TR2/3/3A Scraping Down Under

[PatGalvin]

Hello everyone:

Well, a few of you may remember that I blew out the TR3A rear end last September and had it rebuilt locally. I re-installed and all seemed wonderful, for a while. But it seemed like I was bottoming out (scraping) more frequently, so I had the muffler raised up tight under the body. But, scraping persisted. Hmmm, what could it be? Took a trip last weekend to the Foothills and the scraping was awful. It sounded like the tires were scraping up in the wheel wells on every bump. But there was no paint scrapes under the wheel wells.

But then I noticed that the scraping sound persisted when I was climbing up hills under significant load, regardless of road bumps and dips. That got me worried. I got the car up on jack stands and inspected all and couldn't see anything that was scraping. Today, I got under the midsection and examined the front driveshaft U-joint flange connection to the transmission nose piece. And voila, the nyloc nuts on the transmission nose piece flange are hitting the gearbox mounts when the shaft extends forward, when the rear axle travels upwards (like over a dip in the road). The noise I'm hearing was the nuts being ground away against the gearbox mount. Then, I went back and noticed that I've got clear scraping where the rear end axle tube scrapes against the steel loop axle check strap. My theory is that the strap is forcing the axle forward, as it travels upward in its suspension travel, causing the driveshaft to move forward and thus causing the driveshaft nuts to scrape on the mount. This is odd, as I didn't modify the axle travel check straps in any way, just reinstalled them.

I wondered if maybe I installed the axle incorrectly, but I can't see that is the case. It really only goes in one way and it sets upon the springs, at which time you put the "u" shaped bolts down to mount the axle tube to the spring. I have about 1300 miles on the new axle install.

Fixes? Well, I can pull (muscle) the travel limit strap back a bit with the intention of preventing the scraping between the strap and the axle tube and allowing the axle tube to move freely through its desired travel. I'll need to order new nuts and bolts for the driveshaft where it mounts to the gearbox nosepiece.

I am running the HVDA Toyota 5-speed gearbox conversion so I suppose I can also remove the driveshaft and shorten it, as the Toyota conversion has a driveshaft collar that makes the driveshaft a fixed length (because the gearbox nosepiece slides in and out of the gearbox so driveshaft must be fixed length). I need to go check the HVDA conversion instructions for the driveshaft length and check that against my current install. Maybe the driveshaft slipped and lengthened itself? If so, I risk damaging the rear seal on the gearbox and the nosepiece will be driven into the back of the gearbox.

This all seems very weird to me. Let me know if any of you have any other ideas about what might be going on here. Or any hints on how to properly remedy this. I hope these photos illustrate the problem. You can see the scrape on the axle tube, the check strap orientation, and the ground driveshaft nuts. Thanks very much

Pat

 

[Merlin63Tr4]

Is it possible to reverse the orientation of the fasteners at the transmission yoke/driveshaft? Bolt head toward transmission and nut toward u-joint.Might give you a little extra room till you figure out what is going on.Not sure the nylock will fit without causing problems with the u-joint, be sure to check u-joint for interference at full deflection.M.

 

[PatGalvin]

I called HVDA (Herman Van Den Aker) and he had several tips for me. The first is to reverse the nyloc nuts, as you've suggested. The second is that if you have old weak springs, you need to shorten the driveshaft to make sure there is as much as 7/8 inch space between the gearbox nose flange shoulder and the gear box oil seal. I had only 3/8 inch so that is not nearly enough and my driveshaft is unfortunately pushing forward and could threaten that gearbox seal, if I'm not careful. The third item was to evaluate if there is any elongation (slippage) of the driveshaft length causing it to elongate and move the flange forward towards the gearbox seal.

I had 3/16 slippage (elongation) in the shaft, which trims my clearance from 3/8 to only 3/16 inch, which is nowhere near the 3/4 to 7/8 inch clearance recommended by HVDA.

So, I'm pulling the shaft and taking it to the shop to have a solid shaft made. Should be about $200 and no more worries about the shaft collar slipping and it bumping up on the gearbox. I'll also flip the nyloc nuts. The nuts I'm using are tall - I think Moss will have some short Nylocs for this driveshaft flange bolt.

Thanks

Pat

 

[TR3driver]

I would also be worrying about what is allowing the axle to move forward like that. Looks to me like the head of the bolt through the center of the spring is not properly engaged with the spring perch on the axle. The perch can get bent during installation and allow that to happen.

Also FWIW, I used to have a lot of trouble with those nylocs working loose. The Stover nuts I now use instead are also lower profile, since the locking mechanism is part of the threads, not an extra section on top.

 

[charleyf]

Pat,
i as well am running the HVDA CONVERSION on two TR4's as well as aTR 3 that is now my sons car. One one TR4 I had the same problem with the U joint bolts hitting the special mounts . My problem was that I felt the distance between the tranny and the drive line was to great and had a 1" spacer made which I installed. After determining where the NOISE was coming from I removed the spacer. I recall that I also removed some excess material from the rear of the tranny mount. Problem solved.
Instead of redoing the drive line I would suggest getting a second fixing collar from Herman and using them both. Bet that won't move!
Did you recently replace the springs? In the past I had a problem with one spring set that did push the axle to the rear.
Charley

 

[PatGalvin]

Thanks Randall. I'm going back under and checking the rear axle install to see if there was any error in how I reinstalled the axle.

Charley, you described too much space between the tranny and the driveline. My problem is I have too little space, meaning the driveshaft is too long. I could just move the collar and shorten the driveshaft, but I'd like a more permanent solution.

I am running stock springs (probably orig equipment). During the resto, they were very rusty, so I took them apart and cleaned them up and greased the blades. They are probably way too soft now, but I'm not at all enthusiastic about trying to find good replacements and then changing them out.

I'll let you all know how this progresses.

pat

 

[TexasKnucklehead]

Pat, something is very suspicious there. I understand there are different Toyota transmissions, and mine may not be the same as yours, but I have more than an inch of space where your nylocs are rubbing. I did not modify my driveshaft, but in any case, you could loosen the added HVDA locking collar, and shorten the driveshaft easily. Regardless, the driveshaft should not be changing the location of the rear axle. The rear axle is located by the bolt that hold the springs together. The head of the bolt fits inside a hole in the mount of the axle housing. No matter how soft the springs are, the axle shouldn't move fore/aft enough to hit the brackets.

 

[PatGalvin]

Hi Jerry (Tex).
I went back down under the car and investigated after Randall mentioned that I could possibly have not installed the diff tubes on the springs correctly. But the nuts are properly peeking through the bottom of the "plate" that rides under the spring and the U Bolts are properly positioned.

I don't know which transmission I have, but I had set the driveshaft length when I installed the HVDA conversion kit. I think what has happened here is that the driveshaft locking collar may have shifted and allowed the shaft to elongate. I could just reset the collar, but it could slip again. Once the shaft was in the elongated position, I'm thinking that the gearbox nosepiece flange just moved right into the rear tranny mounts and caused grinding. I'm going to check my gearbox fluid, but I think that I may have also damaged my rear tranny seal as I'm seeing a lot of nice yellow fluid on her underbelly - my engine oil ain't that clean.

I don't think the rear axle is actually moving forward much. If it is, I can't see where it is moving. All my rear suspension parts look good back there.

Pat

 

[CJD]

I admit that I know nothing about the tranny conversion, but in your one picture, if anything, it looks like the diff is farther to the rear than any of my cars were. None of my cars have come close to rubbing the axle on the rear of the bump strap. It has always been pretty much centered between the straps. It also looks like the rubber bumper on the axle could be located better to hit the straps.

 

[charleyf]

Charley, you described too much space between the tranny and the driveline. My problem is I have too little space, meaning the driveshaft is too long. I could just move the collar and shorten the driveshaft, but I'd like a more permanent solution.


pat

Pat,
Yes, my solution was to get rid of the extra spacer and to make sure the collar was allowing sufficient space between the tranny and the drive line. In your case like I said move the collar to allow more like an inch of free space between the rear of the tranny case and the rear flange. My collars have not moved on my drive lines that I have determined. My idea about using a double collar is in lieu of the expensive drive line remodel. But I do think the double collar is still overkill.
Charley

 

[TexasKnucklehead]

Pat, I was concerned that my driveshaft was locked at the max length, but not long enough. I think it's slightly less than Herman suggests. I don't think mine has changed any. My guess is yours slipped. A lot of people get a custom length drive shaft made, and have it balanced. I may consider that option someday but don't want to spend the money at this point.

I found a picture during my assembly that shows my axle is also positioned a little off center. If you're sure the axle is not moving, just bent the straps so there is no rubbing. Also be sure the flange on the bottom of the axle that rests on the top of the springs is tight to the spring on the front and the back side of the axle. And also be sure the pin at the front of each axle is solid, so the only movement is in the shackle end.

 

[kstanley44]

I know nothing about the tranny conversion but it the rear springs were installed backwards, maybe intentionally because of driveshaft issues, wouldn't that result in the rear diff being displaced to the rear. Although I would expect it would be more obvious.
Take care,

 

[PatGalvin]

I dropped the driveshaft at the shop this AM. They will obtain the two slip yokes and cut me a nice new driveshaft. Install the u joints and the flanges, and balance with the tranny nose piece. In Sacramento, $80 labor, $25 for the tube, and some cost for two new weld yokes (TBD). I'll get out of there for less than $200. That seems pretty good to me. I also need to check the gearbox oil seal and see if there is any damage or leakage. That may not be too fun to have to replace.

Thanks for all the ideas. I'll go home and do some measuring tonight. And compare my install with the very useful photos you guys have shared. Things are always twice as difficult when you modify the car. Same issue with R&P steering, brake mods, electrical. It runs better and is more fun to drive, but customization always comes at a price (time and money).

Pat

 

[CJD]

Good luck!

The tranny seal is a piece of cake in a slip-yoke tranny. You just slip off the yoke and pull off the seal. It is a bit tricky getting a tool between the tranny output shaft and the seal, but you can usually find some tool to grab it. Worst case, most Autozones will rent the tool to grab the seal.

 

[sp53]

John are you saying that putting the rear seal in a stock trany tail shaft can be done while the trany is in the car? I kinda always thought so, but never tried.
steve

 

[TR3driver]

Definitely possible, I did it on my 3A. Make sure to lube the seal lips, and that the surface of the yoke is smooth. If you can't polish away the mark from the old seal, consider a speedi-sleeve.
A light smear of RTV or your favorite sealant on the big flat washer will help prevent a leak along the splines. Don't forget to torque the nut and lock it.

 

[CJD]

I think Pat's got a different tranny, that rather than the TR bolted yoke, has a sliding yoke. So it would be like the TR tranny only without a nut holding the yoke in. At least that's what I'm gathering from the thread.

 

[PatGalvin]

Yep, I have the slip yoke Celica gearbox. But reportedly, the rear seal can be changed in the car, if I can access it. May just pull off the gearbox tunnel cover - I think that would be sufficient access, along with access through the box section (driveshaft removed).

Pat

 

[TR3driver]

Right, right, sorry I forgot.