LSD Rebuild?
- Thread starter sethron71
- Start date
Jeff Lange;1361454 said:
Thanks, that's what I thought.
Here's a better link to Jawsgear to the proper bearing/seal kit. I don't see any clutch sets from them for our car.
I'll probably start with this Jawsgear kit and get the rest from Toyota (plus a crush sleeve replacement as suggested by Poodles).
Asterix
Jeff Lange;1361454 said:
Thanks Jeff!
Asterix;1361478 said:
That looks like a good idea, I'll do the same when the time comes too prolly.
Weird you ONLY got the clutch pack and nothing else, and Asterix can't find it lol.
I will call Jeff at Jaws tomorrow, didn't get to it today. I would like to know if Weir has an upgraded kit for the 8" then but I will see what Jeff has to see. As far as I can see no one makes one complete kit. Looks like you have to get a clutch kit and then a bearing and seals kit. I will keep you all updated.
Thanks,
Seth
Thanks,
Seth
sethron71;1361538 said:
The guy I spoke with at Weir said he didn't have a kit for the 8" but he recently replaced the 500lb spring with one of 1500lbs for a customer who drags his car.
Maybe there is just not enough interest in the stock diff and people who wish to rebuild/upgrade go to an aftermarket?
dumbo;1361651 said:
Guys,
We are working on a solution for this LSD. What I want to explain here is what causes this LSD to not function correctly is not due to the clutches. It's our opinion that replacing the clutches is a waste of money. Most LSD units use some sort of mechanical pressure ring or other device that applies a clamping force to the clutch plates under loads. O.E.M. examples of these types can be found in the corolla GTS and Supra MkI and MkII. The MKIII LSD does not have any comparable mechanical device to apply clamping forces to the clutch plates. How this LSD is designed to work is by using a spring to load the clutches. Since the force is applied by a spring only and not by other mechanical means, they filled the LSD with a lot of clutch plates. Basicly there are 5 stationary plates and 4 rotating plates per side gear within the LSD. This is plenty of plates, the MKI & MKII have less than half as many plates as the MKIII.
There are 2 simple problems with the MKIII LSD: The first problem is the pressure spring is not strong enough for performance applications. It works ok for a daily driver where the LSD has to be smooth for drivability reasons.
The second reason is excessive clearance within the LSD casing. Shimming is the solution for the second problem and has already been mentioned in a previous link.
What we have done and is soon to be tested, is to increase the spring load from @500lbs. to @1500lbs., an increase of 3X the spring force. We also shimmed the internal clearances down within the LSD. Shimming the LSD is a precise process and has to be done correctly, no guessing at the shim thicknesses. If you under shim (not enough shim) your results will be poor for the effort involved. If you over shim (too much shim) your LSD will make "popping" sounds (not chatter, but harsh "pops") and will be junk in short order.
Once we have tested the LSD at the drag strip we plan on having kits available for sale. The only obstacle we can see at this point is clear enough instructions so that anyone who installs the kit will get the desired result.
We will post up info once kits are ready. Thanks!
Spence Weir
Weir Performance Engineering LLC
707-315-6638
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Hey Spence,
Thank you very much for the information. In the diff we run in our prototype, hewland type, it has a conical washer the add pressure the plates. We spend hours testing setups of working faces to non working faces ratios to get our desired break away LBS. Maybe a simple conical washer/bucket system like this will work in this case. The diff can have as many as 12 working faces and I think as few as 5 depending on how you stack the disks. Needless to say the difference in our diff from 45lbs of break away to 500lbs is so small it is amazing. We actually had to use combinations of difference disk thickness with different shims to get the desired pre-load.
But again thank you for the information.
Seth
Thank you very much for the information. In the diff we run in our prototype, hewland type, it has a conical washer the add pressure the plates. We spend hours testing setups of working faces to non working faces ratios to get our desired break away LBS. Maybe a simple conical washer/bucket system like this will work in this case. The diff can have as many as 12 working faces and I think as few as 5 depending on how you stack the disks. Needless to say the difference in our diff from 45lbs of break away to 500lbs is so small it is amazing. We actually had to use combinations of difference disk thickness with different shims to get the desired pre-load.
But again thank you for the information.
Seth
Interesting side note: depending on when your MK3 was made, it may have different preload and clutch types. Starting in April, 1990 the preload spring was reduced from 550lbs to 176lbs, and the number, type and thickness of the clutch plates and washers changed as well.
There is a TSB regarding the changes made, but they were mainly made to help reduce noise.
Anyways, what I was thinking is that it may be a worthwhile effort to change to the newer plate types, but with the older higher rated spring.
Regardless, I think Weir's kit is probably the way to go, or an aftermarket LSD.
(EDIT: Interesting side note; in the Toyota parts system the 550lbs spring changes up to the 176lbs spring, but without changing the other parts in there, that would probably result in even lower lockup. It's a strange thing to see, without at least a note saying to check the TSB, etc.)
Jeff
There is a TSB regarding the changes made, but they were mainly made to help reduce noise.
Anyways, what I was thinking is that it may be a worthwhile effort to change to the newer plate types, but with the older higher rated spring.
Regardless, I think Weir's kit is probably the way to go, or an aftermarket LSD.
(EDIT: Interesting side note; in the Toyota parts system the 550lbs spring changes up to the 176lbs spring, but without changing the other parts in there, that would probably result in even lower lockup. It's a strange thing to see, without at least a note saying to check the TSB, etc.)
Jeff
sethron71;1362591 said:
Seth,
The hewland type LSD units also use pressure rings in addition to the conical washers. Since the MKIII supra does not have pressure rings you cannot load the plates with a conical spring washer as done in the Hewland LSD units. This will cause the side gears to be forced hard into the spider gears eliminating the backlash between the gear teeth. This will more than likely damage the gear teeth and will not actualy help the lsd to grip better since the conical spring washers would placing force on the plates in the wrong direction.
The clutch packs are hard to get from toyota its been over a mont now.... Look on the supraforums there is exelent info on the differential rebuild. Dont wory about the ring gear and bearings. Unless they are damaged there is no reason to replace them. The clutches though highly recomended.
Im running them with the old 250kg spring with the new style clutch pack and it chaters A LOT but no wheel slip and no noticeble wear on the clutches or plates.
It is effectivly tripling the spring rate because the new clutches have higher friction coefficient. That is why toyota decreased the spring preload. The new clutch disks are more durable and made entirely out of ceramic. The old ones has the friction material deposited on steel disks and after time it wears out and you change your oil no friction material in left and no friction is produced. It acts very similar to a automatic transmission clutch.
The preload increase by shiming is not the way to go just like that company is saying. You need to play with the spring rates. But DEFINITELY the clutches are much improved. There is something else there is a mechanical link that would increase preload in our diffs. That is the spider gears. As they spin against each other when wheel spin occurs tehy create trust loading on the plates that the spring sits and increase the load on the clutch pack..
Our diffs share solid spacers with the V6 toyota stuff and get few extra packs of shims.
Im running them with the old 250kg spring with the new style clutch pack and it chaters A LOT but no wheel slip and no noticeble wear on the clutches or plates.
It is effectivly tripling the spring rate because the new clutches have higher friction coefficient. That is why toyota decreased the spring preload. The new clutch disks are more durable and made entirely out of ceramic. The old ones has the friction material deposited on steel disks and after time it wears out and you change your oil no friction material in left and no friction is produced. It acts very similar to a automatic transmission clutch.
The preload increase by shiming is not the way to go just like that company is saying. You need to play with the spring rates. But DEFINITELY the clutches are much improved. There is something else there is a mechanical link that would increase preload in our diffs. That is the spider gears. As they spin against each other when wheel spin occurs tehy create trust loading on the plates that the spring sits and increase the load on the clutch pack..
Our diffs share solid spacers with the V6 toyota stuff and get few extra packs of shims.
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To reduce LSD chatter noise during low speed cornering, the following parts have been changed:
1. Thrust Washers - Surface treatment and shape change
2. Clutch Plates - Changed manufacturer
3. Compression Spring - Decreased preload
PRODUCTION EFFECTIVE:
Vin Production Date
JT2MA7 # * # L0150382 May 30, 1990
PART NUMBER INFORMATION
Prev. Part No. Qty. New Part No. Qty. Part Name
41361-35020 10 41361-14200 8 Washer, Differential side
gear thrust (1.8 mm)
- - 41361-14210 2 Washer, Differential side gear thrust (1.7 mm)
41385-22020 8 41385-35010 8 Plate, Clutch
90501-70001 1 90501-06072 1 Spring, Compression
Thrust Washer Thickness:
For outermost position (p/n 41361-14210) 1.7 mm (0.067 in.)
For other positions (p/n 41361-14200) 1.8 mm (0.071 in.)
Adiustment Shims:
Thickness Part No.
0.15 mm (0.0059 in.) 90564-50001
0.20 mm (0.0079 in.) 90564-50002
0.25 mm (0.0098 in.) 90564-50003
0.30 mm (0.0118 in.) 90564-50004
0.35 mm (0.0138 in.) 90564-50005
2. SPRING
Along with the increase in friction coefficient of the thrust washer, the spring has been changed to decrease preload.
Prev. Part New Part
Spring Preload 250 kg. 80 kg.
3. Use adjusting shims to adjust the pinion gear backlash to 0.05-0.20 mm (0.0020-0.0079 in.) (Refer to Repair Manual for Procedure.)
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09-22-2008, 02:11 AM
1. Thrust Washers - Surface treatment and shape change
2. Clutch Plates - Changed manufacturer
3. Compression Spring - Decreased preload
PRODUCTION EFFECTIVE:
Vin Production Date
JT2MA7 # * # L0150382 May 30, 1990
PART NUMBER INFORMATION
Prev. Part No. Qty. New Part No. Qty. Part Name
41361-35020 10 41361-14200 8 Washer, Differential side
gear thrust (1.8 mm)
- - 41361-14210 2 Washer, Differential side gear thrust (1.7 mm)
41385-22020 8 41385-35010 8 Plate, Clutch
90501-70001 1 90501-06072 1 Spring, Compression
Thrust Washer Thickness:
For outermost position (p/n 41361-14210) 1.7 mm (0.067 in.)
For other positions (p/n 41361-14200) 1.8 mm (0.071 in.)
Adiustment Shims:
Thickness Part No.
0.15 mm (0.0059 in.) 90564-50001
0.20 mm (0.0079 in.) 90564-50002
0.25 mm (0.0098 in.) 90564-50003
0.30 mm (0.0118 in.) 90564-50004
0.35 mm (0.0138 in.) 90564-50005
2. SPRING
Along with the increase in friction coefficient of the thrust washer, the spring has been changed to decrease preload.
Prev. Part New Part
Spring Preload 250 kg. 80 kg.
3. Use adjusting shims to adjust the pinion gear backlash to 0.05-0.20 mm (0.0020-0.0079 in.) (Refer to Repair Manual for Procedure.)
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09-22-2008, 02:11 AM
2JZ_MA70;1362755 said:
Well I have to disagree with alot of what you stated here. First, the "old" style clutches do not have any friction material deposited on the clutch plates. They are in fact steel, the rotating plates are polished from the factory, the stationary plates are black phosphate coated. Also, you are not in effect tripling the spring "rate" by using the "new" clutch plates. The spring load is determined by the spring, not the plates. Although I personaly have not seen the "new" clutch plates I very highly doubt they are made entirely out of ceramic. The reason I say this is due to the fact that ceramic is extremely hard, does not have a high coeffiecient of friction (we have all heard of high speed ceramic bearings) and is very very brittle. Ceramic plates in an LSD would simply shatter from the high shock loads.
The very last thing is the comment you made on the spider gears applying thrust loads to the clutch plates. This is true in other types of LSD units that use pressure rings or clutch members. This is not true in the MKIII supra LSD because of the mounting of the spider assembly. This is why they used such a big spring to begin with.
I just want to say here that we have no intention of starting any kind of forum argument. If you are pleased with using the O.E.M. parts that is fine with us. Our goal is to achieve better performance than O.E.M. Since the MKIII LSD relies completley on spring force to clamp the clutch plates that is the direction our efforts will be aimed. More spring load equals less slip of the clutches. Less clutch slippage equals longer LSD life and better performance.
We plan on having different performance level options with our kits. Our base level will be street performance, then a full race version and possibly something in between for guys who race and daily their cars.
Spence Weir
Weir Performance Engineering LLC
707-315-6638
Interesting info, Spence.
My orginial LSD from August 1987 stopped grabbing at one point, and when I drained the oil it was full of gold-colored flecks. I assumed it was friction material of some sort that came off the clutch plates. New oil with not too much friction additive didn't help the action at all. So, I got a replacement from a recycler which has been working well since in the grab department.
What do you think all the gold flecks were, if not friction material? I'm curious, that's all. I never opened the old LSD to look at it and gave it away so I don't have it anymore.
My main reason for rebuilding my LSD is that it rumbles over about 45MPH and vibrates quite a bit over 70. It's probably the bearings. The seals are starting to leak as well, and if I open it to replace those, I may as well do everything else. I'm hoping the ring and pinion gears are still good because new one are way more than I want to spend.
Do you have an estimated availability for your kits? I'm quite interested in a combo street/race setup.
Asterix
My orginial LSD from August 1987 stopped grabbing at one point, and when I drained the oil it was full of gold-colored flecks. I assumed it was friction material of some sort that came off the clutch plates. New oil with not too much friction additive didn't help the action at all. So, I got a replacement from a recycler which has been working well since in the grab department.
What do you think all the gold flecks were, if not friction material? I'm curious, that's all. I never opened the old LSD to look at it and gave it away so I don't have it anymore.
My main reason for rebuilding my LSD is that it rumbles over about 45MPH and vibrates quite a bit over 70. It's probably the bearings. The seals are starting to leak as well, and if I open it to replace those, I may as well do everything else. I'm hoping the ring and pinion gears are still good because new one are way more than I want to spend.
Do you have an estimated availability for your kits? I'm quite interested in a combo street/race setup.
Asterix
WeirPerformance;1362856 said:
I absolutely suport your statement the spring has great effect on it and it would be nice to play around with different spring rates.
The clutches may not be ceramic.. I dont know for a fact what the material is but it is not coated/deposited on steel plates like the old material. I know they are significantly higher friction coefficient because my breakaway has increased from 30ft/lb to 75ft/lb just by installing the new clutch pack and retaining the 250kg spring (updated one is 80kg). Stock that ratio is ~30-35ft/lb. That right there proves your statement that the spring DOES increase the breakaway on it. I can barely steer while pusing the car cause the damn thing is tight. All Im saying is that spring alone may not be enough in some cases.
I have gone through 4 differentials right now. I drag the car a lot... Broke two and replaced two for the axle ratio. 3 out of the 4 were worn out to the point it was steel on steel for the most part.
Jeff Lange;1362660 said:
Jeff,
Is there any chance you can get your hands on both springs to see what the difference is?
Some people out here have bought used LSD assemblies of unkown origin.
If we had some dimensions (wire diameter, length, ID, OD) to go by,
we could see if we had the stiff, or wimpy spring.
I just got done going through mine again.
When I first put it in, I had shimmed the spring.
Measurements showed that the spring was (going from memory here) about 5mm from coil bind when installed.
So I made a 4mm spacer.
At that time, when I put a torque wrench on it, and the break away torque was about 75 ft/lbs.
(yes, I had pre-lubed the plates)
But the other day while changing out half shafts, it seamed weak to me.
So I removed, and opened it up again.
Everything looked nice, so I went looking for some way to increase the clamping force.
I found a heavy wire spring that just fit inside the stock spring, and over the center pin.
It has 3.75mm wire diameter, is 24mm OD, 16.5mm ID, and 31.4mm long.
End result is it now has 95 ft/lbs break away torque.
Still not for killer HP, but an improvement.
I had several of these springs, but have no idea what they came out of, just part of my spring collection.
