Porsche 911/915 Differential Swap And MORE Bad Parts!!!

[@FriendM2010]

MacGyver strikes again .. 👍

[@jeffharrison5265]

Tom, you have almost, almost, convinced me to buy a good used tranny and tear it down myself rather than buying "rebuilt and modified" unit for my V12 upgrade. Great video as always.

[@GarageTimeAutoResto]

Well, I have two more episodes to convince you, ha ha.

[@johnvaluk1401]

Thanks for the update and video. Good information. Have a great weekend also

[@richardh1773]

The detent system that you took apart using the ball method (same way I did it a few months back) is often overlooked because it is a bit of a PITA to service. As such, decades of gunk builds up in there and it is just a matter of time before it stops working and your car gets stuck in a gear (5th as I recall). I believe we used an 8mm ream to clean out that bore.

[@GarageTimeAutoResto]

Good point. The purpose of those detents is to prevent the trans from going into two gears at the same time, but like you say if they malfunction then you are stuck in a gear. Yikes! By all means the case and parts need to be clean!

[@georgebourdeison1750]

Btw the most confusing part building a porsche transmission is setting the backlash depth and preload of the diffbearings. It would a really fantastic video for all of us the diyers if you would like to make a video how exactly you made the diff housing tool and all the measurements step you will make. We thank you

[@GarageTimeAutoResto]

Ok, will try. The pinion depth is the hardest in my opinion. Is this the tool you are referring to?

[@georgebourdeison1750]

Good morning. Yes the tool with the diff housing and the mutitoyo . And how you do the measurements.

[@GarageTimeAutoResto]

It's in this video kzbin.info/www/bejne/bXy0m5Wreq54qpI

[@GregsGarage]

Still enjoying the trans info.

[@GarageTimeAutoResto]

Thx, me too. Even though it's taking forever it still beats sanding!

[@jeffharrison5265]

@@GarageTimeAutoResto yes, sanding sucks!!!!!!!!!!!!!!!!!!

[@georgebourdeison1750]

Hi i was wondering about the diff housing. a good machinist could bring down a few millimeters the damage surface and then put a hardened ring ideally from a bearing case with the cold hot and glue method . And after machining the new ring to the bearing spec installing the new bearing. I hope you understand what i want to say. What do you thing about this method?

[@GarageTimeAutoResto]

Used ones are about $150 if you can find a good one. Repairing as you mentioned is also fine, but probably more expensive.

[@georgebourdeison1750]

@@GarageTimeAutoResto IT cost me only 30 Euros here in Greece. I havent install it till now. I think it will work. I could send you a foto

[@georgebourdeison1750]

I send you a Foto of the diff housing in your email

[@dra911]

"Never done this before" - I appreciate the fact you put efforts like this on YT to show us, it's not something everyone can or wants to do. What do you think of the 8:35 (4.37) ratio for the 915? Apparently strong like 8:31 (3.875:1) but without the loss of "fun factor" when coming from 7:31 (4.43.) I once put 3.9:1 gears in an LS1 car than normally had 3.07:1 and it was honestly like a different car to drive (i.e. awesome.)

[@GarageTimeAutoResto]

8:35 is good! Kind of depends what you want to do with the car and the power? The shorter the gears the faster it feels, but you are shifting more. With 300HP I will be reaching redline very quickly in first and second. That is why I like the 8:31. The car is actually moving further before each shift. If I only had 150 HP I would keep the 7:31 or 8:35.

[@dra911]

That's fair enough. My SC's gearbox already has a 8:31 final drive, so it will be interesting to see how it goes with the increased power (~250bhp) and lighter weight. With 2nd topping out at around 117kph (on stock rims/tyres) I have wondered if this is "too tall" or not... We will find out 🙂

[@sveip]

Would it be possible to tig weld some new material on the races and turn them on the lathe?

[@GarageTimeAutoResto]

Yes, I think so. Someone could fix it with a metal sleeve or spray welding etc. I have a good spare, so I didn't inquire about fixing it.

[@24hourgmtchannel64]

Tom, did you ever consider adding a limited slip differential to your 915?

[@GarageTimeAutoResto]

Yes, I'm building a second one with LSD

[@24hourgmtchannel64]

@@GarageTimeAutoResto I'd like to add one to my 1982 SC as well. I keep checking for a used unit to pop up on eBay. My 1979 928 G28 5 speed has one and I tested the break away torque and it's within spec. I'll have to find out if they used the same carrier unit.

[@GarageTimeAutoResto]

Cool, also check out wavetrac and NPR new diffs. I'm going with one of those

[@AlejoMX5]

Being how rare this is woudl it be a perfect candidate for EUTECTIC addition of metal and then having it torn down to correct size?

[@GarageTimeAutoResto]

Is that spray welding?

[@AlejoMX5]

@@GarageTimeAutoResto yes! kzbin.info/www/bejne/aYXYZaSngKdje6M

[@k708388]

3 things tom 1 dry ice blast 2 use the g50 from the wreck 3 are you raiding the wife's kitchen for the pyrex bowl to put parts in? this will NOT end well for you

[@GarageTimeAutoResto]

Always great to hear from you Joe! Dry ice blasting is the best hands down. A few places near me do it, but I'm lazy and cheap. 2). I like 915's for a lightweight hotrod. G50 is nice though 3). These are my bowls from goodwill. She can borrow them if she wants 🤣

[@Farlig69]

Takes less torque to loosen than to tighten so probably have not lost their preload :) Check out AvE for an explanation if you can tolerate him hahaha :)

[@GarageTimeAutoResto]

Yes this is true, less so for fine pitched bolts. I should have started at 60 ft lbs when loosening to see how loose they are. The other thing is when tightening it's a smooth motion and the coefficient of friction is less. As soon as you stop the friction goes up. This makes loosening harder. It's a bit complicated which is why bolt stretch measurement is best.