The Triumph Dolomite Club - Discussion Forum

I'm about to get the downpipe modified or remanufactured in order to resolve the knocking on the subframe. Long story relates to OS downpipe being dented to shape by mechanic to fit around subframe and then now years later upside down engine mount on one side now replaced has caused slight reposition of engine and constant knocking.

So I need it fixed. Plus it would be good to have the full dia of the downpipe.

The guy who is doing it is a custom exhaust expert but not a Dolly expert - although he did at least do one one years ago

So I know there's a gasket. Best place to buy it from?

Second, it's three bolts but are they captive/fixed on the manifold? I'm thinking not. What size are they? Where could I get replacements? I'm thinking of providing him with replacement gasket and bolts so he has now worries when assembling/disassembling

Thks

I can supply you the manifold/downpipe gasket (or two?) as I bought a job lot a while ago. They are a steel gasket with a corrugation that flattens to seal as you do up the bolts incrementally; you can only use them once.

The standard fixings are three bolts; new bolts are a very good idea as the ones you remove will be compromised on the threads. The manifold has helicoil inserts to receive them. The bolts are 9/16 AF with (from memory) 5/16" UNF threads. Each bolt has a spring washer.

Some folk fit studs into the manifold and then use brass nuts instead, but you have to make sure the studs aren't too long else you can't get at least one of the nuts off. The wisdom of brass nuts is they don't compromise their thread like steel pins do.

^ All of above assumes Sprint flavoured Dolomite!

Thanks. It is a Sprint.

It's also a Sprint in Western Australia. If you fancy the hassle of shipping them then happy to proceed. Need to act quick though. Otherwise suspect something similar at Rimmers?

Any idea where I could get specifically the right bolts? I can't afford the aggravation of someone stripping the helicoils with the wrong bolts. That's assuming it all comes off in the first place of course

thks

Correction: Rimmers website have them as 3/8 inch UNF x 1 1/4 inch (could have sworn they were 5/16!) Part number is SH606101, someone will be along to translate the code in that shortly to confirm.

Surely you must have a local supply of such a standard bolt, or has Australia gone completely metric on us? Searching Ebay in UK for "3/8 UNF" gives various direct suppliers where you can elect the bolt length - you need fully threaded shanks.

Happy to ship a couple of gaskets to WA for you for £6.50 all inclusive. (They are £3.25 each from Rimmers plus P&P)

Happy to adjust that accordingly if you can't get bolts locally, as I can buy a bulk pack here and send you three at cost...

Is there a bracket between the downpipe and transmission? A missing bracket could be the root cause of the knocking. I don't know why the downpipe would foul the subframe unless it was wrongly made in the first place.

Manifold threads are definitely 3/8 unf Dont have any spare thread poking out of the manifold as it'll rust and cause problems later.

Tony

tony g wrote: ↑Thu Jan 11, 2018 12:49 pm Manifold threads are definitely 3/8 unf Dont have any spare thread poking out of the manifold as it'll rust and cause problems later.

Tony

Indeed, but the down pipe flange is 10 mm thick, the manifold flange 16 mm thick. Allowing 1.5 mm for a spring washer and the gasket means about 4 mm thread will protrude from the manifold. Using 1" long bolts will mean only 14 mm of the 16 mm manifold thread is used; should be enough...

Thanks all.

Happy to get from you xvivalve and would actually greatly appreciate a kit of correct parts. I probably "could" get them here for sure but as ever with this whole story there are complications.

I'm working away from home and want to get this job done by this exhaust guy during the week I'm back in Perth late Jan. It's long overdue getting fixed anyway but I want to get it done and then go to a Classic and Coffee monthly event that takes place at Uni of WA last Sunday of the month. So no pressure. Whether I get to the event or not what I definitely don't have the time or capacity for is a problem where the exhaust guy can't complete during the week - either because he doesn't have parts, have right parts or has somehow caused a screw up.

So if you can assemble a kit v quick and express post then all good. Otherwise - and I'd understand if not - then I'll get rimmers to do it based on bolt part number below with 1/4 inch perhaps hacksawed off the end when I get them. Can you let me know asap. I can transfer funds via paypal or direct from UK acct. Paypal prob better

As to why it knocks. Aaah well. First of all there is a bracket. If you have a mind to you can look back at a number of earlier threads I raised related to perceived problems with the sub frame mounts and suspension ride heights; also the engine mount replacement. Basically the car was rebuilt ages ago and few were the issues. Over time a few things came to light and I realised the oversized sports downpipe (which might be the cause of the clearance issue by itself) had been made to avoid the subframe by having a significant recess hammered into its underside. But it worked so....

Fast forward to more recently and I replaced the engine mounts. Pretty sure O/S was upside down. Replaced both and suspect angle of engine rotated slightly clockwise viewed from front of car. Enough - IMO - to then cause the exhaust to just knock/vibrate. Perhaps its caused by having a wider downpipe. Perhaps that downpipe wasn't made right. Either way that's the deal and I'm going to get a custom sports downpipe that has not chance of impact whatsoever - even if it becomes flat and wide around the area in question!!

Happy to facilitate that for you and have ordered a quantity of 3/8" UNF x 1.25".

It will turn letter rate into small package though, so I'll PM you with a total cost when I've worked it out...

If anyone else wants some Sprint downpipe to manifold bolts, I'll have a few spare by the end of the week!

xvivalve wrote: ↑Thu Jan 11, 2018 2:51 pm Happy to facilitate that for you and have ordered a quantity of 3/8" UNF x 1.25".

It will turn letter rate into small package though, so I'll PM you with a total cost when I've worked it out...

If anyone else wants some Sprint downpipe to manifold bolts, I'll have a few spare by the end of the week!

Are you sure there 3/8 UNF, thought they would have been 3/8 UNC,as there going in a alli head

Dave

new to this wrote: ↑Thu Jan 11, 2018 8:06 pm

xvivalve wrote: ↑Thu Jan 11, 2018 2:51 pm Happy to facilitate that for you and have ordered a quantity of 3/8" UNF x 1.25".

It will turn letter rate into small package though, so I'll PM you with a total cost when I've worked it out...

If anyone else wants some Sprint downpipe to manifold bolts, I'll have a few spare by the end of the week!

Are you sure there 3/8 UNF, thought they would have been 3/8 UNC,as there going in a alli head

Dave

No they are going into a cast iron manifold; it's the junction between manifold and downpipe, not manifold and head.

xvivalve wrote: ↑Thu Jan 11, 2018 8:24 pm

new to this wrote: ↑Thu Jan 11, 2018 8:06 pm

xvivalve wrote: ↑Thu Jan 11, 2018 2:51 pm Happy to facilitate that for you and have ordered a quantity of 3/8" UNF x 1.25".

It will turn letter rate into small package though, so I'll PM you with a total cost when I've worked it out...

If anyone else wants some Sprint downpipe to manifold bolts, I'll have a few spare by the end of the week!

Are you sure there 3/8 UNF, thought they would have been 3/8 UNC,as there going in a alli head

Dave

No they are going into a cast iron manifold; it's the junction between manifold and downpipe, not manifold and head.

My mistake mis read the post

For once, I can't fault Royal Mail. I posted the package to Mark at 10:30 Saturday morning and tracking tells me at mid day Sunday it is already on Ascension Island!

Does not sound like Royal Mail,

Alun, your not doing some quantum physics experiment to
send parcels through the planet are you