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Smart Fortwo Steering Rack - Suitable?
thetankwad - 13/1/21 at 10:31 AM

As the title suggests. Had a search about and I cannot really see any mention of its use on a classic 7 build?

Physically it would look to be the boy for the job and avoid the need for any shortening shennanigans on another rack, but has anyone actually used one in a build? Is there any drawbacks or hidden problems?


nick205 - 13/1/21 at 10:52 AM

Talk to "Replicar328" on here. He's buidling a non 7 style car and has considered that very steering rack (and other Smart parts). You appear to have the same line of thinking.

[Edited on 13/1/21 by nick205]


Replicar328 - 13/1/21 at 06:26 PM

Thanks Nick205, you are right that I did consider using a Smart Car as a donor for the whole car because of the narrow track but was talked out of it by experts on this site. I didn't actually look too carefully at the Smart Car steering rack but I believe I thought it looked a bit lightweight, as did most of the mechanicals, so I went back to using an MX5 MkII as the donor and have had to have drive shafts shortened as well as the propshaft.

Take a look at https://www.locostbuilders.co.uk/viewthread.php?tid=217744 . The Seicento rack I bought for a very reasonable price is ideal - 400mm between the rack ends where they meet the tie rods which will allow me to have wishbones almost identical to the standard locost size, but with a smaller track. Cheaper than shortening and in my view safer. Using the MX5 uprights with the rack in front of the wheel hibs I needed an LHD rack flipped upside down.

Hope this helps

Cheers
Adrian


russbost - 13/1/21 at 07:52 PM

To clarify, when you say "a classic 7 build" do you mean a typical 7?

If so, surely by using anything other than the donor rack that matches the rest of the parts you'll have a rack that doesn't match the column, unless you use the Smart column (no idea if it's suitable or not), & the rack wont have the same thread as the TRE's, or if you use the Smart TRE's they won't match the taper on the steering arms unless you're going to use all Smart bits? Or have I completely misunderstood what you're doing?


thetankwad - 13/1/21 at 08:16 PM

Thats great info thank you!

Whats the adaption like to the hubs? Custom work or are the threads on the inner or outer tie rods a match?

Similarly the input shaft?


Replicar328 - 14/1/21 at 10:58 AM

With my Seicento steering rack I haven't checked yet whether the tie rod ends have the same thread or whether the adjustment is sufficient to allow me to have the front track width I need. For now, I'm focusing on the chassis design to accommodate the rack width.

I need a track width which is 44mm less than the Seicento so I may be lucky. I must check the thread! If it doesn't work and I can't find a ball joint tie rod end with the right thread which fits the upright, I've found that you can buy Steering Track Rod / Tie Rod Extenders on ebay so I'd cut the rack tie rods shorter and re-thread them to get the overall length right.

As an alternative I recommend http://www.cpsdrivelink.co.uk/ who did an amazing job of shortening my drive shafts (with friction welding) so well that you really can't see the join. They would probably be able to chop and friction weld two different tie rods together.

I'd welcome any suggestions of a better way!