vairshop Posted March 20, 2014 Share Posted March 20, 2014 hi alllarry claypool here, new to forum. I run a repair shop here in the usa where I specialize in Chevrolet corvairs, but do take on the occasional odd car that appeals to me. I had a customer bring me a usa spec 61 herald convertible that has sat unused since 1971. very original decent car. transmission tunnel cover was off, pointing towards trouble in that area. he had never driven it, so did not know the history. I successfully did all the usual to get the car driving, however the 1st test drive confirmed clutch troubles, it slipped.I pulled the transmission and installed a new disc, pilot bushing, and throw out bearing. neither the flywheel nor pressure plate (cover) was scored or blued, so I reused them. the old disc was oily but not worn badly.reassembled everything only to find it still slipped, though not as badly. ordered a new clutch cover, installed same; it still slips.the adjustment is correct, the clutch arm/pushrod has no tension on it when released so I am certain the throw out bearing is not preventing the cover from releasing all the way. the throw out bearing arm moves freely, no binding.all the parts ordered were for a herald 948, which is what this car is. coil spring type cover. I am a little bit at a loss of what to do next. hate to take it apart again without having a "plan".any suggestions? thanks!across the pondlarry Quote Link to comment Share on other sites More sharing options...
heraldcoupe Posted March 20, 2014 Share Posted March 20, 2014 There are two different types of clutch cover, one has six springs, the other has nine. The coil spring clutch isn't particularly strong but it shouldn't slip easily from new, however the nine spring cover does offer an upgrade over the six spring type.You mentioned that the original plate was oily, presumably there was no sign of oil on the new plate when you subsequently went back in to fit the new cover?Cheers,Bill. Quote Link to comment Share on other sites More sharing options...
vairshop Posted March 21, 2014 Author Share Posted March 21, 2014 Hi Billnope, cleaned everything off so it went together dry, and was still dry after I took it apart the 2nd time. the clutch cover was a 6 spring unit, and that's what I replaced it with.I didn't see a 9 spring unit as an option; what's it from? thankslarry Quote Link to comment Share on other sites More sharing options...
herald948 Posted March 21, 2014 Share Posted March 21, 2014 9-spring units, otherwise the same size, were used on the earliest Spitfire 4 and the Herald 1200. Meanwhile, what is there for clutch hydraulics? Still-functional original master and slave cylinders or recent replacements? (Yes, I'm grasping at straws, trying to figure out possible causes!) Quote Link to comment Share on other sites More sharing options...
Clive Posted March 21, 2014 Share Posted March 21, 2014 how about the clutch release mechanism. IIRC there are a 2 different arms and 2 different bearing carrier? Just a thought it they got mixed, maybe with a gearbox swap, the bearing may be permanently pressing on the cover?Bill may be able to clarify my ramblings, or dismiss them. Quote Link to comment Share on other sites More sharing options...
herald948 Posted March 21, 2014 Share Posted March 21, 2014 Clive, excellent suggestion...and yes, you are correct about the fact that there are different bearings and carriers (actually, the arm didn't change) between the earlier coil spring clutch and the later diaphragm clutch. Always possible that bits got mixed up back in '71, causing the car to be put away then? Who knows?Larry, when you get it apart again (and I suspect you've no choice), get some photographs to us of the related bits. Maybe that will help! Quote Link to comment Share on other sites More sharing options...
Mark Hammond Posted March 21, 2014 Share Posted March 21, 2014 Didn't the 948 have an adjustable clutch?Mark Quote Link to comment Share on other sites More sharing options...
heraldcoupe Posted March 21, 2014 Share Posted March 21, 2014 1218 wrote:Didn't the 948 have an adjustable clutch?MarkYes, for the early ones, however it does nothing meaningful and the clutch self-adjusts perfectly well.It's possible that if badly adjusted it would prevent the clutch from fully engaging, but the OP states there's no tension on the arm so that seems unlikely,Cheers,Bill. Quote Link to comment Share on other sites More sharing options...
herald948 Posted March 21, 2014 Share Posted March 21, 2014 Early ones did, but not all. Offhand, I don't remember when that little feature was dropped, but Bill Davies probably knows! :) Quote Link to comment Share on other sites More sharing options...
heraldcoupe Posted March 21, 2014 Share Posted March 21, 2014 It was during 1960, probably fitted to the earliest 948 Convertibles but gone by the time any of those were sold in the UK,Cheers,Bill. Quote Link to comment Share on other sites More sharing options...
herald948 Posted March 21, 2014 Share Posted March 21, 2014 That's about what I thought. My fairly original, April-1960 built 948 saloon has the adjustment. Quote Link to comment Share on other sites More sharing options...
vairshop Posted March 24, 2014 Author Share Posted March 24, 2014 hi allI replaced both the master and slave cylinders with new ones; that system works fine. the clutch releases well, and engages fine. I can adjust the free play with the threaded slave cylinder pushrod. it simply slips when I give it heavy throttle. I don't think the issue is too much power .-). this is a very original car, it does not appear anybody has 'been there' before me. from what I read, it looks like the 1200 may have used the 9 spring cover; I am not sure if that was to be used with the 6.25 disc (which is what I have) or the 6.5 disc.any suggestions are again welcome as well the exact applications for what I need to order to put a 9 spring cover on this, if that is even possible.I know this will have to come apart, but I want to line up whatever bits I'll need before do so.regardslarry Quote Link to comment Share on other sites More sharing options...
herald948 Posted March 24, 2014 Share Posted March 24, 2014 9112 wrote: from what I read, it looks like the 1200 may have used the 9 spring cover; I am not sure if that was to be used with the 6.25 disc (which is what I have) or the 6.5 disc.Both the 6- and 9-coil covers were used with 6.25" driven discs. The 6.5" driven disc is for a later diaphragm-style clutch cover.Beyond that, I confess to being stumped. I can only assume that nothing has contaminated the friction material, and that something is keeping the clutch from completely releasing? A new clutch just shouldn't slip. Period. Master cylinders are all pretty much the same for clutches, but there are different styles of slave cylinder. I wouldn't think that the wrong slave could cause such a problem, but.... ??? Quote Link to comment Share on other sites More sharing options...
vairshop Posted March 24, 2014 Author Share Posted March 24, 2014 Quote:Beyond that, I confess to being stumped. I can only assume that nothing has contaminated the friction material, and that something is keeping the clutch from completely releasing? A new clutch just shouldn't slip. Period.I agree completely, which is why this has me more than puzzled. I don't want to take it back apart without a plan of attack. any suggestions for a source for the 9 spring cover?I only see the 6 spring style listed from most suppliers thanks againlarry Quote Link to comment Share on other sites More sharing options...
herald948 Posted March 24, 2014 Share Posted March 24, 2014 Excellent question...to which I'm afraid I can't provide an answer. But good vendors to contact in the US include:SpitbitsThe Roadster FactoryTS Imported AutomotiveAll of the above will have someone on one of their phone lines or e-mail addresses who probably can actually answer technical questions such as "how many coil springs are there on an early Spitfire pressure plate?" Note that the early Spitfire used essentially the same clutch, and saying "Spitfire" won't scare off most US vendors as will saying "Herald"! Besides, if saying Herald doesn't scare them, there's a fair chance they'll just give you my phone number or e-mail address unless they happen to know the answer! ;D (I'm well known to many US Triumph parts sellers after decades of being The Vintage Triumph Register's vehicle consultant for the Herald!) Quote Link to comment Share on other sites More sharing options...
Paudman Posted March 25, 2014 Share Posted March 25, 2014 9112 wrote:I agree completely, which is why this has me more than puzzled. I don't want to take it back apart without a plan of attack. any suggestions for a source for the 9 spring cover?I only see the 6 spring style listed from most suppliers thanks againlarry If you have a 9-spring cover, or can get a second-hand one, the springs can be replaced to refurbish the cover. This is something I haven’t yet tried, but I’m told the springs are the same as valve springs? In any case as I have two or there new 6-spring covers in the garage, I may try removing the new springs from those to get enough to refurbish a 9-spring cover. Quote Link to comment Share on other sites More sharing options...
Pete Lewis Posted March 25, 2014 Share Posted March 25, 2014 9 spring cover has 3 9/100 lb springs and 6 blue 75/85lb springs dont have data for the 6 spring to handmy guess is if it slips under load you have a thinner diaphragm disc fitted in a coil cover ... this wont work.coil coveers takes a 0.305" THICK DISC if you strip it out lightly clamp the facings in a vice and measure its thickness .just a thought Pete Quote Link to comment Share on other sites More sharing options...
vairshop Posted May 1, 2014 Author Share Posted May 1, 2014 hi all I finally took this thing back apart again, and using the specs provided by Pete who replied on this thread, found the new (not rebuilt) clutch disc I had bought was too thin (.255). the vendor for it here in the usa (British Victoria) was of no help in measuring any others in stock, nor any technical person to discuss this with, so I contacted Rimmer Bros. where I had bought other parts for this car. Rimmer quickly sent me a reply indicating their discs were .355 thick; I ordered one and it arrived this week. it actually measures .310; I suspect whomever measured it did not compress it before measuring. never the less, that spec was in line with the specs posted. it's all back together, and doesn't slip. problem solved. thanks for all the posts that lead me in the right direction! best regardslarry claypoolusa Quote Link to comment Share on other sites More sharing options...
Pete Lewis Posted May 3, 2014 Share Posted May 3, 2014 glad that all worked out ok happy motoring Pete Quote Link to comment Share on other sites More sharing options...
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