mikeyb Posted December 7, 2013 Share Posted December 7, 2013 Took one of the rear trailing arms off the GT6 today, the plan being to polybush it. At the large (forwards) end, the old metalastik bush would appear to have been formed inside a metal ring which then pushed inside the arm. There is no such ring with the poly replacement bush. Looking at the arm now with all the remains of the old bush removed, I am concerned that what is left is very thin. This leads me to wonder if the ring surrounding the metalistik bush adds to the strength of the arm. Therefore if I fit a polybush without such a ring, will the arm end up weaker?Any ideas? Options as I can see are 1) Fit polybush I have and hope for the best (not convinced!)2) source replacement polybush formed in ring as per original (if such exists)3) source and fit original rubber type metalastik bush (maybe available in uprated rubber)4) fit Spitfire trailing arm instead which has smaller bush and eye both endsWho's done this before, which did you do?Anyone know why GT6's had a larger eye and bush at the forward ends of the rear trailing arms?CheersMike Quote Link to comment Share on other sites More sharing options...
Richard B Posted December 7, 2013 Share Posted December 7, 2013 As the GT6 was upmarket from the Spitfire.I presumed it was there to either increase the comfort (bumps etc) or to lessen the road noise (drone) of a Coupe.I recall that one of the tuning mods for a Gt6 was to fit Spitfire tie-rods. Quote Link to comment Share on other sites More sharing options...
FloydP Posted December 7, 2013 Share Posted December 7, 2013 When I did mine I didn't realise the bush had an outer metal ring, it was so well attached to the trailing arm I assumed it was part of it. Obviously no amount of squeezing the red one piece polybush would get it into the hole, so after a lot of swearing my Father in law popped it on his lathe turned down the bush outside diameter to enable it to fit. I assumed the bush had been made incorrectly and that was why it didn't fit but it all becomes clear now. Anyway I wasn't entirely convinced turning poly urethane was a good idea, I've kept a close eye on it for the last few years, probably been on for five years now two rbrr's and many thousand miles and it still seems fine. Bit late for you to go down that route now though. Quote Link to comment Share on other sites More sharing options...
Tim Bancroft Posted December 8, 2013 Share Posted December 8, 2013 Mike,I would go for a set of adjustable radius arms from Jigsaw, I think Canleys may make them as well. Basically they are shorter versions of the mk2 suspension ones that GT6 mk2 and early 3 have with different geometry.they are made for Spits, but I see no reason why they could not fit a mk1 GT6-I could be wrong though!Here's an excerpt from their internet page:Adjustable Rear Radius Arms, pairfor the Spitfire Mk1, 2, 3, 4 and 1500 modelsmade from solid rod which is machined and threaded to tolerance, with left hand and right hand threaded portion, centred with a left hand/right hand adjuster complete with lock nuts. Spitfire Rear Adjustable Radius ArmsTo ease the enablement of the adjustment of the rear toe when aligning your car, more infinitely adjustable than just shims especially if the heel board of the car has been repaired.Will accept standard rubber road bushes or up-rated Polybush units in both red or blueAvailable for Spitfire Mk1,2,3 or 4 (Short drive shaft)or Spitfire 1500 (Long drive shaft)£ 118.00 per pairhttp://www.jigsawracingservices.co.uk/development.htm Quote Link to comment Share on other sites More sharing options...
JSBulmer Posted December 9, 2013 Share Posted December 9, 2013 When I upgraded the trailing arm bushes on my GT6 MK I, I went with the blue polybushes. Was a lot of work to get the rubber bush with metal ring out, but the blue polybush went in well. Been on the car for over 6000 miles and am happy with them.jb Quote Link to comment Share on other sites More sharing options...
JohnD Posted December 9, 2013 Share Posted December 9, 2013 You know what you are talking about, I know too, but these components are usuallly referred to as "radius arms".In a Trailing arm suspension the similar component would be much more substantial, more like a fore-and-aft wishbone, often that takes the strain of a coil spring.John Quote Link to comment Share on other sites More sharing options...
spittyholly Posted December 9, 2013 Share Posted December 9, 2013 fitted poly bushes to my gt6 mk3 arms 2 years been fitted no problems Quote Link to comment Share on other sites More sharing options...
Tim Bancroft Posted December 9, 2013 Share Posted December 9, 2013 Slightly different radius arms on a mk2 to a mk1 or late mk3. Mk2/mk3 early have threaded adjusters, wheras the others are adjusted for length by the use of shims.I have been thinking about this and I always thought that the late mk3 had the big bush, wheras the GT6 mk1 had the same size bush as the Spit/Herald/Vitesse (6 or mk1) at both ends?If fitting polybushes, I would fit red as I think the stiffer bush helps to keep the geometry in check, not as much deflection. Quote Link to comment Share on other sites More sharing options...
mikeyb Posted December 9, 2013 Author Share Posted December 9, 2013 As per photo earlier in thr thread, my Mk1 has a bigh bush. I also have a pair of long shaft swing spring hubs/arms - these have the same bush but obviously for the longer shaft, the radius arm angles are different to the Mk1 Quote Link to comment Share on other sites More sharing options...
FloydP Posted December 9, 2013 Share Posted December 9, 2013 Big bush in mine too :P Quote Link to comment Share on other sites More sharing options...
RedRooster Posted December 9, 2013 Share Posted December 9, 2013 I have a set of adjustables on my wish list, as i spent a day or so setting up the front camber / castor, but could do little with the rear due to the fixed geometry.RR Quote Link to comment Share on other sites More sharing options...
Tim Bancroft Posted December 10, 2013 Share Posted December 10, 2013 Looks like my memory is playing up, mk1s had the big bush!Helps to explain why those cars do not like corners then! Quote Link to comment Share on other sites More sharing options...
mikeyb Posted December 10, 2013 Author Share Posted December 10, 2013 Well I'm learning something every day - I had always thought that the bigger bushes must have been a upgrade for the more powerful cars! It seems that actually the opposite is the case!Whilst googling I came across some interesting stuff here.http://www.wolfitt.com/wolfitt_products_1.htm#Adjustable%20rear%20radius%20armsScrolling down the page, the adjustable vertical links are something I have never heard of before.... Quote Link to comment Share on other sites More sharing options...
FloydP Posted December 10, 2013 Share Posted December 10, 2013 I thought the big bush was needed for the extra torque of the 6 cylinder lump, but once they put rotoflex on, the lower wishbone handled the umph so normal small bushes could be used, when they went to swing spring they went back to the big bush. I'm sure the bean counters would have used the spitfire arms/bushes if they were thought to be up to the job. Quote Link to comment Share on other sites More sharing options...
mikeyb Posted December 13, 2013 Author Share Posted December 13, 2013 I've done some googling, and the general consensus seems to be that the bigger GT6 bushes (in standard form) lead to soggier handling, so maybe they were designed for comfort rather than performance!Then what Richard said "I recall that one of the tuning mods for a Gt6 was to fit Spitfire tie-rods" may well be correct. We need slimboyfat or someone else in the know to corroborate this! Quote Link to comment Share on other sites More sharing options...
Paudman Posted December 13, 2013 Share Posted December 13, 2013 No idea if mine were soggy or not but I replaced them in red polybushes last year - you can see the state of the old ones so it must have been an improvement. A bollox to fit but well worth the end result. Quote Link to comment Share on other sites More sharing options...
mikeyb Posted December 13, 2013 Author Share Posted December 13, 2013 my polybushes will hopefully be a lot easier as the are in two halves - as seen in photo at beginning of this thread.However mine have shoulders wheras yours looks more like the original bush . . . Quote Link to comment Share on other sites More sharing options...
Velocita Rosso Posted December 15, 2013 Share Posted December 15, 2013 Never looked back since doing what Tim suggested,fitting adjustable radius arms.After fitting and four wheel alignment took place......it was found to be 9 degs out of alignmentJust goes to show how far body work can be out when new panels are fittedRuns straight as a die now ,no tyre wear etc Quote Link to comment Share on other sites More sharing options...
GT6DavidMK1 Posted December 15, 2013 Share Posted December 15, 2013 timbancroft61 wrote:Looks like my memory is playing up, mk1s had the big bush!Helps to explain why those cars do not like corners then!Depends on the driver Tim!!, I have never had a problem with my MK1David. Quote Link to comment Share on other sites More sharing options...
Tim Bancroft Posted December 15, 2013 Share Posted December 15, 2013 Yes, David...You are correct, GT6s if poorly driven can be evil what ever type!Slow in, fast out! Quote Link to comment Share on other sites More sharing options...
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