Advice regarding adding an LSD to my 944T
#16
Exactly, the drive gear for pump is pinned and has two bolts.
I would work a solution myself before tossing a good 944T trans that just needs an lsd vs buying a $1500-$2000 second hand S2 box with lsd.
That's not to even mention ditching the entire factory pump drive for a CV or electric driven pump and cooler.
That loop is always in the way anyway....
T
I would work a solution myself before tossing a good 944T trans that just needs an lsd vs buying a $1500-$2000 second hand S2 box with lsd.
That's not to even mention ditching the entire factory pump drive for a CV or electric driven pump and cooler.
That loop is always in the way anyway....
T
Is that a better solution? I would imagine it can provide better cooling, but I am not sure.
Do you know of any pointer for instructions/ recommended parts for such project?
Does it tap on to existing plugs (i.e. drain and filling holes) or do you have to drill new hole and make case mods?
Thanks again everyone for super useful information
#17
Race Car
Do I understand correctly that you recommend removing the factory cooler and installing an external cooling solution?
Is that a better solution? I would imagine it can provide better cooling, but I am not sure.
Do you know of any pointer for instructions/ recommended parts for such project?
Does it tap on to existing plugs (i.e. drain and filling holes) or do you have to drill new hole and make case mods?
Thanks again everyone for super useful information
Is that a better solution? I would imagine it can provide better cooling, but I am not sure.
Do you know of any pointer for instructions/ recommended parts for such project?
Does it tap on to existing plugs (i.e. drain and filling holes) or do you have to drill new hole and make case mods?
Thanks again everyone for super useful information
Easy way out, contact Dimi. He seems to have everything you need, so there doesn't seem to be a reason to suffer or jump through hoops.
On the coolers,
I doubt if there's any data on thermal units dissipated by the factory loop but all conventional coolers that you could purchase as replacement should be able to supply this info.
Cooler are rated in BTU just like A/C and heaters, what quantity of British thermal units they can remove from the liquid being cooled.
There is a lot of surface area by the way the length of the factory loop is coiled into it's space but way more modern technology such as spiral passages, etc. make less surface area just as efficient.
And yes, you could use just the factory ports in/out to be suction and return with a custom external cooler with no factory drive/driven pump.
If it were me and I were going custom, I would add delivery ports to focus cooled return oil directly on the pinion bearings.
But I wouldn't be racing a turbo car from jump street....
Too complex and too much trouble to repair at the track.
If you want bang for your buck with minimal breakdowns and/or have a midrange problem that is feasible to fix at the track where a similar issue will sent you packing up to go home, get an NA car, 944, S2 or 968.
We have had runs of multiple seasons where we never put a wrench on a car at the track.
While we are polishing the windshield, waxing off rubber, and generally socializing with other drivers, you are trying to change out a simple item with burns on 50% of your arms and hands.
I love the turbo cars, for the street.... but I doubt I'd ever field one.
T
#18
Burning Brakes
Ok, dumb question but is it possible to start with a factory turbo standard non-LSD trans and modify it with factory parts to make a LSD? What are the limiting factors if this is not possible?
Thanks.
Thanks.
#19
If your transmission had a factory oil cooler (external loop), you will need to replace the internal pump gear to match the new diff.
Dimi has the replacement gears available for sale.
All in all, if you are out to buy a trans today and know you will want an LSD in the future, I would consider getting an LSD unit at the first place. It will save you time and money compared to the phased approach.
#20
Rennlist Member
- Measure the case and clutch pack heights to determine needed shims. Do not throw larger shims in there thinking they will improve lock-up. With 0.2 mm free height, (4.20 mm minus the 2 x 2.00 mm cup washer thickness), overshimming will break things. Use the right "outer plates" to get the delta close to 4.20 mm per spec.
- Inspect the NLA thrust washers for cracks around the pressed-in tabs. Replace if this is the case. Design flaw. Guard corrected it with their version of the Salisbury-design LSD for the 944 series.
- Inspect the clutch discs for excessive wear, galling, etc.
- Measure the height of the cup washers (Belleville springs). They fatigue with time and use. New they are about 3.60 mm unloaded; if much less, replace. (There is no factory spec.)
- Once assembled, measure the break-away with the LSD on the bench (not in the transmission) to make sure it's in spec: 10 - 35 Nm.
- You won't need to replace the eight M8 x 25 x 1.0 grade 10.9 case bolts, 999.119.011.00, list $15.20 each, if you heat the case to break down the thread locker before before you unthread them. Use a stubby allen socket. The problem is that the original bolts had shallow heads and it was quite easy to cam out the socket, ruining the head. (If this happens, grab the bolt with a pair of vice grips and turn.) These bolts were NLA for a bunch of years, but Porsche recently reintroduced them with standard head heights. I would replace them in balanced pairs where necessary. The original bolt was similar to a DIN spec bolt but the 1.0 mm fine thread was nonconforming.
The front and rear pinion shaft bearings are pricey, but you can feel good knowing you're spending a lot less on a rebuild than your buddy with a type 915 transmission in his 911 is! Of course his car's value has skyrocketed in the past several years. Oh well. The front bearing, 016-311-220-L is NLA but has been kicked into the Porsche Classic program as PCG-311-220-L, list is $457.14, and to add insult to injury, was not yet available from Porsche last I asked; this may have changed. I have a stock of the 016-311-220-L I am using for customer rebuilds, fingers crossed that the Classic part comes available.
Different differential designs have their pros and cons, there is no right and wrong to them: Salisbury (the factory type aka. "ZF"), Gleason / Torsen types I and II, locked, open, etc. For track use, most racers prefer the Salisbury type on road courses with a variety of corners types. My personal driving experience is that the benefit of a Salisbury is pretty noticeable in the rain or in tight corners, anywhere wheel spin is likely.
Good luck!
Last edited by KevinGross; 04-08-2018 at 10:13 PM.