A few of you may know from my recent posts I recently built a new gearbox for my car, it has all new weddle gears and a hybrid weddle mainshaft.
The box is solid mounted and I have checked the linkage etc... However on testing the car on the street, the gearbox was jumping out of 1st gear under hard exceleration when the motor reaches around 5000rpm but I could manage to hold it in if I tried. I took the car to the track the following week and as I though it just pops straight out of gear on the start line when I drop the clutch
Just hoping its a problem with the 1st-2nd gear slider but as far as I could tell at the time it was in very good condition.
Does anyone have any suggestions why this could be happening before I strip the gearbox again next week.
Worn operating sleeve drive flank? (I like using new Brazilian 113 sleeves for stock-type rebuilds)
Worn main shaft ball bearing bore, combined with beaten nose cone surface?
Improperly adjusted fork?
There could be other possibilities (but I've presently got jet-lag brain) ..
The only thing I can think is the slider is no good or I have set the shift fork up incorrectly? everything else is new and I can't imagane the weddle 1st gear idler is at fault, just hoping I've not damaged the drive teeth on the idler with it jumping out of gear?
Damaging the idler's tooth flanks is a distinct possibility, if the problem isn't corrected quickly.
If a burr exists on a single synchro tooth, this could cause pop-out. I always inspect new gears under magnification. Albins addressed this issue years ago, but handling damage can still occur.
When setting up the forks in the jig, care must be taken that both shafts are perfectly aligned, just as they will be in the trans.
the slider has to be cut on the first gear side and to the second side . So you could get more contact of the teeth on the first side usually will be cut around 0.030 to 0.060 . hope this will help you . ruben rhracing 787-632-9202
This is interesting? Is this because i'm using the weddle gears. I have built a few boxes for frineds with the same weddle mainshaft and new 1st and second gears and this is the first time i've had this problem?
This is normal procedure to approximately double the pathetic stock engagement surface area .. but it isn't the answer for whatever is presently causing your pop-out issue. At this point, I'd suggest posting CLEAR photos of whatever parts you're using.
RHRacing wrote:the slider has to be cut on the first gear side and to the second side . So you could get more contact of the teeth on the first side usually will be cut around 0.030 to 0.060 .
What do you do about the location of the detents on the shift rods?
Most transmissions I built required at least some detent modification. While I had the perfect stone for my Bridgeport, a die grinder can also be used.
Most performance boxes utilize a mix of parts .. typically a pre-shaved EARLY 1st/2nd sleeve (probably available from either ERCO or Weddle), with matching early forged 4mm fork, and LATE 1st/2nd shift rail. This combo leaves the detent locations pretty close to where they need to be.
Pablo2 wrote: .. typically a pre-shaved EARLY 1st/2nd sleeve ...., with matching early forged 4mm fork, and LATE 1st/2nd shift rail. This combo leaves the detent locations pretty close to where they need to be.
If you are cutting ½mm on each side of the early slider, it effectively is the same as the late 60s to about 72 slider and the stock detents line up.
What Ruben suggests is narrowing the slider much more, 2.25mm in total, not 1mm.
Ruben, are you welding up the original detents then grinding new ones?
Not far off from what's used for a Pro-ring drag trans .. around .025 on 1st and .040 on 2nd side, if I remember correctly. It's been so long, I'd have to either look at the parts or refer to the flyers I used to send out with our gears.
Whatever the amount is, it's easy to determine for yourself with the parts in hand. See how much deeper you can go on either side, while not overextending the synchro teeth too deeply into the retaining pockets. After shaving the sleeve, do a trial assembly of the trans. Measure how much the sleeve is kept from full engagement on either side. Modify the detents that amount. There's no need to weld up the old detents. Sure, it's a nice touch .. but it certainly isn't a requirement. The new location merely needs to be slightly deeper than the old, and the perfect shape for the detent ball. Be sure to clearance and round the corner of the reverse teeth on 1st gear side, as there will surely be interference with 1st fixed on the mainshaft.
Very early sliders were 1mm wider than the middle era ones,
and an 091 slider can be used on the weddle/Albins gears...which are another 1mm narrower.
I tend to take a little more off the 2nd gear side,
if using the sliders that need narrowing.
This combination works well with the late shift rail.
YES! Watch for interference with the teeth on reverse and the radius near 1st gear once the slider is narrowed!
Just for the record I am using the late 1st 2nd slider and reverse gear form 1303s AT code gearbox. I have an 091 one I could fit instead?
Will be another week before i get chance to fetch the gearbox out of the car but I will keep you informed as to my findings and hopefully some pics once the box is stripped.
Hopefully narrowing the slider will be the solution
Last edited by johnwalklett on Tue Sep 13, 2011 9:01 am, edited 1 time in total.
