martinh55 Posted March 10, 2017 Share Posted March 10, 2017 I have ordered a set of solid rear subframe bushings to hopefully get rid of some wheel hop and tighten up any movement in the rear of the drive train. They are supplied with a set of shims to lower the subframe. This will change the roll center and anti squat. And that's as much as i know i have done a google search and haven't found any useful information. Does any body know how adjusting the cars roll center and anti squat would effect the cars handling? Or would i be better just fitting the bushings with out the shims? Cheers Martin Quote Link to comment Share on other sites More sharing options...
JoshTSquared Posted November 10, 2017 Share Posted November 10, 2017 Where did you order them from? Quote Link to comment Share on other sites More sharing options...
Keyser Posted November 10, 2017 Share Posted November 10, 2017 Lowering the sub frame on shims should not affect the squat of the car or if it does it would be minimal, rear spring preload has more to do with that, roll centre is to do with converting the spin of the engine through 90 degrees and into the back wheels there are two things here, firstly the rear diff wants to spin not transfer the drive and secondly you want a perfectly straight line from the back of the gearbox down the prop shaft and into the diff, the closer to perfet the less the loss and the strain for the angle, so I would assume the shims will help align the diff and gearbox thereby giving more efficient transfer of power and (by reducing offset) reduce shake I say shake as it's not the same as tramp - shake is caused by the offset from centre so you could say left to right but it's all directions - tramp is up and down - still with me? So solid mounts will reduce the ability of the subframe to move in any direction the diff still has bushes and they can move these could also be replaced with solid, the shims should straighten the drive chain reducing the off centre pressure giving a smoother transition and less side force. FYI - I can tell you from experience that the biggest thing I found that reduced tramp was replacing the rear gearbox mount with a solid bush - this is the other end of the "straight line" problem tighten the rear and the next weakest part will move so basically the gearbox shakes. A solid mount makes a huge difference but the trade of is cabin drum (I was running 450 RWHP in my 350z) How will it affect the handling - when you get it all lined up and solid it won't That's not strictly true! It will mean faster pull away without tram (hopefully) the additional side affects should be a "tighter" more predictable rear end as the "squish" or "cushioning" of the OEM design is removed you are left with the shocks, springs and tyres if these are all good quality (and setup correctly) the car becomes very predictable in the way it responds to any driver input - that can be recovering from a slide or just how much more stable the car is when you stamp on the throttle out of a corner or snatch a gear change the car stays flat and level so less chance of the rear becoming unbalanced. There is a trade off for all this - Noise trust me I had my 350z chassis stiffened and replaced every bush in the car with race or fast road spec replacements handling = awesome, noise = deafening you get loads of cabin noise - worth it???? Hmmm I sold the 350 got a 370 and a track toy but I'm getting old Hope that helps Disclaimer - I know less than John Snow about anything!!! Quote Link to comment Share on other sites More sharing options...
Guest Posted March 22, 2018 Share Posted March 22, 2018 On 10/11/2017 at 09:18, Keyser said: There is a trade off for all this - Noise trust me I had my 350z chassis stiffened and replaced every bush in the car with race or fast road spec replacements handling = awesome, noise = deafening you get loads of cabin noise - worth it???? Hmmm I sold the 350 got a 370 and a track toy but I'm getting old Resurrection time! Keyser, just how much NVH did the solid bushings add? I have been looking at poly or solid for gearbox, diff, and subframe and don't know what direction to go in. I'm ok with some extra harshness, but knocks and rattles trigger me Quote Link to comment Share on other sites More sharing options...
Keyser Posted March 23, 2018 Share Posted March 23, 2018 A lot!!! On a long run it was tiring, if you have ever been in a fully prepared rally car it's very like that just lots of noise, can't say it rattled but all noises like potholes and catseyes are louder. Get on track and you can forgive it all though cause damn that thing went like a scolded cat @AndyJames is worth speaking to we both suffered from noise he seems to live with his so be worth asking how far he has gone stiffening things up, I know he didn't have quite as much bracing as I did. Quote Link to comment Share on other sites More sharing options...
andy james Posted March 23, 2018 Share Posted March 23, 2018 I have witeline diff bushes and polybush suspension joints which transform the handling. i also have fitted a Hardrace gearbox mount which has made the gear action much more precise and has improved launching quite considerably. The big trade off is the noise. Wines like a Land Rover in the lower gears under load!! Quote Link to comment Share on other sites More sharing options...
Guest Posted March 23, 2018 Share Posted March 23, 2018 Thanks both for the additional info =) It sounds as though trade-off of noise versus handling for poly is definitely worth it, can't make my mind up about the solid transmission, diff, subframes though. I did see a couple of people elsewhere saying that poly subframe bushings fare no better for longevity than regular bushings if driven hard on a track, and that they could get mangled pretty quickly. Its annoying that it's so subjective and that you can't test your tolerance to it before purchase Quote Link to comment Share on other sites More sharing options...
ZMANALEX Posted March 23, 2018 Share Posted March 23, 2018 Talking from experience: Leave the sub frame alone. Swop out the gearbox and diff for solid bushings. Avoid Whiteline as they are made of chocolate. That is all that you will require for your set up IMHO. 1 Quote Link to comment Share on other sites More sharing options...
Ebized Posted March 23, 2018 Share Posted March 23, 2018 1 hour ago, ZMANALEX said: Talking from experience: Leave the sub frame alone. Swop out the gearbox and diff for solid bushings. Avoid Whiteline as they are made of chocolate. That is all that you will require for your set up IMHO. Er, and just for the record, roughly how much track time have you had with your 350 roadster to come to that conclusion Quote Link to comment Share on other sites More sharing options...
ZMANALEX Posted March 23, 2018 Share Posted March 23, 2018 21 minutes ago, Ebized said: Er, and just for the record, roughly how much track time have you had with your 350 roadster to come to that conclusion Only since 2005 Colin. Quote Link to comment Share on other sites More sharing options...
ZMANALEX Posted March 23, 2018 Share Posted March 23, 2018 Sorry duplicate post Quote Link to comment Share on other sites More sharing options...
Ebized Posted March 23, 2018 Share Posted March 23, 2018 24 minutes ago, ZMANALEX said: Only since 2005 Colin. Knew that! But couldn't help thinking that your "experience" and "humble opinion" is based on thousands of laps at Knockhill in the 350 alone - something those who have not been around on here as long as you and I might not be more aware of and extends to potentially more active track time knowledge than any other 350 owner .... in the UK, if not the world over. Quote Link to comment Share on other sites More sharing options...
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