Guest Report post Posted September 28, 2014 Having got hold of a set of rear subframe bushes, I thought I might as well stiffen up the diff while im at it, so have been looking at the various options. I see there are some bushes available which raise the diff, which is great for lowered cars. Has anyone tried these bushes? i wonder if there would be clearance problems with the fuel evap syatem? In fact, I'll ask another question... has anyone used any stiffer diff mounts? Share this post Link to post Share on other sites
KevinA 695 Report post Posted September 28, 2014 Nigel love your dog !! 1 rob275 reacted to this Share this post Link to post Share on other sites
rob275 1817 Report post Posted September 28, 2014 I am not aware of anyone using stiffer mounts, though I may be wrong. What would raising the diff do? Share this post Link to post Share on other sites
Guest Report post Posted September 29, 2014 I am not aware of anyone using stiffer mounts, though I may be wrong. What would raising the diff do? Rob, When you lower a car, you are basically moving the diff down closer to the road and adding angle at the driveshafts. Obviously this will increase CV joint wear. It's always best to keep the driveshafts as parallel as possible to the ground. Share this post Link to post Share on other sites
GT86Jay 202 Report post Posted September 29, 2014 I looked into stiffening up the diff mounts. What I learnt, (Not through experience but reading) was that you make the ride very harsh, loud with vibrations and can cause damage to other parts that require a little bit of movement in the diff. It also makes getting a good start off the line good. If you up the power and stiffen up to much, you may find the wheels just try to spin. As I say this is with experience but just reading and talking to various people. I choose not to stiffen the mount on mine. Share this post Link to post Share on other sites
hashiriya 52 Report post Posted September 29, 2014 Rob, When you lower a car, you are basically moving the diff down closer to the road and adding angle at the driveshafts. Obviously this will increase CV joint wear. It's always best to keep the driveshafts as parallel as possible to the ground. how much does the diff move by and if so are you transferring any stress you relieve from the drive shaft to the prop shaft? Share this post Link to post Share on other sites
Guest Report post Posted September 29, 2014 how much does the diff move by and if so are you transferring any stress you relieve from the drive shaft to the prop shaft? That was another concern of mine. If you go for one piece propshaft, the front flange of the diff must be parallel with the back end of the 'box. Running the car with the flanges out of parallel will add stress to the prop. I'm not sure how it works with a split prop? As for solid mounts on the Diff Jay, you are correct, you do induce a lot of noise, but its not deafening if the diff is correctly set up. You will also add stress to the structure the diff is mounted to, but I'm not sure that would be too much of an issue. I made driftworks original prototype solid mounts for their Skyline, i don't think any thing broke on their diff mounting set up?? Anyway, I'm not looking at solid diff mounts, just uprated ones. I have seen the whiteline video on Youtube with the camera under the back of the car. the movement is astonishing, it all floats around like its held together with rubber bands!! I want to add over 100hp to my car, so this standard set up will not do at all. I would imagine the soft diff mounts will cause tramping and a lot of wind up of the driveshafts? Think of it in the realms of a live axled car, say a Mk 2 Escort. They convert to five link from leaf springs for rallying to prevent axle twist among other reasons. Share this post Link to post Share on other sites
Burn! Motorsport 20 Report post Posted October 2, 2014 Rob, When you lower a car, you are basically moving the diff down closer to the road and adding angle at the driveshafts. Obviously this will increase CV joint wear. It's always best to keep the driveshafts as parallel as possible to the ground. From my experiences with the S2000's rather than raising the differential to prevent it premature failure it was possible to just space the driveshaft on the inner CV joint to spread the shafts and limit the excessive movement wear. Maybe this could help? It's a reported problem on other forums too. Share this post Link to post Share on other sites
Sideways? 33 Report post Posted October 3, 2014 good diagram from Burn! Motorsport. Rob, in the states I believe people have had trouble with driveshaft joints going pop when the car is lowered more than a sensible amount because they effectively run out of travel (as per the first diagram above), the idea being to raise the diff up in relation to the rest of the suspension to reduce the angle of the driveshafts and improve the situation... I imagine there are side effects to do with the suspension geometry in relation to the driveshafts but if you're slamming it that far anyway you probably don't care much for outright grip and handling... The spacer option is a clever idea but I think both (risers or spacers) are not required if you only lower a little anyway. As for fitting stiffer bushes I imagine it is the same trade off with all bushes - stiffer = more vibration and noise in the cockpit but better control over movement of the particular component... I haven't heard anyone using stiffer mounts but I would hardly say I'm an oracle on GT86 tuning and who's done what!! Share this post Link to post Share on other sites
Guest Report post Posted October 3, 2014 Great Idea thanks Burn. You are obviously going to help somewhat with those spacers, but not totally eradicate the issue. Anyway, it can't be done on the GT86 as it doesn't have a bolted flange in the shaft, which is a real shame in my opinion. I have actually bought the Whiteline bushes now, front and back on the diff, so along with the sub frame bushes, my ass should be pretty firm It maybe a little noisy too Share this post Link to post Share on other sites
