chewed up diff crownwheel & pinion

[beergutdave]

Could anyone help me locate a replacement diff unit (not comp axle) or new crownwheel & pinion for my Marina 1800 based roadster. I was returning from a trip to a painter friend of mine, whom I'd asked to quote for repraying Dixie (my roadster), when all hell broke loose from the back end. I assumed it was a prop "uv" joint that had gone so I coaxed her home. I have now found the true problem an it aint pretty, several teeth on the crownwheel and a number on the pinion have segments missing. I have checked ebay and nothing to be had, so I would appriciate any help in my quest to find replacements. Kind regards Dave

[stevejgreen]

Re: chewed up diff crownwheel & pinion

It is possible to rebuild a diff but it is a laborious task for a DIY mechanic. The difficulty as Haynes simplifies is the shimming to ensure that the correct toothe engagement is created.

Previously posts have suggested that a recon TR7 diffs from Rimmer Brothers will be a drop in fit. When I spoke to them earlier this year they agreed but they do not know if it has ever been proved. Certainly the ratio's are the same, though the axle casing is quite different due to suspension mounts, the diff casing appears idential.
There is always a chance they could rebuild yours.

[beergutdave]

Re: chewed up diff crownwheel & pinion

Hi Steve, many thanks for your reponse. I did read the postings and with all the uncertainty re the TR7 unit I thought I'd ask if anyone had a Marina unit. I will contact Rimmer Bros and ask if they could repair my unit. Regards Dave

[dcunn]

Re: chewed up diff crownwheel & pinion

Dave : Look on ebay item 120488207946 its an Ital/Marina 1300 diff, ratio 3.89:1
Any use to you ?

[CosworthCabrioLee]

Re: chewed up diff crownwheel & pinion

Hi Dave,
what power do you put through it ??? Try looking around for a dolomite sprint axle same size, same pcd you only have to put spring platforms on. if your car is a SWB then the rear bulkhead neads cut a little but fine if you have a LWB

[dogoncrazy]

Re: chewed up diff crownwheel & pinion

Dave.
There is no problem putting a 1300 diff into the axle case in place of an 1800 unit. I did it on my sons car and vice versa on my own roadster. He completely trashed the crownwheel and pinion putting 135 bhp[at the flywheel] through it. Any dolomite diff unit should fit barring the Sprint unit where you will need the complete axle.

[dogoncrazy]

Re: chewed up diff crownwheel & pinion

Dave
regarding the e bay item - i was sure that 3.89/1 was an 1800 unit. 4.1/1 was a 1300. Anyone wish to correct me on that?

[CABRIOBOB]

Re: chewed up diff crownwheel & pinion

Dave

Give me a call as I might be able to help with a axle as I know of a couple sitting around. My number is in Pitstop mag.

Cheers.....Bob

[lil_red_roadster]

Re: chewed up diff crownwheel & pinion

Alan, iirc the 3.89 was fitted to Itals with the 1.3 A+ engine. Earlier 1.3 cars were all 4.11. 1.8/1.7 were all 3.63 (except autos which were, I think, 3.27).

[stevejgreen]

Re: chewed up diff crownwheel & pinion

Marina 1800 was 3.62 ratio.
Putting a 1.3 diff assy in the casing will reduce top speed and will mean fitting a new speedo gear from a 1500 Spitfire. Simple calculations will need to be done depending on your tyre size.

If Bob has a complete, good, 1800 differential at a reasonable cost then it's an easyer fix.

As Lee suggests the Dolomite Sprint axle conversion both he and I, and others, have completed is possible but involves a fair bit of work with an angle grinder and some welding etc. I posted a lot of info on the Marina Owners Forum. If you do decide to go that way by all means contact me.

Not sure if Alan is correct that 'any' Dolomite diff will fit as several ratios were available for engines from 1300 up.

[daniels917]

Re: chewed up diff crownwheel & pinion

Did just the same last year with my SWB with 155hp pinto, i went for the Dolly Sprint axel, bit of work to remove the suspension mounts, and fit spring seats, grind a bit off the webbs on the diff case, and it went straight in, bonus the speedo is now accurate. i think this is the way to go if you can find one, and you want to use a higher power unit.

[dogoncrazy]

Re: chewed up diff crownwheel & pinion

Guys
Thanks for putting me right regarding the different ratios. Steve - I was aware of the number of ratios available for the Dolomite range but understood that the fitment of such into a Marina axle would cause no dimensional problems [Sprint excepted] but would obviously require changes to correct speedo error, I stand corrected if this is proved NOT to be the case and apologise in advance for providing false information!!

[b_caswell]

Re: chewed up diff crownwheel & pinion

Dave, You will probably have to put the axle stands under the chassis and allow the axle to hang on its springs to get the diff out. Dont forget to clear all the debris out of the bottom of the axle casing.Be careful some bits are quite sharp!.

[stevejgreen]

Re: chewed up diff crownwheel & pinion

Refering to a previous exchange of posts with Jez Cox and myself on another thread, I would like to declare that my memory is not what it might be and some info is buried so far back it's in another time zone. Alan you might be right, and I might be wrong. If only Triumph and BL had used common part numbers through the range.
I would be concerned over power issues though, from a 1300 axle to an 1800 one.
I know that some of the trials boys used 10cwt Marina Van axles.
AFAIK all vans were 1300, but trials are happy putting 1800 power through them, all be it at much lower speeds.

I think it was suggested before, that axles are going to become scarce, that a list of axles, ratios, power capability that are known to work would be useful as a permanent post, to avoid further memory related errors.

Back to Alan's thought, are all the Dolomite half shafts the same as Marina ones as well?

[beergutdave]

Re: chewed up diff crownwheel & pinion

Cheers each and everyone for your help and ideas. Mant thanks Steve, I will phone Rimmers tomorrow, now that I've got the correct number. I'd forgotten to take the piece of paper I'd jotted it on with me to work so I tried guessing, I ended up talking to a womans cloths shop lol. Re the 1300 unit on ebay, I'll be giving it a miss because I have a feeling it will turn out to be a bad purchase. I've no Idea of the bhp of my engine but I do know it is alot stronger than the original engine (from donor vehicle, inc gearbox & alxe)that I recently removed. A big thank you to Bob re the complete axle, his solution would have saved the day but unfortunately won't come off. I am ruling out the "dolly" route because of the hassle of the alterations, and these units are like rocking horse s--t as much as the Marina unit. Once again thank you to all. regards Dave