EliTR6 Posted November 17, 2009 Report Share Posted November 17, 2009 (edited) Hi all, Following on from dblenk's thread, how easy would it be to get a 3.45 ratio diff in good condition rebuilt as a 3.7 or 3.9? Of course by easy, I mean cheap! Could I do it myself or is this a job for a specialist? Thanks PS: this is how not to tow a TR chassis. Great on the flat and going uphill but tends to get stuck under land rovers when facing down a slope! We were too excited to think about braking. Close shave... Edited November 17, 2009 by EliTR6 Quote Link to post Share on other sites
EliTR6 Posted November 17, 2009 Author Report Share Posted November 17, 2009 Would a saloon diff fit? ebay saloon diff I take it that even if it did fit, a spitfire diff would be too weak? ebay spit diff Quote Link to post Share on other sites
rpurchon Posted November 17, 2009 Report Share Posted November 17, 2009 Would a saloon diff fit? ebay saloon diff I take it that even if it did fit, a spitfire diff would be too weak? ebay spit diff yes if you fit the front and rear from a tr richard Quote Link to post Share on other sites
Guest ntc Posted November 17, 2009 Report Share Posted November 17, 2009 Hi all, Following on from dblenk's thread, how easy would it be to get a 3.45 ratio diff in good condition rebuilt as a 3.7 or 3.9? You only need the crown wheel and pinion that decides the ratio, however if you go down the 3.45 route you need to source an original Quote Link to post Share on other sites
88V8 Posted November 17, 2009 Report Share Posted November 17, 2009 Following on from dblenk's thread, how easy would it be to get a 3.45 ratio diff in good condition rebuilt as a 3.7 or 3.9? Of course by easy, I mean cheap! Could I do it myself or is this a job for a specialist? Specialist. However, saloon diffs are cheap, buy one fit it try it see if you like the ratio before you make a commitment of a few hundred quid. Here's how to fit it: http://www.tr-regist...view=&hl=saloon +diff&fromsearch=1 I have a useable 3.7 with TR flange and rear casing. The very same one that stars in the above topic. Hums a bit leaks a bit, done 4,000 with me and many thousand miles of life left, no longer needed as I have my lsd now - £50. Only trouble is, it's here and you're there... Ivor Quote Link to post Share on other sites
Guest ntc Posted November 17, 2009 Report Share Posted November 17, 2009 (edited) Specialist. However, saloon diffs are cheap, buy one fit it try it see if you like the ratio before you make a commitment of a few hundred quid. Here's how to fit it: http://www.tr-regist...view=&hl=saloon +diff&fromsearch=1 I have a useable 3.7 with TR flange and rear casing. The very same one that stars in the above topic. Hums a bit leaks a bit, done 4,000 with me and many thousand miles of life left, no longer needed as I have my lsd now - £50. Only trouble is, it's here and you're there... Ivor Ivor Come on,the full story please Edited November 17, 2009 by ntc Quote Link to post Share on other sites
88V8 Posted November 17, 2009 Report Share Posted November 17, 2009 Come on,the full story please What More than that thread I linked.... you are a glutton for punishment. I just finished editing some pics for a new thread on fitting the Nissan lsd. Maybe tomorrow. Ivor Quote Link to post Share on other sites
Guest ntc Posted November 17, 2009 Report Share Posted November 17, 2009 What More than that thread I linked.... you are a glutton for punishment. I just finished editing some pics for a new thread on fitting the Nissan lsd. Maybe tomorrow. Ivor Does it whine or clunk? punishment bring it on your selling it Quote Link to post Share on other sites
Mk1PI Posted November 18, 2009 Report Share Posted November 18, 2009 That ebay diff with that MG prefix is a 3.45 Ratio not a 3.7 as stated unless someone has been swapping CWP's . NOT likely Quote Link to post Share on other sites
EliTR6 Posted November 18, 2009 Author Report Share Posted November 18, 2009 Dropped Ivor an email. Just found this on ebay: 3.7 CWP Is this all I would need to convert a 3.45 to a 3.7? Apart from a new oil seal maybe. Thanks Quote Link to post Share on other sites
TR 2100 Posted November 18, 2009 Report Share Posted November 18, 2009 Dropped Ivor an email. Just found this on ebay: 3.7 CWP Is this all I would need to convert a 3.45 to a 3.7? Apart from a new oil seal maybe. Thanks Reading between the lines of the auction page, I'm sure this CW&P would have been s/h when the "rebuild" was done. Given the other problems with this rebuild, you have to be more than a bit suspicious as to it's condition. Also, I think it's a bit expensive for a CW&P anyway. But yes,it's all you would need to convert from 3.45 to 3.7. BUT - I would agree with previous posts that for a TR6, it's far better to stick with the 3.45. AlanR Quote Link to post Share on other sites
EliTR6 Posted November 18, 2009 Author Report Share Posted November 18, 2009 BUT - I would agree with previous posts that for a TR6, it's far better to stick with the 3.45. AlanR Thanks Alan, just trying to get my head around it. Its not for now anyway. Haven't even started removing the seats from the 6 yet, let alone rebuilding on the new chassis! I want mine to be more track focused than before. Will aim to drop the weight and fit a 3.7 first and get the engine worked on if and when I can eventually afford it. I already have a 3.45 so there's no harm in trying something different. Quote Link to post Share on other sites
dblenk Posted November 18, 2009 Report Share Posted November 18, 2009 Hi Eli i got a TR4 diff by default and changed the rear casing, someone should have a american diff these were 3.7, like Ivor said try it out then commit, thats what i am doing i got a link from MK1 or Ivor i think linking to a "mintylamb" and there is quite a lot of info on engine and diff ratios there cheer david PS did you sort your exhaust manifold out Quote Link to post Share on other sites
EliTR6 Posted November 18, 2009 Author Report Share Posted November 18, 2009 try it out then commit, thats what i am doing i got a link from MK1 or Ivor i think linking to a "mintylamb" and there is quite a lot of info on engine and diff ratios there PS did you sort your exhaust manifold out Hi David, I'm going to take Ivor's 3.7 off his hands when I get back. Do you mean my manifold or Ivor's? I've still got the 6-1 on mine, thinking about changing to a Phoenix manifold for better torque next year. Need to restore the car first! I've played around with the mintylamb site. How accurate have you found it to be? As far as I know, my TR6 is a standard 1971 CP (pi) with A type overdrive and 15/65 15 tyres. According to the calculator, 70mph should be at 2665rpm and 80mph at 3045rpm. Haven't driven the car for over 6 months and haven't had a working speedo for 3 years but I'm pretty sure that 70mph saw around 3000rpm and 80mph took about 3500-3700rpm. Will definitely be playing with a dwell meter and GPS when the beast is finally up and running again. Quote Link to post Share on other sites
88V8 Posted November 19, 2009 Report Share Posted November 19, 2009 Does it whine or clunk? punishment bring it on your selling it No whine, just a musical hum, unchanged over 4,000 miles. Clonk no but not perfect hence £50. I wouldn't expect it to last forever but it will do a couple of years at least and well worth it to try the ratio. Have swapped diffs twice now, each time about 10% lower, it's amazing what difference a 10% ratio change makes to the feel of the car. I've played around with the mintylamb site. How accurate have you found it to be? As far as I know, my TR6 is a standard 1971 CP (pi) with A type overdrive and 15/65 15 tyres. According to the calculator, 70mph should be at 2665rpm and 80mph at 3045rpm. Haven't driven the car for over 6 months and haven't had a working speedo for 3 years but I'm pretty sure that 70mph saw around 3000rpm and 80mph took about 3500-3700rpm. It's just an arithmetical expression, so exactly accurate. I would suspect your speedo and tacho. However it may be of course that you already have a 3.7... chalk the flanges turn the diff by hand, carefully count the turns. Ivor Quote Link to post Share on other sites
EliTR6 Posted November 19, 2009 Author Report Share Posted November 19, 2009 It's just an arithmetical expression, so exactly accurate. I would suspect your speedo and tacho. However it may be of course that you already have a 3.7... chalk the flanges turn the diff by hand, carefully count the turns. Ivor I'm puzzled. Last time I checked the tacho, it was under-reading too. The figures make it look like I have a 4.1 which I'm pretty sure isn't the case. Have an extra incentive to get the car down to the bare metal now. Quote Link to post Share on other sites
dblenk Posted November 19, 2009 Report Share Posted November 19, 2009 Hi Eli we spoke about your 6-1 manifold, but i guess you are going for a 6-3-1 pheonix which by the forum is the best i found the mintylamb site very good and proved my own calcs form measuring etc it gives a guide if nothing else i will post how things are when i get my diff done probably around xmas now cheers david Quote Link to post Share on other sites
EliTR6 Posted November 20, 2009 Author Report Share Posted November 20, 2009 Hi Eli we spoke about your 6-1 manifold, but i guess you are going for a 6-3-1 pheonix which by the forum is the best i found the mintylamb site very good and proved my own calcs form measuring etc it gives a guide if nothing else i will post how things are when i get my diff done probably around xmas now cheers david I love the noise from the 6-1 single big bore and top end power is good but not as useful as lots of mid-range torque. Looking forward to reading about your diff adventures. E Quote Link to post Share on other sites
jellison Posted November 22, 2009 Report Share Posted November 22, 2009 Ha Eli glad you are enjoying the Exhaust. Pete does not charge much for a TR diff overhaul. You know my ideas on the CWP. Plus he could do the OD with the race valving. Works for me x2 4 in my garage now Quote Link to post Share on other sites
dblenk Posted November 23, 2009 Report Share Posted November 23, 2009 Hi Eli I thought i was getting a bargin but the CWP are F*** eh not very good more money, should have listened to the wife rebuilt the 5 and bugger the 6 the lad doing the diff will see me OK so i have to pay an extra £175 not nice right on xmas, the guy who sold said it was bearing noise, but roy who is doing the diff said if must have had a hell of a racket right thats me finished moaning over i will report when i get it sorted and in teh car cheers david Quote Link to post Share on other sites
Guest ntc Posted November 23, 2009 Report Share Posted November 23, 2009 Hi Eli I thought i was getting a bargin but the CWP are F*** eh not very good more money, should have listened to the wife rebuilt the 5 and bugger the 6 the lad doing the diff will see me OK so i have to pay an extra £175 not nice right on xmas, the guy who sold said it was bearing noise, but roy who is doing the diff said if must have had a hell of a racket right thats me finished moaning over i will report when i get it sorted and in teh car cheers david Cheer up David at least you will know it's a good'un Quote Link to post Share on other sites
dblenk Posted November 26, 2009 Report Share Posted November 26, 2009 Thanks for that Neil its been a busy week so just catching up now Roys going to sort it so yes it will be good the heads coming on the engine i am going to use Northern Rebore in Newcastle the guy there does classics / Vintage and has old cars himself he said to me my engine was modern !!!!!!!! cheers david Quote Link to post Share on other sites
cp7535he Posted November 28, 2009 Report Share Posted November 28, 2009 I have an CR TR to which I fiited a replacement 4.1 diff which I believe is a USA ratio spec diff ~ cannot give any on the road comparasions though as this motor has been in the garage awhile. robin Quote Link to post Share on other sites
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