Michael Downing Posted October 7, 2011 Share Posted October 7, 2011 OK, I have the diff in the car hanging on the top bolt. Naturally, the bottom bolts are not aligned. If I rotate the diff on the top bolt, the bottom bolt holes come closer to being in alignment, but don't reach a perfect alignment and certainly aren't within reach of fitting the bolts. It looks like somewhere between 1 & 2mm out, at best. Is this just a question of bashing and wiggling until it works, or is something seriously awry? Link to comment Share on other sites More sharing options...
swsambler Posted October 7, 2011 Share Posted October 7, 2011 I am sure you will get loads of advice on this. It is a bit of a fiddle and I started the other way round with mine. The things to check are: 1. that the top bolt actually goes all the way through the diff casing often it doesn't, yours seems to be okay. 2. that you have got it centred in the car using the spacer washers. This is worth spending some time on and is a bit fiddly. Try grease or petroleum jelly to hold spacers together in a pack. I think the tolerance from the centre line is + or - 2mm. 3. The mountings do give but it is a case of getting as many bolts in as possible, even iff they are part way through. Personally I used a long thin screwdriver in the top mount and then put in the lower bolts, finally putting in the top bolt. Hope this helps. Four arms or two people is useful for this one. Link to comment Share on other sites More sharing options...
Michael H Posted October 7, 2011 Share Posted October 7, 2011 Hmmmm... Mine went in relatively easily... Does yours look like this? Cheers Mike Link to comment Share on other sites More sharing options...
DJ. Posted October 7, 2011 Share Posted October 7, 2011 As suggested, it is best to get the lower bolts in first, because you don't want to risk a crossed thread forcing the bolt in. I used a narrower rod through the top and played around with washers getting the lower bolts absolutely right. Once I was happy they weren't going to be removed again, I ground a substantial bevel on the top bolt and drove it through pushing the bar out of the way. It needs more force than you think it should on a modern chassis ☹️ Duncan Link to comment Share on other sites More sharing options...
weeman Posted October 7, 2011 Share Posted October 7, 2011 The way I do it is to hang the diff on the upper mounting using a rod of smaller diameter than the bolt. Then get the lower bolts in place and finally drift the rod out using the long bolt. I find the smaller diameter rod gives a lot more wiggle room whilst holding the diff nicely in place. I dare say that someone will be long to say that I'm talking bollox though. 😬 This is something I've done quite a few times now thanks to CC's inability to supply cars with diffs that work properly. I thought that taking a diff out a DD 7 was difficult until I took one out of a CSR 😔 😔 ETA; I do wish that I read other peoples posts before writing my own 😳 😳 Be lucky!! Martin Edited by - weeman on 7 Oct 2011 18:13:05 Link to comment Share on other sites More sharing options...
Support Team c7trp Posted October 7, 2011 Support Team Share Posted October 7, 2011 Just checking you've put the prop in first Otherwise you'll have to do all of this again Dont ask me how I know.... 😔 Link to comment Share on other sites More sharing options...
Michael Downing Posted October 7, 2011 Author Share Posted October 7, 2011 Quoting Michael H: HDoes yours look like this? My diff looks nothing like that! Caterham have just changed to a BMW diff so the actual unit looks very different. (At least it means I don't have to fit indicators though!) In terms of the physical arrangement, it looks very like that though. Sounds like the key is to use a smaller rod on the upper mount so that I have some free play. I'll go and play on that basis. Thanks guys! Link to comment Share on other sites More sharing options...
Michael Downing Posted October 7, 2011 Author Share Posted October 7, 2011 Quoting c7trp: Just checking you've put the prop in first Yes. Oh yes. yes yes yes yes! Link to comment Share on other sites More sharing options...
Titanium7 Posted October 7, 2011 Share Posted October 7, 2011 Bottom bolts first and then I found it a lot easier if the top bolt was chamferred on the front end as per DJ's post but inserted with a bl**dy great hammer 😬 Edited by - Titanium7 on 7 Oct 2011 19:15:13 Link to comment Share on other sites More sharing options...
6speedmanual Posted October 7, 2011 Share Posted October 7, 2011 Quoting DJ.: .........modern chassis ☹️ LoL Link to comment Share on other sites More sharing options...
Martin J Posted October 7, 2011 Share Posted October 7, 2011 but inserted with a bl**dy great hammer I used a copper lump hammer, very handy & doesn't do as much damage I made sure the garage door was shut & the radio on as I didn't want my children to hear the swearing! Edited by - Martin Jeffrey on 7 Oct 2011 19:23:17 Link to comment Share on other sites More sharing options...
Z3MCJez Posted October 7, 2011 Share Posted October 7, 2011 I used two big screwdrivers to hold the top - one from each side. I also ground a bit of a point onto the long top bolt, as described above. Locate each bottom bolt, one screwdriver out, top bolt in and then tighten everything up. Jez Link to comment Share on other sites More sharing options...
diggerman Posted October 7, 2011 Share Posted October 7, 2011 Used masking tape round the perimeter of the washers to hold them together like one fat washer. Hung the diff from top bolt and used trolley jack to push it against the rubber bushes sufficient to make up the couple of mm. Second bolt then went home with light taps from soft faced hammer. Also smeared bolts with copper grease so that they can be removed when you discover how noisy the diff is PeterC Link to comment Share on other sites More sharing options...
Michael Downing Posted October 7, 2011 Author Share Posted October 7, 2011 Right; diff is now hanging off a length of M8 studding in the upper bolt hole, and ONE LOWER BOLT IS IN! Thanks everyone, wish me luck for the second bolt. Link to comment Share on other sites More sharing options...
Michael H Posted October 7, 2011 Share Posted October 7, 2011 Good luck! Does anyone know if CC are supplying the BMW diff as standard on new cars now? Cheers Mike Link to comment Share on other sites More sharing options...
DJ. Posted October 7, 2011 Share Posted October 7, 2011 Yes, it became standard just a couple of months after my car was delivered in December 2010. Duncan Link to comment Share on other sites More sharing options...
Michael Downing Posted October 7, 2011 Author Share Posted October 7, 2011 And another bolt makes two! Now to centre it Link to comment Share on other sites More sharing options...
Alexander Gurr Posted October 7, 2011 Share Posted October 7, 2011 Quoting Michael Downing: And another bolt makes two! Now to centre it Michael I have been doing this today and it is a pig. I had exactly the same challenge as you. I got the two bottom bolts in OK, but the top required a lot of "gentle persuasion" from an Irish screwdriver before it went in. I was reluctant to do so until Caterham gave me the adive "hit it with a hammer" 🙅🏻♂️ Just don't make the same mistake I have, which is to put the handbrake in as per the build manual and not as per the workshop instructions which require the white adjuster nuts to be on the right hand side and not the left as per the build manual. Mile will be coming out again on Sunday so I can go through the whole palarva again just for that simple mistake 🙅🏻♂️ Link to comment Share on other sites More sharing options...
Michael Downing Posted October 7, 2011 Author Share Posted October 7, 2011 Oh Alex, so sorry for you re the handbrake cable. I spotted that, I'm glad to say! Am liking your blog, btw. Well, the diff is now in and centred. 408mm one side, 409 the other. Phew. Now I just need to shim the other bolt and get the top bolt in... but meanwhile there is a dog who is desperate for his evening walk. I suspect those jobs will have to wait for the morning. A thorough coating of coppaslip holds the washers together as one and makes it much easier to put them back when the drop out, and then put them back when they drop out, and then put.... ... thank you to those that suggested this or something like it. Link to comment Share on other sites More sharing options...
Michael H Posted October 7, 2011 Share Posted October 7, 2011 Quoting DJ.: Yes, it became standard just a couple of months after my car was delivered in December 2010. Duncan My car was delivered January 2011, and I had specifically asked CC whether I could have the BMW diff and they told me it was not available... Mike Link to comment Share on other sites More sharing options...
Grubbster Posted October 7, 2011 Share Posted October 7, 2011 Apologies for the hijack - but what roll cage have they supplied this year? On the CC website the photo shows the 'hooped' type, but I don't think this is what gets supplied now is it? Just a curious question Link to comment Share on other sites More sharing options...
Michael Downing Posted October 7, 2011 Author Share Posted October 7, 2011 No, mine is a single diagonal across the top, not the hooped sort. Link to comment Share on other sites More sharing options...
Michael Downing Posted October 7, 2011 Author Share Posted October 7, 2011 Quoting Alexander Gurr: Caterham gave me the advice "hit it with a hammer" 🙅🏻♂️ I think this sums up what I love about Caterham. You just know that if one of the prestige German marques made a kit car, and the diff bolt wouldn't go in, their line would be that you need the special diff bolt insertion tool that fixes to the chassis, supports the diff in the perfect position with computer-controlled servos, and has a robotic arm to encourage the bolt in. A snip at £62k, weighs three tons. Whereas Caterham's answer is "whack it til it gives up and does as it's told". 😬 Link to comment Share on other sites More sharing options...
MBB Posted October 7, 2011 Share Posted October 7, 2011 Back when I was installing my diff if found it would only go if I twisted the top bushing so it aligned with the bolt, I achieved this using the lever arm made of several socket extensions to pull the bush in the right way (it may help at this point to have someone hold these in alignment while you hammer home the bolt, or do what I did & keep the tension on using a cable tie ) Overall it was the single most difficult part of the build. Link to comment Share on other sites More sharing options...
Michael Downing Posted October 8, 2011 Author Share Posted October 8, 2011 It's in... all three bolts, all shimmed, and centred. Thanks to everyone for the tips, I tried pretty well all of them. In the end, to cure the misalignment I had to jack the very rear of the diff up so as to push it slightly forward on its mounts and cure some of the alignment. Then, leaning on the bolt (thanks MBB) and aggressively rotating it got it moving. Phew! Link to comment Share on other sites More sharing options...
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