With the major source of oil leaks under the car sorted, I needed to repair some collateral damage from the previous leaks. The transmission mounts had turned to jello and weren’t doing a lot.
Now, first point I will say is don’t try to be cheap and buy transmission mounts from random suppliers on eBay. Even though they were listed specifically for an SD1, and have “Rover SD1” on the packaging, they didn’t fit without modification. The design of them means they might start to come apart quicker too, but hopefully the center poly bush will slow that down. They were about half the cost of Rimmers, but it wasn’t worth it. Just buy them from a reputable supplier like Rimmers and just deal with the cost.
Whats a sure-fire sign your transmission mounts are poked? When you go over a bump and the transmission tries to launch its self into space through the shifter hole! Every time I would take a large bump in Tess the whole shifter (and thus the transmission) would jump up a good couple of inches. Not really a good thing.
Since I had a serious leak under the car it has been coating everything in oil for a long time. Rubber doesn’t like oil; or well, it might like it too much. It soaks the oil up and softens the rubber to the point that is has the consistency of jello. Its soft, squishy and doesn’t support a large lump of metal too well.
The other issue was that the bolt on the far right in the above photo has a bush on it, which I suspect limits any vertical movement of the transmission. This bush had also suffered from the oil contamination. There wasn’t much bush left
To replace the bushes you must remove the crossmember the bushes are on. First crack off the 1/2″ nuts on the bushes (it’s easier when the crossmember isn’t flopping around) and remove the center large bolt. Be aware there should be a washer that sits between the trans and the nut and will drop off freely. Don’t lose it.
Then support the transmission on a jack. I purchased a bottle jack for this job, as its compact, can take a lot of weight and has a good height. This was much easier than trying to get my trolley jack in there.
The other mount was well stuck on the transmission. Don’t bother trying to grip it to twist it out, that aint going to work. Get a hammer and chisel, scrape some rubber away until you get a clean shot at the steel disc that is screwed into the transmission, and use the chisel to tap it around until it comes free. Then you can spin the mount out by hand.
And then you screw the new rubber spool mounts into the transmission. I smothered the stud in copper grease, as well as the mating face, so that it wouldn’t corrode to the transmission. Now this is where it went a bit wrong. I needed to chop the stud on these down, or they just wouldn’t screw in fully. I think they were bottoming out. I don’t think this should be needed on proper mounts.
I gave the area of the trans around the mounts a quick clean, and then refit the mounts. The two spool mounts screw into the transmission first, as tight as by hand can be, and then the crossmember goes on. Due to the added height of the new mounts vs the old ones, you may need to raise the transmission a little higher to get the crossmember bolts into place. Remember the plate on each side the bolts go through, and refit them. Once again, the 13mm ratchet spanner was the tool of choice here. The exhaust blocked a ratchet from getting in there.
Now, that center bolt. I couldn’t quite work how what the deal was until now. Remove the jack from the transmission first. Fit it like this from the underside of crossmember;
Bolt – large washer – bushing (large section under crossmember) – nut ~ insert through crossmember but don’t screw in. Now slip the other washer on top of the nut, wind the nut down to the bush and screw the bolt into the transmission. I wasn’t sure how tight to do this bolt, so I tightened it until there was compression on the bush, pulling the trans down towards the crossmember, and then wound the nut up and tightening it against the transmission.
In regards to that center bolt, it’s been brought to my attention that there is an actual specification in the manual for this (not in Haynes, but in the BL manual). The manual states for there to be a 3mm gap between the shoulder of the bush and the underside of the crossmember. I’m going to leave mine as it is, because it’s a polybush, and the whole point in a polybush for me is to make a more solid connection than rubber. It makes a lovely solid feeling connection, but may cause more wear on the bushes. I’ll leave this up to the individual to decide how they want to fit it, but I’d probably nip up a polybush, and leave the gap on the standard rubber one.
The results are impressive to say the least. On a quick test drive I took it over a large bump in the road that I knew would usually cause a huge jump in the transmission, and this time it stayed solid as a rock. The shifter is even more direct; obviously moving the shifter was moving the whole rear of the transmission too. Huge improvement.
I do wish there was an off the shelf poly version of the two spool mounts, but in my travels I never found one. Not even for a TVR, which uses the same transmission.
I ended that batch of work by degreasing and water blasting the underside of the car. It’s not perfect under there, but its a lot better. I also “accidentally” blasted a lot of the yellow paint off the swaybar and crossmember… leaving a white instead. not sure which is worse tbh.
CRC454A – Gearbox Mounting Rubber x2
CRC581A – Rubber Buffer, Center of Rear Bracket (this is standard rubber, uprated poly version available via eBay)
Please note these parts are specific to my car and may vary. Please check before ordering.