what to do 915 rebuild or 4speed conversion?

[gorskined]

Well yesterday i came across a new problem . 915 in a 1980sc wide body turbo with a 76 3.0l row turbo . Transmission runs well ( ran well ) up until now, I just could never mash first and second ( synchro's are a little worn ) i don't beat on it its my fair weather driver. engine Built closed to stock for reliability not hp.
I backed the car up the driveway aligned it with my garage bay shut it down to cool came back a few hours later to put it in the garage.
When i put it into reverse it felt more like it was just above reverse closer to neutral. And the car felt like it was trying to pull forward as i eased off the clutch . i didn't force anything . i tried a bunch of other positions still nothing other than the pulling forward like it was bound as i slowly let off the clutch. I also couldn't get the full sweep of the gate, it was like i was stuck just above and below neutral but in forward with the parking brake on.
Eventually just below fist gear position the car engaged and went into reverse, i was able to back it in the garage.
so my dilemma rebuild the 915 or do a 4 speed swap.
what exactly needs to be done to do a 4 speed swap what transmission should i be looing for?
on the other end who rebuilds 915 would like to find someone local to Ct or within a 100 miles ar so if i chooses to go that direction .


Regards Ned

[Mocker]

Check that it's not just worn-out bushings, as your symptoms could be shifter-related, and not related to the transaxle.

[gorskined]

Originally Posted by Mocker

Check that it's not just worn-out bushings, as your symptoms could be shifter-related, and not related to the transaxle.

everything is new all new front bushings and new rear shifter knuckle thing. doesn't make sense finding reverse between 1st and neutral.

[quattrorunner]

I believe you have a loose Allen bolt holding the coupler to the shaft under the access panel behind the seats. The parts may be new but they will come loose.

[gorskined]

I wish that was the first thing I checked.. the front to back and left to right motion is several restricted can't even pick up neutral. But I can get reverse direct under 1st every other position is locked out . And if not in reverse and I feathers the clutch it feels like it wants to pull the car forward but it can't like the brakes are on . And I don't want to fully let off the clutch. Something is definitely stuck between positions in the transmission.

[quattrorunner]

Is the trans in neutral or some gear? If in gear rock it back and fourth and see if that movement might loosen something up.

[mepstein]

A four speed turbo trans doesn’t bolt in without shortening the bell housing and input shaft or doing a bunch of work on the chassis.

The 930 trans is over an inch longer and that extra length prevents it from exchanging with a 915 trans.

We charge $1,450 + parts to rebuild a trans. Shipping is probably about $150 each way to your door. PM me if I can help.

I just started on a mag case 915 today. Our turn around is 2-3 weeks.

[gorskined]

Originally Posted by quattrorunner

Is the trans in neutral or some gear? If in gear rock it back and fourth and see if that movement might loosen something up.

Two options reverse or some Locked up version of a forward gear. When in reverse the shift lever position is between 1st and neutral. Every other spot i can only move the shifter a reduced amount about an inch or so in each direction. When not in the reverse spot if I feathers the clutch the car feels like it wants to move forward... The car rolls fine with the clutch depressed.

[quattrorunner]

So you drove it lightly or at least normally and put into position then back back later after it was cool to start and back into the garage right? It wasn’t a hard drive before stopping in the position it’s currently in?
Try and move back and fourth “in gear” engine off no park brake, Like the pressure plate is holding the car. Rock it so that the engine and transmission move inside just a bit. This action might lossen something that is stuck out of position. This sounds like something that may have happened to me as well. Try that.

[gorskined]

Originally Posted by quattrorunner

So you drove it lightly or at least normally and put into position then back back later after it was cool to start and back into the garage right? It wasn’t a hard drive before stopping in the position it’s currently in?
Try and move back and fourth “in gear” engine off no park brake, Like the pressure plate is holding the car. Rock it so that the engine and transmission move inside just a bit. This action might lossen something that is stuck out of position. This sounds like something that may have happened to me as well. Try that.

yes i backed up the drive way aligned with the garage shut it off .. and everything was locked out except reverse when i restarted to put in the garage

[flat6pilot]

You probably don't need to go down the 4-speed path. Easy drives, don't beat on it, 'stock' HP levels (even with a 76 RoW turbo?) the 915 should hold up fine at 300hp and below. MAae sure your shift lever components and bushings are new and adjusted correctly before rebuilding the 915. And if you do rebuuild the 915, add the recommended 'upgrade' peices to hold it together. Way cheaper than a 4-speed conversion. Ask me how I know.

[mikedsilva]

Originally Posted by flat6pilot

You probably don't need to go down the 4-speed path. Easy drives, don't beat on it, 'stock' HP levels (even with a 76 RoW turbo?) the 915 should hold up fine at 300hp and below. MAae sure your shift lever components and bushings are new and adjusted correctly before rebuilding the 915. And if you do rebuuild the 915, add the recommended 'upgrade' peices to hold it together. Way cheaper than a 4-speed conversion. Ask me how I know.

I didn't realise the box was OK at these levels. I guess 300hp at 6000rpm is different to massive torque at 3000 trying to divide the pinion and input shafts..

I've not really seen charts to suggest a 'sensible' amount of torque and at which rpm, that would keep the 915 alive so long as it's being treated with respect..

[pocv0]

As pointed out earlier, your coupler has moved. Seen this happen many times at the track. Take the cover off over the tunnel and loosen the 13mm pinch bolt that connects the coupler to the shifter rod spline. Grab the shaft and move it forward and aft to find neutral, then you have the fun of re-adjusting the shifter. When you get it in the correct alignment,FWD and AFT , rotation mark it for future reference. Once satisfied with shifting after a few test runs tighten the bolt to factory spec.

[gorskined]

Originally Posted by pocv0

As pointed out earlier, your coupler has moved. Seen this happen many times at the track. Take the cover off over the tunnel and loosen the 13mm pinch bolt that connects the coupler to the shifter rod spline. Grab the shaft and move it forward and aft to find neutral, then you have the fun of re-adjusting the shifter. When you get it in the correct alignment,FWD and AFT , rotation mark it for future reference. Once satisfied with shifting after a few test runs tighten the bolt to factory spec.

Good thought ,already tried that when i checked the Alan set screw something is locked broken or stuck , its either reverse or some form of locked up gear i can move it reduced front to back with the coupler off. easier with it on but not side to side, not going to force it. The good thing it didn't happen while running so hopefully its just some worn guide bushing or stuck interlock . it needed a refresh synchro's on 1 and 2 were worn . The car is already positioned on my lift prepping for removal. that was no easy task. taking the car out of the garage spinning 180 deg and getting it back up on the lift .just as im finishing up a buddy called, was like oh damn you should have said something." i have wheel casters". just disappointed i was looking forward to some driving this fall with the cooler weather .

[pocv0]

The coupler probably moved, then the 1/2 shift rod or 3/4 shift rod was slammed rearward. The slot in each shaft must align in order for the shift rod to rotate freely ( neutral) for gear selection. Could be something else, but sounds like a re-build is in order anyway.

H

[flat6pilot]

Originally Posted by mikedsilva

I didn't realise the box was OK at these levels. I guess 300hp at 6000rpm is different to massive torque at 3000 trying to divide the pinion and input shafts..

I've not really seen charts to suggest a 'sensible' amount of torque and at which rpm, that would keep the 915 alive so long as it's being treated with respect..

I think the consensus is around 350hp or below (torque is usually around 320-ish, give or take at these levels) I guess it depends if it's NA or boosted.

But yea, if you have a healthy or rebuilt 5 speed with the beefed up bearing plate and side cover they should hold up just fine.

Mine had nearly 200k miles on it and I tracked it hard for about 8 years under 10psi of boost.

[mark houghton]

Originally Posted by quattrorunner

I believe you have a loose Allen bolt holding the coupler to the shaft under the access panel behind the seats. The parts may be new but they will come loose.

That would have been my guess as well. Experienced that once while parked nose into a curb and could not find reverse to back up. Embarrassing but easy fix

[gorskined]

I had a conversation yesterday with a local shop . regarding my 1915/62 that is stuck in reverse.
Interestingly enough he actually had a simple fix to get it unstuck and it actually worked. First
drain the oil remove the reverse switch and push the plunger back in that triggers the reverse switch while someone is depressing the clutch . He said he has had clients that he did this for years ago and the issue has never resurfaced.
The plunger is a little difficult to access seeing as the chassis and the trans mount are so close . but with small piece of flat stock and a 1/4-20 tap and bolt you can easily make a tool to depress the internal plunger.

[flightlead404]

Originally Posted by gorskined

I had a conversation yesterday with a local shop . regarding my 1915/62 that is stuck in reverse.
Interestingly enough he actually had a simple fix to get it unstuck and it actually worked. First
drain the oil remove the reverse switch and push the plunger back in that triggers the reverse switch while someone is depressing the clutch . He said he has had clients that he did this for years ago and the issue has never resurfaced.
The plunger is a little difficult to access seeing as the chassis and the trans mount are so close . but with small piece of flat stock and a 1/4-20 tap and bolt you can easily make a tool to depress the internal plunger.

Interesting. For years getting reverse in my car was difficult, even with careful alignment of the coupler and new bushings. At one point it became impossible. My fix was to remove the spring for the reverse plunger and cut off about 1/4". Since thing it's been vastly better.