July Last USA version 246GTS. S/N 08518 July Last Dino 246 built. Estimated 1974 production - 3 246GT, 313 246GTS Total 316 cars http://www.dinoregister.com/production.html Check your serial Number.
i have a dino register printout that says it's 74, however the number now appears too early- 06906, but it also has some (chassis?)parts from 03850 in it, at least the steering column anyway. it appears to be built from 2 written off cars and is heavily modified in the body. this is what had me thinking the case may be distorted. there is definately no detent spring for first
06906 is a series III or type E 1973 production. Your mfg plate on the driver's side door sill should have a model year and MFG date. It should match the serial #'s in the engone bay, and on the steering column. (viewed through the windshield) 03850 would be a 1972 series III or type E car. Wrecked in 78, and parted out and used on at least 3 cars, including your own. It was, according to the Dino register, involved in a head on crash. How about a picture or two? Image Unavailable, Please Login Image Unavailable, Please Login
Thanks for the info on what the car is. the plate on the door sill is long gone, but the id plate and number on the rear chassis section match. so if it's a series E any thoughts on the gear box? I'll post some pictures when the car is painted and back together, at the moment it's not very pretty to look at!
here's a couple of photos of our Dino going back together, note the red hard top, that took some work to make it fit and stay in shape so it looked good in gloss red. the original black hides a really poor shape! anybody got any more thought on the gearbox issue? Image Unavailable, Please Login Image Unavailable, Please Login
That's not very stock is it? I'd like to see more pics of the modified areas if you have any. What's been done to the engine and suspension? What wheel/tire combo are you running to fill those fenders? Did you purchase the car with the modifications or did you do them yourself?
