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Briefly the seal popped out on hwy at 90 mph, looks like driveshaft snout got hot rubbing on the new Atkins bronze bushing in the rear of the trans. Occured after about 300 miles since bushing install.
So this is an FB, was an IT7 car, that I've installed a BP 13B in recently. It is registered for the street which makes breaking in a new engine easier. I just use this car for track days out at the local track, Waterford Hills.
Trans is an FC with FB tail housing so I can use std crossmember. Last year I was plagued with leaking rear seal so replaced seal a few times which didn't fix it. Purchased a driveshaft through Summit Racing but still leaked some. Over the past winter I replaced the tail housing rear bronze bushing with a Atkins Rotary bushing. This fixed a vibration and the leaky seal until....
Yesterday I was doing some Engine tuning on the highway at the highest speed so far. I think I was around 8000 rpm in 3rd gear then I shifted to 4th for a very short time. I backed off when there was a bunch of smoke inside the car, took the next exit and stopped to check it out. There were drips of trans oil under the car but not bad so drove few miles home. I have driven this probably 300 miles with the new engine up to this point.
Next day I find the seal is no longer seated in the housing and the snout of the driveshaft has a couple of serious high heat marks and molten bronze attached to the surface.
What is the solution to fixing this?
Check the tail shaft housing for cracks were the seal is installed. Next make sure that the transmission has a functioning vent. On my Jerico transmission the rear seal is retained by 4 small pieces of sheet metal that are bent at a 90 degree angle and held in place using a radiator hose clamp.
Thanks Scott I'll check for cracks in the tail housing seal area.
I reinstalled the seal as it looked in good shape and fabricated a retainer similar to what Scott suggested. Went to a track day at Waterford Hills here in Michigan and half way through the second outing I smelled tranny fluid. Completed the session as the smell went away but after returning to the pits got a visit from an official who told me they know I have a trans or rear end oil leak and please check for it. I did and yes there was oil on the left side floor, felt like the seal was still in place so I called it, switched tires and drove home.
Since returning home I have found:
Burn/heat marks on the driveshaft snout again
Seal was retained in the tail housing but the sealing surfaces are charred/burnt and therefore not capable of holding the oil in.
The Atkin's bushing in the tail housing has moved rearward and is most likely why the seal popped out last week. Since the bushing moved to the rear I assume the oiling hole has been covered up/blocked so no oil would get into the bushing which has made the snout and bushing get very hot.
Therefore I'm considering my options. Trans has to come out whatever I do. I'm not going to consider reusing the 1st gen tail housing as the bushing has probably turned inside the housing. Whatever I do I should somehow increase the amount of oil going to the rear bushing.
Install 2nd gen tail housing which I think means cutting the trans tunnel to accommodate the gear shift, and making a trans mount.
Time to purchase a TII transmission and install. Same changes as above. Plus do I need to change the clutch plate/pressure plate?
By the way first time driving the 13B BP and it is awesome. My best lap time on Sunday was within a couple of tenths of my best from last year with stock 12A.
Dorman driveshaft balance after the new tail housing bushing was installed this winter was perfect. With the old worn bushing and the Dorman in 2019 there was vibration. I have the 4.77 Hyundai rear gears.
I would vote for another 1st Gen tail housing and install a new bushing and sleeve if it needs it. I've killed a few NA transmissions but nothing like what you have described. I have had to have tail shaft bushings replaced though. I did it mainly to solve drive live vibrations.
For drive shafts, I tried rebuilt ones but for me only a new drive shaft from Mazda did the trick. I bought the early style for a small flange rear end through Mazdaspeed.
I have two transmissions on the ground right now that have "racking" bearings. You can have the tail housings from them. It would help me greatly by freeing up shop space
Heck, take the whole transmissions, rebuild them or scrap them for the gas money...
I ended up installing a 2nd Gen tail housing with the 1st gen shifter housing and control rods so I didn't have to cut the floor. This tail housing has a different mount than the 1st gen and means the original 1st gen rubber mount can not be used as it would raise the transmission too high. I modified an engine mount (not as tall as the trans mount) to fit in place of the trans mount to get the height close to correct.
Found the nose on the Dorman driveshaft is too damaged causing continued leakage. Swapped in the original driveshaft which has a worn nose on it but doesn't leak.
Took to a track day few weeks ago and there is a slight leak but nothing close too as bad as before. Not going to make anymore changes except get the Dorman driveshaft nose replaced.
I just wonder if there is insufficient clearance for a new driveshaft nose to stay lubricated if a new bushing is installed in the tail housing when turned at high rpm on track. Maybe this is the cause of my original problem: nose seizing in tail housing bushing.
Thanks for the helpful suggestions
I had tail housing bushing and seal problems on my endurance race car. They were all solved when I replaced the bushing in the end of the transmission with the Mazda Competition parts roller bearing.
It requires machine shop work to the tailhousing to insert the bearing and retaining ring. Also, you are supposed to use a hardened steel driveshaft
"nose." I was lucky enough to find the driveshaft part, but I think you could have a standard driveshaft nose "hardened."
The underlying cause may be small misalignment of the transmission and differential angles, caused by lowering the rear of the car. I am using all stock rear end links (not adjustable) with shorter springs,''
06-07-20, 01:03 PM
