Click here to sign up  Click here to go to the galleries  Click here to go to the code of conduct  Click here to go to the video page  Click here to go to the SW Meets page
Page 3 of 4 FirstFirst 1 2 3 4 LastLast
Results 21 to 30 of 32

Thread: Clunking Differential - play/ backlash?

  1. #21 Re: Clunking Differential - play/ backlash? 
    club member Club Member
    Join Date
    Jun 2020
    Posts
    14
    Hi all, finally found the time to look back into this diff issue! Currently I have the exhaust off which gave me enough room to get the cover plate off so I now know it’s a 3.38 ratio.
    I’m now ready to get a new diff. But struggling to find one, seems to mainly be 3.62.
    Any suggestions for where to look?
    Reply With Quote  
     

  2. #22 Re: Clunking Differential - play/ backlash? 
    club member Club Member
    Join Date
    Nov 2011
    Posts
    490
    Will it make much difference?

    With your current 3.38 the engine revs at 30 will be 1,456 and 2,912 at 60mph (depending on wheels and tyres). For comparison with a 3.62 diff, 30 will be 1,560 and 3,119rpm at 60. Only about 200rpm higher at 60 mph. Slightly less noisy but the power of the engine should be fine in the light weight car.

    I have been told a 3.9 is best for my Cabrio although I am quite happy with the 3.62.
    Paul
    Reply With Quote  
     

  3. #23 Re: Clunking Differential - play/ backlash? 
    club member Club Member chris_cussen's Avatar
    Join Date
    Nov 2011
    Location
    South Somerset
    Posts
    626
    If you are thinking of a refurbished diff then Rally Design do 3.9 and 3.6 diffs. https://www.rallydesign.co.uk/index.php?cPath=1783 £495+VAT

    I've a 3.6 diff with a bit of backlash lying by my shed. You are welcome to have that and get it refurbished yourself. I did have a quote from a gearbox company of £150 + parts for the job.
    Cabrio, Omex 2.0l 170bhp Zetec blacktop, Omex ECU and wiring loom.
    Reply With Quote  
     

  4. #24 Re: Clunking Differential - play/ backlash? 
    club member Club Member
    Join Date
    Jun 2020
    Posts
    14
    I have thought the same, just wanted to play it safe.

    It’s a 3.5L RV8 with a bw65 box (Can’t remember tyre size right now) so not sure if anyone knows what diff ratio works well with this?

    I just worry that it will be revving high when cruising, but I suppose the added acceleration would be enjoyable ahah!
    Reply With Quote  
     

  5. #25 Re: Clunking Differential - play/ backlash? 
    frequent forum contributor Club Member greyV8pete's Avatar
    Join Date
    Nov 2011
    Location
    Exeter
    Posts
    1,293
    I have a 3.38 diff fitted now in my 3.9i V8 Hunter with 205/55 x16 Toyo tyres. It gives good cruising revs but plenty of acceleration when needed. 1st gear is only needed on uphill starts. There is so much torque low down in a V8 you just don’t need to rev them. If you start changing diff ratios you then have issues matching the speedo to read correctly!
    Reply With Quote  
     

  6. #26 Re: Clunking Differential - play/ backlash? 
    club member Club Member
    Join Date
    Nov 2011
    Posts
    490
    Quote Originally Posted by charlh94 View Post
    ...It’s a 3.5L RV8...
    With that engine I’m not even sure you need a gearbox!

    With a 3.9 diff 60mph will give 3,361rpm in fourth. But I don’t think you need the extra oomph. The 3.9 recommendation was given to me to match the Pinto engine I had at the time. Pinto output was 66 kW (89 hp) and 140 Nm (103 lb⋅ft). At cruising speed I find the engine is mostly drowned out by the wind noise.

    The Sierra diff has a good reputation for being strong so should not be problem in any ratio. Other V8 owners may be able confirm this and recommend ratio choice.
    Paul
    Reply With Quote  
     

  7. #27 Re: Clunking Differential - play/ backlash? 
    club member Club Member
    Join Date
    Jun 2020
    Posts
    14
    Thanks Chris! I’ll have a bit more of a look and bare this in mind. Do you know what gearbox company it was?
    Reply With Quote  
     

  8. #28 Re: Clunking Differential - play/ backlash? 
    club member Club Member
    Join Date
    Jun 2020
    Posts
    14
    Quote Originally Posted by greyV8pete View Post
    If you start changing diff ratios you then have issues matching the speedo to read correctly!
    Good point! Would definitely rather play it safe and keep a 3.38 ratio!
    Reply With Quote  
     

  9. #29 Re: Clunking Differential - play/ backlash? 
    club member Club Member chris_cussen's Avatar
    Join Date
    Nov 2011
    Location
    South Somerset
    Posts
    626
    The place I contacted was TES transmissions http://www.testransmissions.co.uk/ in Westbury.
    I used them to rebuild a gearbox for a Fiesta ST

    If you have an electronic Speedo then you can re-calibrate it for the new diff ratio.
    Cabrio, Omex 2.0l 170bhp Zetec blacktop, Omex ECU and wiring loom.
    Reply With Quote  
     

  10. #30 Re: Clunking Differential - play/ backlash? 
    club member Club Member
    Join Date
    Nov 2011
    Posts
    223
    Hi - Welcome to the club! There have been a few threads on this over the years. Put 'Cabrio diff' into the advanced search box in the top right corner and see what you can find. Also see FAQs at the top of this forum for comments on wheels/tyres.

    My Cabrio runs a tuned Rover 3.5 V8, about 200bhp through a Rover 5-speed and Sierra 3.92 on the 'standard' wheels and tyres. At 70mph in 5th it does an indicated 2800rpm. Not excessive to my mind, but if you want better economy, go for a lower ratio diff. But if you want economy, you shouldn't be running a Rover V8!!

    I've just looked on ebay, and there are a few Sierra diffs, no idea if they are any good, but they are supposed to be pretty tough. Mine whines at about 50mph, not uncommon apparently, easily cured by going faster. I would stick to whatever ratio you have, unless you want to recalibrate the speedo. Or unless you are changing wheels/tyres, but see FAQs. I remember that the build manual suggested filling the D-shaped rubber doughnut with Sikaflex 221 to make it stiffer - may even be possible to repair it this way, at least temporarily, if that is the source of your clunk. Use clingfilm to retain the filler till it goes off.

    If memory serves, the oil level in the diff should be 5mm below the filler hole - check with Haynes manual. For a dipstick, bend a piece of rod at right angles and put grooves in the dipping end at 5mm intervals, by gripping gently with side cutters and turning. Whatever you do, don't drop it in the diff!
    Hope that helps - Dave
    Reply With Quote  
     

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •