• Hi Guest!
    If you appreciate British Car Forum and our 25 years of supporting British car enthusiasts with technical and anicdotal information, collected from our thousands of great members, please support us with a low-cost subscription. You can become a supporting member for less than the dues of most car clubs.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

Three broken spiders later.....

Share this page

racingenglishcars said:
Or on wet pavement both tires will spin and the back end goes flying out a.la Porsche 911.
Click to expand...
For dirt track cars we would weld up the gears so they were locked and you had to let off the gas and then nail it down again to make it slide or it would go straight into the wall.
I had a bad experience with an old Trans Am that my brother had. It had the limited slip and that would make both tires bite and no slip on take off, but in a very light snow where everybody else's car seemed to be doing fine, that one was completely undrivable. It fishtailed all over the road.
 
nomad said:
By 4 bar I assume it is similiar to the setup on a BE with a panhard rod to keep it centered. The 11 ought to be light, how much are we talking?? How much power?? I would think the stock axle ought to be good enough. If not,the RX7 axle only had the limited slip for certain years. Any one know what to look for from the RX7??? I've heard of quite a few diff problems but broken spiders is new to me.


Kurt.
Click to expand...

When we did the chassis set-up the car weighed 1249lbs with 1/2 fuel and my 180lbs in the seat IIRC.The rear suspension is a typical 4link with panhard rod and coil overs and I have 97hp at the flywheel on 87 octane on the dyno at APT. The RX7 info is easy to find online, just try the google. The 81 to 84 GSL seem to be the one to go for.
 
Westfield_XI said:
nomad said:
By 4 bar I assume it is similiar to the setup on a BE with a panhard rod to keep it centered. The 11 ought to be light, how much are we talking?? How much power?? I would think the stock axle ought to be good enough. If not,the RX7 axle only had the limited slip for certain years. Any one know what to look for from the RX7??? I've heard of quite a few diff problems but broken spiders is new to me.


Kurt.
Click to expand...

When we did the chassis set-up the car weighed 1249lbs with 1/2 fuel and my 180lbs in the seat IIRC.The rear suspension is a typical 4link with panhard rod and coil overs and I have 97hp at the flywheel on 87 octane on the dyno at APT. The RX7 info is easy to find online, just try the google. The 81 to 84 GSL seem to be the one to go for.
Click to expand...
Now that sounds like a fun ride :smile:
 
Agree!!! That dose sound like fun!
That light and even with that much power it amazes me that the spider's are a problem though.

Kurt.
 
The car has only 700 miles on as I work out the bugs, (blown head gasket, tuning issues, etc.) so I am certain that all of these units were broken during their previous service including the one that started all of this with the three broken teeth. Since there was no trace of the broken pieces, and I did look while I have the axle on my bench, it must have been broken when I bought it on eBay and I never noticed. That means that while these may crack in normal service, they also can last for years with small cracks without any problem. I just thought while it was apart and while I was paying the shop to set it up correctly anyway, I should put in the best used parts I could find. Now, we will blend away the crack in the best of the bunch and smooth the edges of the "windows" to avoid stress risers and use that one.
 
IIRC, I once read something about the phantoms breaking diff parts.
 
Phantom Grips are junk IMHO, thats probably your problem, we gave up on them long ago, a s did many ofthe vndors that originally sold them. Just for grins why not try a open diff for awhile, bet your problems go away. I'm not a big fan of LSDs for racing, I much prefer locked diffs, but not really a option for street driven car. There are always the better LSD units like the TranX or Quaife, but I known racers who hated them as well, I ran with both the Quaife and TranX in Spridget raqce car, didn't notice any better handling or lap times over the welded diff, and the welded diff cost 1500 bucks less than the Tran EX or Quaife LSDs.

If it were me, rather than spend huge money for REAL LSD, I just try the open diff first, I bet you will find it just to your likings, LSD is not all that big of a deal in street car with this amount of HP.
 
Hap your points about the Phantom grip may be valid regarding the handling issue. But I doubt very much if the 650 miles with the PG broke off three gear teeth and vaporized them. As for the other four cracked spider housings, the closest they got to the PG was when I dropped them off at the shop for inspection and they all sat on the same workbench. It would an interesting test to check out one of your diffs at random in a Magnaglo machine to see if my situation, getting 5 cracked housings, is unique. Maybe they all are cracked and it makes no functional difference at all. After all they are all 40 years old at least......
 
If I was going to change out the whole rearend, something like a rear diff from an older Subaru 4wd might be fun. The independent rear always seemd to make old wagon handle well and it had 13 inch tires so the gearing should be about right too.
 
Theres got to be something weird going on, and it ain't HP, we have 140 HP in full prep 1275 race engine and have to be alot harder on them than anything you could be doing with them. As I told yo Ive had only one diff failure in a couple of decades of racing these things, and it was my fault, used 1st gear in my dog engagment racing gearbox going into T1 at Charlotte, I engaged 1st gear way to soon, was still going to fast for that gear choice, when I released the clutch it chirped the rear tire pretty darn good, chirped them hard enough I knew to stick the clutch back in, and when I did get back on the gas I heard the clunk-clunk. Turns out the early downshift spun a few gears off the pinion gear and twisted the inboad splines on my trick racing axles, other than that in a couple of decades of doing this, I never had a diff failure and can count the diff failure I know others have had at the track on one hand and not run out of fingers. Bottom line something wierd is going on here, these diffs are normally bullet proof.
 
From engineering point of view comparatively the Phantom Grip to a Quaife or Tran-X. One must look at how and what your dealing with. Your Quaife and Tran-X are manufacture under ISO 9000 standards with certified testing after assembly as well your dealing with a true limited slip. The Phantoms are generally home installed or by local repair shop with no qualified testing. The negatives of the phantom is having to disassemble the assembly and having to install and reset up the back lashes with the hopes of obtain the goal of what percent of slip you’re trying to achieve is very unlikely. There’s no catch here, but with all things you get what you pay for. Frankly I would rather take an unmolested diff and weld it if I were going to race the car. If not stay with your standard diff with competition axles your problems will go away.
 
OK, for the sake of argument, let's say that the PG managed to crack my spider housing and destroy three gear teeth to the extent that they have vanished, in only 650 miles. What broke the other 4 housings that were never on the car, and never had a PG installed? We're they all four so frightened at the possibility of having a PG installed that they spontaneously cracked from stress?

Not wanting to be argumentative, but something cracked them and it was not the PG. Is there room to consider the possibility that maybe the used diffs left out there are old and worn out after all these years even if the gear teeth still look good. Maybe a design of diff housing that is suitable for 25 to 50 HP eventually cracks after years of 65 HP service. Perhaps British engineering was not the best in the world back then and the diffs could have been designed stronger.
 
Perhaps you are starting with inferior worn out parts to begin with? Would you know the history of the parts that you have purchase? Were the components disassembled clean and Magnaflux for cracks prier to their re-assembly? Were your backlashes set at the appropriate tolerances and then tested? Is the pivot angle of your differential set correctly? Even for a quality rebuild you should be looking for an ISO 9000 standards.

If you have 100hp at the flywheel you will have about 80hp at the differential, not knowing what tire you running but let’s say that you have a 205x60x14 with less than a 100 tread wear which would be a lot of tire for your car. Even with this you still would only produce 60lbs of torque at 7000 RPM which is still within the failsafe of these differentials, the weakest point in these rear-ends would be the axle!
 
BlueMax said:
Perhaps you are starting with inferior worn out parts to begin with? Would you know the history of the parts that you have purchase? Were the components disassembled clean and Magnaflux for cracks prier to their re-assembly? Were your backlashes set at the appropriate tolerances and then tested? Is the pivot angle of your differential set correctly? Even for a quality rebuild you should be looking for an ISO 9000 standards.

If you have 100hp at the flywheel you will have about 80hp at the differential, not knowing what tire you running but let’s say that you have a 205x60x14 with less than a 100 tread wear which would be a lot of tire for your car. Even with this you still would only produce 60lbs of torque at 7000 RPM which is still within the failsafe of these differentials, the weakest point in these rear-ends would be the axle!
Click to expand...

If you go back and read the entire thread, you will discover that 1(one) diff, purchased on eBay, was installed and run in my car. That had a howl and was removed after some 650 miles at which time it was discovered that it had three missing teeth. The operative word here is "missing" as in not found in the axle housing after disassembly on the bench. Thus it was installed with three broken teeth and was not damaged by the Phantom Grip. Unless the PG has developed the ability to vaporize steel gear teeth....

Four more diff assemblies were delivered to Transaxle Engineering after they informed me that in addition to a broken crownwheel and pinion, the spider housing on the diff removed from the car was cracked in many places. All of those diffs had cracked spider housings discovered after disassembly and Magnaflux inspection. All four were used and were said to be in good condition, of course, sellers always say that......

Perhaps the first diff was perfect when I put it into the car and the housing cracked due to incorrect assembly by me, but that does not explain why 100% of the used diffs we inspected had cracks in exactly the same place. My whole point in posting this was to take issue with the prevailing view that these diffs never wear out and that the smart thing to do is to just buy 'em used and swap them out for another used one when they fail. That might have been OK way back in the old days like the 80's or 90's, but today it would be good sense to have them inspected for serviceability before spending time and money to install broken parts.

BTW, these cracks are NOT visible to the naked eye with a magnifier, only Magnaglo shows them, although a Dye Penetrant kit would probably do the job too. Just messier.

Transaxle Engineering has a very good reputation in SCORE and BAJA racing and knows their business. The final unit will be set up correctly once we get parts. Also I am running Frontline axles with double bearings already and mount Dunlop 5.00/15 bias vintage racing tires on wire wheels at the rear.
 
Shucks at 50 years old who knows. Run em till they break, might be a long time yet.
 
Can you see the cracks, or is this the results of a test?

I'm with Hap, sounds weird four in a row. PIcked up a 3.90 today. I might be able to help you out.
 
As I stated several times before, most recently in my last post:the cracks are not visible to the naked eye, but are quite obvious under Magnaglo. I am trained in NDI, but even a novice could see these cracks. This means that if you look closely, 100% of a random sample of diffs had cracked housings. Now, they might have lasted for years to come, but I know they weren't cracked when they were new and I'll be darned if I will pay a shop to properly set up a new pinion and crownwheel based upon a cracked housing.

I wonder if anyone else has ever done a proper crack check of any more of these?
 
I have not been happy with the Spridget rears either, but for a slightly different reason.

In my case, it was the difficulty in keeping them from leaking oil onto the rear brakes under racing conditions. I've killed at least 5 diffs in the last 10 years, but I think a lot of it was from running low on oil (I ran a lot of enduros).
And I have to admit, I seen plenty of used ones in junk yards that were low on oil, so maybe you're starting with used units that have already been run with poor lubrication?

For reference, my car has about 70 HP, but is pushing 1800+ lbs (it's a '78 tub with crash reinforcements and a full cage).

As far as differentials. I've raced welded, Quaife and open. Honestly, at racing speeds, it's hard to notice the difference. I've run an open diff for the last year with no issues. Even the slow speed stuff at PVGP was no big deal.

Anyway, I'm building another car. And for me, the idea of spending another $500 for double bearing hubs, $500 for race axles, plus $$$ for new bearings and seals.........and <span style="text-decoration: underline">still</span> having the <span style="font-style: italic">blankity-blank</span> thing <span style="text-decoration: underline">leak</span>, drives me crazy.

So I'm looking at the Datsun B210 axle.
As it turns out the Datsun width from drum to drum is about 52". Even though this rear axle is a rwd unit, I am planning on fitting fwd Nissan Sentra steel wheels (which have a lot of back-spacing, as is normal in fwd). With these wheels (13" X 5" wide) the total width to the outer edges of the rims is 54".
This is close enough for me to use it on my "new" car (an A35). Overall it seems like a better and cheaper solution than having a wider rear axle narrowed since spares don't require modification and are still fairly abundant. I'm planning on running the Nissan wheels in the rear and Spridget steel wheels in front for now (I'll have different bolt patterns front to rear.....I can live with that).
I'm sure they could be redrilled to accept 4" X 4 bolt pattern (probably by Moser). It looks like there's plenty of room for this.
By the way, the rear of the BMC driveshaft will bolt directly up to the Datsun axle, so this is one less thing to deal with.

I have a B210 axle in my car right now ($100 at a local junk yard). I'm just trial fitting it, but it looks promising.
 
Nial, the rear of Spridget, hub wise on a race is almost a art from to seal up, but first on race car, you must go for DB hubs, has your car got them, if not that's probably contributing to your problems. I use to drill my race axle in 4 places, as for hub retention, the drill and tap 4 palces on the DB hubs as well, use no paper gasket, a new o ring and Permatex Ultimate Balck, I would do this n a drained rear end, and I would even flood the bearings with spray can brake clean to get them from oozing rear end dope in the area I was sealing and let it all sit up for 24 hours to seal. With this routune I got where I hardly ever had a hub/axle leak.

As for the cracks rear diff cases, I cant really comment there, but I can say that I raced a Spridgets (4 different Spridgets in total) in well over 100 SCCA races, and told you all here of the only diff failure I had in all those years, and it was my fault, and lets safely say, we talking about well over a dozen different diffs used on these 4 different cars, not counting all the buudy and customer cars I worked with as well. My commnets on the PG was it totally failed under race conditions, I was given tougher springs to try, and they failed as well, the well known vendor that sold me this unit, now no longer offers the PG anymore, I'm not alone, several other experienced exactly what I did, did the PG break your rear end, I don't know, I just know as LSD, they don't work. AS for your expereicne with cracked cases, Ill trust you in your expereience to read cracks, can't dispute that one way or the other, its just in almost 3 decades of doing this, I never seen anyone have this much trouble with these diffs. SO do I think it is something wierd, based on decades of experience, yep, you betcha I do.
 
Back
Top