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Wedge TR8 Diff

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JFS

JFS

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The TR8 has developed a nasty howl/whine from the differential. I understand this is usually caused by the carrier bearings and the required crush collar is no longer available. A TR7 diff or a Quaife unit seem to be among the alternatives. I want a reliable car that can travel distances as well as be driven spiritedly upon occasion. Has anyone dealt with this problem?
 
Todd should be back in soon. He will have an answer and probably the parts to fix it.
 
If you do the quaife unit its about $1,200.00 and then you need the crush collar or hammer the old one flat and reuse it. I have one spare and woody @ the wedge shop bought about 3 last year at Carlisle. You will need to also do axle bearings and then while doing the carrier. In all you could have up to $1,600 to $1,800.00 in a TR8 rear axle rebuild with limited slip. You have options of a Ford 8.8, or a Dana 44. Both require some shortening and new brackets but will never go bad. You cannot reuse your 13 inch rims and will need to redrill the hub for the 4 bolt pattern unless you change the spacing for more rim selections. Anyway you will have to go to 14s or even 15s to clear the rear disc brakes.
 
Haven't tried it (yet), but I don't see why you couldn't use a fixed collar and shims. Of course then you would have to measure the bearing preload, the way you do for the earlier differentials. Not terribly difficult, just tedious with having to assemble it, check the torque, disassemble, change a shim, lather, rinse, repeat, repeat, repeat.
 
The cheap easy way out is to install a 3.45 ratio rear end out of a TR7 convertible. The 81 auto TR7s had the 3.08 same as a TR8, but those models are extremely rare. Just about any competent rear end specialist should be able to rebuild the 8 unit. The only possible problem being the unavailable crush collar. Either reuse the old one or have a machinist make something up. Somehow over the years there has gotten to be this myth that these rear ends are next to impossible to rebuild unless you have some special place in heaven reserved for you. Same thing with BMW rear ends. I've pulled apart and rebuild both, with no special training. I don't get the hype. I suspect it's driven by vendors wanting to sell you something at very top dollar rather than seeing some local Ford drag racer guy take much less of your money. See if you can find someone local to rebuild it. If he fails, it was broken anyway, so don't sweat it. Then you can go out and get a 3.45 to throw in. You'll like the extra acceleration anyway. If anybody needs a 3.08 Ring and pinion, I have an SD1 rear end out in back of my garage.(same R&P as the TR8 but different axles and tubes) I've been close to dragging it to the junk yard with the last two parts cars. I'm really getting sick of looking at it!!!
 
Todd's advice about rebuilding the 8's diff seems good to me. I much prefer a rebuilt 8 unit to a used TR7 unit. The local shop could work on it over the winter. Thanks for the input.
 
Guys - I opened up a thread on this that is basically leading me to the same place.

I thought a TR8 would chew up a TR7 differential in short order?
 
I could be wrong, but I thought that the later TR7 rear axles were essentially the same as the TR8 axles, the change coming about when the five-speed gearbox was offered? Some quick glances at part numbers on the Rimmer Bros. web site would seem to bear this out.
 
Hi Andy - I have a differential from a 4 speed box but that won't last long. Ping me offline if that is useful to anyone.

I have a spare Rover SD1, would those innards with new bearings like address the whine?
 
TR7 4 speed and automatics thru 1980 were the flimsy 3.63 and 3.27 ratio rear ends originally found in the Austin Marina. The five speed, the 81 automatics, and all of the TR8s got the rear end that was found in the SD1. It was much beefier but by no means indestructible.
 
It's not. In principle they are the same much like all Ford 8.8s are the same. The axles and tubes are longer and have a 5X5 wheel bolt pattern. The mounts are different and it has a cool aluminum rear cover that has a centered mounting bolt for a Watts linkage. I'll snap a couple of pictures and post them later.
 
Hi Todd, I know the whole axle won't but how about the innards?

The SD1 rear suspension <span style="font-weight: bold">is</span> a cool set up.
 
The axle is 5 inches wider but the inerts are the same. In Europe, some of the SD1s came with a real low ratio. Something in the order of 2.83. I've seen where people have swapped those gears into TR8s to get a high mileage highway cruiser. Here are the pics.
 

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So - assuming one has a good Rover SD1 unit how would one go about moving it over and what would I need to replace still?
 
You could swap the R&P into a wedge rear end. This would require a complete rebuild because you would be removing and replacing the complete R&P, the bearings, axles, and crush collar. The only reason for doing this would be if you didn't all ready have a 3.08 or you had a bad 3.08 R&P, and you really wanted one. You could narrow the Rover unit, send the axles out to be shortened, resplined and hardened and weld on appropriate mounts to the Rover tubes. This is what some of the English tuners would do so that they could get a 5 lug wheel bolt pattern. On this side of the pond, it's more common to narrow a Ford or Dana rear end and install that. If you go the Ford/Dana route, you need to source a rear end from the junkyard, grind off the existing mounts and perches, cut the axle tubes to the right length, weld the ends back on, weld on brackets in the same locations as the wedge, order custom made axles with the right bolt pattern and length, and reassemble.(not as hard as it sounds, and there are some tricks to make sure it comes out straight) Every street rodder in the world is familiar with narrowing a rear end. The tricky part is locating and welding on the brackets so it will slide into the wedge just like an original. The last one I did came from a Ford Explorer. I only had to narrow one side, and was able to use two short axles.(truck rear ends are usually offset 3 inches or so to one side where cars are only offset 1 inch or so)
 
tr8todd said:
You could swap the R&P into a wedge rear end. This would require a complete rebuild because you would be removing and replacing the complete R&P, the bearings, axles, and crush collar. The only reason for doing this would be if you didn't all ready have a 3.08 or you had a bad 3.08 R&P, and you really wanted one. You could narrow the Rover unit, send the axles out to be shortened, resplined and hardened and weld on appropriate mounts to the Rover tubes. This is what some of the English tuners would do so that they could get a 5 lug wheel bolt pattern. On this side of the pond, it's more common to narrow a Ford or Dana rear end and install that. If you go the Ford/Dana route, you need to source a rear end from the junkyard, grind off the existing mounts and perches, cut the axle tubes to the right length, weld the ends back on, weld on brackets in the same locations as the wedge, order custom made axles with the right bolt pattern and length, and reassemble.(not as hard as it sounds, and there are some tricks to make sure it comes out straight) Every street rodder in the world is familiar with narrowing a rear end. The tricky part is locating and welding on the brackets so it will slide into the wedge just like an original. The last one I did came from a Ford Explorer. I only had to narrow one side, and was able to use two short axles.(truck rear ends are usually offset 3 inches or so to one side where cars are only offset 1 inch or so)
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Todd,

Any pictures or specifics re this rear end? Ratio, etc?

Martin
 
Are you talking about the TR7/8/SD1 rear end or the Ford 8.8? I went junkyarding this past week looking for a Lincoln MK VII 8.8 limited slip 3.27- no luck this time. Only found an open 3.08.
 
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